JP2010008559A - Reduction imaging optical system, illumination optical system, and surface light emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bright and telecentric wide angle lens with less distortion aberration. <P>SOLUTION: The reduction imaging optical system that forms an image of an object point on a long conjugate distance side on an imaging surface on a short conjugate distance side includes, in order from the long conjugate distance side, a diaphragm that regulates a light beam, a first lens element having biconvex shape that has positive refractive power at least in a first direction orthogonal to an optical axis near the optical axis, and has a convex surface having larger curvature facing the short conjugate distance side, and a second lens element that has positive refractive power at least in the first direction near the optical axis, and has a convex surface facing the long conjugate distance side. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a reduction imaging optical system, an illumination optical system, and a surface light emitting device, and more specifically, can be used as a relay optical system that relays light emitted from a light source unit and guides it to an illuminated area of an object. The present invention relates to a reduction imaging optical system, and an illumination optical system and a surface light emitting device using the reduction imaging optical system.

  In recent years, liquid crystal displays have been widely used as display devices for televisions and computers. However, since the liquid crystal itself does not emit light, the liquid crystal display includes a surface light emitting device (backlight) for illuminating the display surface.

A light source used in a surface light emitting device has non-uniform light distribution characteristics. Therefore, in order to make the brightness of the illuminated area uniform, the light from the light source is once incident on a uniformizing optical system such as a rod integrator, and the light emitted from the rod integrator is relayed by a relay optical system to be illuminated area. The structure leading to is known.
JP 2002-207167 A

  The relay optical system used in such an illumination optical system is required to have the following characteristics.

  First, the relay optical system is required to be a telecentric optical system in order to effectively capture the light emitted from the integrator. Second, in order to obtain uniform illumination light, it is necessary to emit light having the same intensity from the central part to the peripheral part of the optical system, and it is necessary to provide an optical system that does not squeeze the light beam in the peripheral part. Third, it is required that the distortion is small. When there is distortion, the magnification changes between the peripheral part and the central part of the optical system, so that the brightness changes. Further, when there is distortion, it is necessary to enlarge the illumination area by the amount of distortion, and the illumination efficiency is reduced.

  Further, while the screen size of the display is increased, there is a demand for thinning the device size. Therefore, even when the illumination area of the illumination optical system is large, it is required that the entire optical system can be made compact. In order to make the entire optical system compact, it is desirable that the uniformizing optical system such as the light emitting unit and the rod integrator is small. Therefore, it is necessary to increase the illumination area by increasing the magnification of the relay optical system. Become. However, if the magnification of the relay optical system is increased, the total length of the relay optical system becomes longer. Therefore, it is necessary to shorten the total length by increasing the angle of view, that is, by widening the relay optical system.

  However, when it is attempted to construct a wide-angle optical system that satisfies the above characteristics required for the relay optical system, that is, telecentric, bright, and less distorted on the reduction side, the relay optical system Since the number of lens elements constituting the lens increases, there arises a problem that the cost increases. Therefore, it is desirable that the number of lens elements required for the relay optical system is small.

  Therefore, one of the objects of the present invention is to provide a reduction imaging optical system that is bright and telecentric with little distortion.

  Another object of the present invention is to provide a compact illumination optical system and surface light emitting device that can illuminate a large illumination area brightly and uniformly.

  In order to achieve the above object, the reduction imaging optical system according to the present invention is a reduction imaging optical system that connects an image of an object point having a long conjugate distance on an imaging surface having a short conjugate distance. In order from the longer conjugate distance side, the diaphragm that restricts the light beam, and has a positive refractive power in the first direction orthogonal to the optical axis at least in the vicinity of the optical axis, and has a large curvature on the shorter conjugate distance side. A biconvex first lens element having a convex surface on one side and a second lens element having a positive refractive power in at least the first direction in the vicinity of the optical axis and having the convex surface facing the long conjugate distance side. Prepare.

  With this configuration, a wide-angle lens having a large angle of view can be obtained with a small number of lens elements. In addition, distortion, which is a problem with wide-angle lenses, can be reduced.

