TW201800796A - Optical lens - Google Patents

Abstract

An optical lens includes a first lens group, a second lens group and an aperture stop between the first lens group and the second lens group. The first lens group has negative refractive power and a number of lenses with refractive power of less than three. The second lens group has positive refractive power and a number of lenses with refractive power of less than five, and the second lens group has at least one aspheric lens with a diffraction surface. The optical lens satisfies the condition: 0 < |([psi]d*V)/[psi]r| < 2, where [Phi] d denotes refractive power of the diffraction surface, [Phi] r denotes refractive power of the lens with the diffraction surface, and V denotes the Abbe number of the lens with the diffraction surface.

Description

Optical lens

The present invention relates to an optical lens having a diffractive element and day and night confocal performance.

In recent years, the cameras for smart home surveillance have become more and more prosperous, and the requirements for thinning and optical performance are getting higher and higher. To meet the needs of such lenses, it is generally required to have low cost, large aperture, wide viewing angle, light weight and day and night confocal features. Therefore, there is an urgent need for an image taking lens design that can achieve both light weight and day and night confocal, and can provide lower manufacturing cost and better image quality.

Other objects and advantages of the present invention will be further understood from the technical features disclosed in the embodiments of the present invention.

An embodiment of the present invention provides an optical lens including a first lens group having a negative refracting power and a second lens group having a positive refracting power, and an aperture disposed between the first lens group and the second lens group, the first lens group and The second lens group is sequentially disposed from a direction in which the first lens group includes a number of lenses having a diopter of less than 3, the second lens group includes a lens having a diopter number less than 5, and the second lens group includes a lens having a diffraction surface And the lens of the diffraction surface meets the following conditions: 0<|(Ød*V)/Ør|<2 Where Φd, Φr and V are the diffractive surface diopter, refractive refracting power and Abbe number of the diffraction surface lens, respectively.

With the design of the embodiment of the present invention, an optical lens design capable of achieving both weight reduction and day and night confocal, and providing lower manufacturing cost and better image quality can be provided.

Other objects and advantages of the present invention will become apparent from the technical features disclosed herein. The above and other objects, features, and advantages of the invention will be apparent from

10a-10b‧‧‧Optical lens

12‧‧‧ optical axis

14‧‧‧ aperture

16‧‧‧glass cover

18‧‧‧ imaging plane

20‧‧‧First lens group

30‧‧‧Second lens group

L1-L5‧‧ lens

S1-S13‧‧‧ surface

1 is a schematic view of an optical lens 10a according to an embodiment of the present invention.

2 to FIG. 5 are imaging optical simulation data diagrams of the optical lens of FIG. 1, wherein FIG. 2-3 are light ray diagrams of visible light and 850 nm infrared light, respectively, and FIG. 4-5 is 587 nano green light and 850, respectively. The diffraction optical transfer function curve of nano infrared light.

FIG. 6 is a schematic view of an optical lens 10b according to another embodiment of the present invention.

7 to FIG. 10 are imaging optical simulation data diagrams of the optical lens of FIG. 6, wherein FIG. 7-8 are light ray diagrams of visible light and 850 nm infrared light, respectively, and FIG. 9-10 is 587 nano green light and 850, respectively. The diffraction optical transfer function curve of nano infrared light.

The above and other technical contents, features and advantages of the present invention will be apparent from the following detailed description of the embodiments of the invention. The directional terms mentioned in the following embodiments, such as up, down, left, right, front or back, etc., are only directions referring to the additional drawings. Therefore, the directional terminology used is for the purpose of illustration and not limitation.

