Optical system for measurement and photometric and colorimetric device

Abstract

To take a larger amount of light and suppress increase in size.SOLUTION: An optical system 20 for measurement includes, in order from the object side, a first lens group LG1 including at least one lens and having positive refractive power, a second lens group LG2 including at least one lens and having positive refractive power, a first diaphragm S1, and a third lens group LG3 including at least one lens and having positive refractive power. The optical system 20 for measurement further includes a second diaphragm S2 which is arranged at least any one of the vicinity of a position of an image side focus f1 of the first lens group LG1, and vicinity of a position conjugate with the image side focus f1 of the first lens group LG1 as for the second lens group LG2 and the third lens group LG3. An absolute value of a lateral magnification of the first diaphragm S1 to a surface conjugate with the first diaphragm S1 as for the first lens group LG1 and the second lens group LG2 is 0.7 or less.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a measurement optical system that guides light from an object to be measured to a light receiving section, and a photometric and colorimetric device including the same. [Background technology]

[0002] In recent years, there has been an increasing demand for high-contrast display devices such as organic electroluminescence (EL) displays. To achieve high contrast, it is essential to improve low-luminance performance, which requires a photometric and colorimetric device that can evaluate low-luminance performance. Such a photometric and colorimetric device requires a measurement optical system that can guide a large amount of light from the object to be measured to the light receiving section.

[0003] For example, in the measurement optical system described in Patent Document 1, an aperture is placed on a plane conjugate with the surface to be measured to define the area to be measured, and the incident surface of the optical waveguide is placed at the focal point of the entire optical system to define the angle of the light beam to be captured. This reduces the amount of light that cannot enter the optical waveguide due to the large incident angle of the off-axis light beam. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2018 / 230177 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the measurement optical system described in Patent Document 1, the size of the aperture is large relative to the measurement surface, where the measurement surface and the aperture are in a conjugate relationship. Therefore, if the measurement area is to be expanded to secure a larger amount of light, the aperture must also be expanded at the same rate. As a result, the measurement optical system and therefore the entire photometric and colorimetric device become larger. An object of the present invention is to capture a larger amount of light while preventing the size from increasing. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention provides a measurement optical system, comprising: From the object side, a first lens group including at least one lens and having positive refractive power; a second lens group including at least one lens and having positive refractive power; The first aperture and a third lens group including at least one lens and having positive refractive power; Equipped with a second aperture disposed at least either near a position of an image-side focal point of the first lens group or near a position conjugate with the image-side focal point of the first lens group with respect to the second lens group and the third lens group; The absolute value of the lateral magnification of the first aperture with respect to a surface conjugate with the first aperture with respect to the first lens group and the second lens group is 0.7 or less. Effect of the Invention

[0007] According to the present invention, it is possible to take in a larger amount of light while preventing the size from increasing. [Brief description of the drawings]

[0008] [Figure 1] 1 is a block diagram showing a configuration of a photometric and colorimetric device according to an embodiment. [Diagram 2] FIG. 2 is a diagram showing a configuration of a measurement optical system according to the first embodiment. [Diagram 3] 5 is a diagram for explaining the angle at which light from the first aperture is incident on the second aperture via the third lens group according to the first embodiment. FIG. [Figure 4] 4 is a table showing the focal length of each lens group in the lens units of the first to third embodiments. [Diagram 5] 1 is a table showing distances on the optical axis when each lens group in the lens units of the first to third embodiments is made of a thin lens. [Figure 6]FIG. 13 is a diagram showing a configuration of a measurement optical system according to a second embodiment. [Figure 7] FIG. 13 is a diagram showing a configuration of a measurement optical system according to a third embodiment. [Figure 8] FIG. 13 is a diagram showing a configuration of a measurement optical system according to a fourth embodiment. [Figure 9] FIG. 13 is a diagram showing a configuration of a measurement optical system according to a fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0010] First Embodiment [Overall configuration of photometric and colorimetric device] FIG. 1 is a block diagram showing the configuration of a photometric and colorimetric device 100 according to this embodiment. As shown in this figure, the photometric and colorimetric device 100 includes a measurement optical system 20, a light receiving section 11, a control section 12, an input section 13, and a display section .

