JP2023019759A - Optical characteristic measurement device - Google Patents

Abstract

To measure optical characteristics of a measurement object with high accuracy by suppressing the loss of light quantity.SOLUTION: A reflected light measuring device 1-1 for measuring the reflection characteristics of a measurement object 11 includes: an illumination light source 13 for irradiating the measurement object 11; an optical lens 14 for refracting the reflected light in a plurality of directions by the measurement object 11; and a light receiving element 15 for receiving the light refracted by the optical lens 14. The measurement object 11 is arranged at a front focal position of the light receiving element 15. The optical lens 14 has a positive focal distance. The light receiving element 15 is arranged in a plane perpendicular to an optical axis of the optical lens 14 on the side opposite to the measurement object 11 with respect to the optical lens 14.SELECTED DRAWING: Figure 1

Description

The present invention relates to an optical property measuring device for measuring optical properties of an object to be measured.

Conventionally, as the optical characteristics of the object to be measured, the reflection component for the illumination light source is a bidirectional reflectance distribution function, the transmission component for the illumination light source is a bidirectional transmittance distribution function, and if the object to be measured is a self-luminous body, the self-luminous body is known.

In order to measure such optical characteristics, the object to be measured is illuminated by an illumination light source, and the light reflected by the object to be measured, the light transmitted by the object to be measured, and the light emitted by the object itself are measured. Devices for measuring optical properties are known.

As a technique for measuring such optical characteristics, an apparatus has been proposed that measures the characteristics of light reflected by an object to be measured by using an ellipsoidal mirror and a semitransparent mirror (see, for example, Non-Patent Document 1).

FIG. 12(1) is a schematic diagram showing a configuration example of a conventional reflected light measuring device using an elliptical mirror and a semitransparent mirror. This reflected light measurement apparatus 100 is an apparatus for measuring the characteristics of light reflected by a measurement object 101, and includes an elliptical mirror 102, a projector 103, a camera 104, a semitransparent mirror 105, and an image plane .

In the reflected light measurement apparatus 100, a measurement target 101 is arranged at one focal position of two focal points on an elliptical mirror 102, and a projector 103 and a camera 104, which are illumination light sources, are arranged at the other focal position. The image plane 106 forms a pattern according to the irradiation of light from the projector 103 .

However, since the projector 103 and the camera 104 cannot be physically arranged at the same position, the optical path is branched by placing a semitransparent mirror 105 in the middle of the optical path. As a result, the projector 103 and the camera 104 are arranged at the same optical position.

With such a configuration, it is possible to measure the luminance distribution of light reflected from the measurement target 101 in a plurality of angular directions. Specifically, by determining the angles θi and θr according to the pattern of the image plane 106, the ratio of the reflected luminance in the viewing direction (θr, φr) to the incident light illuminance from the light source direction (θi, φi) can be expressed. A directional reflectance distribution function is measured.

In addition, as a method for measuring optical characteristics, an apparatus has been proposed that measures the characteristics of light reflected by an object to be measured by using an elliptical transmission mirror dome and a specular reflector (see, for example, Patent Document 1).

FIG. 12(2) is a schematic diagram showing a configuration example of a conventional reflected light measuring apparatus using an elliptical transmitting mirror dome and a mirror reflecting plate. This reflected light measurement device 110 is a device for measuring the characteristics of light reflected by a measurement target 111 and is provided with an elliptical transmission mirror dome 112 , a specular reflector plate 113 , an illumination light source 114 and a camera 115 . Elliptical transmission mirror dome 112 and camera 115 are housed in tubular member 116 .

In this reflected light measurement apparatus 110, a measurement target 111 is placed at one of two focal points on an elliptical transmission mirror dome 112, and an illumination light source 114 is used to move the elliptical transmission mirror dome 112 and the mirror surface in the direction of an arrow 118. The object 111 to be measured is illuminated through the opening 117 of the reflector 113 .

The light reflected by the object 111 to be measured is further reflected by the specular reflector 113 and input to the camera 115 . Here, the camera 115 is placed at a position of mirror symmetry with respect to the other of the two focal points on the elliptical transmission mirror dome 112 .

With such a configuration, it is possible to measure the luminance distribution of light reflected in a plurality of angular directions, as in FIG. 12(1).

