JP2015094878A - Anti-reflection film, optical element, optical system, and optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anti-reflection film having anti-reflection characteristics which is superior in terms of a wavelength property and incident angle property.SOLUTION: An anti-reflection film comprises first through seventh layers having refractive indexes of N-Nand thicknesses of D-D, respectively, and an eighth layer which is a concavo-convex structure having an average pitch of 400 nm or less, a refractive index that continuously changes from Nto 1.0, and a layer thickness of D, laminated in order from a side of an optical substrate having a refractive index of Nfor an incident wavelength of 550 nm. The anti-reflection film satisfies the following expressions: 1.40≤N≤2.20, 1.90≤N≤2.40, 5.0≤D≤45.0 nm, 1.36≤N≤1.58, 3.0≤D≤80.0 nm, 1.90≤N≤2.40, 15.0≤D≤165.0 nm, 1.36≤N≤1.58, 11.0≤D≤58.0 nm, 1.90≤N≤2.40, 13.0≤D≤38.0 nm, 1.36≤N≤1.58, 9.0≤D≤75.0 nm, 1.35≤N≤1.65, 22.0≤D≤60.0 nm, 1.35≤N≤1.65, and 180.0≤D≤350.0 nm.

Description

  The present invention relates to an antireflection film formed on an optical substrate such as a lens.

  A dielectric multilayer film called multi-coat is often formed on the surface of an optical element such as a camera lens in order to reduce the light loss of incident light. Dielectric multilayer films are made by laminating a plurality of dielectric thin films with different refractive indexes at appropriate thicknesses, thereby adjusting the amplitude and phase of reflected waves generated on the surface and interface of each film and causing them to interfere. To reduce the reflected light. Such a dielectric multilayer film has excellent antireflection performance with respect to a light beam having a specific wavelength and a specific incident angle. However, the interference condition is broken for light beams having a wavelength different from the specific wavelength and the incident angle, and the incident angle is high, so that it is high over a wide wavelength band such as the entire visible wavelength range or a large incident angle range such as 0 to 60 °. It is difficult to achieve antireflection performance.

  On the other hand, digital cameras that have become widespread in recent years use image sensors such as CCD sensors and CMOS sensors that have a higher surface reflectance than photographic films. For this reason, when the light reflected by the sensor surface reaches the lens surface again and is reflected, and reaches the sensor surface again, specific unnecessary light called “digital ghost” is likely to be generated.

  Furthermore, digital camera lenses are required not only to achieve high image quality, but also to have high specifications (high zoom magnification and bright image formation) as well as portability, that is, small size and light weight. For this reason, anomalous dispersion glass, aspherical lenses, lenses with a large curvature, etc. tend to be used frequently. Among these, a lens with a large curvature emits and emits light at a large angle at the periphery, so the conventional multi-coat cannot sufficiently reduce reflection, and the quality of the captured image such as flare and ghost Unnecessary light may be generated that lowers. Therefore, development of a high-performance antireflection film that is superior in wavelength band characteristics and incident angle characteristics to those of multi-coats is required.

  Patent Document 1 discloses an antireflection film in which a magnesium fluoride layer is formed by a sol-gel method on a three-layered dielectric thin film formed by using a vacuum evaporation method. Patent Document 2 discloses an antireflection film in which excellent antireflection characteristics can be obtained by appropriately setting the refractive index and film thickness of each layer. Furthermore, in Patent Document 3, a coating layer formed of a transparent material is provided on the outside of the fine concavo-convex structure, thereby maintaining antireflection performance, high temperature resistance, high humidity environment resistance, and scratch resistance. An antireflection film with excellent properties can be realized.

JP 2005-284040 A JP 2012-189846 A

  However, the antireflection film disclosed in Patent Document 1 has a reflectance of about 0.3 to 0.4% in the range of an incident angle of 0 ° and a wavelength of 500 to 600 nm. Sufficient antireflection performance is not realized. Furthermore, the reflectivity is about 2% in the range of the incident angle of 60 ° and the wavelength of 400 to 620 nm, and the reflectivity exceeding 2.5% in the range of the wavelength of 650 to 700 nm, which means that excellent incident angle characteristics are realized. I can not say.

  Patent Document 2 discloses a characteristic in which the reflectance is about 0.2% or less in the range of the incident angle of 0 ° and the wavelength of 400 to 700 nm in Example 4. However, the reflectance characteristics at angles other than 0 ° are not disclosed, and the incident angle characteristics are unknown. As a result of verification of Example 4 of Patent Document 2 by the present inventor, it has been found that the reflectance characteristic at an incident angle of 45 ° is greatly deteriorated as compared with the reflectance characteristic at an incident angle of 0 °. Further, as a result of investigation by the inventor on the case where the thickness of the layer having a refractive index gradient is 150 nm or less, it has been found that excellent incident angle characteristics cannot be realized.

  The present invention provides an antireflection film having excellent reflectance characteristics (wavelength characteristics and incident angle characteristics). The present invention also provides an optical element, an optical system, and an optical apparatus provided with this antireflection film.

The antireflection film as one aspect of the present invention is formed on an optical substrate. When the incident light wavelength is 550 nm, the antireflection film has a refractive index with respect to the incident wavelength of the optical substrate of N _sub . From the optical substrate side, the refractive index with respect to the incident wavelength is N ₁ and the film thickness is D. _{A first} layer that is a film ₁ , a second layer that is a film having a refractive index N ₂ and a film thickness D ₂ with respect to the incident wavelength, and a film having a refractive index N ₃ and a film thickness D ₃ with respect to the incident wavelength. A third layer, a fourth layer that is a film having a refractive index N ₄ and a film thickness D ₄ with respect to an incident wavelength, and a fifth layer that is a film having a refractive index N ₅ and a film thickness D ₅ with respect to the incident wavelength A sixth layer that is a film having a refractive index N ₆ and a film thickness D ₆ with respect to the incident wavelength, a seventh layer that is a film N ₇ having a refractive index N ₇ and a film thickness D ₇ with respect to the incident wavelength, and an average pitch Is composed of a concavo-convex structure having a thickness of 400 nm or less, and the refractive index with respect to the incident wavelength is continuous from N ₈ toward 1.0. Changes to, and a eighth layer thickness is D _8. The refractive index and film thickness of the first to eighth layers satisfy the following conditions.

1.40 ≦ N _sub ≦ 2.20
1.90 ≦ N ₁ ≦ 2.40, 5.0 nm ≦ D ₁ ≦ 45.0 nm
_{1.36 ≦ N 2 ≦ 1.58, 3.0nm} ≦ D 2 ≦ 80.0nm
1.90 ≦ N ₃ ≦ 2.40, 15.0 nm ≦ D ₃ ≦ 165.0 nm
1.36 ≦ N ₄ ≦ 1.58, 11.0 nm ≦ D ₄ ≦ 58.0 nm
1.90 ≦ N ₅ ≦ 2.40, 13.0 nm ≦ D ₅ ≦ 38.0 nm
1.36 ≦ N ₆ ≦ 1.58, 9.0 nm ≦ D ₆ ≦ 75.0 nm
1.35 ≦ N ₇ ≦ 1.65, 22.0 nm ≦ D ₇ ≦ 60.0 nm
1.35 ≦ N ₈ ≦ 1.65, 180.0 nm ≦ D ₈ ≦ 350.0 nm.

  Note that an optical element including the antireflection film, an optical system including the optical element, and an optical apparatus including the optical system also constitute another aspect of the present invention.

  According to the present invention, an antireflection film having excellent reflectance characteristics in both wavelength characteristics and incident angle characteristics can be realized. And by using the optical element provided with this antireflection film for an optical system or an optical instrument, an optical system and an optical instrument having good optical characteristics can be realized.

The figure which shows the refractive index structure and layer structure of an antireflection film which are typical Examples of this invention. The figure which shows the refractive index structure and reflectance characteristic of the anti-reflective film which are Example 1 and Example 2 of this invention. The figure which shows the refractive index structure and reflectance characteristic of the anti-reflective film which is Example 3 and Example 4 of this invention. The figure which shows the refractive index structure and reflectance characteristic of the antireflection film which is Example 5 of this invention. The figure which shows the refractive index structure and reflectance characteristic of the anti-reflective film which is Example 6 and Example 7 of this invention. The figure which shows the refractive index structure and reflectance characteristic of the anti-reflective film which are Example 8 and Example 9 of this invention. The figure which shows the refractive index structure and reflectance characteristic of the antireflection film which is Example 10 of this invention. The figure which shows the refractive index structure and reflectance characteristic of the anti-reflective film which is Example 11 and Example 12 of this invention. The figure which shows the refractive index structure and reflectance characteristic of the anti-reflective film which is Example 13 and Example 14 of this invention. The figure which shows the refractive index structure and reflectance characteristic of the antireflection film which is Example 15 of this invention. The figure which shows the refractive index structure and reflectance characteristic of the anti-reflective film which is Example 16 and Example 17 of this invention. The figure which shows the refractive index structure and reflectance characteristic of the anti-reflective film which is Example 18 and Example 19 of this invention. The figure which shows the refractive index structure and reflectance characteristic of the antireflection film which is Example 20 of this invention. The figure which shows the refractive index structure and reflectance characteristic of the anti-reflective film which is Example 21 and Example 22 of this invention. The figure which shows the refractive index structure and reflectance characteristic of the anti-reflective film which is Example 23 and Example 24 of this invention. The figure which shows the refractive index structure and reflectance characteristic of the antireflection film of the comparative example 1 and the comparative example 2. The figure which shows the refractive index structure and reflectance characteristic of the antireflection film of the comparative example 3 and the comparative example 4. The figure which shows the structure of the optical system which is Example 25 of this invention, and the optical apparatus which is Example 26 of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. First, prior to description of specific embodiments, an antireflection film that is a typical embodiment of the present invention will be described. In the following description, the refractive index is a value for light having a wavelength of 550 nm (incident wavelength) except for Example 23. In Example 23, optical design values (Numerical Example 1) for the d-line (wavelength 587.56 nm) are shown.

  FIGS. 1A and 1B show the refractive index structure and the layer structure when the antireflection film of the embodiment as a multilayer film is formed on an optical substrate such as a lens (on the optical element body), respectively. Yes.

The optical substrate 101 has a value in the range of 1.40 ≦ N _sub ≦ 2.20 as the refractive index N _sub . The antireflection film 102 includes, in order from the optical substrate side, the first layer 103, the second layer 104, the third layer 105, the fourth layer 106, the fifth layer 107, the sixth layer 108, the seventh layer 109, and the eighth layer. 110 is laminated. The first layer 103 to the seventh layer 109 are formed of a dielectric thin film, and the eighth layer 110 is formed of a fine concavo-convex structure having an average pitch of 400 nm or less. The refractive index and film thickness (layer thickness) from the first layer 103 to the eighth layer 110 satisfy the following condition (1).