The reduction imaging optical system preferably satisfies the following conditions at least in the first direction.
−0.45 <P ₅ / P _all <0.05 (1)
0.8 <P ₃₄ / P _all + 0.4 × P ₅ / P _all <1.2 (2)
here,
P ₃₄ : Combined power of surface power on the short conjugate distance side of the first lens element and surface power on the long conjugate distance side of the second lens element P ₅ : Short conjugate distance on the second lens element Surface power on the side P _all : The total power of the reduction imaging optical system.

  Each of the first and second lens elements is an anamorphic lens having a positive refractive power only in a first direction orthogonal to the optical axis, and is refracted in a second direction orthogonal to the optical axis and the first direction. It is preferable not to have force.

  The second lens element preferably has a meniscus shape.

  If comprised in this way, it can utilize for the illumination optical system which illuminates a wide to-be-illuminated area | region.

The reduction imaging optical system preferably satisfies the following conditions.
−2.0 <(D0 + D1) / R3 <−1.2 (3)
here,
D0: Distance between the stop and the first lens element on the optical axis D1: Center thickness of the first lens element R3: Radius of curvature on the short conjugate distance side of the first lens element.

  If comprised in this way, concentricity will become favorable and will be advantageous to aberration correction.

  The first lens element preferably includes at least one aspheric surface.

  If comprised in this way, spherical aberration can be correct | amended favorably.

  More preferably, the first lens element includes at least one aspheric surface having at least one inflection point.

  If comprised in this way, spherical aberration can be corrected more favorably.

  The second lens element preferably includes at least one aspheric surface.

  If comprised in this way, a distortion aberration can be correct | amended favorably.

  More preferably, the second lens element includes at least one aspheric surface having at least one inflection point.

  If comprised in this way, a distortion aberration can be corrected more favorably.

  Preferably, the first lens element includes an aspheric surface on the side with a long conjugate distance, and the second lens element includes an aspheric surface on the side with a short conjugate distance.

  With this configuration, both spherical aberration and distortion can be corrected satisfactorily.

  Preferably, the first lens element includes an aspheric surface having at least one inflection point on the long conjugate distance side, and the second lens element includes an aspheric surface on the short conjugate distance side.

  With this configuration, both spherical aberration and distortion can be corrected more favorably.

  In the reduction imaging optical system, it is preferable that the side having a short conjugate distance has telecentricity.

  In order to achieve the above object, an illumination optical system according to the present invention is an illumination optical system that guides light emitted from a light source to illuminate an illuminated area of an object, and emits light emitted from the light source. A homogenizing optical system that emits light having a uniform intensity distribution and a uniform imaging optical system that relays the light emitted from the homogenizing optical system and guides it to the illuminated area.

  If comprised in this way, since the distance between the object images of the reduction | decrease imaging optical system which functions as a relay optical system can be made small, it becomes possible to comprise an illumination optical system compactly.

  You may further provide the Fresnel lens arrange | positioned in the focal position vicinity of the long conjugate distance of a reduction image formation optical system.

  With this configuration, telecentricity can be imparted also to the side having a long conjugate distance, so that a telecentric illumination optical system can be configured on both sides.

  In order to achieve the above object, a surface light emitting device according to the present invention includes a surface light emitting panel that emits light incident from an incident surface from an output surface, and a light source unit that emits light having a uniform intensity distribution. And the above-described reduced imaging optical system that relays the light emitted from the light source unit and guides it to the incident surface.

  If comprised in this way, since the distance between the object images of the reduction | decrease imaging optical system which functions as a relay optical system can be made small, it becomes possible to comprise a surface emitting device compactly.

  According to the present invention, a wide-angle lens that is well corrected for distortion, bright to the periphery, and telecentric can be configured with a small number of lens elements. In addition, by using such a wide-angle lens, it is possible to realize a compact illumination optical system and a surface emitting device that can illuminate a large illumination region brightly and uniformly.

(Embodiments 1 to 4)
1, 3, 5, and 7 are configuration diagrams of the wide-angle lens according to Embodiments 1, 2, 3, and 4. FIG. In each figure, an asterisk “*” attached to a specific surface indicates that the surface is aspheric. In each figure, “A” represents an aperture and “S” represents an image plane. The image plane S corresponds to a film or a CCD in the imaging apparatus, corresponds to an LCD that is a spatial modulation element in the projection apparatus, and corresponds to an exit end face of the rod integrator in the illumination apparatus.