Japanese Patent No. 6678901

Kadono, Mukaigawa, Yagi, “High-speed measurement of bidirectional reflectance distribution function using an elliptical mirror”, Transactions of the Institute of Electronics, Information and Communication Engineers. D, Vol.J90-D, No.8, pp.1930-1937, 2007

In the conventional reflected light measurement device 100 using the elliptical mirror 102 and the semitransparent mirror 105 shown in FIG. .

However, since part of the light is transmitted through the semitransparent mirror 105, it does not travel in the direction of the camera 104, resulting in loss in the amount of light to be measured. A loss in the amount of light deteriorates the signal-to-noise ratio, which poses a problem of a decrease in measurement accuracy.

Also, in the reflected light measurement apparatus 110 using the elliptical transmission mirror dome 112 and the mirror reflector 113 shown in FIG.

However, when the light passes through the elliptical transmission mirror dome 112, there is a possibility that unnecessary scattered light is generated, which poses a problem of degrading measurement accuracy.

Also, the light reflected by the specular reflector 113 is transmitted through the elliptical transmission mirror dome 112 and is input to the camera 115 . However, some of the light is reflected by the elliptical transmission mirror dome 112 and does not travel toward the camera 115, resulting in a loss in the amount of light to be measured. A loss in the amount of light deteriorates the signal-to-noise ratio, which poses a problem of a decrease in measurement accuracy.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above problems, and its object is to provide an optical characteristic measuring apparatus capable of suppressing the loss of light quantity and measuring the optical characteristics of an object to be measured with high accuracy. be.

In order to solve the above-described problems, an optical characteristic measuring apparatus according to claim 1 is an optical characteristic measuring apparatus for measuring optical characteristics of an object to be measured. an optical lens that refracts the light reflected by the optical lens; and a light-receiving element that receives the light refracted by the optical lens. and the light-receiving element is arranged on a plane perpendicular to the optical axis of the optical lens on the side opposite to the object to be measured with respect to the optical lens.

According to claim 2, there is provided an optical characteristic measuring apparatus according to claim 1, wherein the optical lens refracts light transmitted in a plurality of directions through the object to be measured. .

Further, the optical characteristic measuring apparatus according to claim 3 is the optical characteristic measuring apparatus according to claim 1 or 2, further comprising light refracted by the optical lens and condensed between the optical lens and the light receiving element. a condenser lens array, said condenser lens array comprising a plurality of lenses having a positive focal length, arranged parallel to said light receiving elements, said light receiving elements being aligned with said lenses of said plurality of lenses; It is characterized in that it is arranged at a position separated by a focal length and receives light condensed by the condensing lens array.

According to a fourth aspect of the present invention, there is provided an optical characteristic measuring apparatus for measuring optical characteristics of an object to be measured. a first parabolic mirror that allows the light reflected by the first parabolic mirror to be reflected, a second parabolic mirror that reflects the light reflected by the first parabolic mirror, and optics that refract the light reflected by the second parabolic mirror a lens and a light-receiving element that receives light refracted by the optical lens, the object to be measured is arranged at a focal position of the first parabolic mirror, and the first parabolic mirror is: an annular opening for passing light reflected by the second parabolic mirror toward the optical lens, wherein the second parabolic mirror and the optical lens are connected to the second paraboloid; The optical lens is arranged so that the focal position of the surface mirror and the front focal position of the optical lens are aligned, the optical lens has a negative focal length, and the light receiving element is arranged so that the measurement target is positioned with respect to the optical lens. On the opposite side, it is arranged in a plane perpendicular to the optical axis of said optical lens.

Further, the optical characteristic measuring apparatus according to claim 5 is the optical characteristic measuring apparatus according to claim 4, wherein the first parabolic mirror reflects light transmitted in a plurality of directions by the measurement object. It is characterized by

Further, the optical characteristic measuring apparatus according to claim 6 is the optical characteristic measuring apparatus according to claim 4 or 5, further comprising: collecting light refracted by the optical lens between the optical lens and the light receiving element. a condenser lens array, said condenser lens array comprising a plurality of lenses having a positive focal length, arranged parallel to said light receiving elements, said light receiving elements being aligned with said lenses of said plurality of lenses; It is characterized in that it is arranged at a position separated by a focal length and receives light condensed by the condensing lens array.