The first layer 103 has a value in the range of 1.90 ≦ N ₁ ≦ 2.40 as the refractive index N ₁ , and a value in the range of 5.0 nm ≦ D ₁ ≦ 45.0 nm as the film thickness D _1. Have

The second layer 104 has a value in the range of 1.36 ≦ N ₂ ≦ 1.58 as the refractive index N _{2 and} a value in the range of 3.0 nm ≦ D ₂ ≦ 80.0 nm as the film thickness D _2. Have

The third layer 105 has a value in the range of 1.90 ≦ N ₃ ≦ 2.40 as the refractive index N ₃ , and a value in the range of 15.0 nm ≦ D ₃ ≦ 165.0 nm as the film thickness D _3. Have

The fourth layer 106 has a value in the range of 1.36 ≦ N ₄ ≦ 1.58 as the refractive index N ₄ , and a value in the range of 11.0 nm ≦ D ₄ ≦ 58.0 nm as the film thickness D _4. Have

The fifth layer 107 has a value in the range of 1.90 ≦ N ₅ ≦ 2.40 as the refractive index N ₅ , and a value in the range of 13.0 nm ≦ D ₅ ≦ 38.0 nm as the film thickness D _5. Have

The sixth layer 108 has a value in the range of 1.36 ≦ N ₆ ≦ 1.58 as the refractive index N ₆ , and a value in the range of 9.0 nm ≦ D ₆ ≦ 75.0 nm as the film thickness D _6. Have

The seventh layer 109 has a value within the range of 1.35 ≦ N ₇ ≦ 1.65 as the refractive index N ₇ , and a value within the range of 22.0 nm ≦ D ₇ ≦ 60.0 nm as the film thickness D _7. Have

The eighth layer 110 has a value in the range of 180.0 nm ≦ D ₈ ≦ 350.0 nm as the layer thickness D ₈ , and a refractive index N _{8 in} the range of 1.35 ≦ N ₈ ≦ 1.65. From this value, it has a value that continuously changes toward a refractive index of 1.0, which is the medium with which the eighth layer 110 is in contact. However, the fact that the refractive index of the eighth layer 110 “continuously changes” does not mean that the refractive index itself of the medium (material) forming the eighth layer 110 changes continuously. It means that the “effective refractive index” of the concavo-convex structure changes continuously when the space filling factor of the fine concavo-convex structure changes continuously in the thickness direction (layer thickness direction). This is because light incident on the fine concavo-convex structure is a medium having an “effective refractive index” corresponding to the space occupancy of the structure, with the fine concavo-convex structure having a size (average pitch) equal to or smaller than the wavelength of the light. It depends on the nature of recognition.

  FIG. 1B shows that the fine concavo-convex structure has a random structure rather than a complete periodic structure (regular arrangement structure). Even in such a case, if the average pitch of each convex portion is smaller than the wavelength of incident light, unnecessary light such as diffraction and scattering and harmful light hardly occur. However, it does not occur at all, and minute scattered light is generated according to randomness. In the case of the same randomness, the amount of scattered light increases in proportion to the height of the convex portion. Therefore, depending on the application of the optical system using the antireflection film of the embodiment, it may be necessary to suppress the height of the convex portion.

  The fine concavo-convex structure is not limited to the structure having randomness as described above, and may have a complete periodic structure.

The effective refractive index N _eff of the fine concavo-convex structure is N _m , which is the refractive index of a material that forms convex portions with an average pitch equal to or less than the wavelength of incident light (however, 400 nm or less in this embodiment). When the space occupancy is ff, it is the Lorentz-Lorenz equation,
(N _eff ² −1) / (N _eff ² +2) = ff (N _m ² −1) / (N _m ² +2)
Can be obtained using That is, by forming a structure in which the space occupancy continuously changes at an average pitch equal to or less than the wavelength of incident light (or smaller than the wavelength), the effective refractive index, which is a substantial refractive index, is continuously increased. A changing layer (film) can be formed.

Further, in FIG. 1 (a), as the effective refractive index of the eighth layer 110, different changes in three regions toward the refractive index _{N 8} 1.0 (air) at the interface portion between the seventh layer 109 The refractive index changing with the rate is shown by a solid line. However, the method of changing the effective refractive index is not limited to this, and any method may be used as long as it changes continuously. For example, as shown by two broken lines in FIG. 1A, it may change in a curve or change in a straight line. However, it is not preferable to make a change that is convex upward with respect to a linear change, and it is preferable to make a change that is convex downward than a linear change.

The antireflection film of the embodiment having such a refractive index structure can realize high antireflection performance that satisfies both the wavelength characteristic and the incident angle characteristic satisfying the reflectance standard 1 shown below.
≪Reflectance standard 1≫
For rays in the incident angle range of 0-30 °,
(1) The reflectance is 0.15% or less in the wavelength range of 430 nm to 670 nm. (2) The reflectance is 0.25% or less at the wavelengths of 400 nm and 700 nm.
(3) The reflectance is 0.4% or less in the wavelength range of 430 nm to 670 nm. (4) The reflectance is 0.5% or less at the wavelengths of 400 nm and 700 nm.
(5) The reflectance is 2.5% or less in the wavelength range of 430 nm to 670 nm. (6) The reflectance is 3.0% or less at the wavelengths of 400 nm and 700 nm.

  Here, the reflectance standard 1 as a high performance standard of the antireflection film in the embodiment will be described. In the antireflection film of the embodiment, the reflectance characteristics at wavelengths of 430 to 670 nm are particularly emphasized, and the demand for the reflectance characteristics at wavelengths of 400 to 430 nm and wavelengths of 670 to 700 nm is relaxed. This is in consideration of the spectral sensitivity characteristics of a CCD sensor or a CMOS sensor used as an image sensor in an imaging apparatus (hereinafter referred to as a camera) such as a digital still camera or a video camera. That is, an image sensor for a camera faithfully reproduces an optical image seen by a human as a captured image, and thus has high sensitivity in the wavelength range of 430 to 670 nm, but low sensitivity in the wavelength range of 400 to 430 nm and wavelength of 670 to 700 nm. Is set to be For this reason, even if the reflectance at wavelengths of 400 to 430 nm and wavelengths of 670 to 700 nm is somewhat high, unnecessary light such as flare and ghost and harmful light hardly affect the captured image.

In the antireflection film of the example, more preferably, the thickness of each layer is set so as to satisfy the following condition (2). The refractive indexes N1 to N8 (Neff) of each layer are desirably values within the range indicated by the above condition (1).
5.5 nm ≦ D ₁ ≦ 43.0 nm
3.5 nm ≦ D ₂ ≦ 75.0 nm
17.0 nm ≦ D ₃ ≦ 160.0 nm
14.8 nm ≦ D ₄ ≦ 58.0 nm
14.0 nm ≦ D ₅ ≦ 35.0 nm
10.0 nm ≦ D ₆ ≦ 70.0 nm
28.0 nm ≦ D ₇ ≦ 55.0 nm
200.0 nm ≦ D ₈ ≦ 350.0 nm. . . (2)
By satisfying the condition (2), the reflectance standard 2 that is further superior to the reflectance standard 1 can be satisfied.
≪Reflectance standard 2≫
For rays in the incident angle range of 0-30 °,
(1) Reflectance is 0.1% or less in the wavelength range of 430 nm to 670 nm (2) Reflectance is 0.2% or less at wavelengths of 400 nm and 700 nm, for light rays with an incident angle of 45,
(3) The reflectance is 0.3% or less in the wavelength range of 430 nm to 670 nm. (4) The reflectance is 0.4% or less at wavelengths of 400 nm and 700 nm.
(5) The reflectance is 2.0% or less in the wavelength range of 430 nm to 670 nm. (6) The reflectance is 2.5% or less at the wavelengths of 400 nm and 700 nm.

  More preferably, the film thickness of each layer is set so as to satisfy the following condition (3). The refractive indexes N1 to N8 (Neff) of each layer are desirably values within the range indicated by the above condition (1).

6.0 nm ≦ D ₁ ≦ 40.0 nm
6.0 nm ≦ D ₂ ≦ 72.0 nm
19.0 nm ≦ D ₃ ≦ 72.0 nm
18.0 nm ≦ D ₄ ≦ 52.0 nm
15.0 nm ≦ D ₅ ≦ 33.0 nm
25.0 nm ≦ D ₆ ≦ 65.0 nm
30.0 nm ≦ D ₇ ≦ 45.0 nm
220.0 nm ≦ D ₈ ≦ 300.0 nm. . . (3)
By satisfying the condition (3), the reflectance standard 2 that is further superior to the reflectance standard 1 can be satisfied.
≪Reflectance standard 3≫
For rays in the incident angle range of 0-30 °,
(1) The reflectance is 0.05% or less in the wavelength range of 430 nm to 670 nm. (2) The reflectance is 0.15% or less at wavelengths of 400 nm and 700 nm.
(3) The reflectance is 0.2% or less in the wavelength range of 430 nm to 670 nm. (4) The reflectance is 0.3% or less at wavelengths of 400 nm and 700 nm.
(5) The reflectance is 1.5% or less in the wavelength range of 430 nm to 670 nm. (6) The reflectance is 2.0% or less at the wavelengths of 400 nm and 700 nm.

In the embodiment, the film material of the first layer 103, the third layer 105, and the fifth layer 107 is tantalum pentoxide (Ta ₂ O ₅ ). However, a dielectric thin film having a refractive index in the range of 1.90 to 2.40 can be substituted for this. For example, a simple substance of titania (TiO ₂ ), zirconia (ZrO ₂ ), silicon nitride (SiN), silicon oxynitride (SiON), or a mixed material thereof can be used. Among these, silicon nitride and silicon oxynitride can suppress the permeation and elution of external humidity and alkali components from the inside of the glass material, and may be preferable from the viewpoint of environmental reliability. In addition, the refractive index of silicon oxynitride can be adjusted in the range of about 1.4 to 2.2 by changing the ratio of oxygen and nitrogen. When used for the first layer 103, the third layer 105, and the fifth layer 107, the ratio of nitrogen may be increased so that the refractive index is 1.9 or more.

Further, the film material of the second layer 104, the fourth layer 106, and the sixth layer 108 in the embodiment is silica (SiO ₂ ). However, a dielectric thin film having a refractive index in the range of 1.36 to 1.58 can be used instead. For example, magnesium fluoride (MgF ₂ ), silicon oxynitride (SiON), or a mixed material thereof can be used. In the case where silicon oxynitride is used for the second layer 104, the fourth layer 106, and the sixth layer 108, the ratio of oxygen may be increased so that the refractive index is 1.58 or less.

  In the antireflection film of the embodiment, any method may be used for forming each layer, and any method such as a vacuum deposition method, a sputtering method, a plasma CVD method, or the like can be used. In the formation of a dielectric thin film, the refractive index and refractive index dispersion slightly vary depending on the film formation conditions (substrate temperature, ultimate vacuum, etc.) even if the material is the same. If the film thickness is corrected so that the value of (rate × physical film thickness) matches, almost the same high performance can be obtained.

  In the embodiment, the first layer 103, the third layer 105, and the fifth layer 107 have a refractive index in the same range, and the second layer 104, the fourth layer 106, and the sixth layer 108 have a refractive index in the same range. . However, the first layer 103, the third layer 105, the fifth layer 107, the second layer 104, the fourth layer 106, and the sixth layer 108 need not be formed of the same material or have the same refractive index. Of course, using the same material is preferable from the viewpoint of reducing the manufacturing cost because fewer types of vapor deposition sources, target materials, source gases, and the like are used in film formation.

As a manufacturing method of the seventh layer 109 and the eighth layer 110, there are the following methods. For example, when alumina (Al ₂ O ₃ ) is used as a material for these layers, a film formed by applying a solution containing alumina on the sixth layer 108 and drying is immersed in warm water. There is a method of depositing plate crystals on the surface. The plate-like crystal portion precipitated from the layer containing alumina becomes the eighth layer 110, and the porous layer (porous film) remaining in the base portion without being precipitated becomes the seventh layer 109. By using this method, the seventh layer 109 and the eighth layer 110 can be formed simultaneously and simply.