上述的公式(1)中，Z為光軸方向之偏移量(sag)，c是密切球面 (osculating sphere)的半徑之倒數，也就是接近光軸處的曲率半徑的倒數，k是二次曲面係數(conic)，r是非球面高度，即為從透鏡中心往透鏡邊緣的高度。表二的A-D分別代表非球面多項式的4階項、6階項、8階項、10階項係數值。於本發明如下的各個設計實例中，繞射面多項式可用下列公式表示：

上述的公式(2)中，

(r)為繞射元件(diffractice optical element)的相位函數(phase)，r是與光學鏡頭光軸的徑向距離(radial distance)，λ ₀是參考波長(reference wavelength)，也就是說繞射面(diffractice optical surface)為透鏡表面加上相位函數(phase)。表三的C1-C2分別代表繞射面多項式的2階項、4階項係數值。 1 is a schematic view showing an optical lens 10a according to an embodiment of the present invention. The optical lens 10a is disposed between an enlarged side (left side of FIG. 1; for example, an object side) and a reduced side (right side of FIG. 1; for example, an image side). As shown in FIG. 1, the optical lens 10a includes a first lens group (for example, a front group) 20 having a negative refracting power and located between the magnification side and the reduction side, having a positive refracting power and located between the first lens group 20 and the reduction side. A second lens group (for example, a rear group) 30 and an aperture 14 located in the second lens group 30. Furthermore, the reduction side can be provided with a glass cover 16 and an image sensor, the imaging plane of the visible light effective focal length of the optical lens 10a is indicated as 18, and the glass cover 16 is located between the second lens group 30 and the imaging plane 18 on the effective focal length of visible light. . The first lens group 20 may include a first lens L1 and a second lens L2 which are sequentially arranged along the optical axis 12 of the optical lens 10a from the magnification side to the reduction side, and the second lens group 30 may include the optical lens 10a. A third lens L3, a fourth lens L4, and a fifth lens L5 are sequentially arranged from the magnification side to the reduction side, and the diopter of the first lens L1 to the fifth lens L5 are negative, positive, positive, respectively. Negative, positive. In this embodiment, the fourth lens L4 may be an aspherical lens including a diffraction surface, the first lens L1, the second lens L2, and the fifth lens L5 are aspherical lenses, and the third lens L3 is a lenticular lens. In addition, the first lens L1 to the fifth lens L5 are separated from each other by two. In an embodiment, the two adjacent sides of the two lenses have the same radius of curvature and form a cemented lens, which is not limited by the embodiment of the present invention. The lens design parameters, the shape, the aspherical coefficient and the diffraction surface of the optical lens 10a are respectively shown in Table 1, Table 2 and Table 3. In the following design examples of the present invention, the aspherical polynomial can be expressed by the following formula:

In the above formula (1), Z is the offset (sag) in the optical axis direction, c is the reciprocal of the radius of the osculating sphere, that is, the reciprocal of the radius of curvature near the optical axis, and k is twice The surface coefficient (conic), r is the aspherical height, which is the height from the center of the lens to the edge of the lens. The AD of Table 2 represents the 4th order term, the 6th order term, the 8th order term, and the 10th order term coefficient value of the aspherical polynomial, respectively. In each of the following design examples of the present invention, the diffractive surface polynomial can be expressed by the following formula:

In the above formula (2),

(r) is the phase function of the diffractory optical element, r is the radial distance from the optical axis of the optical lens, and λ ₀ is the reference wavelength, that is, the diffraction A diffractice optical surface adds a phase to the lens surface. C1-C2 of Table 3 represent the 2nd order and 4th order coefficient values of the diffractive surface polynomial, respectively.

The spacing of S1 is the distance of the surfaces S1 to S2 on the optical axis 12, the spacing of S2 is the distance of the surfaces S2 to S3 on the optical axis 12, and the spacing of S13 is the effective focal length of the glass cover S13 to the visible light. The imaging plane 18 is on the optical axis 12. distance

EFL of visible light = 3.984mm

Infrared effective focal length (EFL of NIR 850nm light) = 3.981mm

Aperture value (F-Number) = 2.0

Max.field of view (FOV) = 103.2 degrees

The maximum imaging circle of the imaging plane on the effective focal length of visible light (Max. Image Circle, IMA) = 7.54 mm