[0011] The measurement optical system 20 receives light from the object to be measured OB, and guides the received light to the light receiving section 11. The object to be measured OB is a light emitting body in this embodiment. The configuration of the measurement optical system 20 will be described in detail later.

[0012] The light receiving unit 11 receives light from the object to be measured OB guided by the measurement optical system 20, photoelectrically converts the received light, and outputs an electrical signal according to the light intensity. The light receiving unit 11 includes, for example, a spectroscopic unit that disperses the light from the object to be measured OB, and a photoelectric conversion element that photoelectrically converts the light dispersed by the spectroscopic unit. Specifically, the light receiving unit 11 of this embodiment has a configuration for measuring the color and luminance of the object OB from the tristimulus values ​​of XYZ. More specifically, the light receiving unit 11 has three filters, an X filter 11a, a Y filter 11b, and a Z filter 11c, which correspond to color matching functions X, Y, and Z defined by the CIE (Commission Internationale de Illumination), and an X-filter light receiving element 11d, a Y-filter light receiving element 11e, and a Z-filter light receiving element 11f, which receive the light filtered by these filters and perform photoelectric conversion. The X filter 11a, the Y filter 11b, and the Z filter 11c correspond to examples of color filters according to the present invention. In the light receiving unit 11, light from the object under test OB is filtered by the X filter 11a and photoelectrically converted by the X-filter light receiving element 11d, and an electrical signal (X signal) according to the light intensity is output. Similarly, an electrical signal (Y signal) is output through the Y filter 11b and the Y-filter light receiving element 11e, and an electrical signal (Z signal) is output through the Z filter 11c and the Z-filter light receiving element 11f. These X signal, Y signal, and Z signal are output to the control unit 12.

[0013] The input unit 13 is an input means for an operator to input various information for operating the photometric and colorimetric device 100. The input unit 13 includes, for example, various buttons and input devices, and outputs to the control unit 12 an input signal corresponding to the operation content of these. The display unit 14 is, for example, a liquid crystal display, an organic electroluminescence display, or other display. The display unit 14 displays various information such as the color and brightness of the measured object OB based on a display signal input from the control unit 12. The display unit 14 may be a touch panel that also serves as a part of the input unit 13, or may include a speaker capable of displaying (outputting) audio.

[0014] The control unit 12 is configured with, for example, a CPU (Central Processing Unit) and controls the operation of each unit of the photometric and colorimetric device 100. For example, the control unit 12 causes the measurement optical system 20 and the light receiving unit 11 to measure light from the object to be measured OB based on an operation command input from the input unit 13. Then, the control unit 12 determines the color and luminance of the object to be measured OB based on the electrical signal output from the light receiving unit 11.

[0015] [Configuration of the measurement optical system] FIG. 2 is a diagram showing the configuration of the measurement optical system 20 according to the first embodiment. As shown in this figure, the measurement optical system 20 includes a lens unit 21 and a light guiding member 22 .

[0016] The light guide member 22 guides the light incident from the lens unit 21 to the light receiving unit 11. More specifically, the light guide member 22 has an incident surface disposed near a second aperture S2 of the lens unit 21 described later, and guides the light incident to the second aperture S2. The light guide member 22 of this embodiment is an optical splitter that splits the incident light into three to guide it to three filters of the light receiving unit 11. Specifically, the light guide member 22 is a bundle fiber that splits a bundle of multiple optical fiber strands into three bundles midway and causes the incident light incident from one incident surface to exit from three exit surfaces. However, the light guide member 22 is not limited to a bundle fiber and may be, for example, a light pipe or the like.