  The seventh layer 109 and the eighth layer 110 can be controlled by appropriately setting the concentration of the alumina component of the solution, the type of the stabilizer, the catalyst, etc., and the coating conditions. Further, the refractive index and the film thickness can be controlled by the drying temperature after coating, the temperature and time of the hot water to be immersed, and the like. As for the coating method of this film, various wet coating methods such as a dip coating method, a spin coating method and a spray coating method can be used. However, when applying to a lens surface or the like having a large curvature, the spin coating method is most suitable from the viewpoint of making the in-plane film thickness uniform. In this case, the film thickness can be adjusted by adjusting the spin rotation speed and rotation time during coating.

  When a vacuum deposition method or a sputtering method is used for a lens having a large opening angle (curvature), the film thickness generally changes according to the opening angle. That is, the film thickness is reduced at the periphery of the lens having a large opening angle. However, in the spin coating method, when the film is formed on the concave surface of the lens having a large opening angle, the film thickness is increased at the periphery of the lens. In the film configuration as in the embodiment, the antireflection performance is significantly deteriorated when the film thickness is changed so as to be thin in all layers. However, even if the film thicknesses of the first layer 103 to the sixth layer 108 change so as to become thinner toward the lens peripheral part, the film thicknesses (layer thicknesses) of the seventh layer 109 and the eighth layer 110 become the lens peripheral part. By changing so as to become thicker, performance deterioration can be suppressed. Also from this viewpoint, the spin coating method is preferable as the method for forming the seventh layer and the eighth layer.

  High-quality optics that suppresses the generation of unwanted and harmful light such as flares and ghosts by using the optical elements with antireflection films described above in the optical systems of optical equipment such as camera optical systems Systems and optical instruments can be realized.

  Hereinafter, specific examples (numerical examples) will be described. Table 1 summarizes the refractive index and film thickness of each layer in each example.

FIG. 2A shows a refractive index structure of an antireflection film that is Embodiment 1 of the present invention. In this embodiment, S-LAH79 manufactured by OHARA INC. Is used as the optical substrate 101, and its refractive index N _sub is 2.011.

Refractive index _{N 1} of the first layer 103 is 2.127, the thickness _{D 1} is 30.9Nm. The second layer 104 has a refractive index N ₂ of 1.487 and a film thickness D ₂ of 8.39 nm. Refractive index _{N 3} of the third layer 105 is 2.127, the thickness _{D 3} is 57.3Nm. The fourth layer 106 has a refractive index N ₄ of 1.487 and a film thickness D ₄ of 21.8 nm. The refractive index _{N 5} of the fifth layer 107 is 2.127, the thickness _{D 5} is 27.2 nm. The sixth layer 108 has a refractive index N ₆ of 1.487 and a film thickness D ₆ of 36.1 nm. Refractive index _{N 7} of the seventh layer 109 is 1.505, the thickness _{D 7} is 34.0Nm.

Thickness _{D 8} of the eighth layer 110 is 237.0Nm, the refractive index _{N 8} varies profile shown in FIG. 2 (a) toward the 1.0 to 1.505. Specifically, the eighth layer 110 has a region in which the refractive index changes from 1.505 to 1.229 from the interface with the seventh layer 109 over a thickness of 39.4 nm, and a refractive index of 1 over a thickness of 48.5 nm. .229 to 1.147. Further, the eighth layer 110 has a region where the refractive index changes from 1.147 to 1.0 over a thickness of 149.2 nm.

  FIGS. 2B and 2C show the reflectance characteristics of the antireflection film of this example. FIG.2 (c) is the figure which expanded the full scale of the vertical axis | shaft (reflectance) of FIG.2 (b) from 3.0% to 0.5%. This relationship is the same in the figures (for example, FIGS. 2 (e) and 2 (f) and FIGS. 3 (b) and 3 (c)) showing the reflectance characteristics of other examples and comparative examples described later.

  2 (b) and 2 (c), it can be seen that the antireflection film of this example achieves high antireflection performance over the entire visible wavelength range (wavelength 400 to 700 nm). The antireflection film of this example satisfies the reflectance standard 3 shown above, and has both excellent wavelength characteristics and incident angle characteristics. In particular, an extremely high antireflection performance of 0.007% or less for a light beam having a wavelength of 430 to 670 nm and an incident angle of 0 to 30 ° is realized.

FIG. 2D shows a refractive index structure of an antireflection film that is Embodiment 2 of the present invention. Also in the present embodiment, as in the first embodiment, S-LAH79 manufactured by OHARA INC. Is used as the optical substrate 101, and the refractive index N _sub is 2.011.

Refractive index _{N 1} of the first layer 103 is 2.127, the thickness _{D 1} is 37.1Nm. The second layer 104 has a refractive index N ₂ of 1.487 and a film thickness D ₂ of 6.28 nm. Refractive index _{N 3} of the third layer 105 is 2.127, the thickness _{D 3} is 65.7Nm. The refractive index N ₄ of the fourth layer 106 is 1.487, and the film thickness D ₄ is 20.9 nm. The refractive index _{N 5} of the fifth layer 107 is 2.127, the thickness _{D 5} is 27.2 nm. The sixth layer 108 has a refractive index N ₆ of 1.487 and a film thickness D ₆ of 28.0 nm. The refractive index N ₇ of the seventh layer 109 is 1.505, and the film thickness D ₇ is 40.4 nm.

The thickness D ₈ of the eighth layer 110 is 282.0 nm, and the refractive index N ₈ changes from 1.505 to 1.0 in the profile shown in FIG. Specifically, the eighth layer 110 has a region where the refractive index changes from 1.505 to 1.229 from the interface with the seventh layer 109 over a thickness of 46.8 nm, and a refractive index of 1 over a thickness of 57.7 nm. .229 to 1.147. Further, the eighth layer 110 has a region where the refractive index changes from 1.147 to 1.0 over a thickness of 177.5 nm.

  FIGS. 2E and 2F show the reflectance characteristics of the antireflection film of this example. From these figures, it can be seen that the antireflection film of this example achieves high antireflection performance over the entire visible wavelength range (wavelength 400 to 700 nm). The antireflection film of this example satisfies the reflectance standard 3 shown above, and has both excellent wavelength characteristics and incident angle characteristics. In particular, an extremely high antireflection performance of 0.05% or less with respect to a light beam having a wavelength of 430 to 670 nm and an incident angle of 0 to 45 ° is realized.

  Also in this embodiment, the manufacturing method is not limited as long as the above refractive index structure can be realized. For example, as in the description in the first embodiment, each material and parameter may be selected or adjusted. The same applies to the following embodiments.

FIG. 3A shows a refractive index structure of an antireflection film that is Embodiment 3 of the present invention. Also in the present embodiment, as in the first embodiment, S-LAH79 manufactured by OHARA INC. Is used as the optical substrate 101, and the refractive index N _sub is 2.011.

Refractive index _{N 1} of the first layer 103 is 2.127, the thickness _{D 1} is 20.7Nm. The second layer 104 has a refractive index N ₂ of 1.487 and a film thickness D ₂ of 5.72 nm. Refractive index _{N 3} of the third layer 105 is 2.127, the thickness _{D 3} is 138.8Nm. The refractive index N ₄ of the fourth layer 106 is 1.487, and the film thickness D ₄ is 18.5 nm. The refractive index _{N 5} of the fifth layer 107 is 2.127, the thickness _{D 5} is 23.2 nm. The sixth layer 108 has a refractive index N ₆ of 1.487 and a film thickness D ₆ of 11.4 nm. The refractive index N ₇ of the seventh layer 109 is 1.505, and the film thickness D ₇ is 50.0 nm.

Thickness _{D 8} of the eighth layer 110 is 348.4Nm, the refractive index _{N 8} toward the 1.0 to 1.505, is changing the profile shown in FIG. 3 (a). Specifically, the eighth layer 110 has a region where the refractive index changes from 1.505 to 1.229 over a thickness of 57.9 nm from the interface with the seventh layer 109, and a refractive index of 1 over a thickness of 71.3 nm. .229 to 1.147. Further, the eighth layer 110 has a region where the refractive index changes from 1.147 to 1.0 over a thickness of 219.3 nm.

  FIGS. 3B and 3C show the reflectance characteristics of the antireflection film of this example. From these figures, it can be seen that the antireflection film of this example achieves high antireflection performance over the entire visible wavelength range (wavelength 400 to 700 nm). The antireflection film of this example satisfies the reflectance standard 2 shown above, and has both excellent wavelength characteristics and incident angle characteristics. In particular, an extremely high antireflection performance of 0.1% or less with respect to a light beam with an incident angle of 0 to 45 ° and 0.35% or less with respect to a light beam with an incident angle of 60 ° is realized at a wavelength of 430 to 670 nm.

  From this example, it can be seen that when the thickness of the eighth layer 110 having the fine concavo-convex structure is increased, the reflectance characteristics at a large incident angle are improved.

FIG. 3D shows a refractive index structure of an antireflection film that is Embodiment 4 of the present invention. Also in the present embodiment, as in the first embodiment, S-LAH79 manufactured by OHARA INC. Is used as the optical substrate 101, and the refractive index N _sub is 2.011.

Refractive index _{N 1} of the first layer 103 is 2.127, the thickness _{D 1} is 24.3Nm. The second layer 104 has a refractive index N ₂ of 1.487 and a film thickness D ₂ of 3.78 nm. Refractive index _{N 3} of the third layer 105 is 2.127, the thickness _{D 3} is 102.3Nm. Refractive index _{N 4} of the fourth layer 106 is 1.487, the thickness _{D 4} is 15.5 nm. The refractive index _{N 5} of the fifth layer 107 is 2.127, the thickness _{D 5} is 24.8 nm. The refractive index N ₆ of the sixth layer 108 is 1.487, and the film thickness D ₆ is 32.9 nm. The refractive index N ₇ of the seventh layer 109 is 1.505, and the film thickness D ₇ is 29.7 nm.

Thickness _{D 8} of the eighth layer 110 is 207.3Nm, the refractive index _{N 8} toward the 1.0 to 1.505, is changing the profile shown in Figure 3 (d). Specifically, the eighth layer 110 has a region where the refractive index changes from 1.505 to 1.229 from the interface with the seventh layer 109 over a thickness of 34.4 nm, and a refractive index of 1 over the thickness of 42.4 nm. .229 to 1.147. Further, the eighth layer 110 has a region where the refractive index changes from 1.147 to 1.0 over a thickness of 130.5 nm.

  FIGS. 3E and 3F show the reflectance characteristics of the antireflection film of this example. From these figures, it can be seen that the antireflection film of this example achieves high antireflection performance over the entire visible wavelength range (wavelength 400 to 700 nm). The antireflection film of this example satisfies the reflectance standard 2 shown above, and has both excellent wavelength characteristics and incident angle characteristics. In particular, an extremely high antireflection performance of 0.015% or less with respect to a light beam having a wavelength of 430 to 670 nm and an incident angle of 0 to 30 ° is realized.

FIG. 4A shows a refractive index structure of an antireflection film that is Embodiment 5 of the present invention. Also in the present embodiment, as in the first embodiment, S-LAH79 manufactured by OHARA INC. Is used as the optical substrate 101, and the refractive index N _sub is 2.011.

