KR102803451B1 - Imaging Lens System - Google Patents

Abstract

An imaging optical system according to one embodiment of the present invention includes a lens group including a plurality of lenses and an optical path changing means arranged between the lens group and an image surface. The lens group may include three or more lenses arranged sequentially from an object side. The optical path changing means may include a first prism and a second prism. At least one of the first prism and the second prism includes a sunshade for preventing flare.

Description

Imaging Lens System

The present invention relates to an imaging optical system including an optical path conversion means.

A long focal length imaging optical system (hereinafter referred to as a telephoto imaging optical system) is not easy to make thin and miniaturized, and thus is difficult to install in a small terminal. To solve this problem, an imaging optical system (folded imaging lens system) including an optical path changing means is being used. The aforementioned imaging optical system reduces the external size of the optical path by using a prism, and thus can be installed in a small terminal with narrow space. However, an imaging optical system including an optical path changing means may lower the resolution of the imaging optical system because unintended light may be incident to the image surface by the optical path changing means.

The present invention has been made in consideration of the above points, and its purpose is to provide an imaging optical system capable of resolving problems that may be caused by an optical path conversion means.

According to an embodiment of the present invention for achieving the above object, an imaging optical system includes a lens group including a plurality of lenses and an optical path changing means arranged between the lens group and an image surface. The lens group may include three or more lenses arranged sequentially from an object side. The optical path changing means may include a first prism and a second prism. At least one of the first prism and the second prism includes a sunshade for preventing flare.

The present invention can provide an imaging optical system capable of reducing or blocking a flare phenomenon that may be caused by an optical path changing means.

Figure 1 is a configuration diagram of an imaging optical system according to the first embodiment.
Figure 2 is a perspective view according to one form of the first prism illustrated in Figure 1.
Figure 3 is a perspective view according to one form of the second prism illustrated in Figure 1.
Figure 4 is a perspective view according to one form of the third prism illustrated in Figure 1.
FIG. 5 is an example drawing according to another shape of the entrance port (EP) and exit port (OP) shown in FIGS. 2 to 4.
Figures 6 to 8 are modified forms of the optical path conversion means illustrated in Figure 1.
Figure 9 is an aberration curve of the imaging optical system shown in Figure 1.
Figure 10 is a configuration diagram of an imaging optical system according to the second embodiment.
Figure 11 is an aberration curve of the imaging optical system shown in Figure 10.
Figure 12 is a configuration diagram of an imaging optical system according to the third embodiment.
Figure 13 is an aberration curve of the imaging optical system shown in Figure 12.
Figure 14 is a configuration diagram of an imaging optical system according to the fourth embodiment.
Figure 15 is an aberration curve of the imaging optical system shown in Figure 14.
Figure 16 is a configuration diagram of an imaging optical system according to the fifth embodiment.
Figure 17 is an aberration curve of the imaging optical system shown in Figure 16.
Figure 18 is a configuration diagram of an imaging optical system according to the sixth embodiment.
Figure 19 is an aberration curve of the imaging optical system illustrated in Figure 18.
FIG. 20 is a perspective view of an electronic device according to one embodiment.

In describing the present invention below, terms referring to components of the present invention are named in consideration of the functions of each component, and therefore should not be understood to limit the technical components of the present invention.

In addition, throughout the specification, when a component is said to be 'connected' to another component, it means not only that these components are 'directly connected', but also that they are 'indirectly connected' with other components in between. Also, when a component is said to 'include', it means that other components may be included, rather than excluding other components, unless otherwise specifically stated.

In this specification, the first lens means the lens closest to the object (or subject). In addition, the number of the lenses means the order in which they are arranged along the optical axis from the object side. For example, the second lens means the lens located second from the object side, and the third lens means the lens located third from the object side. In this specification, the units of the lens curvature radius (Radius), thickness (Thickness), TTL (the distance from the object side of the first lens to the image surface), ImgHT (the height of the image surface), and focal length are mm.

The thickness of the lens, the distance between the lenses, the TTL, and the angle of incidence are calculated sizes based on the optical axis of the imaging optical system. In addition, in the description of the shape of the lens, the meaning of a convex shape on one side means that the paraxial region of the corresponding surface is convex, and the meaning of a concave shape on one side means that the paraxial region of the corresponding surface is concave. Therefore, even if one side of the lens is described as a convex shape, the edge part of the lens may be concave. Likewise, even if one side of the lens is described as a concave shape, the edge part of the lens may be convex.

The imaging optical system described in this specification may be configured to be mounted on a portable electronic device. For example, the imaging optical system may be mounted on a smart phone (portable terminal), a laptop, an augmented reality device, a virtual reality device (VR), a portable game console, etc. However, the scope and examples of use of the imaging optical system described in this specification are not limited to the aforementioned electronic devices. For example, the imaging optical system may be applied to an electronic device that provides a narrow mounting space but requires high-resolution imaging.

The imaging optical system described in this specification can be configured to secure a long back focal length (or BFL: the distance from the image side surface of the rearmost lens to the image surface) while reducing the external size of the imaging optical system. For example, the imaging optical system according to this specification can secure a BFL necessary for implementing a telephoto imaging optical system through a reflective means while reducing the external size of the imaging optical system. As another example, the imaging optical system according to this specification can provide an image surface of a considerable size so as to enable high resolution implementation. As yet another example, the imaging optical system according to this specification can be configured in an integrated form so as to be mountable on a portable terminal while securing a long focal length and a long BFL.

In this specification, the optical path changing means may refer to any member that enables reflection of light. For example, the optical path changing means may be used to encompass all reflectors, prisms, etc. Therefore, in this specification, it is made clear that the reflectors, prisms, and optical path changing means all refer to the same configuration or are mutually replaceable configurations.

According to a first aspect of the present invention, an imaging optical system includes a lens group including a plurality of lenses, and an optical path changing means arranged between the lens group and an image surface. In the imaging optical system according to the first aspect, the lens group may include three or more lenses arranged sequentially from the object side. For example, the lens group may include a first lens, a second lens, and a third lens arranged sequentially from the object side. As another example, the lens group may include a first lens, a second lens, a third lens, and a fourth lens arranged sequentially from the object side. In the imaging optical system according to the first aspect, the optical path changing means may be composed of a plurality of members. For example, the optical path changing means may include two prisms. As another example, the optical path changing means may include three prisms. The imaging optical system according to the fourth aspect may satisfy a specific conditional expression. For example, the imaging optical system can satisfy the conditional expression 0.7 < BFL/TTL < 1.20. For reference, in the conditional expression, TTL is the distance from the object-side surface of the front-most lens (the first lens) in the lens group to the image plane, and BFL is the distance from the image-side surface of the rear-most lens in the lens group to the image plane.

In the imaging optical system according to the first form, the optical path changing means may include a plurality of reflective surfaces as necessary.

According to a second aspect of the present invention, an imaging optical system includes a lens group including a plurality of lenses, and an optical path changing means arranged between the lens group and an image surface. In the imaging optical system according to the second aspect, the lens group may include three or more lenses arranged sequentially from the object side. For example, the lens group may include a first lens, a second lens, and a third lens arranged sequentially from the object side. As another example, the lens group may include a first lens, a second lens, a third lens, and a fourth lens arranged sequentially from the object side. In the imaging optical system according to the second aspect, the optical path changing means may be composed of a plurality of members. For example, the optical path changing means may include two prisms. As another example, the optical path changing means may include three prisms. The imaging optical system according to the second aspect may satisfy a specific conditional expression. For example, the imaging optical system may satisfy the conditional expression 1.05 < TTL/f. For reference, in the conditional expression, f is the focal length of the imaging optical system.