  The wide-angle lens according to Embodiments 1 to 4 is a reduction imaging optical system that connects an image of an object point having a long conjugate distance on an image plane S having a short conjugate distance. In order, the aperture stop A is configured to limit a light beam, a first lens element L1 having a positive refractive power, and a second lens element L2 having a positive refractive power. The first lens element L1 has a biconvex shape in which the convex surface with the larger curvature is directed to the side with the shorter conjugate distance. In the wide-angle lens according to Embodiments 1 to 4, the second lens element L2 has a positive meniscus shape with the convex surface facing the side with the long conjugate distance.

  The first lens element mainly corrects spherical aberration, and the second lens element mainly corrects distortion. In order to provide telecentricity on the side with the short conjugate distance, the positive second lens element L2 arranged on the side with the shortest conjugate distance mainly adjusts the power.

Furthermore, the wide-angle lens according to Embodiments 1 to 4 satisfies the following conditions.
−0.45 <P ₅ / P _all <0.05 (1)
0.8 <P ₃₄ / P _all + 0.4 × P ₅ / P _all <1.2 (2)
here,
P ₃₄ : Combined power of surface power on the short conjugate distance side of the first lens element and surface power on the long conjugate distance side of the second lens element P ₅ : Short conjugate distance on the second lens element Surface power on the side P _all : The total power of the reduction imaging optical system.

Condition (1) defines the surface power on the short conjugate distance side of the second lens element. When the value of P ₅ / P _all falls below the lower limit of the condition (1), the surface power on the short conjugate distance side of the second lens element L2 becomes a large negative value, so as to ensure the total power of the optical system. Since the first lens element L1 has a large positive power, the radius of curvature of the first lens element L1 becomes small and it becomes difficult to correct spherical aberration. On the other hand, if the value of P ₅ / P _all exceeds the upper limit of the condition (1), the surface power on the short conjugate distance side of the second lens element L2 becomes a large positive value, so that the field curvature and distortion aberration Correction becomes difficult.

Condition (2) is that the combined power of the surface power on the short conjugate distance side of the first lens element and the surface power on the long conjugate distance side of the second lens element, and the conjugate distance on the second lens element This defines the relationship with the surface power on the short side. If the value of P ₃₄ / P _all + 0.4 × P ₅ / P _all falls below the lower limit of condition (2) within the range of condition (1), P ₃₄ becomes smaller when P ₅ is constant, Since the surface power on the long conjugate distance side of the first lens element is increased, it is difficult to secure the peripheral light amount. On the other hand, if the value of P ₃₄ / P _all + 0.4 × P ₅ / P _all exceeds the upper limit of the condition (2) within the range of the condition (1), P ₃₄ becomes large when P ₅ is constant. Thus, since the curvature radius of the surface on the short conjugate distance side of the first lens element L1 and the curvature radius of the surface on the long conjugate distance side of the second lens element L2 are small, it is difficult to correct spherical aberration.

In addition, as for the wide angle lens which concerns on Embodiment 1-4, it is more preferable to satisfy the following conditions.
−0.4 <P ₅ / P _all <0 (1 ′)
0.9 <P ₃₄ / P _all + 0.4 × P ₅ / P _all <1.1 (2 ′)

  With such a configuration, a bright wide-angle lens can be realized with a small number of lens elements.

  In the first to fourth embodiments, in order to improve the optical performance, the surface on the side with the long conjugate distance of the first lens element L1 is an aspherical surface. Since the first lens element L1 includes at least one aspherical surface, spherical aberration can be favorably corrected. More preferably, the aspherical surface of the first lens element L1 has at least one inflection point. In this case, spherical aberration can be corrected more favorably.

  Furthermore, in Embodiments 1 to 4, the surface on the side with the short conjugate distance of the second lens element L2 is an aspherical surface. When the second lens element L2 includes at least one aspherical surface, distortion can be favorably corrected. More preferably, the aspherical surface of the second lens element L2 has at least one inflection point. In this case, the distortion can be corrected more favorably.