Refractive index _{N 1} of the first layer 103 is 2.127, the thickness _{D 1} is 22.1 nm. The refractive index N ₂ of the second layer 104 is 1.487, and the film thickness D ₂ is 4.27 nm. Refractive index _{N 3} of the third layer 105 is 2.127, the thickness _{D 3} is 107.5Nm. The refractive index N ₄ of the fourth layer 106 is 1.487, and the film thickness D ₄ is 14.7 nm. The refractive index _{N 5} of the fifth layer 107 is 2.127, the thickness _{D 5} is 23.9Nm. Refractive index _{N 6} of the sixth layer 108 is 1.487, the thickness _{D 6} is 33.9Nm. The refractive index N ₇ of the seventh layer 109 is 1.505, and the film thickness D ₇ is 27.5 nm.

Thickness _{D 8} of the eighth layer 110 is 192.0Nm, the refractive index _{N 8} toward the 1.0 to 1.505, is changing the profile shown in Figure 4 (a). Specifically, the eighth layer 110 has a region where the refractive index changes from 1.505 to 1.229 over a thickness of 31.9 nm from the interface with the seventh layer 109, and a refractive index of 1 over a thickness of 39.3 nm. .229 to 1.147. Furthermore, the eighth layer 110 has a region where the refractive index changes from 1.147 to 1.0 over a thickness of 120.8 nm.

  FIGS. 4B and 4C show the reflectance characteristics of the antireflection film of this example. From these figures, it can be seen that the antireflection film of this example achieves high antireflection performance over the entire visible wavelength range (wavelength 400 to 700 nm). The antireflection film of this example satisfies the reflectance standard 1 shown above, and has both excellent wavelength characteristics and incident angle characteristics.

FIG. 5A shows a refractive index structure of an antireflection film that is Embodiment 6 of the present invention. In this embodiment, S-LAH65V manufactured by OHARA INC. Is used as the optical substrate 101, and its refractive index N _sub is 1.808.

Refractive index _{N 1} of the first layer 103 is 2.127, the thickness _{D 1} is 20.0 nm. The second layer 104 has a refractive index N ₂ of 1.487 and a film thickness D ₂ of 23.4 nm. Refractive index _{N 3} of the third layer 105 is 2.127, the thickness _{D 3} is 43.1Nm. The fourth layer 106 has a refractive index N ₄ of 1.487 and a film thickness D ₄ of 29.6 nm. The refractive index N ₅ of the fifth layer 107 is 2.127, and the film thickness D ₅ is 27.0 nm. The sixth layer 108 has a refractive index N ₆ of 1.487 and a film thickness D ₆ of 39.7 nm. Refractive index _{N 7} of the seventh layer 109 is 1.505, the thickness _{D 7} is 34.0Nm.

Thickness _{D 8} of the eighth layer 110 is 237.0Nm, refractive index _{N 8} has changed the profile shown in FIGS. 5 (a) toward the 1.0 to 1.505. Specifically, the eighth layer 110 has a region in which the refractive index changes from 1.505 to 1.229 from the interface with the seventh layer 109 over a thickness of 39.4 nm, and a refractive index of 1 over a thickness of 48.5 nm. .229 to 1.147. Further, the eighth layer 10 has a region where the refractive index changes from 1.147 to 1.0 over a thickness of 149.2 nm.

  5 (b) and 5 (c) show the reflectance characteristics of the antireflection film of this example. From these figures, it can be seen that the antireflection film of this example achieves high antireflection performance over the entire visible wavelength range (wavelength 400 to 700 nm). The antireflection film of this example satisfies the reflectance standard 3 shown above, and has both excellent wavelength characteristics and incident angle characteristics. In particular, an extremely high antireflection performance of 0.01% or less with respect to a light beam having a wavelength of 430 to 670 nm and an incident angle of 0 to 30 ° is realized.

FIG. 5D shows a refractive index structure of an antireflection film that is Embodiment 7 of the present invention. In this example, S-LAH65V manufactured by OHARA INC. Is used as the optical substrate 101 as in Example 6, and the refractive index N _sub is 1.808.

Refractive index _{N 1} of the first layer 103 is 2.127, the thickness _{D 1} is 22.3 nm. Refractive index _{N 2} of the second layer 104 is 1.487, the thickness _{D 2} is 23.0 nm. Refractive index _{N 3} of the third layer 105 is 2.127, the thickness _{D 3} is 46.4 nm. The fourth layer 106 has a refractive index N ₄ of 1.487 and a film thickness D ₄ of 29.1 nm. The refractive index _{N 5} of the fifth layer 107 is 2.127, the thickness _{D 5} is 27.6Nm. The sixth layer 108 has a refractive index N ₆ of 1.487 and a film thickness D ₆ of 33.3 nm. The refractive index N ₇ of the seventh layer 109 is 1.505, and the film thickness D ₇ is 39.4 nm.

Thickness _{D 8} of the eighth layer 110 is 275.0Nm, refractive index _{N 8} has changed in profile shown in FIG. 5 (d) toward the 1.0 to 1.505. Specifically, the eighth layer 110 has a region where the refractive index changes from 1.505 to 1.229 from the interface with the seventh layer 109 over a thickness of 45.7 nm, and a refractive index of 1 over a thickness of 56.2 nm. .229 to 1.147. Furthermore, the eighth layer 110 has a region where the refractive index changes from 1.147 to 1.0 over a thickness of 173.0 nm.

  FIGS. 5E and 5F show the reflectance characteristics of the antireflection film of this example. From these figures, it can be seen that the antireflection film of this example achieves high antireflection performance over the entire visible wavelength range (wavelength 400 to 700 nm). The antireflection film of this example satisfies the reflectance standard 3 shown above, and has both excellent wavelength characteristics and incident angle characteristics. In particular, an extremely high antireflection performance of 0.05% or less with respect to a light beam having a wavelength of 430 to 670 nm and an incident angle of 0 to 45 ° is realized.

FIG. 6A shows a refractive index structure of an antireflection film that is Embodiment 8 of the present invention. In this example, S-LAH65V manufactured by OHARA INC. Is used as the optical substrate 101 as in Example 6, and the refractive index N _sub is 1.808.

The refractive index N ₁ of the first layer 103 is 2.127, and the film thickness D ₁ is 24.0 nm. The refractive index N ₂ of the second layer 104 is 1.487, and the film thickness D ₂ is 21.3 nm. Refractive index _{N 3} of the third layer 105 is 2.127, the thickness _{D 3} is 48.8 nm. The fourth layer 106 has a refractive index N ₄ of 1.487 and a film thickness D ₄ of 27.6 nm. The refractive index _{N 5} of the fifth layer 107 is 2.127, the thickness _{D 5} is 26.7Nm. The sixth layer 108 has a refractive index N ₆ of 1.487 and a film thickness D ₆ of 18.6 nm. The refractive index N ₇ of the seventh layer 109 is 1.505, and the film thickness D ₇ is 49.9 nm.

Thickness _{D 8} of the eighth layer 110 is 348.5Nm, refractive index _{N 8} has changed the profile shown in FIGS. 6 (a) toward the 1.0 to 1.505. Specifically, the eighth layer 110 has a region where the refractive index changes from 1.505 to 1.229 over a thickness of 57.9 nm from the interface with the seventh layer 109, and a refractive index of 1 over a thickness of 71.3 nm. .229 to 1.147. Further, the eighth layer 110 has a region where the refractive index changes from 1.147 to 1.0 over a thickness of 219.3 nm.

  FIGS. 6B and 6C show the reflectance characteristics of the antireflection film of this example. From these figures, it can be seen that the antireflection film of this example achieves high antireflection performance over the entire visible wavelength range (wavelength 400 to 700 nm). The antireflection film of this example satisfies the reflectance standard 2 shown above, and has both excellent wavelength characteristics and incident angle characteristics. In particular, an extremely high antireflection performance of 0.07% or less for a light beam having an incident angle of 0 to 45 ° and a light beam having an incident angle of 60 ° of 0.30% or less at a wavelength of 430 to 670 nm is realized.

FIG. 6D shows a refractive index structure of an antireflection film that is Embodiment 9 of the present invention. In this example, S-LAH65V manufactured by OHARA INC. Is used as the optical substrate 101 as in Example 6, and the refractive index N _sub is 1.808.

Refractive index _{N 1} of the first layer 103 is 2.127, the thickness _{D 1} is 23.1 nm. The refractive index N ₂ of the second layer 104 is 1.487, and the film thickness D ₂ is 20.2 nm. Refractive index _{N 3} of the third layer 105 is 2.127, the thickness _{D 3} is 51.2Nm. The fourth layer 106 has a refractive index N ₄ of 1.487 and a film thickness D ₄ of 23.8 nm. The refractive index N ₅ of the fifth layer 107 is 2.127, and the film thickness D ₅ is 28.7 nm. The sixth layer 108 has a refractive index N ₆ of 1.487 and a film thickness D ₆ of 38.4 nm. The seventh layer 109 has a refractive index N ₇ of 1.505 and a film thickness D ₇ of 29.8 nm.

Thickness _{D 8} of the eighth layer 110 is 207.8Nm, refractive index _{N 8} has changed in profile shown in FIG. 6 (d) toward the 1.0 to 1.505. Specifically, the eighth layer 110 has a region in which the refractive index changes from 1.505 to 1.229 over a thickness of 34.5 nm from the interface with the seventh layer 109, and a refractive index of 1 over a thickness of 42.5 nm. .229 to 1.147. Further, the eighth layer 110 has a region where the refractive index changes from 1.147 to 1.0 over a thickness of 130.8 nm.

  FIGS. 6E and 6F show the reflectance characteristics of the antireflection film of this example. From these figures, it can be seen that the antireflection film of this example achieves high antireflection performance over the entire visible wavelength range (wavelength 400 to 700 nm). The antireflection film of this example satisfies the reflectance standard 2 shown above, and has both excellent wavelength characteristics and incident angle characteristics. In particular, an extremely high antireflection performance of 0.02% or less with respect to a light beam having a wavelength of 430 to 670 nm and an incident angle of 0 to 30 ° is realized.

FIG. 7A shows a refractive index structure of an antireflection film that is Embodiment 10 of the present invention. In this example, S-LAH65V manufactured by OHARA INC. Is used as the optical substrate 101 as in Example 6, and the refractive index N _sub is 1.808.

Refractive index _{N 1} of the first layer 103 is 2.127, the thickness _{D 1} is 24.1Nm. The refractive index N ₂ of the second layer 104 is 1.487, and the film thickness D ₂ is 17.3 nm. Refractive index _{N 3} of the third layer 105 is 2.127, the thickness _{D 3} is 58.8Nm. The fourth layer 106 has a refractive index N ₄ of 1.487 and a film thickness D ₄ of 19.3 nm. The refractive index _{N 5} of the fifth layer 107 is 2.127, the thickness _{D 5} is 29.5Nm. The refractive index N ₆ of the sixth layer 108 is 1.487, and the film thickness D ₆ is 37.4 nm. The refractive index N ₇ of the seventh layer 109 is 1.505, and the film thickness D ₇ is 27.2 nm.

Thickness _{D 8} of the eighth layer 110 is 189.6Nm, refractive index _{N 8} has changed the profile shown in FIGS. 7 (a) toward the 1.0 to 1.505. Specifically, the eighth layer 110 has a region where the refractive index changes from 1.505 to 1.229 from the interface with the seventh layer 109 over a thickness of 31.5 nm, and a refractive index of 1 over a thickness of 38.8 nm. .229 to 1.147. Further, the eighth layer 110 has a region where the refractive index changes from 1.147 to 1.0 over a thickness of 119.3 nm.