According to a third aspect of the present invention, an imaging optical system includes a lens group including a plurality of lenses, and an optical path changing means arranged between the lens group and an image surface. In the imaging optical system according to the third aspect, the lens group may include three or more lenses arranged sequentially from the object side. For example, the lens group may include a first lens, a second lens, and a third lens arranged sequentially from the object side. As another example, the lens group may include a first lens, a second lens, a third lens, and a fourth lens arranged sequentially from the object side. In the imaging optical system according to the first aspect, the optical path changing means may be composed of a plurality of members. For example, the optical path changing means may include two prisms. As another example, the optical path changing means may include three prisms. In the imaging optical system according to the third aspect, the optical path changing means may include a means for adjusting the amount of incident light or the amount of emitted light. For example, a visor may be formed on at least one of the incident and exit surfaces of the first prism. The visor may be configured in various shapes capable of controlling the amount of incident light or the amount of exit light. For example, the aperture of the visor may be circular, elliptical, polygonal, or a combination of the shapes described above.

The imaging optical system according to the fourth aspect of the present invention can be configured to satisfy at least one of the following conditional expressions. However, the imaging optical system according to the fourth aspect does not satisfy the following conditional expressions. For example, the imaging optical system according to the first to third aspects described above can satisfy at least one of the following conditional expressions.

0.70 < BFL/TTL

10 mm < f

1.05 < TTL/f

1.60 ≤ Nmax ≤ 1.70

0.70 < BFL/f < 1.20

In the above conditional expression, BFL is the distance from the image side surface to the image surface of the rearmost lens in the lens group, and Nmax is the maximum refractive index of the lenses constituting the lens group.

The imaging optical system can satisfy some of the above-described conditions in a more limited form, as follows.

0.70 < BFL/TTL < 0.90

15.0 mm < f < 23.0 mm

1.16 < TTL/f < 1.36

The imaging optical system according to the fifth aspect of the present invention can be configured to satisfy at least one of the following conditional expressions. However, the imaging optical system according to the fifth aspect does not satisfy the following conditional expressions. For example, the imaging optical system according to the first to fourth aspects described above can satisfy at least one of the following conditional expressions.

0.10 < ImgHT/BFL < 0.13

0.60 < fF/BFL < 1.30

-1.0 < fR/BFL < -0.40

0.06 < |(fF+fR)/BFL| < 0.40

0.30 < LFS1/BFL < 0.50

0.42 < (LFS1+LRS2)/BFL < 0.74

-1.0 < fR/f < -0.50

In the above conditional expression, ImgHT is the height of the image plane, fF is the focal length of the frontmost lens arranged closest to the object in the lens group, fR is the focal length of the rearmost lens arranged closest to the image plane in the lens group, LFS1 is the radius of curvature of the object-side surface of the frontmost lens, and LRS2 is the radius of curvature of the image-side surface of the rearmost lens.

The lens group according to the first to fifth forms may have the following characteristics. For example, the frontmost lens in the lens group may have positive refractive power. For another example, the rearmost lens in the lens group may have negative refractive power.

The imaging optical system according to the first to fifth forms may include one or more lenses having the following characteristics, as needed. For example, the imaging optical system according to the first form may include one of the first lens to the fourth lens according to the following characteristics. As another example, the imaging optical system according to the second form may include two or more of the first lens to the fourth lens according to the following characteristics. However, the imaging optical system according to the above-described forms does not necessarily include the lenses according to the following characteristics.

The first lens can have refractive power. For example, the first lens can have positive refractive power. The first lens can have a convex shape on one side. For example, the first lens can have a convex shape on the object side. The first lens can have a predetermined refractive index. For example, the refractive index of the first lens can be 1.5 or greater. As a specific example, the refractive index of the first lens can be greater than 1.5 and less than 1.6. The first lens can have a predetermined Abbe number. For example, the Abbe number of the first lens can be 50 or greater. As a specific example, the Abbe number of the first lens can be greater than 50 and less than 90. The first lens can have a predetermined focal length. For example, the focal length of the first lens can be determined in a range of 10.0 mm to 22.0 mm.

The second lens can have refractive power. For example, the second lens can have positive or negative refractive power. The second lens can have a convex shape on one side. For example, the second lens can have a convex shape on the object side. The second lens can have a predetermined refractive index. For example, the refractive index of the second lens can be greater than the refractive index of the first lens. The second lens can have a predetermined Abbe number. For example, the Abbe number of the second lens can be 20 or greater.

The third lens may have refractive power. For example, the third lens may have positive or negative refractive power. The third lens may have a convex shape on one side. For example, the third lens may have a convex shape on the object side. The third lens may have a predetermined refractive index. For example, the refractive index of the third lens may be 1.5 or greater. As a specific example, the refractive index of the third lens may be greater than 1.5 and less than 1.7.

The fourth lens may have refractive power. For example, the fourth lens may have negative refractive power. The fourth lens may have a convex shape on one side. For example, the fourth lens may have a convex shape on the object-side surface. The fourth lens may have a predetermined refractive index. For example, the refractive index of the fourth lens may be 1.6 or greater. As a specific example, the refractive index of the fourth lens may be greater than 1.6 and less than 1.7. The fourth lens may have a predetermined Abbe number. For example, the Abbe number of the fourth lens may be 30 or less. As a specific example, the Abbe number of the fourth lens may be greater than 20 and less than 30. The fourth lens may have a predetermined focal length. For example, the focal length of the first lens may be determined in a range of -20.0 mm to -8.0 mm.

The aspherical surfaces of the first to fourth lenses can be expressed by mathematical expression 1. In mathematical expression 1, c is the reciprocal of the radius of curvature of the corresponding lens, k is the conic constant, r is the distance from any point on the aspherical surface to the optical axis, A to J are aspherical surface constants, and Z (or SAG) is the height in the direction of the optical axis from any point on the aspherical surface to the vertex of the corresponding aspherical surface.

The optical path conversion means according to the present invention may be formed with a structure for controlling the amount of light. For example, a light-shielding means may be formed on the incident surface and the exit surface of the optical path conversion means to block light in a portion other than the incident port and the exit port. As a specific example, an aperture may be formed on the incident surface and the exit surface of the optical path conversion means. As another example, a groove may be formed in a portion of the optical path conversion means. As yet another example, an inclined surface having a slope substantially parallel to the reflected light of the optical path conversion means may be formed in a portion of the optical path conversion means.

The electronic device according to the first aspect of the present invention may be configured in a slimmed down form for easy portability or storage. For example, the electronic device according to one aspect may be configured in the form of a smartphone, a laptop, etc. The electronic device according to one aspect may include a camera module capable of high resolution and having a long focal length. For example, the electronic device may be equipped with a camera module including one of the imaging optical systems according to the first to fourth aspects described above. However, the form of the imaging optical system constituting the camera module is not limited to the imaging optical system according to the first to fourth aspects described above.

Hereinafter, preferred embodiments of the present invention will be described in detail based on the attached exemplary drawings.

First, an imaging optical system according to a first embodiment will be described with reference to FIG. 1.

The imaging optical system (100) according to the present embodiment includes a lens group (LG) and an optical path conversion means (P). However, the configuration of the imaging optical system (100) is not limited to the above-described members. For example, the imaging optical system (100) may further include a filter (IF) and an image plane (IP). The lens group (LG) and the optical path conversion means (P) may be arranged sequentially from the object side. For example, the lens group (LG) may be arranged on the object side of the optical path conversion means (P), and the optical path conversion means (P) may be arranged between the lens group (LG) and the image plane (IP).

The components described above are described in turn below.

The lens group (LG) may include a plurality of lenses. For example, the lens group (LG) may include a first lens (110), a second lens (120), a third lens (130), and a fourth lens (140) that are sequentially arranged from the object side. The first lens (110) to the fourth lens (140) may be arranged at a predetermined interval. For example, the image side of the first lens (110) may be arranged so that it does not contact the object side of the second lens (120), and the image side of the second lens (120) may be arranged so that it does not contact the object side of the third lens (130). However, the first lens (110) to the fourth lens (140) are not necessarily arranged in a non-contact state. For example, the image side of the first lens (110) may be arranged to contact the object side of the second lens (120), or the image side of the second lens (120) may be arranged to contact the object side of the third lens (130).