[0017] The lens unit 21 causes light from the object to be measured OB to be incident on the light guiding member 22. Specifically, the lens unit 21 includes, in order from the object side (the object to be measured OB side), a first lens group LG1, a second lens group LG2, a first aperture S1, a third lens group LG3, and a second aperture S2.

[0018] The first lens group LG1 includes at least one lens and has a positive refractive power. In this embodiment, the first lens group LG1 includes a first lens L1 that is a convex lens. The first lens group LG1 focuses light (light beam) taken in from the measurement surface SM near a focal point f1 of the first lens group LG1.

[0019] The second lens group LG2 includes at least one lens and has a positive refractive power. In this embodiment, the second lens group LG2 includes a second lens L2 that is a convex lens. The light beam collected by the first lens group LG1 at the focal point f1 of the first lens group LG1 spreads after passing through the focal point f1. The second lens group LG2 converges the spread light beam toward the first aperture S1. In other words, the first lens group LG1 and the second lens group LG2 form an optical image from the object to be measured OB as an intermediate image on the aperture surface of the first aperture S1.

[0020] The third lens group LG3 includes at least one lens and has a positive refractive power. In this embodiment, the third lens group LG3 includes a third lens L3 and a fourth lens L4, which are convex lenses. The third lens group LG3 converges the light beam that has been converged by the second lens group LG2 and passed through the first aperture stop S1 toward the second aperture stop S2.

[0021] An infrared cut filter CF is disposed between the second lens group LG2 and the first aperture S1. In a photometric and colorimetric device in which the light path is split into multiple paths by the light guiding member 22 as in this embodiment, the light receiving unit 11 (light receiving element) is also sensitive to the infrared wavelength region. Therefore, in a photometric and colorimetric device that handles only the visible light region, it is necessary to cut infrared rays in front of the light receiving unit 11 by the infrared cut filter CF. The position of the infrared cut filter CF is not particularly limited, but it is more preferable from the viewpoint of miniaturization to dispose it in an area where the light beam diameter is small.

[0022] The first aperture S1 is an optical member that defines the measurement diameter, and is, for example, a plate-like member having a circular opening that corresponds to the measurement diameter. The first aperture S1 is disposed near the focal point on the object side of the third lens group LG3 (hereinafter, this arrangement may be referred to as the "ideal arrangement"). Here, being disposed "near" the focal point means that, although it is ideal to be disposed at the focal point in terms of paraxial optics, in an actual optical system, it is disposed at an optimal position near the focal point depending on the residual aberration.

[0023] The second aperture S2 is disposed near a position conjugate with the focal point f1 on the image side (light-guiding member 22 side) of the first lens group LG1 with respect to the second lens group LG2 and the third lens group LG3. That is, the second aperture S2 is disposed near the second focal point of the entire measurement optical system 20 (lens unit 21). The first focal point of the entire measurement optical system 20 is the focal point f1 of the first lens group LG1. Here, being disposed "near" the focal point means that, although it is ideal to be disposed at the focal point in terms of paraxial optics, in an actual optical system, it is disposed at an optimal position near the focal point depending on residual aberration. The second aperture S2 may be a plate-like member having an opening like the first aperture S1, or the entrance surface (diameter) of the light-guiding member 22 may also serve as the second aperture S2.

[0024] In the measurement optical system 20 configured as above, the first lens group LG1 first focuses the light (light beam) taken in from the measurement surface SM near the focal point f1 of the first lens group LG1. The light focused at the focal point f1 by the first lens group LG1 spreads after passing through the focal point f1. The second lens group LG2 converges the spread light toward the first aperture S1. The light that passes through the first aperture S1 is converged toward the second aperture S2 by the third lens group LG3. In this case, since the first aperture S1 and the measurement surface SM are in a conjugate relationship with each other, if there is unevenness in brightness on the measurement surface SM, similar unevenness in the amount of light will occur at each point on the opening surface of the first aperture S1. However, the third lens group LG3 guides the light beams emitted from each point of the first aperture S1 so that they spread over the entire second aperture S2, so that the influence of unevenness in brightness on the measurement surface SM can be suppressed.