  FIGS. 7B and 7C show the reflectance characteristics of the antireflection film of this example. From these figures, it can be seen that the antireflection film of this example achieves high antireflection performance over the entire visible wavelength range (wavelength 400 to 700 nm). The antireflection film of this example satisfies the reflectance standard 1 shown above, and has both excellent wavelength characteristics and incident angle characteristics.

FIG. 8A shows a refractive index structure of an antireflection film that is Embodiment 11 of the present invention. In the present embodiment, L-BAL42 manufactured by OHARA INC. Is used as the optical substrate 101, and the refractive index N _sub is 1.585.

The refractive index N ₁ of the first layer 103 is 2.127, and the film thickness D ₁ is 11.9 nm. The second layer 104 has a refractive index N ₂ of 1.487 and a film thickness D ₂ of 44.3 nm. Refractive index _{N 3} of the third layer 105 is 2.127, the thickness _{D 3} is 29.9Nm. Refractive index _{N 4} of the fourth layer 106 is 1.487, the thickness _{D 4} is 40.2 nm. The refractive index _{N 5} of the fifth layer 107 is 2.127, the thickness _{D 5} is 24.7Nm. The refractive index N ₆ of the sixth layer 108 is 1.487, and the film thickness D ₆ is 43.3 nm. Refractive index _{N 7} of the seventh layer 109 is 1.505, the thickness _{D 7} is 34.0Nm.

Thickness _{D 8} of the eighth layer 110 is 237.0Nm, refractive index _{N 8} has changed in profile shown in FIG. 8 (a) toward the 1.0 to 1.505. Specifically, the eighth layer 110 has a region in which the refractive index changes from 1.505 to 1.229 from the interface with the seventh layer 109 over a thickness of 39.4 nm, and a refractive index of 1 over a thickness of 48.5 nm. .229 to 1.147. Further, the eighth layer 110 has a region where the refractive index changes from 1.147 to 1.0 over a thickness of 149.2 nm.

  8B and 8C show the reflectance characteristics of the antireflection film of this example. From these figures, it can be seen that the antireflection film of this example achieves high antireflection performance over the entire visible wavelength range (wavelength 400 to 700 nm). The antireflection film of this example satisfies the reflectance standard 3 shown above, and has both excellent wavelength characteristics and incident angle characteristics. In particular, an extremely high antireflection performance of 0.015% or less with respect to a light beam having a wavelength of 430 to 670 nm and an incident angle of 0 to 30 ° is realized.

FIG. 8D shows a refractive index structure of an antireflection film that is Embodiment 12 of the present invention. In the present embodiment, as the optical substrate 101, L-BAL42 manufactured by OHARA INC. Is used as in Embodiment 11, and the refractive index N _sub is 1.585.

Refractive index _{N 1} of the first layer 103 is 2.127, the thickness _{D 1} is 12.8 nm. The refractive index N ₂ of the second layer 104 is 1.487, and the film thickness D ₂ is 44.5 nm. Refractive index _{N 3} of the third layer 105 is 2.127, the thickness _{D 3} is 31.4Nm. The refractive index N ₄ of the fourth layer 106 is 1.487, and the film thickness D ₄ is 40.0 nm. The refractive index _{N 5} of the fifth layer 107 is 2.127, the thickness _{D 5} is 25.2 nm. The refractive index N ₆ of the sixth layer 108 is 1.487, and the film thickness D ₆ is 38.1 nm. The refractive index N ₇ of the seventh layer 109 is 1.505, and the film thickness D ₇ is 38.4 nm.

Thickness _{D 8} of the eighth layer 110 is 267.8Nm, refractive index _{N 8} has changed in profile shown in FIG. 8 (d) toward the 1.0 to 1.505. Specifically, the eighth layer 110 has a region where the refractive index changes from 1.505 to 1.229 from the interface with the seventh layer 109 over a thickness of 44.5 nm, and a refractive index of 1 over a thickness of 54.8 nm. .229 to 1.147. Further, the eighth layer 110 has a region where the refractive index changes from 1.147 to 1.0 over a thickness of 168.5 nm.

  FIGS. 8E and 8F show the reflectance characteristics of the antireflection film of this example. From these figures, it can be seen that the antireflection film of this example achieves high antireflection performance over the entire visible wavelength range (wavelength 400 to 700 nm). The antireflection film of this example satisfies the reflectance standard 3 shown above, and has both excellent wavelength characteristics and incident angle characteristics. In particular, an extremely high antireflection performance of 0.06% or less with respect to a light beam having a wavelength of 430 to 670 nm and an incident angle of 0 to 45 ° is realized.

FIG. 9A shows a refractive index structure of an antireflection film that is Embodiment 13 of the present invention. In the present embodiment, as the optical substrate 101, L-BAL42 manufactured by OHARA INC. Is used as in Embodiment 11, and the refractive index N _sub is 1.585.

Refractive index _{N 1} of the first layer 103 is 2.127, the thickness _{D 1} is 14.2 nm. The second layer 104 has a refractive index N ₂ of 1.487 and a film thickness D ₂ of 42.5 nm. Refractive index _{N 3} of the third layer 105 is 2.127, the thickness _{D 3} is 33.4 nm. The fourth layer 106 has a refractive index N ₄ of 1.487 and a film thickness D ₄ of 37.9 nm. The refractive index _{N 5} of the fifth layer 107 is 2.127, the thickness _{D 5} is 24.8 nm. The sixth layer 108 has a refractive index N ₆ of 1.487 and a film thickness D ₆ of 22.4 nm. The refractive index N ₇ of the seventh layer 109 is 1.505, and the film thickness D ₇ is 49.9 nm.

Thickness _{D 8} of the eighth layer 110 is 348.5Nm, refractive index _{N 8} has changed in profile shown in FIG. 9 (a) toward the 1.0 to 1.505. Specifically, the eighth layer 110 has a region where the refractive index changes from 1.505 to 1.229 over a thickness of 57.9 nm from the interface with the seventh layer 109, and a refractive index of 1 over a thickness of 71.3 nm. .229 to 1.147. Further, the eighth layer 110 has a region where the refractive index changes from 1.147 to 1.0 over a thickness of 219.3 nm.

  FIGS. 9B and 9C show the reflectance characteristics of the antireflection film of this example. From these figures, it can be seen that the antireflection film of this example achieves high antireflection performance over the entire visible wavelength range (wavelength 400 to 700 nm). The antireflection film of this example satisfies the reflectance standard 2 shown above, and has both excellent wavelength characteristics and incident angle characteristics. In particular, an extremely high antireflection performance of 0.08% or less with respect to a light beam having a wavelength of 430 to 670 nm and an incident angle of 0 to 30 ° is realized.

FIG. 9D shows a refractive index structure of an antireflection film that is Embodiment 14 of the present invention. In the present embodiment, as the optical substrate 101, L-BAL42 manufactured by OHARA INC. Is used as in Embodiment 11, and the refractive index N _sub is 1.585.

Refractive index _{N 1} of the first layer 103 is 2.127, the thickness _{D 1} is 13.7 nm. The refractive index N ₂ of the second layer 104 is 1.487, and the film thickness D ₂ is 41.8 nm. Refractive index _{N 3} of the third layer 105 is 2.127, the thickness _{D 3} is 34.1 nm. The refractive index N ₄ of the fourth layer 106 is 1.487, and the film thickness D ₄ is 35.0 nm. The refractive index _{N 5} of the fifth layer 107 is 2.127, the thickness _{D 5} is 26.8Nm. The sixth layer 108 has a refractive index N ₆ of 1.487 and a film thickness D ₆ of 42.9 nm. The refractive index N ₇ of the seventh layer 109 is 1.505, and the film thickness D ₇ is 30.1 nm.

Thickness _{D 8} of the eighth layer 110 is 209.7Nm, refractive index _{N 8} has changed in profile shown in FIG. 9 (d) toward the 1.0 to 1.505. Specifically, the eighth layer 110 has a region where the refractive index changes from 1.505 to 1.229 from the interface with the seventh layer 109 over a thickness of 34.8 nm, and a refractive index of 1 over a thickness of 42.9 nm. .229 to 1.147. Further, the eighth layer 110 has a region where the refractive index changes from 1.147 to 1.0 over a thickness of 132.0 nm.

  FIGS. 9E and 9F show the reflectance characteristics of the antireflection film of this example. From these figures, it can be seen that the antireflection film of this example achieves high antireflection performance over the entire visible wavelength range (wavelength 400 to 700 nm). The antireflection film of this example satisfies the reflectance standard 2 shown above, and has both excellent wavelength characteristics and incident angle characteristics. In particular, an extremely high antireflection performance of 0.025% or less with respect to a light beam having a wavelength of 430 to 670 nm and an incident angle of 0 to 30 ° is realized.

FIG. 10A shows a refractive index structure of an antireflection film that is Embodiment 15 of the present invention. In the present embodiment, as the optical substrate 101, L-BAL42 manufactured by OHARA INC. Is used as in Embodiment 11, and the refractive index N _sub is 1.585.

Refractive index _{N 1} of the first layer 103 is 2.127, the thickness _{D 1} is 14.9 nm. The second layer 104 has a refractive index N ₂ of 1.487 and a film thickness D ₂ of 38.8 nm. Refractive index _{N 3} of the third layer 105 is 2.127, the thickness _{D 3} is 37.7Nm. The refractive index N ₄ of the fourth layer 106 is 1.487, and the film thickness D ₄ is 30.7 nm. The refractive index _{N 5} of the fifth layer 107 is 2.127, the thickness _{D 5} is 28.4Nm. The sixth layer 108 has a refractive index N ₆ of 1.487 and a film thickness D ₆ of 41.6 nm. The refractive index N ₇ of the seventh layer 109 is 1.505, and the film thickness D ₇ is 27.9 nm.

Thickness _{D 8} of the eighth layer 110 is 194.4Nm, refractive index _{N 8} has changed in profile shown in FIG. 10 (a) toward the 1.0 to 1.505. Specifically, the eighth layer 110 has a region where the refractive index changes from 1.505 to 1.229 from the interface with the seventh layer 109 over a thickness of 32.3 nm, and a refractive index of 1 over a thickness of 39.8 nm. .229 to 1.147. Furthermore, the eighth layer 110 has a region where the refractive index changes from 1.147 to 1.0 over a thickness of 122.3 nm.

  FIGS. 10B and 10C show the reflectance characteristics of the antireflection film of this example. From these figures, it can be seen that the antireflection film of this example achieves high antireflection performance over the entire visible wavelength range (wavelength 400 to 700 nm). The antireflection film of this example satisfies the reflectance standard 1 shown above, and has both excellent wavelength characteristics and incident angle characteristics.

FIG. 11A shows a refractive index structure of an antireflection film that is Embodiment 16 of the present invention. In this embodiment, S-FPL53 manufactured by OHARA INC. Is used as the optical substrate 101, and the refractive index N _sub is 1.440.