The characteristics of the first lens (110) to the fourth lens (140) are described below.

The first lens (110) has positive refractive power, and has a shape in which the object side is convex and the image side is concave. The second lens (120) has negative refractive power, and has a shape in which the object side is convex and the image side is concave. The third lens (130) has positive refractive power, and has a shape in which the object side is convex and the image side is concave. The fourth lens (140) has negative refractive power, and has a shape in which the object side is convex and the image side is concave.

The following describes the optical path conversion means (P).

The optical path changing means (P) may be composed of a plurality of prisms (P1, P2, P3). For example, the optical path changing means (P) may include a first prism (P1), a first prism (P2), and a third prism (P3) sequentially arranged along the optical path. The optical path changing means (P) may include a plurality of reflective surfaces. For example, the optical path changing means (P) may include two reflective surfaces. As a specific example, the first prism (P1) and the third prism (P3) may each be formed with one reflective surface.

The optical path conversion means (P) may be configured to control the amount of incident light and the amount of emitted light. For example, the first prism (P1), the second prism (P2), and the third prism (P3) may be configured in a form in which a portion except for the incident port (EP) and the output port (OP) is covered by a light-shielding means (e.g., a light-shielding film, a light-shielding paint, etc.) as shown in FIGS. 2 to 4.

The entrance port (EP) and the exit port (OP) can be formed in various shapes by the shading means as illustrated in FIG. 5. For example, the entrance port (EP) and the exit port (OP) can be formed in a longitudinal direction as illustrated in (a) of FIG. 5. As another example, the entrance port (EP) and the exit port (OP) can be formed with wavy edges as illustrated in (b) to (e) of FIG. 5. The entrance port (EP) and the exit port (OP) formed in this manner can be advantageous in reducing the flare phenomenon.

The entrance ports (EP) and exit ports (OP) of the prisms (P1, P2, P3) may be formed to have different sizes. For example, the entrance ports (EP) of the prisms (P1, P2, P3) may be formed larger than the exit ports (OP) of the prisms (P1, P2, P3). The entrance ports (EP) and exit ports (OP) of each prism (P1, P2, P3) may be formed to have different sizes. For example, the entrance port (EP) of the first prism (P1) may be larger than the entrance port (EP) of the second prism (P2), and the entrance port (EP) of the second prism (P2) may be larger than the entrance port (EP) of the third prism (P3). As another example, the exit opening (OP) of the first prism (P1) may be larger than the exit opening (OP) of the second prism (P2), and the exit opening (OP) of the second prism (P2) may be larger than the exit opening (OP) of the third prism (P3). However, the size relationship of the entrance openings (EPs) and exit openings (OPs) of the prisms (P1, P2, and P3) is not limited to the aforementioned form. For example, the entrance openings (EPs) of the first prism (P1) to the third prism (P3) may all be formed to have the same size. As another example, the exit openings (EPs) of the first prism (P1) to the third prism (P3) may all be formed to have the same size.

A configuration for controlling the amount of light may be further arranged between the first prism (P1) and the third prism (P3). For example, an aperture may be arranged in at least one of the portions between the first prism (P1) and the second prism (P2) and between the second prism (P2) and the third prism (P3).

The optical path conversion means according to the present invention can be modified into the form shown in FIGS. 6 to 8.

First, a first modified example of the optical path conversion means will be described with reference to Fig. 6.

The optical path conversion means may be composed of one prism (P1) as illustrated in FIG. 6. The prism (P) may be configured to reduce a flare phenomenon. For example, a first groove (Pg1) and a second groove (Pg2) may be formed in some areas of the prism (P). The first groove (Pg1) may be formed in a boundary area between the second surface (PS1) and the third surface (PS2), and the second groove (Pg2) may be formed in a boundary area between the first surface (PS1) and the fourth surface (PS4). The first groove (Pg1) and the second groove (Pg2) may be formed to be generally parallel to the internally reflected light of the prism. For example, the first inclined surface (g1s1) of the first groove (Pg1) may be formed to be parallel to the light reflected by the second surface (PS2), and the second inclined surface (g1s2) of the first groove (Pg1) may be formed to be parallel to the light reflected by the first surface (PS1). As another example, the first inclined surface (g2s1) of the second groove (Pg2) may be formed to be parallel to the light reflected by the first surface (PS1), and the second inclined surface (g2s2) of the second groove (Pg2) may be formed to be parallel to the light reflected by the third surface (PS3).

Next, a second modified example of the optical path conversion means will be described with reference to Fig. 7.

The optical path conversion means may be composed of two prisms (P1, P2) as illustrated in FIG. 7. The first prism (P1) and the second prism (P2) may be arranged at a predetermined interval. For example, the distance from the exit surface of the first prism (P1) to the incident surface of the second prism (P2) may be 0.05 mm to 10 mm. The first prism (P1) and the second prism (P2) may have different optical characteristics. For example, the first prism (P1) and the second prism (P2) may have different refractive indices. As another example, the first prism (P1) and the second prism (P2) may have different Abbe numbers. The optical path conversion means composed of prisms having different optical characteristics as described above may be advantageous in improving the resolution and aberration of an imaging optical system.

The first prism (P1) and the second prism (P2) can be configured to reduce a flare phenomenon. For example, a first groove (Pg1) and a second groove (Pg2) can be formed in the first prism (P1) and the second prism (P2), respectively. The first groove (Pg1) and the second groove (Pg2) can be formed to be generally parallel to the internal reflection light of the optical path conversion means. For example, the first inclined surface (g1s1) of the first groove (Pg1) can be formed to be parallel to the light reflected by the second surface (P1S2) of the first prism (P1), and the second inclined surface (g1s2) of the first groove (Pg1) can be formed to be parallel to the light reflected by the first surface (P1S1) of the first prism (P1). As another example, the first inclined surface (g2s1) of the second groove (Pg2) may be formed to be parallel to the light reflected by the first surface (P1S1) of the first prism (P1), and the second inclined surface (g2s2) of the second groove (Pg2) may be formed to be parallel to the light reflected by the first surface (P2S1) of the second prism (P2).

Next, a third variation example of the optical path conversion means will be described with reference to Fig. 8.

The optical path conversion means may be composed of three prisms (P1, P2, P3) as illustrated in Fig. 8. The first prism (P1) to the third prism (P3) may be arranged at a predetermined interval. For example, the distance from the exit surface of the first prism (P1) to the incident surface of the second prism (P2) may be 0.05 mm to 10 mm. As another example, the distance from the exit surface of the second prism (P2) to the incident surface of the third prism (P3) may be 0.05 mm to 10 mm.

The first prism (P1) to the third prism (P3) may have different optical characteristics. For example, the first prism (P1) to the third prism (P3) may have different refractive indices. For another example, the first prism (P1) to the third prism (P3) may have different Abbe numbers. An optical path conversion means composed of prisms having different optical characteristics as described above may be advantageous in improving the resolution and aberration of an imaging optical system.

The first prism (P1) to the third prism (P3) may be configured to reduce the flare phenomenon. For example, the first prism (P1) to the third prism (P3) may each have inclined surfaces (Pc1, Pc21, Pc22, Pc3) formed thereon. The inclined surfaces (Pc1, Pc21, Pc22, Pc3) may be formed at portions where the first prism (P1) to the third prism (P3) face each other. For example, the first inclined surface (Pc1) may be formed on the exit surface side of the first prism (P1), the second inclined surface (Pc21) may be formed on the incident surface side of the second prism (P2), the third inclined surface (Pc22) may be formed on the exit surface side of the second prism (P2), and the fourth inclined surface (Pc3) may be formed on the incident surface side of the third prism (P3).