According to a seventh aspect of the present invention, there is provided an optical characteristic measuring apparatus for measuring optical characteristics of an object to be measured, wherein an illumination light source irradiates the object to be measured, and light reflected in a plurality of directions by the object to be measured is reflected. a first parabolic mirror that reflects the light reflected by the first parabolic mirror; and a second parabolic mirror that reflects the light reflected by the measurement object in a plurality of directions. one optical lens, a second optical lens, a third optical lens that refracts light reflected by the second parabolic mirror, the first optical lens, the second optical lens, and the third optical lens. a light-receiving element that receives light refracted by each of three optical lenses, wherein the measurement object is arranged at the focal position of the first parabolic mirror, and the first parabolic mirror is: Light reflected by the second parabolic mirror passes toward the third optical lens, and light reflected by the object to be measured passes toward the second optical lens. An aperture is provided, and the second parabolic mirror and the third optical lens are arranged such that the focal position of the second parabolic mirror and the front focal position of the third optical lens are aligned. wherein the first optical lens has a positive focal length, is arranged so that the object to be measured and the light receiving element are in an optically conjugate relationship, and the second optical lens has a positive focal point and is arranged so that the front focal position of the second optical lens and the position of the object to be measured match, the third optical lens has a negative focal length, and the light receiving element is , the first optical lens, the second optical lens and the third optical lens on the opposite side of the measurement object with respect to the first optical lens, the second optical lens and the third optical lens It is characterized by being arranged on a plane perpendicular to the optical axis of the optical lens.

Further, the optical characteristic measuring apparatus according to claim 8 is the optical characteristic measuring apparatus according to claim 7, wherein the first parabolic mirror reflects the light transmitted in a plurality of directions by the measurement object, It is characterized in that the first optical lens and the second optical lens refract light transmitted in a plurality of directions through the object to be measured.

Further, the optical characteristic measuring apparatus according to claim 9 is the optical characteristic measuring apparatus according to claim 7 or 8, further comprising the first optical lens, the second optical lens, the third optical lens, and the a condenser lens array for condensing the light refracted by the second optical lens and the third optical lens, the condenser lens array having a positive focal length; A lens is provided parallel to the light receiving element, and the light receiving element is disposed at a position separated by the focal length of the plurality of lenses, and receives light refracted by the first optical lens. and receiving the light condensed by the condensing lens array.

An optical characteristic measuring apparatus according to claim 10 is an optical characteristic measuring apparatus for measuring optical characteristics of an object to be measured, wherein the object to be measured is a self-luminous body, and light emitted from the object to be measured in a plurality of directions is refracted. an optical lens and a light receiving element that receives light refracted by the optical lens, the measurement object is arranged at a front focal position of the optical lens, the optical lens has a positive focal length, The light-receiving element is arranged on a plane perpendicular to the optical axis of the optical lens on the side opposite to the object to be measured with respect to the optical lens.

As described above, according to the present invention, it is possible to suppress the loss of the amount of light and measure the optical characteristics of the object to be measured with high accuracy.

1 (1) is a schematic diagram showing a configuration example of a reflected light measurement apparatus in Example 1. FIG. (2) is a schematic diagram showing a configuration example of a reflected light measuring device in a modified example of the first embodiment; (1) is a schematic diagram showing a configuration example of a transmitted light measurement device in Example 2. FIG. (2) is a schematic diagram showing a configuration example of a transmitted light measurement apparatus in a modified example of the second embodiment; FIG. 11 is a schematic diagram showing a configuration example of a reflected light measurement device in Example 3; FIG. 11 is a schematic diagram showing a configuration example of a reflected light measuring device in a modification of Example 3; FIG. 11 is a schematic diagram showing a configuration example of a transmitted light measurement device in Example 4; FIG. 11 is a schematic diagram showing a configuration example of a transmitted light measuring device in a modification of Example 4; FIG. 11 is a schematic diagram showing a configuration example of a reflected light measurement device in Example 5; FIG. 11 is a schematic diagram showing a configuration example of a reflected light measuring device in a modification of Example 5; FIG. 11 is a schematic diagram showing a configuration example of a transmitted light measurement device in Example 6; FIG. 21 is a schematic diagram showing a configuration example of a transmitted light measuring device in a modified example of Example 6; (1) is a schematic diagram showing a first installation example of shielding members in Examples 3 and 4 and modifications thereof. (2) is a schematic diagram showing a second installation example of the shielding member in Examples 3 and 4 and their modifications. (3) is a schematic diagram showing a first installation example of the shielding member in Examples 5 and 6 and their modifications. (4) is a schematic diagram showing a second installation example of the shielding member in Examples 5 and 6 and their modifications. (1) is a schematic diagram showing a configuration example of a conventional reflected light measurement device using an elliptical mirror and a semitransparent mirror. (2) is a schematic diagram showing a configuration example of a conventional reflected light measurement device using an elliptical transmission mirror dome and a mirror reflector.