Refractive index _{N 1} of the first layer 103 is 2.127, the thickness _{D 1} is 6.29Nm. The second layer 104 has a refractive index N ₂ of 1.487 and a film thickness D ₂ of 66.8 nm. Refractive index _{N 3} of the third layer 105 is 2.127, the thickness _{D 3} is 21.7 nm. The fourth layer 106 has a refractive index N ₄ of 1.487 and a film thickness D ₄ of 47.1 nm. The refractive index _{N 5} of the fifth layer 107 is 2.127, the thickness _{D 5} is 22.6 nm. The sixth layer 108 has a refractive index N ₆ of 1.487 and a film thickness D ₆ of 45.0 nm. Refractive index _{N 7} of the seventh layer 109 is 1.505, the thickness _{D 7} is 34.0Nm.

Thickness _{D 8} of the eighth layer 110 is 237.0Nm, refractive index _{N 8} has changed in profile shown in FIG. 11 (a) toward the 1.0 to 1.505. Specifically, the eighth layer 110 has a region in which the refractive index changes from 1.505 to 1.229 from the interface with the seventh layer 109 over a thickness of 39.4 nm, and a refractive index of 1 over a thickness of 48.5 nm. .229 to 1.147. Further, the eighth layer 110 has a region where the refractive index changes from 1.147 to 1.0 over a thickness of 149.2 nm.

  FIGS. 11B and 11C show the reflectance characteristics of the antireflection film of this example. From these figures, it can be seen that the antireflection film of this example achieves high antireflection performance over the entire visible wavelength range (wavelength 400 to 700 nm). The antireflection film of this example satisfies the reflectance standard 3 shown above, and has both excellent wavelength characteristics and incident angle characteristics. In particular, an extremely high antireflection performance of 0.02% or less with respect to a light beam having a wavelength of 430 to 670 nm and an incident angle of 0 to 30 ° is realized.

FIG. 11D shows a refractive index structure of an antireflection film that is Embodiment 17 of the present invention. In this example, S-FPL53 manufactured by OHARA INC. Is used as the optical substrate 101 as in Example 16, and the refractive index N _sub is 1.440.

Refractive index _{N 1} of the first layer 103 is 2.127, the thickness _{D 1} is 6.75 nm. The refractive index N ₂ of the second layer 104 is 1.487, and the film thickness D ₂ is 66.9 nm. Refractive index _{N 3} of the third layer 105 is 2.127, the thickness _{D 3} is 22.6 nm. The refractive index N ₄ of the fourth layer 106 is 1.487, and the film thickness D ₄ is 47.0 nm. The refractive index _{N 5} of the fifth layer 107 is 2.127, the thickness _{D 5} is 22.9 nm. Refractive index _{N 6} of the sixth layer 108 is 1.487, the thickness _{D 6} is 40.7Nm. The seventh layer 109 has a refractive index N ₇ of 1.505 and a film thickness D ₇ of 37.7 nm.

Thickness _{D 8} of the eighth layer 110 is 263.1Nm, refractive index _{N 8} has changed the profile shown in FIG. 11 (d) toward the 1.0 to 1.505. Specifically, the eighth layer 110 has a region where the refractive index changes from 1.505 to 1.229 from the interface with the seventh layer 109 over a thickness of 43.7 nm, and a refractive index of 1 over a thickness of 53.8 nm. .229 to 1.147. Further, the eighth layer 110 has a region where the refractive index changes from 1.147 to 1.0 over a thickness of 165.6 nm.

  FIGS. 11E and 11F show the reflectance characteristics of the antireflection film of this example. From these figures, it can be seen that the antireflection film of this example achieves high antireflection performance over the entire visible wavelength range (wavelength 400 to 700 nm). The antireflection film of this example satisfies the reflectance standard 3 shown above, and has both excellent wavelength characteristics and incident angle characteristics. In particular, an extremely high antireflection performance of 0.09% or less with respect to a light beam having a wavelength of 430 to 670 nm and an incident angle of 0 to 45 ° is realized.

FIG. 12A shows a refractive index structure of an antireflection film that is Embodiment 18 of the present invention. In this example, S-FPL53 manufactured by OHARA INC. Is used as the optical substrate 101 as in Example 16, and the refractive index N _sub is 1.440.

Refractive index _{N 1} of the first layer 103 is 2.127, the thickness _{D 1} is 8.09Nm. The refractive index N ₂ of the second layer 104 is 1.487, and the film thickness D ₂ is 63.2 nm. Refractive index _{N 3} of the third layer 105 is 2.127, the thickness _{D 3} is 24.6Nm. The fourth layer 106 has a refractive index N ₄ of 1.487 and a film thickness D ₄ of 44.8 nm. The refractive index _{N 5} of the fifth layer 107 is 2.127, the thickness _{D 5} is 22.7Nm. The sixth layer 108 has a refractive index N ₆ of 1.487 and a film thickness D ₆ of 24.5 nm. The refractive index N ₇ of the seventh layer 109 is 1.505, and the film thickness D ₇ is 49.9 nm.

Thickness _{D 8} of the eighth layer 110 is 348.5Nm, refractive index _{N 8} has changed in profile shown in FIG. 12 (a) toward the 1.0 to 1.505. Specifically, the eighth layer 110 has a region where the refractive index changes from 1.505 to 1.229 over a thickness of 57.9 nm from the interface with the seventh layer 109, and a refractive index of 1 over a thickness of 71.3 nm. .229 to 1.147. Further, the eighth layer 110 has a region where the refractive index changes from 1.147 to 1.0 over a thickness of 219.3 nm.

  FIGS. 12B and 12C show the reflectance characteristics of the antireflection film of this example. From these figures, it can be seen that the antireflection film of this example achieves high antireflection performance over the entire visible wavelength range (wavelength 400 to 700 nm). The antireflection film of this example satisfies the reflectance standard 2 shown above, and has both excellent wavelength characteristics and incident angle characteristics. In particular, an extremely high antireflection performance of 0.08% or less with respect to a light beam having a wavelength of 430 to 670 nm and an incident angle of 0 to 30 ° is realized.

FIG. 12D shows a refractive index structure of an antireflection film that is Embodiment 19 of the present invention. In this example, S-FPL53 manufactured by OHARA INC. Is used as the optical substrate 101 as in Example 16, and the refractive index N _sub is 1.440.

Refractive index _{N 1} of the first layer 103 is 2.127, the thickness _{D 1} is 7.83Nm. The refractive index N ₂ of the second layer 104 is 1.487, and the film thickness D ₂ is 62.2 nm. Refractive index _{N 3} of the third layer 105 is 2.127, the thickness _{D 3} is 25.4 nm. The refractive index N ₄ of the fourth layer 106 is 1.487, and the film thickness D ₄ is 41.7 nm. The refractive index _{N 5} of the fifth layer 107 is 2.127, the thickness _{D 5} is 24.8 nm. The sixth layer 108 has a refractive index N ₆ of 1.487 and a film thickness D ₆ of 45.0 nm. The refractive index N ₇ of the seventh layer 109 is 1.505, and the film thickness D ₇ is 29.9 nm.

Thickness _{D 8} of the eighth layer 110 is 208.6Nm, refractive index _{N 8} has changed the profile shown in FIG. 12 (d) toward the 1.0 to 1.505. Specifically, the eighth layer 110 has a region where the refractive index changes from 1.505 to 1.229 from the interface with the seventh layer 109 over a thickness of 34.6 nm, and a refractive index of 1 over a thickness of 42.7 nm. .229 to 1.147. Further, the eighth layer 110 has a region where the refractive index changes from 1.147 to 1.0 over a thickness of 131.3 nm.

  FIGS. 12E and 12F show the reflectance characteristics of the antireflection film of this example. From these figures, it can be seen that the antireflection film of this example achieves high antireflection performance over the entire visible wavelength range (wavelength 400 to 700 nm). The antireflection film of this example satisfies the reflectance standard 2 shown above, and has both excellent wavelength characteristics and incident angle characteristics. In particular, an extremely high antireflection performance of 0.03% or less with respect to a light beam having a wavelength of 430 to 670 nm and an incident angle of 0 to 30 ° is realized.

FIG. 13A shows a refractive index structure of an antireflection film that is Embodiment 20 of the present invention. In this example, S-FPL53 manufactured by OHARA INC. Is used as the optical substrate 101 as in Example 16, and the refractive index N _sub is 1.440.

Refractive index _{N 1} of the first layer 103 is 2.127, the thickness _{D 1} is 8.39Nm. The refractive index N ₂ of the second layer 104 is 1.487, and the film thickness D ₂ is 59.8 nm. Refractive index _{N 3} of the third layer 105 is 2.127, the thickness _{D 3} is 27.0Nm. The fourth layer 106 has a refractive index N ₄ of 1.487 and a film thickness D ₄ of 39.3 nm. The refractive index _{N 5} of the fifth layer 107 is 2.127, the thickness _{D 5} is 25.8Nm. The sixth layer 108 has a refractive index N ₆ of 1.487 and a film thickness D ₆ of 44.6 nm. The refractive index N ₇ of the seventh layer 109 is 1.505, and the film thickness D ₇ is 28.4 nm.

Thickness _{D 8} of the eighth layer 110 is 197.9Nm, refractive index _{N 8} has changed in profile shown in FIG. 13 (a) toward the 1.0 to 1.505. Specifically, the eighth layer 110 has a region where the refractive index changes from 1.505 to 1.229 from the interface with the seventh layer 109 over a thickness of 32.9 nm, and a refractive index of 1 over a thickness of 40.5 nm. .229 to 1.147. Further, the eighth layer 110 has a region where the refractive index changes from 1.147 to 1.0 over a thickness of 124.5 nm.

  FIGS. 13B and 13C show the reflectance characteristics of the antireflection film of this example. From these figures, it can be seen that the antireflection film of this example achieves high antireflection performance over the entire visible wavelength range (wavelength 400 to 700 nm). The antireflection film of this example satisfies the reflectance standard 1 shown above, and has both excellent wavelength characteristics and incident angle characteristics. In particular, an extremely high antireflection performance of 0.04% or less with respect to a light beam having a wavelength of 430 to 670 nm and an incident angle of 0 to 30 ° is realized.

FIG. 14A shows a refractive index structure of an antireflection film that is Embodiment 21 of the present invention. In the present embodiment, as the optical substrate 101, L-BAL42 manufactured by OHARA INC. Is used as in Examples 11 to 15, and the refractive index N _sub is 1.585.

Refractive index _{N 1} of the first layer 103 is 2.323, the thickness _{D 1} is 8.32Nm. The second layer 104 has a refractive index N ₂ of 1.507 and a film thickness D ₂ of 49.9 nm. Refractive index _{N 3} of the third layer 105 is 2.323, the thickness _{D 3} is 19.9 nm. The refractive index N ₄ of the fourth layer 106 is 1.507, and the film thickness D ₄ is 46.6 nm. The refractive index _{N 5} of the fifth layer 107 is 2.323, the thickness _{D 5} is 16.2 nm. The sixth layer 108 has a refractive index N ₆ of 1.507 and a film thickness D ₆ of 45.8 nm. Refractive index _{N 7} of the seventh layer 109 is 1.505, the thickness _{D 7} is 34.0Nm.

Thickness _{D 8} of the eighth layer 110 is 237.0Nm, toward the refractive index _{N 8} 1.0 from 1.505, it is changing the profile shown in FIG. 14 (a). Specifically, the eighth layer 110 has a region in which the refractive index changes from 1.505 to 1.229 from the interface with the seventh layer 109 over a thickness of 39.4 nm, and a refractive index of 1 over a thickness of 48.5 nm. .229 to 1.147. Further, the eighth layer 110 has a region where the refractive index changes from 1.147 to 1.0 over a thickness of 149.2 nm.