The inclined surfaces (Pc1, Pc21, Pc22, Pc3) may be formed to be generally parallel to the internal reflection light of the optical path conversion means. For example, the first inclined surface (Pc1) may be formed to be parallel to the light reflected by the reflection surface (P1SR) of the first prism (P1), the second inclined surface (Pc21) and the third inclined surface (Pc22) may be formed to be parallel to the light reflected by the reflection surface (P2SR) of the second prism (P2), and the fourth inclined surface (Pc3) may be formed to be parallel to the light reflected by the reflection surface (P3SR) of the third prism (P3).

The filter (IF) and the upper surface (IP) can be placed on the exit surface side of the prism (P).

The filter (IF) may be configured to block light of a specific wavelength. For example, the filter (IF) according to the present embodiment may be configured to block infrared rays. However, the type of light blocked by the filter (IF) is not limited to infrared rays. For example, the filter (IF) may be configured to block ultraviolet rays or visible light.

The upper surface (IP) is located at the point where light reflected from the prism (P) converges or is focused, and may be formed by an image sensor (IS), etc. For example, the upper surface (IP) may be formed on the surface or inside of the image sensor (IS).

The imaging optical system (100) configured as above can exhibit aberration characteristics of the type illustrated in Fig. 9. Tables 1 and 2 show lens characteristics and aspherical values of the imaging optical system according to the present embodiment.

Face number composition Radius of curvature Thickness/Distance Refractive index Abe's number S1 1st lens 6.3057 1.400 1.537 55.7 S2 167.727 0.300 S3 Second lens 429.758 0.600 1.668 20.4 S4 54.126 0.200 S5 3rd lens 4.7978 0.600 1.546 56.0 S6 6.3194 0.150 S7 4th lens 5.5711 0.500 1.620 25.9 S8 3.3441 1.000 S9 1st prism Infinity 2.500 1.519 64.2 S10 Infinity 3.000 1.519 64.2 S11 Infinity 0.500 S12 2nd prism Infinity 4.000 1.519 64.2 S13 Infinity 0.500 S14 Third Prism Infinity 3.000 1.519 64.2 S15 Infinity 2.500 1.519 64.2 S16 Infinity 0.500 S17 filter Infinity 0.210 1.519 64.2 S18 Infinity 0.334 S19 Top surface Infinity 0.001

Face number S1 S2 S3 S4 K -5.700E-02 -1.140E+03 -2.230E+03 2.250E+01 A -3.350E-05 1.830E-05 -8.500E-06 1.030E-05 B -1.020E-06 4.040E-07 2.890E-07 9.240E-07 C 7.380E-08 -3.130E-08 7.420E-08 2.940E-07 D 2.420E-08 -1.390E-08 1.710E-08 7.150E-08 E 4.440E-09 -4.240E-09 5.290E-09 1.230E-08 F 6.150E-10 -9.970E-10 1.470E-09 1.230E-09 G 3.680E-11 -1.620E-10 3.270E-10 -1.360E-10 H -1.520E-11 -6.190E-12 5.380E-11 -1.250E-10 J -8.190E-12 8.240E-12 3.620E-12 -4.770E-11 Face number S5 S6 S7 S8 K -1.610E-02 -1.670E-02 -3.360E-02 -2.630E-03 A -2.370E-05 2.650E-05 -3.470E-05 1.340E-05 B -3.010E-06 3.230E-06 -4.820E-06 -1.810E-05 C -8.000E-07 8.210E-07 -1.250E-06 -8.030E-06 D -2.060E-07 2.310E-07 -4.080E-07 -2.530E-06 E -4.490E-08 5.560E-08 -1.270E-07 -7.130E-07 F -8.080E-09 1.090E-08 -3.650E-08 -1.900E-07 G -1.040E-09 1.380E-09 -9.980E-09 -4.130E-08 H 8.630E-12 -1.170E-10 -2.640E-09 -9.220E-09 J 7.060E-11 -1.720E-10 -6.950E-10 -1.110E-09

An imaging optical system according to a second embodiment is described with reference to FIG. 10.

The imaging optical system (200) according to the present embodiment includes a lens group (LG) and an optical path conversion means (P). However, the configuration of the imaging optical system (200) is not limited to the above-described members. For example, the imaging optical system (200) may further include a filter (IF) and an image plane (IP). The lens group (LG) and the optical path conversion means (P) may be arranged sequentially from the object side. For example, the lens group (LG) may be arranged on the object side of the optical path conversion means (P), and the optical path conversion means (P) may be arranged between the lens group (LG) and the image plane (IP).

The components described above are described in turn below.

The lens group (LG) may include a plurality of lenses. For example, the lens group (LG) may include a first lens (210), a second lens (220), a third lens (230), and a fourth lens (240) that are sequentially arranged from the object side. The first lens (210) to the fourth lens (240) may be arranged at a predetermined interval. For example, the image side of the first lens (210) may be arranged so that it does not contact the object side of the second lens (220), and the image side of the second lens (220) may be arranged so that it does not contact the object side of the third lens (230). However, the first lens (210) to the fourth lens (240) are not necessarily arranged in a non-contact state. For example, the image side of the first lens (210) may be arranged to contact the object side of the second lens (220), or the image side of the second lens (220) may be arranged to contact the object side of the third lens (230).

The characteristics of the first lens (210) to the fourth lens (240) are described below.

The first lens (210) has positive refractive power, and has a shape in which the object side is convex and the image side is concave. The second lens (220) has positive refractive power, and has a shape in which the object side is convex and the image side is concave. The third lens (230) has positive refractive power, and has a shape in which the object side is convex and the image side is concave. The fourth lens (240) has negative refractive power, and has a shape in which the object side is convex and the image side is concave.

The following describes the optical path conversion means (P).

The optical path changing means (P) may be composed of a plurality of prisms (P1, P3). For example, the optical path changing means (P) may include a first prism (P1) and a third prism (P3) that are sequentially arranged along the optical path. The optical path changing means (P) may include a plurality of reflective surfaces. For example, the optical path changing means (P) may include two reflective surfaces. As a specific example, the first prism (P1) and the third prism (P3) may each be formed with one reflective surface.

The optical path conversion means (P) may be configured to control the amount of incident light and the amount of emitted light. For example, the first prism (P1) and the third prism (P3) may be configured in a form in which the portions except for the incident port (EP) and the output port (OP) are covered with a light-shielding film, light-shielding paint, or the like, as shown in FIGS. 2 and 4.

The filter (IF) and the upper surface (IP) can be placed on the exit surface side of the prism (P).

The filter (IF) may be configured to block light of a specific wavelength. For example, the filter (IF) according to the present embodiment may be configured to block infrared rays. However, the type of light blocked by the filter (IF) is not limited to infrared rays. For example, the filter (IF) may be configured to block ultraviolet rays or visible light.

The upper surface (IP) is located at the point where light reflected from the prism (P) converges or is focused, and may be formed by an image sensor (IS), etc. For example, the upper surface (IP) may be formed on the surface or inside of the image sensor (IS).

The imaging optical system (200) configured as above can exhibit aberration characteristics of the type illustrated in Fig. 11. Tables 3 and 4 show lens characteristics and aspherical values of the imaging optical system according to the present embodiment.