[0025] In addition, the first aperture S1 is disposed near the object-side focal point of the third lens group LG3 (ideal arrangement). Therefore, light emitted from each point of the first aperture S1 is incident on the second aperture S2 (light-guiding member 22) at the same angle. In other words, light emitted from the center of the first aperture S1 is incident on the second aperture S2 perpendicularly. In addition, light emitted from the outermost periphery of the first aperture S1 is incident on the second aperture S2 at the largest angle with respect to an axis perpendicular to the optical axis Ax. Since the light guide member 22 has a limited range of angles for the light rays that it can take in, this ideal arrangement is suitable for collecting light into the light guide member 22 more efficiently. If the arrangement is not ideal, the angle of incidence of light emitted from each point of the first aperture S1 will differ depending on the position at which it enters the second aperture S2 (light-guiding member 22), as shown in Fig. 3. Under the same condition of the aperture angle of the light beam entering the center of the second aperture S2, the light rays shown by the dashed lines in the figure will enter the second aperture S2 at a larger angle than in the ideal arrangement. If that angle is larger than the light ray angle that the light-guiding member 22 can take in, the amount of light that can be taken in by the light-guiding member 22 will be reduced compared to the ideal arrangement. In this embodiment, the first aperture stop S1 is disposed near the object-side focal point of the third lens group LG3, which reduces the loss of light caused by off-axis light beams having a large angle of incidence.

[0026] In the lens unit 21, the absolute value of the lateral magnification of the first aperture S1 with respect to a surface conjugate with the first aperture S1 with respect to the first lens group LG1 and the second lens group LG2 is 0.7 or less. This lateral magnification is the lateral magnification of the first aperture S1 with respect to the measurement surface SM, that is, the ratio of the aperture diameter of the first aperture S1 to the measurement diameter of the measurement surface SM. However, the absolute value of the lateral magnification is more preferably 0.65 or less, and further preferably 0.61 or less. In the lens unit 21 of the first embodiment, the absolute value of the lateral magnification is 0.40. In conventional optical systems, the lateral magnification of the first aperture S1 with respect to the measurement surface SM is large. Therefore, when the measurement area of ​​the measurement surface is expanded, the first aperture becomes correspondingly larger. In this regard, in this embodiment, the lateral magnification of the first aperture S1 with respect to the measurement surface SM is kept to 0.7 or less, thereby making it possible to avoid an increase in the size of the measurement optical system 20 (lens unit 21).

[0027] In addition, the lens unit 21 satisfies the following conditional expression. F1G / F2G>1.1 ···(1) Here, F1G is the focal length of the first lens group LG1, and F2G is the focal length of the second lens group LG2. Preferably, the lens unit 21 satisfies the following conditional formula (1a). F1G / F2G>1.2 (1a) It is more preferable that the lens unit 21 satisfies the following conditional formula (1b): F1G / F2G>1.3 (1b) It is even more preferable that the lens unit 21 satisfy the following conditional formula (1c): F1G / F2G>1.4 (1c) In the lens unit 21 of the first embodiment, F1G / F2G=2.52.

[0028] The above conditional formula (1) specifies that the refractive power of the second lens group LG2 is greater than the refractive power of the first lens group LG1. By satisfying this conditional formula, the light taken in from the measurement surface SM can be suitably guided to the first aperture S1, which is in a conjugate relationship with the measurement surface SM and has an area smaller than the measurement surface SM. In other words, the measurement optical system 20 (lens unit 21) can be suitably miniaturized.

[0029] In addition, the lens unit 21 satisfies the following conditional expression. F2G / F3G>1.1 ···(2) Here, F2G is the focal length of the second lens group LG2, and F3G is the focal length of the third lens group LG3. Preferably, the lens unit 21 satisfies the following conditional formula (2a): F2G / F3G>1.3 (2a) It is more preferable that the lens unit 21 satisfies the following conditional formula (2b): F2G / F3G>1.4 (2b) It is even more preferable that the lens unit 21 satisfy the following conditional formula (2c): F2G / F3G>1.5 (2c) In the lens unit 21 of the first embodiment, F2G / F3G=2.15.