Total track length (TTL, distance from S1 to the imaging plane on the effective focal length of visible light) = 23.5mm

Figure 2-3 shows the ray fan plot of visible light and 850 nm infrared light, where the X-axis is the position where the light passes through the pupil, and the Y-axis is the main ray projected onto the image plane (eg, imaging plane 18). The relative value of the position. 4 to FIG. 5 are imaging optical simulation data diagrams of the optical lens 10a of the present embodiment, wherein FIG. 4-5 is a diffraction transfer function of 587 nm green light and 850 nm infrared light, respectively. MTF), the focal plane offset of both is about 7 microns. It should be noted that the 555 nm green light can also be used instead of the 587 nm green light to draw an imaging optical simulation data map. The graphs shown in Fig. 2-5 of the simulation data are all within the standard range, thereby verifying that the optical lens 10a of the present embodiment can indeed have both good optical imaging quality and day/night confocal characteristics.

The optical lens of this embodiment may include two lens groups and the aperture value may be 2.0. The optical lens may include a piece of aspherical lens having a diffraction surface to correct aberrations and chromatic aberrations. Furthermore, the following conditions can be satisfied: -2<(Ød*V)/Ør<0---(3)

20<V<60---(4)

|(0.5*IMA)/(EFL*TAN(X))-1|<0.3---(5)

TTL/IMA<3.3---(6)

Where Φd is the diffractive surface (S8) diopter, which is C1/(-0.5) in Table 3, Φr is the refractive power of the aspherical lens (L4), and V is the Abbe number of the aspherical lens (L4), EFL For the effective focal length of the visible light of the lens, IMA is the maximum imaging circle of the imaging plane on the effective focal length of visible light, X is 1/2 of the maximum angle of view, and TTL is the total length of the lens (S1 to visible visible light) The distance from the upper imaging plane). Specifically, it is assumed that the optical lens of the present embodiment is designed to conform to (Ød*V)/Ør<-2, and the diffracting power is large at this time, and the number of turns of the diffraction microstructure is large, making it difficult to manufacture. Furthermore, if the optical lens of the present embodiment is designed to conform to |(0.5*IMA)/(EFL*TAN(X))-1|>0.3, the image deformation amount on the imaging plane on the effective focal length of visible light is large. If the optical lens of the present embodiment is designed to comply with TTL/IMA>3.3, the lens volume is relatively large, which is disadvantageously miniaturized. Therefore, the optical lens of the embodiment is designed to meet the conditions of the formulas (3), (4), (5), and (6), so that the optical lens has good optical imaging quality, low manufacturing difficulty, and day and night confocal. characteristic.

FIG. 6 is a schematic view showing an optical lens 10b according to another embodiment of the present invention. The optical lens 10b is disposed between an enlarged side (left side of FIG. 6; for example, an object side) and a reduced side (right side of FIG. 6; for example, an image side). As shown in FIG. 6, the optical lens 10b includes a first lens group (for example, a front group) 20 having a negative refracting power and located between the magnification side and the reduction side, having a positive refracting power and located between the first lens group 20 and the reduction side. A second lens group (for example, a rear group) 30 and an aperture 14 located in the second lens group 30. Furthermore, the reduction side can be provided with a glass cover 16 and an image sensor, the imaging plane of the visible light effective focal length of the optical lens 10b is indicated as 18, and the glass cover 16 is located between the second lens group 30 and the imaging plane 18 on the effective focal length of visible light. . The first lens group 20 may include a first lens L1 and a second lens L2 which are sequentially arranged along the optical axis 12 of the optical lens 10b from the magnification side to the reduction side, and the second lens group 30 may include the optical lens 10b. A third lens L3, a fourth lens L4, and a fifth lens L5 are sequentially arranged from the magnification side to the reduction side, and the diopter of the first lens L1 to the fifth lens L5 are negative, positive, positive, respectively. Negative, positive. In the embodiment, the fifth lens L5 may be an aspherical lens including a diffraction surface, the first lens L1, the second lens L2, and the fourth lens L4 are aspherical lenses, and the third lens L3 is a lenticular lens. In addition, the first lens L1 to the fifth lens L5 are separated from each other by two. In a real In the embodiment, the two adjacent sides of the two lenses have the same radius of curvature and form a cemented lens, which is not limited by the embodiment of the present invention. The lens design parameters, shape, aspherical coefficient and diffraction surface of the optical lens 10b are shown in Table 4, Table 5 and Table 6, respectively, wherein the AD of Table 5 represents the 4th order of the aspheric polynomial (as shown in Equation 1). Item, 6th order, 8th order, 10th order coefficient value. C1-C2 of Table 6 represent the 2nd order and 4th order coefficient values of the diffractive surface polynomial (as shown in Equation 2).