Face number composition Radius of curvature Thickness/Distance Refractive index Abe's number S1 1st lens 6.1155 1.400 1.537 55.7 S2 6680.474 0.300 S3 Second lens 137.211 0.600 1.668 20.4 S4 253.331 0.200 S5 3rd lens 5.0441 0.600 1.546 56.0 S6 7.5884 0.150 S7 4th lens 7.4045 0.500 1.620 25.9 S8 3.2403 1.000 S9 1st prism Infinity 2.500 1.519 64.2 S10 Infinity 5.000 1.519 64.2 S11 Infinity 0.500 S12 2nd prism Infinity 5.000 1.519 64.2 S13 Infinity 2.500 1.519 64.2 S14 Infinity 0.500 S15 filter Infinity 0.210 1.519 64.2 S16 Infinity 0.500 S17 Top surface Infinity 0.005

Face number S1 S2 S3 S4 K -1.210E-01 5.690E+05 -6.040E+03 7.160E+02 A -8.370E-05 3.530E-05 -4.450E-05 5.350E-05 B 1.090E-06 -2.350E-06 -2.530E-06 8.370E-06 C 2.610E-07 -8.660E-07 2.120E-07 7.060E-07 D -1.450E-08 -1.580E-07 8.120E-08 6.300E-08 E -8.590E-09 -2.620E-08 1.630E-08 8.770E-09 F -1.650E-09 -4.250E-09 2.660E-09 1.790E-09 G -2.350E-10 -6.450E-10 3.370E-10 3.720E-10 H -3.140E-11 -7.840E-11 1.330E-11 6.490E-11 J -5.150E-12 -2.740E-12 -1.170E-11 7.420E-12 Face number S5 S6 S7 S8 K -7.470E-02 -1.420E-01 1.410E-01 -9.750E-02 A -9.190E-05 -4.400E-05 8.250E-05 -5.580E-04 B -2.720E-05 1.540E-05 -1.230E-05 -5.440E-05 C -3.400E-06 1.670E-06 -1.340E-06 -1.560E-05 D -4.370E-07 1.640E-07 -1.480E-07 -3.940E-06 E -6.870E-08 3.270E-08 -4.350E-08 -7.510E-07 F -1.240E-08 8.110E-09 -1.340E-08 -1.010E-07 G -2.150E-09 1.070E-09 -2.570E-09 7.350E-10 H -2.800E-10 -3.020E-10 -7.570E-12 2.800E-09 J 2.000E-12 -2.910E-10 2.380E-10 1.050E-09

An imaging optical system according to a third embodiment is described with reference to FIG. 12.

The imaging optical system (300) according to the present embodiment includes a lens group (LG) and an optical path conversion means (P). However, the configuration of the imaging optical system (300) is not limited to the above-described members. For example, the imaging optical system (300) may further include a filter (IF) and an image plane (IP). The lens group (LG) and the optical path conversion means (P) may be arranged sequentially from the object side. For example, the lens group (LG) may be arranged on the object side of the optical path conversion means (P), and the optical path conversion means (P) may be arranged between the lens group (LG) and the image plane (IP).

The components described above are described in turn below.

The lens group (LG) may include a plurality of lenses. For example, the lens group (LG) may include a first lens (310), a second lens (320), and a third lens (330) that are sequentially arranged from the object side. The first lens (310) to the third lens (330) may be arranged at a predetermined interval. For example, the image side of the first lens (310) may be arranged so that it does not contact the object side of the second lens (320), and the image side of the second lens (320) may be arranged so that it does not contact the object side of the third lens (330). However, the first lens (310) to the third lens (330) are not necessarily arranged in a non-contact state. For example, the image side of the first lens (310) may be arranged so that it contacts the object side of the second lens (320), or the image side of the second lens (320) may be arranged so that it contacts the object side of the third lens (330).

The characteristics of the first lens (310) to the third lens (330) are described below.

The first lens (310) has positive refractive power, and has a shape in which the object side is convex and the image side is concave. The second lens (320) has positive refractive power, and has a shape in which the object side is convex and the image side is concave. The third lens (330) has negative refractive power, and has a shape in which the object side is convex and the image side is concave.

The following describes the optical path conversion means (P).

The optical path changing means (P) may be composed of a plurality of prisms (P1, P2, P3). For example, the optical path changing means (P) may include a first prism (P1), a first prism (P2), and a third prism (P3) sequentially arranged along the optical path. The optical path changing means (P) may include a plurality of reflective surfaces. For example, the optical path changing means (P) may include two reflective surfaces. As a specific example, the first prism (P1) and the third prism (P3) may each be formed with one reflective surface.

The optical path conversion means (P) may be configured to control the amount of incident light and the amount of emitted light. For example, the first prism (P1), the second prism (P2), and the third prism (P3) may be configured in a form in which the portions except for the incident port (EP) and the exit port (OP) are covered with a light-shielding film, light-shielding paint, or the like, as shown in FIGS. 2 to 4.

The filter (IF) and the upper surface (IP) can be placed on the exit surface side of the prism (P).

The filter (IF) may be configured to block light of a specific wavelength. For example, the filter (IF) according to the present embodiment may be configured to block infrared rays. However, the type of light blocked by the filter (IF) is not limited to infrared rays. For example, the filter (IF) may be configured to block ultraviolet rays or visible light.

The upper surface (IP) is located at the point where light reflected from the prism (P) converges or is focused, and may be formed by an image sensor (IS), etc. For example, the upper surface (IP) may be formed on the surface or inside of the image sensor (IS).

The imaging optical system (300) configured as above can exhibit aberration characteristics of the type illustrated in Fig. 13. Tables 5 and 6 show lens characteristics and aspherical values of the imaging optical system according to the present embodiment.

Face number composition Radius of curvature Thickness/Distance Refractive index Abe's number S1 1st lens 8.0938 1.400 1.537 55.7 S2 27.535 0.300 S3 Second lens 3.5912 0.600 1.546 56.0 S4 6.1365 0.150 S5 3rd lens 3.7308 0.500 1.668 20.4 S6 2.5271 1.000 S7 1st prism Infinity 2.500 1.519 64.2 S8 Infinity 3.000 1.519 64.2 S9 Infinity 0.500 S10 2nd prism Infinity 3.000 1.519 64.2 S11 Infinity 0.500 S12 Third Prism Infinity 3.000 1.519 64.2 S13 Infinity 2.500 1.519 64.2 S14 Infinity 0.500 S15 filter Infinity 0.210 1.519 64.2 S16 Infinity 0.244 S17 Top surface Infinity 0.003

Face number S1 S2 S3 K -4.830E-02 1.660E+00 -7.850E-03 A -1.510E-05 -1.140E-05 6.940E-06 B 1.160E-05 6.450E-06 -2.420E-05 C 2.550E-06 1.440E-06 -8.360E-06 D 3.650E-07 -7.670E-08 -1.780E-06 E 1.700E-08 -1.310E-07 -2.740E-07 F -1.050E-08 -4.880E-08 -2.500E-08 G -4.260E-09 -1.190E-08 7.920E-10 H -7.500E-10 -1.680E-09 2.570E-10 J 1.100E-10 2.420E-10 -5.230E-10 Face number S4 S5 S6 K -4.210E-03 3.000E-03 -9.730E-03 A 2.710E-05 -8.950E-06 -1.620E-06 B 2.360E-05 -1.400E-05 -1.080E-04 C 6.550E-06 -5.490E-06 -5.370E-05 D 1.130E-06 -1.640E-06 -1.870E-05 E 8.540E-08 -4.490E-07 -5.020E-06 F -2.270E-08 -1.240E-07 -8.430E-07 G -1.000E-08 -3.260E-08 6.310E-08 H -6.300E-10 -5.040E-09 5.860E-08 J 1.380E-09 2.540E-09 -2.770E-08

An imaging optical system according to a fourth embodiment is described with reference to FIG. 14.

The imaging optical system (400) according to the present embodiment includes a lens group (LG) and an optical path conversion means (P). However, the configuration of the imaging optical system (400) is not limited to the above-described members. For example, the imaging optical system (400) may further include a filter (IF) and an image plane (IP). The lens group (LG) and the optical path conversion means (P) may be arranged sequentially from the object side. For example, the lens group (LG) may be arranged on the object side of the optical path conversion means (P), and the optical path conversion means (P) may be arranged between the lens group (LG) and the image plane (IP).

The components described above are described in turn below.