[0030] The above conditional formula (2) specifies that the refractive power of the third lens group LG3 is greater than the refractive power of the second lens group LG2. By satisfying this conditional formula, the light passing through the focal point f1 of the first lens group LG1 can be suitably guided to the second aperture stop S2, which is in a conjugate relationship with the focal point f1 and has an area smaller than the focal point f1 plane. In other words, the measurement optical system 20 (lens unit 21) can be suitably miniaturized.

[0031] 4 and 5 show the focal length of each lens group in the lens unit 21 of the first embodiment and the distance on the optical axis Ax when each lens group is made of a thin lens.

[0032] [Technical effect of the first embodiment] As described above, according to this embodiment, the measurement area of ​​the measurement surface SM is defined by the first aperture S1 that is in a conjugate relationship with the measurement surface SM. In addition, the angle of the light rays captured from the measurement surface SM is defined by disposing the second aperture S1 at the focal position of the entire measurement optical system 20. This makes it possible to reduce the light loss caused by off-axis light beams having large angles of incidence, and improve the light collection efficiency. In addition, the absolute value of the lateral magnification of the first aperture S1 with respect to the surface (measurement surface SM) conjugate with the first aperture S1 with respect to the first lens group LG1 and the second lens group LG2 is 0.7 or less. Therefore, unlike the conventional case in which the absolute value of the lateral magnification was large, it is possible to avoid an increase in the size of the first aperture S1 due to an increase in the measurement area of ​​the measurement surface SM. Therefore, it is possible to take in a larger amount of light while preventing the size from increasing.

[0033] Moreover, according to this embodiment, the measurement optical system 20 satisfies the above conditional expression (1). This allows the light captured from the measurement surface SM to be appropriately guided to the first aperture S1, which is in a conjugate relationship with the measurement surface SM and has an area smaller than the measurement surface SM. In other words, the measurement optical system 20 (lens unit 21) can be appropriately downsized.

[0034] Moreover, according to this embodiment, the measurement optical system 20 satisfies the above conditional expression (2). This allows the light that has passed through the focal point f1 of the first lens group LG1 to be appropriately guided to the second aperture S2, which is in a conjugate relationship with the focal point f1 and has an area smaller than the focal point f1 plane. In other words, the measurement optical system 20 (lens unit 21) can be appropriately downsized.

[0035] Furthermore, according to this embodiment, the first aperture diaphragm S1 is disposed near the object-side focal point of the third lens group LG3. This makes it possible to reduce the loss of light intensity that occurs when off-axis light beams have a large angle of incidence.

[0036] <Second embodiment> FIG. 6 is a diagram showing the configuration of a measurement optical system 20B according to the second embodiment. As shown in this figure, the measurement optical system 20B according to the second embodiment differs from the measurement optical system 20 of the first embodiment in the configurations of the first lens group, the second lens group, and the third lens group. In the following description of each embodiment, differences in configuration from the measurement optical system 20 of the first embodiment will be mainly described, and descriptions of common configurations will be omitted.

[0037] Specifically, the lens unit 21B of the measurement optical system 20B includes, in order from the object side (measurement object OB side), a first lens group LG1b, a second lens group LG2b, a first aperture S1, a third lens group LG3b, and a second aperture S2.

[0038] The first lens group LG1b has a first lens L1 and a second lens L2, which are convex lenses. The second lens group LG2b has a third lens L3 which is a convex lens. The third lens group LG3b has a fourth lens L4, a fifth lens L5, and a sixth lens L6 and a seventh lens L7 which are convex lenses. The fourth lens L4 and the fifth lens L5 are cemented together. The infrared cut filter CF is disposed on the object side of the second lens group LG2b. The arrangement of the first diaphragm S1 and the second diaphragm S2 on the optical axis Ax is the same as in the first embodiment.