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this invention is demonstrated in detail using drawing. The optical characteristic measuring apparatuses of Examples 1, 3, and 5 are reflected light measuring apparatuses that measure the reflection characteristics of the measuring object by illuminating the measuring object with an illumination light source and measuring the light reflected by the measuring object. The optical characteristic measuring apparatuses of Examples 2, 4, and 6 are transmitted light measuring apparatuses that measure the transmission characteristics of the measuring object by illuminating the measuring object with an illumination light source and measuring the light transmitted through the measuring object. be.

[Example 1]
First, Example 1 will be described. FIG. 1(1) is a schematic diagram showing a configuration example of a reflected light measurement apparatus according to the first embodiment. This figure shows a cross-section of the reflected light measuring device as seen from the side. The same applies to FIGS. 1(2), 3, 4, 7 and 8 which will be described later.

(Composition and arrangement)
This reflected light measurement apparatus 1-1 includes a measurement object setting unit 12 for setting a measurement object 11, an illumination light source 13 for illuminating the measurement object 11, and an optical lens 14 for refracting light reflected in a plurality of directions by the measurement object 11. , and a light receiving element 15 for receiving light refracted by the optical lens 14 .

FIG. 1(1) also shows a solid angle 16a representing the range of light incident on the optical lens 14. FIG. A measurement object 11 is an object whose optical properties are measured.

The illumination light source 13 is arranged at a position capable of illuminating the measurement object 11 and at a position where the light reflected by the measurement object 11 is not blocked. The optical lens 14 has a positive focal length, and the measurement object 11 is arranged at the front side (measurement object 11 side) focal position of the optical lens 14 . The light-receiving element 15 is arranged on a plane orthogonal to the optical axis of the optical lens 14 on the opposite side of the measurement target 11 (with respect to the optical lens 14 ). The light-receiving element 15 is an element that outputs an electric signal according to the amount of light. For example, a CMOS (Complementary Metal Oxide Semiconductor) image sensor or the like is used, but the light-receiving element 15 is not limited to the CMOS image sensor.

(optical path)
When the object to be measured 11 is illuminated by the illumination light source 13 , the light reflected by the object to be measured 11 , traveling in the direction of the optical lens 14 , is refracted by the optical lens 14 , and then reaches the light receiving element 15 . light is received.

Light is reflected in various directions within the range of the solid angle 16 a on the object 11 to be measured. The light reaches the light receiving element 15 as parallel light. For example, in FIG. 1(1), the light reflected from the measurement target 11 toward the direction 16b of the optical lens 14 becomes parallel light due to the refraction action of the optical lens 14, and is received at the position 15a of the light receiving element 15. FIG.

With such a configuration, the reflected light measurement device 1-1 measures the reflection angles (θ, φ) of light reflected in a plurality of directions by the measurement object 11 (θ is the reflection angle of light in the vertical direction, φ is the horizontal direction The reflected light luminance distribution L _obj (θ, φ) can be measured in a form in which the light reflection angle of light) is associated with the position where the light is received by the light receiving element 15 .

The reflected light measuring device 1-1 may measure the output value of each pixel constituting the light receiving element 15 as the luminance of the light reflected in the direction of the reflection angle (θ, φ). Further, the reflected light measurement device 1-1 may perform statistical processing such as calculating an average value on the output values of a plurality of pixels forming the light receiving element 15. FIG.

The reflected light measurement device 1-1 may also calculate a bidirectional reflectance distribution function representing the reflected light characteristics of the measurement target 11. FIG. In order to calculate the bidirectional reflectance distribution function of the measurement object 11, a reference object whose bidirectional reflectance distribution function is known is prepared. The bidirectional reflectance distribution function of this reference object is defined as a function f _std (θ, φ) of the reflection angle θ of light in the vertical direction and the angle of reflection φ in the horizontal direction.

A calculation unit (not shown in FIG. 1(1)) provided in the reflected light measurement device 1-1 calculates the luminance distribution L Measure _std (θ, φ). Then, the calculation unit measures the luminance distribution L _obj (θ, φ) of the reflected light for the measurement target 11 .