  FIGS. 14B and 14C show the reflectance characteristics of the antireflection film of this example. From these figures, it can be seen that the antireflection film of this example achieves high antireflection performance over the entire visible wavelength range (wavelength 400 to 700 nm). The antireflection film of this example satisfies the reflectance standard 3 shown above, and has both excellent wavelength characteristics and incident angle characteristics. In particular, an extremely high antireflection performance of 0.025% or less with respect to a light beam having a wavelength of 430 to 670 nm and an incident angle of 0 to 30 ° is realized.

FIG. 14D shows a refractive index structure of an antireflection film that is Embodiment 22 of the present invention. In this example, as in Example 21, L-BAL42 manufactured by OHARA INC. Is used as the optical substrate 101, and the refractive index N _sub is 1.585.

Refractive index _{N 1} of the first layer 103 is 2.038, the thickness _{D 1} is 15.0 nm. The refractive index N ₂ of the second layer 104 is 1.427, and the film thickness D ₂ is 38.1 nm. Refractive index _{N 3} of the third layer 105 is 2.038, the thickness _{D 3} is 36.5 nm. Refractive index _{N 4} of the fourth layer 106 is 1.427, the thickness _{D 4} is 35.9Nm. The refractive index _{N 5} of the fifth layer 107 is 2.038, the thickness _{D 5} is 29.9Nm. The refractive index N ₆ of the sixth layer 108 is 1.427, and the film thickness D ₆ is 38.3 nm. Refractive index _{N 7} of the seventh layer 109 is 1.505, the thickness _{D 7} is 34.0Nm.

Thickness _{D 8} of the eighth layer 110 is 237.0Nm, refractive index _{N 8} has changed the profile shown in FIG. 14 (d) toward the 1.0 to 1.505. Specifically, the eighth layer 110 has a region in which the refractive index changes from 1.505 to 1.229 from the interface with the seventh layer 109 over a thickness of 39.4 nm, and a refractive index of 1 over a thickness of 48.5 nm. .229 to 1.147. Further, the eighth layer 110 has a region where the refractive index changes from 1.147 to 1.0 over a thickness of 149.2 nm.

  FIGS. 14E and 14F show the reflectance characteristics of the antireflection film of this example. From these figures, it can be seen that the antireflection film of this example achieves high antireflection performance over the entire visible wavelength range (wavelength 400 to 700 nm). The antireflection film of this example satisfies the reflectance standard 3 shown above, and has both excellent wavelength characteristics and incident angle characteristics. In particular, an extremely high antireflection performance of 0.01% or less with respect to a light beam having a wavelength of 430 to 670 nm and an incident angle of 0 to 30 ° is realized.

FIG. 15A shows a refractive index structure of an antireflection film that is Embodiment 23 of the present invention. In this example, as in Example 21, L-BAL42 manufactured by OHARA INC. Is used as the optical substrate 101, and the refractive index N _sub is 1.585.

Refractive index _{N 1} of the first layer 103 is 2.127, the thickness _{D 1} is 12.8 nm. The second layer 104 has a refractive index N ₂ of 1.487 and a film thickness D ₂ of 42.0 nm. Refractive index _{N 3} of the third layer 105 is 2.127, the thickness _{D 3} is 34.1 nm. The refractive index N ₄ of the fourth layer 106 is 1.487, and the film thickness D ₄ is 33.7 nm. The refractive index _{N 5} of the fifth layer 107 is 2.127, the thickness _{D 5} is 30.8 nm. The sixth layer 108 has a refractive index N ₆ of 1.487 and a film thickness D ₆ of 33.6 nm. The refractive index N ₇ of the seventh layer 109 is 1.575, and the film thickness D ₇ is 34.0 nm.

Thickness _{D 8} of the eighth layer 110 is 237.0Nm, refractive index _{N 8} has changed in profile shown in FIG. 15 (a) toward the 1.0 to 1.575. Specifically, the eighth layer 110 has a region where the refractive index changes from 1.575 to 1.259 from the interface with the seventh layer 109 over a thickness of 39.4 nm, and a refractive index of 1 over a thickness of 48.5 nm. .259 to 1.164. Furthermore, the eighth layer 110 has a region where the refractive index changes from 1.164 to 1.0 over a thickness of 149.2 nm.

  FIGS. 15B and 15C show the reflectance characteristics of the antireflection film of this example. From these figures, it can be seen that the antireflection film of this example achieves high antireflection performance over the entire visible wavelength range (wavelength 400 to 700 nm). The antireflection film of this example satisfies the reflectance standard 3 shown above, and has both excellent wavelength characteristics and incident angle characteristics. In particular, an extremely high antireflection performance of 0.02% or less with respect to a light beam having a wavelength of 430 to 670 nm and an incident angle of 0 to 30 ° is realized.

FIG. 15D shows a refractive index structure of an antireflection film that is Embodiment 24 of the present invention. In this example, as in Example 21, L-BAL42 manufactured by OHARA INC. Is used as the optical substrate 101, and the refractive index N _sub is 1.585.

Refractive index _{N 1} of the first layer 103 is 2.127, the thickness _{D 1} is 11.5 nm. The second layer 104 has a refractive index N ₂ of 1.487 and a film thickness D ₂ of 45.9 nm. Refractive index _{N 3} of the third layer 105 is 2.127, the thickness _{D 3} is 27.3 nm. The fourth layer 106 has a refractive index N ₄ of 1.487 and a film thickness D ₄ of 44.5 nm. The refractive index _{N 5} of the fifth layer 107 is 2.127, the thickness _{D 5} is 20.0 nm. The sixth layer 108 has a refractive index N ₆ of 1.487 and a film thickness D ₆ of 60.9 nm. The refractive index N ₇ of the seventh layer 109 is 1.405, and the film thickness D ₇ is 34.0 nm.

Thickness _{D 8} of the eighth layer 110 is 237.0Nm, refractive index _{N 8} has changed the profile shown in FIG. 15 (d) toward the 1.0 to 1.405. Specifically, the eighth layer 110 has a region where the refractive index changes from 1.405 to 1.184 over a thickness of 39.4 nm from the interface with the seventh layer 109, and a refractive index of 1 over a thickness of 48.5 nm. 184 to 1.120. Furthermore, the eighth layer 110 has a region where the refractive index changes from 1.120 to 1.0 over a thickness of 149.2 nm.

  FIGS. 15E and 15F show the reflectance characteristics of the antireflection film of this example. From these figures, it can be seen that the antireflection film of this example achieves high antireflection performance over the entire visible wavelength range (wavelength 400 to 700 nm). The antireflection film of this example satisfies the reflectance standard 3 shown above, and has both excellent wavelength characteristics and incident angle characteristics. In particular, an extremely high antireflection performance of 0.016% or less with respect to a light beam having a wavelength of 430 to 670 nm and an incident angle of 0 to 45 ° is realized.

[Comparative Example 1]
FIG. 16A shows a refractive index structure of an antireflection film (Comparative Example 1) as a comparative example with respect to Examples 1-5. In this comparative example, S-LAH79 manufactured by OHARA INC. Is used as the optical substrate 101 as in Examples 1 to 5, and the refractive index N _sub is 2.011.

Refractive index _{N 1} of the first layer 103 is 2.127, the thickness _{D 1} is 21.6 nm. The refractive index N ₂ of the second layer 104 is 1.487, and the film thickness D ₂ is 4.42 nm. Refractive index _{N 3} of the third layer 105 is 2.127, the thickness _{D 3} is 105.5Nm. Refractive index _{N 4} of the fourth layer 106 is 1.487, the thickness _{D 4} is 14.1 nm. The refractive index _{N 5} of the fifth layer 107 is 2.127, the thickness _{D 5} is 23.6Nm. The sixth layer 108 has a refractive index N ₆ of 1.487 and a film thickness D ₆ of 35.3 nm. The refractive index N ₇ of the seventh layer 109 is 1.505, and the film thickness D ₇ is 25.5 nm.

Thickness _{D 8} of the eighth layer 110 is 178.2Nm, refractive index _{N 8} has changed in profile shown in FIG. 16 (a) toward the 1.0 to 1.505. Specifically, the eighth layer 110 has a region where the refractive index changes from 1.505 to 1.229 over a thickness of 29.6 nm from the interface with the seventh layer 109, and a refractive index of 1 over a thickness of 36.5 nm. .229 to 1.147. Further, the eighth layer 110 has a region where the refractive index changes from 1.147 to 1.0 over a thickness of 112.2 nm.

  FIGS. 16B and 16C show the reflectance characteristics of the antireflection film of this comparative example. As can be seen from these figures, the antireflection film of this comparative example does not satisfy any of the reflectance standards 1 to 3.

[Comparative Example 2]
FIG. 16D shows a refractive index structure of an antireflection film (Comparative Example 2) as a comparative example with respect to Examples 6-10. In this comparative example, S-LAH65V manufactured by OHARA INC. Is used as the optical substrate 101 as in Examples 6 to 10, and the refractive index N _sub is 1.808.

Refractive index _{N 1} of the first layer 103 is 2.127, the thickness _{D 1} is 22.4Nm. The second layer 104 has a refractive index N ₂ of 1.487 and a film thickness D ₂ of 13.0 nm. Refractive index _{N 3} of the third layer 105 is 2.127, the thickness _{D 3} is 88.1Nm. Refractive index _{N 4} of the fourth layer 106 is 1.487, the thickness _{D 4} is 12.1 nm. The refractive index _{N 5} of the fifth layer 107 is 2.127, the thickness _{D 5} is 26.0 nm. The sixth layer 108 has a refractive index N ₆ of 1.487 and a film thickness D ₆ of 33.4 nm. The refractive index N ₇ of the seventh layer 109 is 1.505, and the film thickness D ₇ is 25.5 nm.

Thickness _{D 8} of the eighth layer 110 is 178.2Nm, refractive index _{N 8} has changed the profile shown in FIG. 16 (d) toward the 1.0 to 1.505. Specifically, the eighth layer 110 has a region where the refractive index changes from 1.505 to 1.229 over a thickness of 29.6 nm from the interface with the seventh layer 109, and a refractive index of 1 over a thickness of 36.5 nm. .229 to 1.147. Further, the eighth layer 110 has a region where the refractive index changes from 1.147 to 1.0 over a thickness of 112.2 nm.

  FIGS. 16E and 16F show the reflectance characteristics of the antireflection film of this comparative example. As can be seen from these figures, the antireflection film of this comparative example does not satisfy any of the reflectance standards 1 to 3.

[Comparative Example 3]
FIG. 17A shows a refractive index structure of an antireflection film (Comparative Example 3) as a comparative example for Examples 11 to 15 and Examples 21 to 24. In this comparative example, L-BAL42 manufactured by OHARA INC. Is used as the optical substrate 101 as in Examples 11 to 15 and Examples 21 to 24, and the refractive index N _sub is 1.585.

Refractive index _{N 1} of the first layer 103 is 2.127, the thickness _{D 1} is 15.8 nm. The second layer 104 has a refractive index N ₂ of 1.487 and a film thickness D ₂ of 36.4 nm. Refractive index _{N 3} of the third layer 105 is 2.127, the thickness _{D 3} is 41.9Nm. The refractive index N ₄ of the fourth layer 106 is 1.487, and the film thickness D ₄ is 26.8 nm. The refractive index _{N 5} of the fifth layer 107 is 2.127, the thickness _{D 5} is 30.5 nm. The sixth layer 108 has a refractive index N ₆ of 1.487 and a film thickness D ₆ of 41.8 nm. The refractive index N ₇ of the seventh layer 109 is 1.505, and the film thickness D ₇ is 25.5 nm.