  The aspherical surface may be formed only on either the first lens element L1 or the second lens element L2. However, it is preferable to form an aspheric surface on both the first lens element L1 and the second lens element L2 as in Embodiments 1 to 4 because spherical aberration and distortion can be corrected simultaneously. . In this case, if an aspheric surface is formed on the side with the long conjugate distance of the first lens element L1 and the side with the short conjugate distance of the second lens element L2, spherical aberration and distortion can be corrected well.

Furthermore, the wide-angle lens according to the present invention preferably satisfies the following conditions.
−2.0 <(D0 + D1) / R3 <−1.2 (3)
here,
D0: Distance between the stop and the first lens element on the optical axis D1: Center thickness of the first lens element R3: Radius of curvature on the short conjugate distance side of the first lens element.

  Condition (3) defines the concentricity of the first lens element L1. When the value of (D0 + D1) / R3 is below the lower limit of the condition (3), it is necessary to increase the positive power of the second lens element L2 in order to obtain a required field angle. As a result, the first lens element The aberration generated in L1 cannot be corrected by the second lens element L2. In addition, since light at a large angle of view cannot pass, the brightness of the peripheral portion decreases. On the other hand, if the value of (D0 + D1) / R3 exceeds the upper limit of the condition (3), the total length of the lens becomes large, which hinders compactification.

In addition, as for the wide angle lens which concerns on Embodiment 1-4, it is more preferable to satisfy the following conditions.
−1.8 <(D0 + D1) / R3 <−1.4 (3 ′)

(Embodiment 5)
FIG. 9 is a schematic configuration diagram of an illumination optical system according to Embodiment 5 of the present invention.

  The illumination optical system 10 according to the fifth embodiment includes a homogenizing optical system 2 that receives light emitted from the light emitting element 3 serving as a light source, and a light emitted from the homogenizing optical system 2 as an illuminated area of the object. And a wide-angle lens 1 led to 5.

  The light emitting element 3 is, for example, a laser element, an LED, or a cold cathode tube, and has nonuniform light distribution characteristics. The homogenizing optical system 2 equalizes the intensity of light emitted from the light emitting element 3 and emits light having a uniform intensity distribution from the emission end face. Therefore, a uniform secondary light source surface without light source unevenness is formed on the exit end face of the uniformizing optical system 2. For the homogenizing optical system 2, for example, a rod integrator can be used.

  In the present embodiment, the light source unit 4 that emits light having a uniform intensity distribution is configured by combining the light emitting element 3 and the uniformizing optical system 2. However, the light source unit 4 may have another configuration as long as it has uniform light distribution characteristics.

  The wide-angle lens 1 is a reduction imaging optical system having the above-described configuration, and functions as a relay optical system that relays light emitted from the light source unit 4 and guides it to the incident surface. The wide-angle lens 1 enlarges and projects the secondary light source surface formed on the exit end face of the uniformizing optical system 2 onto the illuminated area 5.

  Since the illumination optical system 10 according to the present embodiment includes the wide-angle lens 1 having the above-described configuration, it is possible to uniformly illuminate a wide illuminated area. Moreover, since the distance between the object images of the relay optical system can be reduced by using the wide-angle lens 1, the illumination optical system can be made compact. Furthermore, since the illumination optical system 10 can be configured with a small number of lens elements, the cost can be reduced.

  In the present embodiment, the illumination optical system 10 including the wide-angle lens 1 and the uniformizing optical system 2 has been described. However, the light incident from the light source unit 4 and the wide-angle lens 1 and the incident surface is surface-emitted from the output surface. You may comprise a surface emitting device by combining with the surface emitting panel to be made. The surface light-emitting panel corresponds to a light guide plate or a diffusion plate, and is arranged so that its incident surface is located in the illuminated area 5 of FIG. The wide angle lens 1 relays the light emitted from the light source unit 4 to illuminate the incident surface of the surface light emitting panel.

  Also in the surface light emitting device configured as described above, the above wide angle lens is used as a relay optical system, so that a surface light emitting device having a large and bright illumination area can be realized in a compact manner.

  In the wide-angle lens, the illumination optical system, and the surface light emitting device according to each of the above embodiments, a Fresnel lens may be disposed in the vicinity of the focal position on the side having a long conjugate distance. With this configuration, telecentricity can be imparted even on the side with a long conjugate distance, so that it is possible to configure a telecentric relay optical system on both sides using the wide-angle lens according to the present invention. .