The lens group (LG) may include a plurality of lenses. For example, the lens group (LG) may include a first lens (410), a second lens (420), and a third lens (430) that are sequentially arranged from the object side. The first lens (410) to the third lens (430) may be arranged at a predetermined interval. For example, the image side of the first lens (410) may be arranged so that it does not contact the object side of the second lens (420), and the image side of the second lens (420) may be arranged so that it does not contact the object side of the third lens (430). However, the first lens (410) to the third lens (430) are not necessarily arranged in a non-contact state. For example, the image side of the first lens (410) may be arranged so that it contacts the object side of the second lens (420), or the image side of the second lens (420) may be arranged so that it contacts the object side of the third lens (430).

The characteristics of the first lens (410) to the third lens (430) are described below.

The first lens (410) has positive refractive power, and has a shape in which the object side is convex and the image side is concave. The second lens (420) has positive refractive power, and has a shape in which the object side is convex and the image side is concave. The third lens (430) has negative refractive power, and has a shape in which the object side is convex and the image side is concave.

The following describes the optical path conversion means (P).

The optical path changing means (P) may be composed of a plurality of prisms (P1, P3). For example, the optical path changing means (P) may include a first prism (P1) and a third prism (P3) that are sequentially arranged along the optical path. The optical path changing means (P) may include a plurality of reflective surfaces. For example, the optical path changing means (P) may include two reflective surfaces. As a specific example, the first prism (P1) and the third prism (P3) may each be formed with one reflective surface.

The optical path conversion means (P) may be configured to control the amount of incident light and the amount of emitted light. For example, the first prism (P1) and the third prism (P3) may be configured in a form in which the portions except for the incident port (EP) and the output port (OP) are covered with a light-shielding film, light-shielding paint, or the like, as shown in FIGS. 2 to 4.

The filter (IF) and the upper surface (IP) can be placed on the exit surface side of the prism (P).

The filter (IF) may be configured to block light of a specific wavelength. For example, the filter (IF) according to the present embodiment may be configured to block infrared rays. However, the type of light blocked by the filter (IF) is not limited to infrared rays. For example, the filter (IF) may be configured to block ultraviolet rays or visible light.

The upper surface (IP) is located at the point where light reflected from the prism (P) converges or is focused, and may be formed by an image sensor (IS), etc. For example, the upper surface (IP) may be formed on the surface or inside of the image sensor (IS).

The imaging optical system (400) configured as above can exhibit aberration characteristics of the type illustrated in Fig. 15. Tables 7 and 8 show lens characteristics and aspherical values of the imaging optical system according to the present embodiment.

Face number composition Radius of curvature Thickness/Distance Refractive index Abe's number S1 1st lens 8.2689 1.400 1.537 55.7 S2 35.4841 0.300 S3 Second lens 3.5988 0.600 1.546 56.0 S4 5.8750 0.150 S5 3rd lens 3.7972 0.500 1.668 20.4 S6 2.5753 1.000 S7 1st prism Infinity 2.500 1.519 64.2 S8 Infinity 5.000 1.519 64.2 S9 Infinity 0.500 S10 2nd prism Infinity 5.000 1.519 64.2 S11 Infinity 2.500 1.519 64.2 S12 Infinity 0.500 S13 filter Infinity 0.210 1.519 64.2 S14 Infinity 0.097 S15 Top surface Infinity 0.003

Face number S1 S2 S3 K -3.640E-03 1.740E-01 -5.160E-03 A -2.950E-06 -3.240E-07 -1.280E-06 B 5.350E-06 5.960E-06 -1.450E-05 C 1.600E-06 1.500E-06 -5.100E-06 D 3.260E-07 1.690E-07 -1.190E-06 E 4.700E-08 -1.790E-08 -2.210E-07 F 2.660E-09 -1.640E-08 -3.170E-08 G -1.090E-09 -5.800E-09 -2.570E-09 H -4.790E-10 -1.500E-09 3.030E-10 J -9.720E-11 -2.870E-10 1.600E-10 Face number S4 S5 S6 K 5.130E-02 -6.750E-04 -7.070E-03 A 2.300E-05 5.640E-07 -1.070E-05 B 1.470E-05 -2.290E-06 -7.070E-05 C 4.680E-06 -1.820E-06 -3.400E-05 D 1.070E-06 -6.970E-07 -1.250E-05 E 1.890E-07 -2.350E-07 -3.840E-06 F 2.410E-08 -8.170E-08 -9.470E-07 G 9.610E-10 -2.870E-08 -1.530E-07 H -5.060E-10 -9.240E-09 -5.210E-09 J -1.290E-10 -2.240E-09 -9.110E-09

An imaging optical system according to the fifth embodiment is described with reference to FIG. 16.

The imaging optical system (500) according to the present embodiment includes a lens group (LG) and an optical path conversion means (P). However, the configuration of the imaging optical system (500) is not limited to the above-described members. For example, the imaging optical system (500) may further include a filter (IF) and an image plane (IP). The lens group (LG) and the optical path conversion means (P) may be arranged sequentially from the object side. For example, the lens group (LG) may be arranged on the object side of the optical path conversion means (P), and the optical path conversion means (P) may be arranged between the lens group (LG) and the image plane (IP).

The components described above are described in turn below.

The lens group (LG) may include a plurality of lenses. For example, the lens group (LG) may include a first lens (510), a second lens (520), a third lens (530), and a fourth lens (540) that are sequentially arranged from the object side. The first lens (510) to the fourth lens (540) may be arranged at a predetermined interval. For example, the image side of the first lens (510) may be arranged so that it does not contact the object side of the second lens (520), and the image side of the second lens (520) may be arranged so that it does not contact the object side of the third lens (530). However, the first lens (510) to the fourth lens (540) are not necessarily arranged in a non-contact state. For example, the image side of the first lens (510) may be arranged to contact the object side of the second lens (520), or the image side of the second lens (520) may be arranged to contact the object side of the third lens (530).

The characteristics of the first lens (510) to the fourth lens (540) are described below.

The first lens (510) has positive refractive power, and has a shape in which the object side is convex and the image side is concave. The second lens (520) has positive refractive power, and has a shape in which the object side is convex and the image side is concave. The third lens (530) has positive refractive power, and has a shape in which the object side is convex and the image side is concave. The fourth lens (540) has negative refractive power, and has a shape in which the object side is convex and the image side is concave.

The following describes the optical path conversion means (P).

The optical path changing means (P) may be composed of a plurality of prisms (P1, P3). For example, the optical path changing means (P) may include a first prism (P1) and a third prism (P3) that are sequentially arranged along the optical path. The optical path changing means (P) may include a plurality of reflective surfaces. For example, the optical path changing means (P) may include four reflective surfaces. As a specific example, the first prism (P1) and the third prism (P3) may each be formed with two reflective surfaces.

The optical path conversion means (P) may be configured to control the amount of incident light and the amount of emitted light. For example, the first prism (P1) and the third prism (P3) may be configured in a form in which the portions other than the incident area and the emitted area are covered with a light-shielding film, light-shielding paint, or the like.

The filter (IF) and the upper surface (IP) can be placed on the exit surface side of the prism (P).

The filter (IF) may be configured to block light of a specific wavelength. For example, the filter (IF) according to the present embodiment may be configured to block infrared rays. However, the type of light blocked by the filter (IF) is not limited to infrared rays. For example, the filter (IF) may be configured to block ultraviolet rays or visible light.

The upper surface (IP) is located at the point where light reflected from the prism (P) converges or is focused, and may be formed by an image sensor (IS), etc. For example, the upper surface (IP) may be formed on the surface or inside of the image sensor (IS).

The imaging optical system (500) configured as above can exhibit aberration characteristics of the type illustrated in Fig. 17. Tables 9 and 10 show lens characteristics and aspherical values of the imaging optical system according to the present embodiment.