Thickness _{D 8} of the eighth layer 110 is 178.2Nm, refractive index _{N 8} has changed in profile shown in FIG. 17 (a) toward the 1.0 to 1.505. Specifically, the eighth layer 110 has a region where the refractive index changes from 1.505 to 1.229 over a thickness of 29.6 nm from the interface with the seventh layer 109, and a refractive index of 1 over a thickness of 36.5 nm. .229 to 1.147. Further, the eighth layer 110 has a region where the refractive index changes from 1.147 to 1.0 over a thickness of 112.2 nm.

  FIGS. 17B and 17C show the reflectance characteristics of the antireflection film of this comparative example. As can be seen from these figures, the antireflection film of this comparative example does not satisfy any of the reflectance standards 1 to 3.

[Comparative Example 4]
FIG. 17D shows a refractive index structure of an antireflection film (Comparative Example 4) as a comparative example with respect to Examples 16-20. In this comparative example, S-FPL53 manufactured by OHARA INC. Is used as the optical substrate 101 as in Examples 16 to 20, and the refractive index N _sub is 1.440.

Refractive index _{N 1} of the first layer 103 is 2.127, the thickness _{D 1} is 9.93Nm. The refractive index N ₂ of the second layer 104 is 1.487, and the film thickness D ₂ is 54.7 nm. Refractive index _{N 3} of the third layer 105 is 2.127, the thickness _{D 3} is 31.9Nm. Refractive index _{N 4} of the fourth layer 106 is 1.487, the thickness _{D 4} is 33.5 nm. The refractive index _{N 5} of the fifth layer 107 is 2.127, the thickness _{D 5} is 28.8 nm. Refractive index _{N 6} of the sixth layer 108 is 1.487, the thickness _{D 6} is 44.0Nm. The refractive index N ₇ of the seventh layer 109 is 1.505, and the film thickness D ₇ is 25.5 nm.

Thickness _{D 8} of the eighth layer 110 is 178.2Nm, refractive index _{N 8} has changed the profile shown in FIG. 17 (d) toward the 1.0 to 1.505. Specifically, the eighth layer 110 has a region where the refractive index changes from 1.505 to 1.229 over a thickness of 29.6 nm from the interface with the seventh layer 109, and a refractive index of 1 over a thickness of 36.5 nm. .229 to 1.147. Further, the eighth layer 110 has a region where the refractive index changes from 1.147 to 1.0 over a thickness of 112.2 nm.

  FIGS. 17E and 17F show the reflectance characteristics of the antireflection film of this comparative example. As can be seen from these figures, the antireflection film of this comparative example does not satisfy any of the reflectance standards 1 to 3.

In all of Comparative Examples 1 to 4 described above, the configurations of the first to sixth layers are the same as those of Examples 1 to 20, and the reflectance is set to an appropriate design value so as to be low in the entire visible wavelength range. However, the thickness D ₈ of the eighth layer is that becomes less than 180 nm, high-performance anti-reflection film having both an incident angle characteristics and wavelength characteristics to satisfy the reflectance standard 1-3 can not be realized. Therefore, in order to realize a high-performance antireflection film having both an incident angle characteristics and wavelength characteristics, it is necessary more than 180nm as a thickness D ₈ of the eighth layer.

  FIG. 18A shows an example in which the optical element including the antireflection film shown in Example 6 is applied to an optical system. Design values of the optical system 1001 of this example are shown in Numerical Example 1 (Tables 2 to 5). The ninth surface is an aspherical surface, and is a surface represented by the following expression when the optical axis direction is the Z axis and the optical axis orthogonal direction is the Y axis.

  The optical system 1001 is a fisheye zoom lens for a camera having a focal length of 8 to 15 mm. In the figure, 1002 is an image sensor or film, 1003 is an aperture, and 1004 is a sub-aperture. In this optical system 1001, the optical element 101 is provided with the antireflection film 102 shown in Example 6 on the image side surface of the lens as the optical element body. The antireflection film 102 may be the antireflection film shown in Examples 1 to 5 and Examples 7 to 24. The optical system may be configured to include an optical element provided with an antireflection film and at least one other optical element.

  The image-side surface of the optical element 101 has a large angle in which the half opening angle at the outer peripheral portion exceeds 80 °. For this reason, light enters and exits at a large angle at the periphery of the optical element 101. However, since the antireflection film of Example 6 achieves good antireflection performance in the wavelength range of 430 to 670 nm and the incident angle range of 0 to 60 °, it generates harmful light such as flare and ghost. A reduced high-quality optical system can be realized.

  In this embodiment, the case of a fish-eye zoom lens for a camera is shown as an example of an optical system. However, an optical element including the antireflection film of Embodiments 1 to 24 is used for a standard lens or a telephoto lens having a long focal length. You can also. Furthermore, the optical element provided with the anti-reflective film of Examples 1-24 can also be used for observation optical systems, such as binoculars.

  FIG. 18B shows an example in which the optical system of Example 25 is applied to a digital camera as an optical apparatus. In the drawing, an optical system 1001 of Example 25 is housed in a lens barrel 2001a which is a part of a main body (optical apparatus main body) of a digital camera 2001 as a photographing optical system. According to the present embodiment, it is possible to obtain a high-quality image in which generation of unnecessary images due to unnecessary light such as flare and ghost is suppressed.

  In addition, as an optical apparatus, observation apparatuses, such as an interchangeable lens and binoculars, and an image projection apparatus are also contained.

[Numerical example 1]

  Each embodiment described above is only a representative example, and various modifications and changes can be made to each embodiment in carrying out the present invention.

  It is possible to provide an antireflection film having excellent antireflection performance, and an optical system and an optical apparatus having the antireflection film.

101 Optical substrate (lens)
102 Antireflection film 103 1st layer 104 2nd layer 105 3rd layer 106 4th layer 107 5th layer 108 6th layer 109 7th layer 110 8th layer (fine concavo-convex structure layer)

Claims (11)

An antireflection film formed on an optical substrate,
When the incident light wavelength is 550 nm,
The refractive index of the optical substrate with respect to the incident wavelength is N _sub ,
In order from the optical substrate side,
A first layer that is a film having a refractive index of N ₁ and a film thickness of D ₁ with respect to the incident wavelength;
A _second layer having a refractive index of N ₂ and a film thickness of D ₂ with respect to the incident wavelength;
A _third layer having a refractive index of N ₃ and a film thickness of D ₃ with respect to the incident wavelength;
A fourth layer that is a film having a refractive index of N ₄ and a film thickness of D ₄ with respect to the incident wavelength;
A _fifth layer having a refractive index of N ₅ and a film thickness of D ₅ with respect to the incident wavelength;
A sixth layer which is a film having a refractive index of N ₆ and a film thickness of D ₆ with respect to the incident wavelength;
A seventh layer which is a film having a refractive index N ₇ and a film thickness D ₇ with respect to the incident wavelength;
Average pitch is constituted by the following uneven structure 400 nm, the refractive index with respect to the incident wavelength is continuously changed toward the N ₈ to 1.0, and a eighth layer thickness is D _8,
An antireflection film characterized by satisfying the following conditions.
1.40 ≦ N _sub ≦ 2.20
1.90 ≦ N ₁ ≦ 2.40, 5.0 nm ≦ D ₁ ≦ 45.0 nm
1.36 ≦ N ₂ ≦ 1.58, 3.0 nm ≦ D ₂ ≦ 80.0 nm
1.90 ≦ N ₃ ≦ 2.40, 15.0 nm ≦ D ₃ ≦ 165.0 nm
1.36 ≦ N ₄ ≦ 1.58, 11.0 nm ≦ D ₄ ≦ 58.0 nm
1.90 ≦ N ₅ ≦ 2.40, 13.0 nm ≦ D ₅ ≦ 38.0 nm
1.36 ≦ N ₆ ≦ 1.58, 9.0 nm ≦ D ₆ ≦ 75.0 nm
1.35 ≦ N ₇ ≦ 1.65, 22.0 nm ≦ D ₇ ≦ 60.0 nm
1.35 ≦ N ₈ ≦ 1.65, 180.0 nm ≦ D ₈ ≦ 350.0 nm The antireflection film according to claim 1, wherein the following condition is satisfied.
5.5 nm ≦ D ₁ ≦ 43.0 nm
3.5 nm ≦ D ₂ ≦ 75.0 nm
17.0 nm ≦ D ₃ ≦ 160.0 nm
14.8 nm ≦ D ₄ ≦ 58.0 nm
14.0 nm ≦ D ₅ ≦ 35.0 nm
10.0 nm ≦ D ₆ ≦ 70.0 nm
28.0 nm ≦ D ₇ ≦ 55.0 nm
200.0 nm ≦ D ₈ ≦ 350.0 nm The antireflection film according to claim 1, wherein the following condition is satisfied.
6.0 nm ≦ D ₁ ≦ 40.0 nm
6.0 nm ≦ D ₂ ≦ 72.0 nm
19.0 nm ≦ D ₃ ≦ 72.0 nm
18.0 nm ≦ D ₄ ≦ 52.0 nm
15.0 nm ≦ D ₅ ≦ 33.0 nm
25.0 nm ≦ D ₆ ≦ 65.0 nm
30.0 nm ≦ D ₇ ≦ 45.0 nm
220.0 nm ≦ D ₈ ≦ 300.0 nm The antireflection film according to any one of claims 1 to 3, wherein the following condition is satisfied.
The incident angle with respect to the antireflection film is in the range of 0 to 30 °, and the reflectance for light having a wavelength of 430 to 670 nm is 0.15% or less,
The incident angle with respect to the antireflection film is in the range of 0 to 30 °, and the reflectance for light rays having a wavelength of 400 nm to 700 nm is 0.25% or less,
An incident angle with respect to the antireflection film is 45 °, and a reflectance with respect to a light beam having a wavelength of 430 nm to 670 nm is 0.4% or less,
The incident angle with respect to the antireflection film is 45 °, and the reflectance with respect to a light beam having a wavelength of 400 nm to 700 nm is 0.5% or less,
The incident angle with respect to the antireflection film is 60 °, and the reflectance with respect to a light beam having a wavelength of 430 nm to 670 nm is 2.5% or less,
The incident angle with respect to the antireflection film is 60 °, and the reflectance for light rays having a wavelength of 400 nm to 700 nm is 3.0% or less. Each of the first layer, the third layer, and the fifth layer is a film formed of any one of Ta ₂ O ₅ , TiO ₂ , ZrO ₂ , SiN, and SiON, or a mixed material thereof. The antireflection film according to any one of claims 1 to 4. 6. The second layer, the fourth layer, and the sixth layer are films formed of any one of SiO ₂ , MgF _2, and SiON, or a mixed material thereof, respectively. The antireflection film according to any one of the above. The antireflection film according to claim 1, wherein the seventh layer is formed as a porous film made of a material containing Al ₂ O ₃ . The antireflection film according to claim 1, wherein the eighth layer is a concavo-convex structure made of a material containing Al ₂ O ₃ . An optical element body as the optical substrate;
An optical element comprising the antireflection film according to claim 1, which is formed on a surface of the optical element body. An optical element according to claim 9;
An optical system comprising at least one other optical element. An optical device body;
An optical apparatus comprising: the optical system according to claim 10 housed in the optical apparatus main body.