  In the wide-angle lens, the illumination optical system, and the surface light emitting device according to each of the above embodiments, one or both of the first lens element L1 and the second lens element L2 is positive only in a predetermined direction orthogonal to the optical axis. An anamorphic lens having a refractive power and not having a refractive power in a direction orthogonal to both the optical axis and the predetermined direction may be used. More specifically, all lens elements constituting the wide-angle lens may be cylindrical lenses having no refractive power in the extending direction. With this configuration, the planar light beam from the exit end face of the uniformizing optical system can be efficiently converted into a linear light flux by the wide-angle lens and irradiated to the incident end face of the surface emitting panel, so that bright surface light emission A device can be realized.

  Hereinafter, numerical examples in which the wide-angle lenses according to Embodiments 1 to 4 are specifically implemented will be described. Numerical Examples 1 to 4 correspond to Embodiments 1 to 4, respectively.

ただし、数式中の各符号の意味は以下の通りである。
Ｘ：光軸からの高さがｈの非球面上の点から、非球面頂点の接平面までの距離
ｈ：光軸からの高さ
Ｃｊ：第ｊ面の非球面頂点の曲率（Ｃｊ＝１／Ｒｊ）
Ｋｊ：第ｊ面の円錐定数
Ａｊ，ｎ：第ｊ面のｎ次の非球面係数 In each numerical example, the unit of length in the table is “mm”, and the unit of angle of view is “°”. In the surface data of each numerical example, r is a radius of curvature, d is a surface interval or thickness, nd is a refractive index with respect to the d line, and vd is an Abbe number with respect to the d line. In each numerical example, the surface marked with * is an aspheric surface, and the aspheric shape is defined by the following equation.

However, the meaning of each symbol in the mathematical formula is as follows.
X: distance from a point on the aspherical surface having a height from the optical axis to the tangent plane of the aspherical vertex h: height from the optical axis Cj: curvature of the aspherical vertex of the jth surface (Cj = 1) / Rj)
Kj: conic constant of the jth surface Aj, n: nth-order aspheric coefficient of the jth surface

  In various data of each numerical example, the total lens length represents the distance between the first surface and the image surface. The entrance pupil position represents the distance from the first surface, and the exit pupil position represents the distance from the final surface. The front principal point position and the rear principal point position represent distances from the first surface.

Further, the various data in each numerical example, P ₃₄ is calculated as follows.
P ₃₄ = P ₃ + P ₄ −d ₃₄ × P ₃ × P ₄
However,
d ₃₄ : the distance between the first lens element and the second lens element P ₃ : the surface power on the short conjugate distance side of the first lens element P ₄ : the surface power on the long conjugate distance side of the second lens element is there.

  2, 4, 6, and 8 are longitudinal aberration diagrams of the wide-angle lenses according to Numerical Examples 1, 2, 3, and 4, respectively. Each longitudinal aberration diagram shows spherical aberration (SA (mm)), astigmatism (AST (mm)), and distortion (DIS (%)) in order from the left side. In the spherical aberration diagram, the vertical axis represents the F number (indicated by F in the figure), the solid line is the d line (d-line), the short broken line is the F line (F-line), and the long broken line is the C line (C- line). In the astigmatism graph, the vertical axis represents the image height (indicated by H in the figure), the solid line represents the sagittal plane (indicated by s), and the broken line represents the meridional plane (indicated by m in the figure). To express. In the distortion diagram, the vertical axis represents the image height (indicated by H in the figure).

(Numerical example 1)
The wide-angle lens of Numerical Example 1 corresponds to Embodiment 1 shown in FIG. Table 1 shows surface data of the zoom lens system of Numerical Example 1, Table 2 shows aspheric data, and Table 3 shows various data.