Face number composition Radius of curvature Thickness/Distance Refractive index Abe's number S1 1st lens 6.5602 1.400 1.537 55.7 S2 79.3679 0.300 S3 Second lens 97.9657 0.600 1.668 20.4 S4 1122.997 0.200 S5 3rd lens 25.4805 0.600 1.546 56.0 S6 280.361 0.150 S7 4th lens 6.8578 0.500 1.668 20.4 S8 4.1539 1.000 S9 1st prism Infinity 1.500 1.519 64.2 S10 Infinity 3.000 1.519 64.2 S11 Infinity 3.700 1.519 64.2 S12 Infinity 0.300 S13 2nd prism Infinity 4.000 1.519 64.2 S14 Infinity 3.700 1.519 64.2 S15 Infinity 1.850 1.519 64.2 S16 Infinity 0.300 S17 filter Infinity 0.210 1.519 64.2 S18 Infinity 0.090 S19 Top surface Infinity 0.010

Face number S1 S2 S3 S4 K -2.480E-01 -5.260E+02 -2.870E+03 -3.880E+05 A -1.360E-04 7.070E-05 -2.790E-05 3.670E-06 B -9.940E-06 3.290E-06 -1.360E-07 -1.010E-06 C -6.830E-07 -6.520E-08 3.070E-07 -2.130E-07 D -4.670E-08 -5.170E-08 7.380E-08 -2.610E-08 E -3.490E-09 -9.820E-09 1.200E-08 9.620E-10 F -2.510E-10 -1.480E-09 1.610E-09 1.160E-09 G -1.550E-11 -1.860E-10 1.700E-10 2.660E-10 H -4.290E-12 -9.400E-12 1.150E-12 2.230E-11 J -2.570E-12 6.090E-12 -8.410E-12 -8.690E-12 Face number S5 S6 S7 S8 K 1.050E+00 -2.010E+02 1.790E-01 -3.640E-02 A 2.980E-05 -7.580E-05 4.940E-05 -1.170E-04 B 3.930E-06 -7.350E-06 -3.320E-06 -2.820E-07 C 4.620E-07 -6.770E-07 -2.030E-06 2.680E-06 D 7.920E-08 -1.340E-07 -4.730E-07 2.310E-07 E 8.200E-09 -2.660E-08 -1.120E-07 -1.280E-07 F -4.760E-10 -4.720E-09 -3.030E-08 -7.780E-08 G -3.780E-10 -1.090E-09 -8.660E-09 -2.240E-08 H -5.210E-11 -4.270E-10 -2.490E-09 -7.210E-09 J 1.970E-11 -1.960E-10 -7.100E-10 -1.430E-09

An imaging optical system according to the sixth embodiment is described with reference to FIG. 18.

The imaging optical system (600) according to the present embodiment includes a lens group (LG) and an optical path conversion means (P). However, the configuration of the imaging optical system (600) is not limited to the above-described members. For example, the imaging optical system (600) may further include a filter (IF) and an image plane (IP). The lens group (LG) and the optical path conversion means (P) may be arranged sequentially from the object side. For example, the lens group (LG) may be arranged on the object side of the optical path conversion means (P), and the optical path conversion means (P) may be arranged between the lens group (LG) and the image plane (IP).

The components described above are described in turn below.

The lens group (LG) may include a plurality of lenses. For example, the lens group (LG) may include a first lens (610), a second lens (620), a third lens (630), and a fourth lens (640) that are sequentially arranged from the object side. The first lens (610) to the fourth lens (640) may be arranged at a predetermined interval. For example, the image side of the first lens (610) may be arranged so that it does not contact the object side of the second lens (620), and the image side of the second lens (620) may be arranged so that it does not contact the object side of the third lens (630). However, the first lens (610) to the fourth lens (640) are not necessarily arranged in a non-contact state. For example, the image side of the first lens (610) may be arranged to contact the object side of the second lens (620), or the image side of the second lens (620) may be arranged to contact the object side of the third lens (630).

The characteristics of the first lens (610) to the fourth lens (640) are described below.

The first lens (610) has positive refractive power, and has a shape in which the object side is convex and the image side is concave. The second lens (620) has positive refractive power, and has a shape in which the object side is convex and the image side is concave. The third lens (630) has positive refractive power, and has a shape in which the object side is convex and the image side is concave. The fourth lens (640) has negative refractive power, and has a shape in which the object side is convex and the image side is concave.

The following describes the optical path conversion means (P).

The optical path changing means (P) may be composed of a plurality of prisms (P1, P3). For example, the optical path changing means (P) may include a first prism (P1) and a third prism (P3) that are sequentially arranged along the optical path. The optical path changing means (P) may include a plurality of reflective surfaces. For example, the optical path changing means (P) may include four reflective surfaces. As a specific example, the first prism (P1) and the third prism (P3) may each be formed with two reflective surfaces.

The optical path conversion means (P) may be configured to control the amount of incident light and the amount of emitted light. For example, the first prism (P1) and the third prism (P3) may be configured in a form in which the portions other than the incident area and the emitted area are covered with a light-shielding film, light-shielding paint, or the like.

The filter (IF) and the upper surface (IP) can be placed on the exit surface side of the prism (P).

The filter (IF) may be configured to block light of a specific wavelength. For example, the filter (IF) according to the present embodiment may be configured to block infrared rays. However, the type of light blocked by the filter (IF) is not limited to infrared rays. For example, the filter (IF) may be configured to block ultraviolet rays or visible light.

The upper surface (IP) is located at the point where light reflected from the prism (P) converges or is focused, and may be formed by an image sensor (IS), etc. For example, the upper surface (IP) may be formed on the surface or inside of the image sensor (IS).

The imaging optical system (600) configured as above can exhibit aberration characteristics of the type illustrated in Fig. 19. Tables 11 and 12 show lens characteristics and aspherical values of the imaging optical system according to the present embodiment.

Face number composition Radius of curvature Thickness/Distance Refractive index Abe's number S1 1st lens 6.5295 1.400 1.537 55.7 S2 71.2541 0.300 S3 Second lens 33.5535 0.600 1.668 20.4 S4 36.8741 0.200 S5 3rd lens 15.2751 0.600 1.546 56.0 S6 38.0680 0.150 S7 4th lens 5.7571 0.500 1.668 20.4 S8 3.7105 1.000 S9 1st prism Infinity 2.000 1.519 64.2 S10 Infinity 3.111 1.519 64.2 S11 Infinity 2.900 1.519 64.2 S12 Infinity 0.500 S13 2nd prism Infinity 2.900 1.519 64.2 S14 Infinity 3.800 1.519 64.2 S15 Infinity 2.440 1.519 64.2 S16 Infinity 0.300 S17 filter Infinity 0.210 1.519 64.2 S18 Infinity 0.096 S19 Top surface Infinity 0.004

Face number S1 S2 S3 S4 K -2.480E-01 -9.900E+01 -9.900E+01 -9.900E+01 A -1.730E-04 7.970E-05 -6.500E-05 4.540E-05 B -5.530E-06 -3.860E-07 -1.790E-06 3.170E-06 C 2.410E-08 -4.040E-07 8.540E-08 5.130E-07 D 1.200E-08 -6.080E-08 5.370E-08 6.010E-08 E -2.960E-09 -6.020E-09 1.320E-08 3.680E-09 F -1.130E-09 -2.540E-10 2.520E-09 -5.610E-10 G -1.850E-10 7.900E-11 3.700E-10 -2.710E-10 H -8.750E-12 3.670E-11 2.270E-11 -6.110E-11 J 5.820E-12 1.200E-11 -1.120E-11 -7.360E-12 Face number S5 S6 S7 S8 K 1.050E+00 -9.900E+01 1.790E-01 -3.640E-02 A 2.930E-05 -7.440E-05 -7.870E-07 -6.690E-05 B 5.380E-06 -7.120E-06 -7.080E-06 -1.800E-05 C 1.550E-07 1.930E-07 -3.070E-06 -3.260E-06 D 9.560E-09 8.310E-08 -6.910E-07 -1.190E-06 E 6.850E-09 8.130E-09 -1.420E-07 -3.900E-07 F 2.240E-09 -1.560E-10 -3.090E-08 -1.030E-07 G 5.210E-10 -3.150E-10 -7.320E-09 -1.670E-08 H 1.080E-10 -1.510E-10 -1.800E-09 -3.820E-09 J 2.390E-11 -7.230E-11 -4.330E-10 -1.090E-09