The pitch of S1 is the distance of the surfaces S1 to S2 on the optical axis 12, the pitch of S2 is the distance of the surfaces S2 to S3 on the optical axis 12, and the pitch of S13 is the distance from the surface of the glass cover S13 to the imaging plane 18 at the optical axis 12.

EFL of visible light = 3.883mm

Infrared effective focal length (EFL of NIR 850nm light) = 3.876mm

Aperture value (F-Number) = 2.0

Maximum field of view (FOV) = 104.9 degrees

The maximum imaging circle of the imaging plane on the effective focal length of visible light (Max. Image circle, IMA) = 7.54 mm

Total track length (TTL, distance from S1 to the imaging plane on the effective focal length of visible light) = 23.5mm

Figure 7-8 shows the ray fan plot of visible light and 850 nm infrared light, where the X-axis is the position where the light passes through the pupil, and the Y-axis is the main ray projected onto the image plane (eg, imaging plane 18). The relative value of the position. 9 to FIG. 10 are imaging optical simulation data diagrams of the optical lens 10b of the present embodiment, wherein FIG. 9-10 is a diffraction optical transfer function curve of 587 nanometer green light and 850 nanometer infrared light, respectively. (modulation transfer function, MTF), the focal plane offset of both is about 1 micron. It should be noted that the 555 nm green light can also be used instead of the 587 nm green light to draw an imaging optical simulation data map. The graphs shown in the simulated data graphs of Figures 7-10 are all within the standard range, thereby verifying that the optical lens 10b of the present embodiment can indeed have both good optical imaging quality and day and night confocal characteristics.

The optical lens of this embodiment may include two lens groups and the aperture value may be 2.0. The optical lens may include a piece of aspherical lens having a diffraction surface to correct aberrations and chromatic aberrations. Furthermore, the following conditions can be satisfied: 0 < (Ød * V) / Ør < 2--- (7)

20<V<60---(4)

|(0.5*IMA)/(EFL*TAN(X))-1|<0.3---(5)

TTL/IMA<3.3---(6)

Where Φd is the diffractive surface (S11) diopter, which is C1/(-0.5) in Table 6, Φr is the refractive power of the aspherical lens (L5), V is the Abbe number of the aspherical lens (L5), EFL For the effective focal length of the visible light of the lens, IMA is the maximum imaging circle of the imaging plane on the effective focal length of visible light, X is 1/2 of the maximum angle of view, and TTL is the total length of the lens (the distance from the imaging plane on the effective focal length of visible light from S1). Specifically, it is assumed that the optical lens of the present embodiment is designed to conform to (Ød*V)/Ør>2, and the diffracting power is large at this time, and the number of turns of the diffraction microstructure is large, making it difficult to manufacture. Furthermore, if the optical lens of the present embodiment is designed to conform to |(0.5*IMA)/(EFL*TAN(X))-1|>0.3, the amount of image distortion on the visible light effective focal length imaging plane is large. If the optical lens of the present embodiment is designed to comply with TTL/IMA>3.3, the lens volume is relatively large, which is disadvantageously miniaturized. Therefore, the optical lens of the embodiment is designed to meet the conditions of the formulas (4), (5), (6), and (7), so that the optical lens has good optical imaging quality, low manufacturing difficulty, and day/night confocal. characteristic.