Table 1 (Surface data)

Surface number rd nd vd
Surface ∞ 500
1 (Aperture) ∞ 1.42300
2 * 9.68900 5.92800 1.49178 57.2
3 -4.32500 0.80000
4 4.37600 2.00900 1.49178 57.2
5 * 9.48100 0.00000
6 ∞ 2.00851
Image plane ∞ 0.00000

Table 2 (Aspherical data)

Second side
K = -6.42090E + 01, A4 = 3.80284E-03, A6 = -9.02436E-04
5th page
K = -2.84486E + 01, A4 = 9.25453E-03, A6 = 2.00770E-04

Table 3 (various data)

Focal length 5.0442
F number 1.66584
Half angle of view 20.0000
Statue height 1.8363
Total lens length 12.1313
BF 0.00026
Entrance pupil position 0.0000
Exit pupil position -1862.1647
Front principal point position 5.0305
Rear principal point position 7.0871

(Numerical example 2)
The wide-angle lens of Numerical Example 2 corresponds to Embodiment 2 shown in FIG. Table 4 shows surface data of the zoom lens system of Numerical Example 2, Table 5 shows aspheric data, and Table 6 shows various data.

Table 4 (Surface data)

Surface number rd nd vd
Surface ∞ 500
1 (Aperture) ∞ 1.42300
2 * 6.09800 5.72200 1.49178 57.2
3 -4.76300 1.20000
4 3.42100 1.00200 1.49178 57.2
5 * 6.61500 0.00000
6 ∞ 1.83724
Image plane ∞ 0.00000

Table 5 (Aspherical data)

Second side
K = -8.43571E + 00, A4 = 2.40212E-03, A6 = -3.78711E-04
5th page
K = -1.88688E + 01, A4 = 1.35310E-02, A6 = -1.19183E-04

Table 6 (various data)

Focal length 5.0384
F number 1.66613
Half angle of view 20.0000
Statue height 1.8360
Total lens length 11.1466
BF -0.00045
Entrance pupil position 0.0000
Exit pupil position -2086.7772
Front principal point position 5.0262
Rear principal point position 6.1082

(Numerical Example 3)
The wide-angle lens of Numerical Example 3 corresponds to Embodiment 3 shown in FIG. Table 7 shows surface data of the zoom lens system of Numerical Example 3, Table 8 shows aspheric data, and Table 9 shows various data.

Table 7 (Surface data)

Surface number rd nd vd
Surface ∞ 500
1 (Aperture) ∞ 1.42300
2 * 10.65400 5.26100 1.49178 57.2
3 -4.08600 2.34200
4 4.69700 1.00000 1.49178 57.2
5 * 2500.00000 0.00000
6 ∞ 1.86451
Image plane ∞ 0.00000

Table 8 (Aspherical data)

Second side
K = 1.68737E + 01, A4 = -5.17321E-03, A6 = -5.88669E-04
5th page
K = -1.77529E + 03, A4 = 4.60295E-03, A6 = -9.78945E-05

Table 9 (various data)

Focal length 5.0382
F number 1.73354
Angle of View 20.0526
Statue height 1.8350
Total lens length 11.8905
BF 0.01451
Entrance pupil position 0.0000
Exit pupil position 23.2561
Front principal point position 6.1280
Rear principal point position 6.8016

(Numerical example 4)
The wide-angle lens of Numerical Example 4 corresponds to Embodiment 4 shown in FIG. Table 10 shows surface data of the zoom lens system of Numerical Example 4, Table 11 shows aspheric data, and Table 12 shows various data.

Table 10 (Surface data)

Surface number rd nd vd
Surface ∞ 500
1 (Aperture) ∞ 1.42300
2 * 13.56200 5.41500 1.49178 57.2
3 -4.02700 2.63300
4 4.25100 1.00000 1.49178 57.2
5 * 191.25500 0.00000
6 ∞ 1.86426
Image plane ∞ 0.00000

Table 11 (Aspherical data)

Second side
K = 3.05779E + 01, A4 = -5.13649E-03, A6 = -6.40470E-04
5th page
K = -5.00000E + 03, A4 = 4.44826E-03, A6 = -1.21236E-04

Table 12 (various data)

Focal length 5.0379
F number 1.73195
Angle of View 20.0695
Statue height 1.8350
Total lens length 12.3353
BF 0.00026
Entrance pupil position 0.0000
Exit pupil position 16.6207
Front principal point position 6.5604
Rear principal point position 7.2467

  The corresponding values of the conditions (1), (2), and (3) in the wide-angle lens according to each numerical example are shown in Table 13 below.

Table 13 (corresponding values of conditions)

  The wide-angle lens according to the present invention can be used as, for example, a relay optical system used in a surface light emitting device.