Tables 13 to 15 show optical characteristic values and conditional expression values of the imaging optical system according to the first to sixth embodiments described above.

note First embodiment Second embodiment Third embodiment Example 4 Example 5 Example 6 f 18.000 18.000 16.000 16.000 18.000 18.000 f1 12.161 11.395 20.818 19.717 13.225 13.282 f2 -92.715 446.972 14.629 15.554 160.555 519.879 f3 32.012 25.419 -14.060 -14.322 51.259 46.267 f4 -14.761 -9.741 - - -17.025 -17.311 TTL 21.794 21.465 19.906 20.260 23.410 23.011 BFL 18.044 17.715 16.956 17.310 19.660 19.261 ImgHT 2.100 2.100 2.100 2.100 2.400 2.400

Conditional expression First embodiment Second embodiment Third embodiment Example 4 Example 5 Example 6 BFL/TTL 0.828 0.825 0.852 0.854 0.840 0.837 f 18.000 18.000 16.000 16.000 18.000 18.000 TTL/f 1.211 1.193 1.244 1.266 1.301 1.278 Nmax 1.668 1.668 1.668 1.668 1.668 1.668 BFL/f 1.002 0.984 1.060 1.082 1.092 1.070

Conditional expression First embodiment Second embodiment Third embodiment Example 4 Example 5 Example 6 ImgHT/BFL 0.1164 0.1185 0.1238 0.1213 0.1221 0.1246 fF/BFL 0.6740 0.6432 1.2277 1.1391 0.6727 0.6896 fR/BFL -0.8180 -0.5499 -0.8292 -0.8274 -0.8660 -0.8988 |(fF+fR)/BFL| 0.1441 0.0934 0.3985 0.3117 0.1933 0.2092 LFS1/BFL 0.3495 0.3452 0.4773 0.4777 0.3337 0.3390 (LFS1+LRS2)/BFL 0.5348 0.5281 0.6264 0.6265 0.5450 0.5316 fR/f -0.8200 -0.5411 -0.8788 -0.8951 -0.9458 -0.9617

In the following, an electronic device according to the present invention is described with reference to FIG. 20.

The electronic device according to the present invention may include an imaging optical system according to one embodiment. For example, the electronic device may include one or more of the imaging optical systems according to the first to sixth embodiments. As a specific example, the electronic device may include an imaging optical system (100) according to the first embodiment.

An electronic device according to one embodiment may be a portable terminal (1000) as illustrated in FIG. 20. However, the form of the electronic device is not limited to the portable terminal (1000). For example, an electronic device according to another embodiment may be configured in the form of a notebook.

The portable terminal (1000) may include one or more camera modules (10, 20). For example, two camera modules (10, 20) may be installed at a predetermined interval on the body (1002) of the portable terminal (1000). The first camera module (10) and the second camera module (20) may be configured to capture an object in the same direction. For example, the first camera module (10) and the second camera module (20) may be mounted side by side on one side of the portable terminal (1000).

At least one of the first camera module (10) and the second camera module (20) may include an imaging optical system according to the first to fourth embodiments. For example, the first camera module (10) may include an imaging optical system (100) according to the first embodiment.

The first camera module (10) may be configured to capture an object located at a distance. To elaborate, the focal length of the first camera module (10) may be greater than the focal length of the second camera module (20).

The present invention is not limited to the embodiments described above, and those skilled in the art to which the present invention pertains can make various modifications and implement the present invention without departing from the gist of the technical idea of the present invention described in the following claims. For example, various features described in the above-described embodiments can be combined and applied to other embodiments unless the contrary description is explicitly stated.

Claims (16)

A lens group including a first lens, a second lens, a third lens, and a fourth lens arranged sequentially from the object side; and
A plurality of optical path changing means arranged between the above lens group and the image surface;
Including,
The above first lens has a concave shape on the image side,
An imaging optical system satisfying the following conditions:
0.70 < BFL/f < 1.20
(In the above conditional expression, BFL is the distance from the image side of the rearmost lens positioned closest to the image surface in the lens group to the image surface, and f is the focal length of the imaging optical system.) In the first paragraph,
The above optical path conversion means is an imaging optical system configured in a form in which a portion other than the entrance and exit ports is covered by a light blocking means. In the first paragraph,
An imaging optical system in which a structure for controlling the amount of light is formed in the above optical path conversion means. In the third paragraph,
The above structure is an imaging optical system in the form of a groove or an inclined surface. In the first paragraph,
The above optical path conversion means is an imaging optical system including an inclined surface formed parallel to the internally reflected light. In the first paragraph,
The above optical path conversion means is an imaging optical system configured to include two or more reflective surfaces. In the first paragraph,
The above first lens is an imaging optical system having a defined refractive power. delete In the first paragraph,
The above rearmost lens is an imaging optical system having negative refractive power. A lens group consisting of a first lens, a second lens, a third lens, and a fourth lens arranged sequentially from the object side; and
A plurality of optical path changing means arranged between the above lens group and the image surface;
Including,
The above first lens has a concave shape on the image side,
The above fourth lens has a convex shape on the object side,
An imaging optical system satisfying the following conditions:
1.05 < TTL/f
(In the above conditional expression, TTL is the distance from the object side of the front lens (first lens) that is placed closest to the object in the lens group to the image surface, and f is the focal length of the imaging optical system.) In Article 10,
An imaging optical system satisfying the following conditions:
0.10 < ImgHT/BFL < 0.13
(In the above conditional expression, ImgHT is the height of the upper surface, and BFL is the distance from the upper surface to the upper surface of the rearmost lens that is arranged closest to the upper surface in the lens group.) In Article 10,
An imaging optical system satisfying the following conditions:
0.6 < fF/BFL < 1.30
(In the above conditional expression, fF is the focal length of the frontmost lens, and BFL is the distance from the image side of the rearmost lens that is positioned closest to the image surface in the lens group to the image surface.) In Article 10,
An imaging optical system satisfying the following conditions:
-1.0 < fR/BFL < -0.40
(In the above conditional expression, fR is the focal length of the rearmost lens positioned closest to the image surface in the lens group, and BFL is the distance from the image side surface of the rearmost lens positioned closest to the image surface in the lens group to the image surface.) In Article 10,
An imaging optical system satisfying the following conditions:
0.06 < |(fF+fR)/BFL| < 0.40
(In the above conditional expression, fF is the focal length of the frontmost lens, fR is the focal length of the rearmost lens that is positioned closest to the image surface in the lens group, and BFL is the distance from the image side of the rearmost lens that is positioned closest to the image surface in the lens group to the image surface.) In Article 10,
An imaging optical system satisfying the following conditions:
0.30 < LFS1/BFL < 0.50
(In the above conditional expression, LFS1 is the radius of curvature of the object side of the frontmost lens, and BFL is the distance from the image side of the rearmost lens that is arranged closest to the image surface in the lens group to the image surface.) In Article 10,
An imaging optical system satisfying the following conditions:
0.42 < (LFS1+LRS2)/BFL < 0.74
(In the above conditional expression, LFS1 is the radius of curvature of the object-side surface of the frontmost lens, LRS2 is the radius of curvature of the image-side surface of the rearmost lens that is arranged closest to the image surface in the lens group, and BFL is the distance from the image-side surface of the rearmost lens that is arranged closest to the image surface in the lens group to the image surface.)

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