[0039] In the lens unit 21B, the absolute value of the lateral magnification of the first aperture stop S1 with respect to a surface conjugate with the first aperture stop S1 with respect to the first lens group LG1b and the second lens group LG2b is 0.61.

[0040] 4 and 5 show the focal length of each lens group in lens unit 21B of the second embodiment and the distance on the optical axis Ax when each lens group is made of a thin lens.

[0041] The second embodiment described above can also provide the same effects as the first embodiment.

[0042] <Third embodiment> FIG. 7 is a diagram showing the configuration of a measurement optical system 20C according to the third embodiment. As shown in this figure, the measurement optical system 20C according to the third embodiment differs from the measurement optical system 20 of the first embodiment in the configurations of the first lens group, the second lens group, and the third lens group.

[0043] Specifically, the lens unit 21C of the measurement optical system 20C includes, in order from the object side (measurement object OB side), a first lens group LG1c, a second lens group LG2c, a first aperture S1, a third lens group LG3c, and a second aperture S2.

[0044] The first lens group LG1c has a first lens L1 which is a convex lens. The second lens group LG2c has a second lens L2 which is a convex lens. The third lens group LG3c has a third lens L3 which is a convex lens. The arrangement of the first diaphragm S1 and the second diaphragm S2 on the optical axis Ax is the same as in the first embodiment.

[0045] In the lens unit 21C, the absolute value of the lateral magnification of the first aperture stop S1 with respect to a surface conjugate with the first aperture stop S1 with respect to the first lens group LG1c and the second lens group LG2c is 0.44. Furthermore, the lens unit 21C has a basic configuration similar to that of the first and second embodiments, but uses aspherical lenses for the convex lenses of the second lens group LG2c and the third lens group LG3c. This realizes a configuration with the minimum number of lenses, with only one convex lens in each lens group. As the number of lenses increases, the loss of light due to reflection at the interface between the lens and the air increases, so reducing the number of lenses can suppress this loss of light.

[0046] 4 and 5 show the focal length of each lens group in the lens unit 21C of the third embodiment and the distance on the optical axis Ax when each lens group is made of a thin lens.

[0047] The third embodiment described above can also provide the same effects as the first embodiment. Furthermore, the use of aspherical lenses in the second lens group LG2c and the third lens group LG3c makes it possible to reduce the number of lenses, which in turn makes it possible to suppress light loss due to reflection at the interface between the lens and the air.

[0048] <Fourth embodiment> FIG. 8 is a diagram showing the configuration of a measurement optical system 20D according to the fourth embodiment. As shown in FIG. 8, a measurement optical system 20D according to the fourth embodiment differs from the measurement optical system 20 according to the first embodiment in that it includes an ND filter (Neutral Density Filter) 25d.

[0049] In the lens unit 21D of the measurement optical system 20D, an ND filter 25d is disposed between the third lens group LG3 and the second aperture stop S2. The ND filter 25d is supported so as to be insertable and removable. The position of the ND filter 25d is not particularly limited, but it is more preferable from the viewpoint of miniaturization to dispose it in an area where the light beam diameter is small.

[0050] The fourth embodiment described above can also provide the same effects as the first embodiment. Furthermore, by providing the ND filter 25d, it is possible to suitably measure areas with higher brightness. That is, the measurement optical system (lens unit) according to this embodiment can take in a larger amount of light, so it is suitable as a photometric and colorimetric device for low luminance areas. However, in high luminance areas, there is a risk that the amount of light that the light receiving element can take in may exceed its allowable value. Therefore, by inserting the ND filter 25d, it becomes possible to perform photometric and colorimetric measurement in a higher luminance area without changing the spectral distribution of the taken-in light beam. In addition, by arranging the ND filter 25d so that it can be inserted and removed, it is possible to expand the measurement range compared to the conventional case. It goes without saying that the ND filter 25d can be similarly arranged in the second or third embodiment.