Configuration diagram of wide-angle lens according to Embodiment 1 (Example 1) Longitudinal aberration diagram of the wide-angle lens according to Example 1 Configuration diagram of wide-angle lens according to Embodiment 2 (Example 2) Longitudinal aberration diagram of the wide-angle lens according to Example 2 Configuration diagram of wide-angle lens according to Embodiment 3 (Example 3) Longitudinal aberration diagram of the wide-angle lens according to Example 3 Configuration diagram of wide-angle lens according to Embodiment 4 (Example 4) Longitudinal aberration diagram of the wide-angle lens according to Example 4 Schematic configuration diagram of illumination optical system according to Embodiment 5

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wide angle lens 2 Uniformization optical system 3 Light emitting element 4 Light source part 5 Illuminated area 10 Illumination optical system

Claims (15)

A reduction imaging optical system that connects an image of an object point having a long conjugate distance on an imaging surface having a short conjugate distance,
From the longest conjugate distance,
An aperture to limit the rays,
A biconvex first lens element having a positive refractive power at least in a first direction orthogonal to the optical axis in the vicinity of the optical axis and having a convex surface having a larger curvature on the side having a shorter conjugate distance;
A reduction coupling optical system comprising: a second lens element having a positive refractive power in at least the first direction in the vicinity of the optical axis and having a convex surface facing the long conjugate distance side. The reduced imaging optical system according to claim 1, wherein the following condition is satisfied at least in the first direction:
−0.45 <P ₅ / P _all <0.05 (1)
0.8 <P ₃₄ / P _all + 0.4 × P ₅ / P _all <1.2 (2)
here,
P ₃₄ : Combined power of surface power on the short conjugate distance side of the first lens element and surface power on the long conjugate distance side of the second lens element P ₅ : Short conjugate distance on the second lens element Surface power on the side P _all : The total power of the reduction imaging optical system.   Each of the first and second lens elements is an anamorphic lens having a positive refractive power only in a first direction orthogonal to the optical axis, and in the second direction orthogonal to the optical axis and the first direction. The reduced-magnification imaging optical system according to claim 1 or 2, characterized in that has no refractive power.   The reduced image-forming optical system according to claim 1, wherein the second lens element has a meniscus shape. The reduced imaging optical system according to claim 1, wherein the following condition is satisfied:
−2.0 <(D1 + D2) / R3 <−1.2 (3)
here,
D1: Distance between the diaphragm and the first lens element on the optical axis D2: Center thickness of the first lens element R3: Radius of curvature on the short conjugate distance side of the first lens element   The reduced image-forming optical system according to claim 1, wherein the first lens element includes at least one aspheric surface.   6. The reduction imaging optical system according to claim 1, wherein the first lens element includes at least one aspheric surface having at least one inflection point.   6. The reduction imaging optical system according to claim 1, wherein the second lens element includes at least one aspheric surface.   6. The reduction imaging optical system according to claim 1, wherein the second lens element includes at least one aspheric surface having at least one inflection point. The first lens element includes an aspherical surface on the long conjugate distance side,
6. The reduction imaging optical system according to claim 1, wherein the second lens element includes an aspheric surface on a side having a short conjugate distance. The first lens element includes an aspherical surface having at least one inflection point on a long conjugate distance side,
6. The reduction imaging optical system according to claim 1, wherein the second lens element includes an aspheric surface on a side having a short conjugate distance.   12. The reduction imaging optical system according to claim 1, wherein a side having a short conjugate distance has telecentricity. An illumination optical system that guides light emitted from a light source to illuminate an illuminated area of an object,
Uniformizing light emitted from the light source and emitting light having a uniform intensity distribution; and
An illumination optical system comprising: the reduced imaging optical system according to any one of claims 1 to 12, which relays light emitted from the homogenization optical system and guides the light to the illuminated region.   The illumination optical system according to claim 13, further comprising a Fresnel lens disposed in the vicinity of a focal position on the longer conjugate distance side of the reduced imaging optical system. A surface emitting device,
A surface emitting panel for emitting light incident from the incident surface from the exit surface;
A light source unit that emits light having a uniform intensity distribution;
A surface light-emitting device comprising: the reduced imaging optical system according to claim 1, wherein the light emitted from the light source unit is relayed and guided to the incident surface.

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