By the design of the embodiments 10a and 10b, it is possible to provide a light weight and day/night confocal property, and can provide a lower manufacturing cost and a better image forming product. The image pickup lens design of the present invention may further have an angle of view between 80 degrees and 110 degrees.

While the present invention has been described in its preferred embodiments, the present invention is not intended to limit the invention, and the present invention may be modified and modified without departing from the spirit and scope of the invention. The scope of protection is subject to the definition of the scope of the patent application. In addition, any of the objects or advantages or features of the present invention are not required to be achieved by any embodiment or application of the invention. In addition, the abstract sections and headings are only used to assist in the search of patent documents and are not intended to limit the scope of the invention.

10a‧‧‧Optical lens

12‧‧‧ optical axis

14‧‧‧ aperture

16‧‧‧glass cover

18‧‧‧ imaging plane

20‧‧‧First lens group

30‧‧‧Second lens group

L1-L5‧‧ lens

S1-S13‧‧‧ surface

Claims (10)

An optical lens comprising: a first lens group having a negative refracting power and a second lens group having a positive refracting power; an aperture disposed between the first lens group and the second lens group, wherein the first lens The group includes a number of lenses having a diopter of less than 3, the second lens group includes a lens having a refracting power of less than 5 and the second lens group includes a lens having a diffraction surface; and the lens having the diffraction surface conforms to the following Condition: 0<|(Ød*V)/Ør|<2, where Φd, Φr, and V are the diffractive refracting power, refractive refracting power, and Abbe number of the diffraction surface lens, respectively. An optical lens comprising: a first lens group having a negative refracting power, comprising two lenses; a second lens group having a positive refracting power, comprising three lenses, wherein one of the lenses comprises a diffraction surface, the first lens The group and the second lens group are sequentially disposed from an object side to an image side; an aperture is disposed between the first lens group and the second lens group; and the optical lens meets the following condition: | *IMA)/(EFL*TAN(X))-1|<0.3 where EFL is the visible focal length of the optical lens, IMA is the maximum imaging circle of the imaging plane on the visible focal length of the optical lens, and X is the largest of the optical lens 1/2 of the field of view. An optical lens comprising: a first lens group having a negative refracting power, the first lens group comprising a flex The number of lenses of luminosity is less than 3; a second lens group having positive diopter, the second lens group comprising a lens having a refracting power of less than 5 and the second lens group comprising a lens having a diffraction surface; an aperture, setting Between the first lens group and the second lens group; and the optical lens meets the following condition: TTL/IMA<3.3, where TTL is the total length of the optical lens, and IMA is the maximum imaging plane on the visible focal length of the optical lens circle. The optical lens according to any one of claims 1 to 3, wherein the lens having the diffraction surface meets the following condition: 20 < V < 60. The optical lens of any one of claims 1-3, wherein the first lens group has a negative refracting power and includes a positive refractive power aspherical lens and a negative refracting aspherical lens. The optical lens of any one of claims 1-3, wherein the second lens group has a positive refracting power and includes an aspherical lens having a positive refracting power and an aspherical lens having a negative refracting power. The optical lens of any one of claims 1-3, wherein the lens is an aspherical lens. The optical lens of any one of claims 1-3, wherein the lens of the second lens group closest to the aperture is a spherical lens. The optical lens of claim 8, wherein the spherical lens meets the following condition: V>70. The optical lens according to any one of claims 1-3, wherein the optical lens meets the following conditions: if a green light of 555 nm or 587 nm passes through a focal plane of the optical lens as a measurement reference The optical lens can satisfy the displacement of the 850 nm infrared light at the focal plane, which is less than 8 micrometers from the measurement reference.