[0051] <Fifth embodiment> FIG. 9 is a diagram showing the configuration of a measurement optical system 20E according to the fifth embodiment. As shown in this figure, the measurement optical system 20E according to the fifth embodiment differs from the measurement optical system 20 according to the first embodiment in the position of the second aperture stop S2.

[0052] Specifically, in the lens unit 21E of the measurement optical system 20E, the second aperture S2 is disposed near the focal point f1 of the first lens group LG1. In this case, the second aperture S2 is a plate-like member having a circular opening.

[0053] The fifth embodiment described above can also provide the same effects as the first embodiment. That is, according to this embodiment, the second aperture stop S2 is disposed near the focal point f1 on the image side of the first lens group LG1. That is, the second aperture stop S2 is disposed near a position that is in a conjugate relationship with respect to the second lens group LG2 and the third lens group LG3 with respect to the position of the second aperture stop S2 in the first embodiment. Therefore, the angle of the light ray taken in from the measurement surface SM can also be determined by such a second aperture stop S2. Needless to say, the second aperture diaphragm S2 can be moved in the same way in the second or third embodiment. The second aperture diaphragm S2 may be disposed both near the focal point f1 on the image side of the first lens group LG1 and near a position conjugate with the focal point f1.

[0054] [others] Although one embodiment of the present invention has been described above, embodiments to which the present invention can be applied are not limited to the above-described embodiment and can be modified as appropriate without departing from the spirit of the present invention. [Explanation of symbols]

[0055] 100 Photometric colorimeter 11 Light receiving part 11a, 11b, 11c X filter, Y filter, Z filter (color filter) 11d, 11e, 11f X filter light receiving element, Y filter light receiving element, Z filter light receiving element (light receiving element) 12 Control section 20, 20B, 20C, 20D, 20E measurement optical system 21, 21B, 21C, 21D, 21E Lens Unit 22 Light guide member 25d ND Filter CF Infrared cut filter f1 Focus (image side focus of the first lens group) LG1, LG1b, LG1c First lens group LG2, LG2b, LG2c Second lens group LG3, LG3b, LG3c Third lens group S1 First aperture S2 2nd aperture OB Measured object SM surface to be measured Ax optical axis

Claims

1. From the object side, a first lens group including at least one lens and having a positive refractive power; a second lens group including at least one lens and having a positive refractive power; The first aperture, a third lens group including at least one lens and having positive refractive power; Equipped with a second aperture disposed at least either near a position of an image-side focal point of the first lens group or near a position conjugate with the image-side focal point of the first lens group with respect to the second lens group and the third lens group; an absolute value of a lateral magnification of the first aperture with respect to a surface conjugate with the first aperture with respect to the first lens group and the second lens group is 0.7 or less; Measurement optical system.

2. 2. The measuring optical system according to claim 1, which satisfies the following condition: F1G / F2G>1.1...(1) however, F1G: focal length of the first lens group F2G: focal length of the second lens group

3. 3. The measuring optical system according to claim 1, which satisfies the following condition: F2G / F3G>1.1...(2) however, F2G: focal length of the second lens group F3G: focal length of the third lens group

4. the first aperture is disposed near a focal point on the object side of the third lens group; 2. The measuring optical system according to claim 1.

5. Equipped with an infrared cut filter, 2. The measuring optical system according to claim 1.

6. Equipped with an ND filter; 2. The measuring optical system according to claim 1.

7. a light guiding member that is disposed on an image side of a position conjugate with an image side focal point of the first lens group with respect to the second lens group and the third lens group and that guides light that has entered the second aperture; 2. The measuring optical system according to claim 1.

8. The measurement optical system according to claim 1 ; a color filter that filters the light guided by the measurement optical system; a light receiving element that photoelectrically converts the light filtered by the color filter; a control unit that determines the color and luminance of the object based on the electrical signal output from the light receiving element; A photometric and colorimetric device comprising:

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