The calculation unit calculates the preset bidirectional reflectance distribution function f _std (θ, φ) of the reference object, the measured luminance distribution L _std (θ, φ) of the reflected light of the reference object, and the measured Using the luminance distribution L _obj (θ, φ) of the reflected light, the bidirectional reflectance distribution function f _obj (θ, φ) of the measurement object 11 is calculated by the following equation.
[Number 1]
f _obj (θ, φ)=(L _obj (θ, φ)/L _std (θ, φ)) f _std (θ, φ) (1)
Thereby, the bidirectional reflectance distribution function f _obj (θ, φ) of the measurement object 11 can be obtained.

As described above, according to the reflected light measurement apparatus 1-1 of the first embodiment, by using the optical lens 14 in the configuration shown in FIG. I made it

As described above, in the conventional method shown in FIGS. 12(1) and 12(2), part of the light is transmitted through the semi-transparent mirror 105, unwanted scattered light is generated in the elliptical transmitting mirror dome 112, and There is a problem that a part of the light is reflected and the amount of light received by the cameras 104 and 115 for measurement is lost, resulting in a decrease in measurement accuracy.

On the other hand, in Example 1, although the optical lens 14 corresponding to the lenses in the cameras 104 and 115 in the conventional technique is provided, the semitransparent mirror 105, the elliptical transmitting mirror dome 112, etc., which cause loss of the amount of received light, are used. does not have Therefore, the loss of light quantity can be suppressed, and the optical characteristics of the measurement target 11 can be measured with high accuracy.

[Modification of Embodiment 1]
Next, a modified example of Example 1 will be described. FIG. 1(2) is a schematic diagram showing a configuration example of a reflected light measuring device in a modified example of the first embodiment.

(Composition and arrangement)
This reflected light measurement apparatus 1-2 includes a measuring object installation section 12, an illumination light source 13, an optical lens 14, a light receiving element 15, and a condenser lens array 17 between the optical lens 14 and the light receiving element 15. .

The condenser lens array 17 is configured with a plurality of optical lenses 17 a having a positive focal length and arranged parallel to the light receiving element 15 . A light receiving element 15 is arranged at a position separated by the focal length of the optical lens 17a.

The reflected light measurement device 1-2 has a condensing lens array 17 in addition to the configuration of the reflected light measurement device 1-1 of the first embodiment shown in FIG. It differs from -1. Other configurations are the same. In FIG. 1(2), parts common to those in FIG. 1(1) are given the same reference numerals as those in FIG. 1(1), and detailed description thereof will be omitted.

FIG. 1(2) also shows a solid angle 16c indicating the range of light incident on the optical lens 17a constituting the condenser lens array 17 among the light incident on the optical lens 14. FIG.

(optical path)
When the measurement object 11 is illuminated by the illumination light source 13, the light reflected by the measurement object 11, which travels in the direction of the optical lens 14, is refracted by the optical lens 14 and becomes parallel light. , and advances in the direction of the condenser lens array 17 .

Then, of the light reflected by the measurement object 11 and proceeding in the direction of the optical lens 14, the light having a solid angle 16c centered on the direction 16b is condensed by the optical lens 17a via the optical lens 14 and received. Light is received at position 15 b of element 15 .

With such a configuration, the reflected light measurement device 1-2 can measure the luminance distribution L _obj (θ, φ) of the reflected light in the same manner as the reflected light measurement device 1-1. , the bidirectional reflectance distribution function f _obj (θ, φ) of the measurement object 11 can be calculated.

As described above, according to the reflected light measurement device 1-2 of the modified example of the first embodiment, similarly to the reflected light measurement device 1-1, the loss of the amount of light is suppressed, and the optical characteristics of the measurement target 11 are measured with high accuracy. can be measured to

Since the reflected light measurement apparatus 1-1 of the first embodiment shown in FIG. It is associated with the reflection angle (θ, φ) of the light reflected in the direction. Therefore, there is an advantage that the reflection characteristics can be measured with high angular resolution, but if the luminance of the reflected light is low, the signal-to-noise ratio will decrease, and it is assumed that luminance measurement will become difficult.

On the other hand, in the reflected light measuring device 1-2 of the modified example of the first embodiment, light having a solid angle 16c centered on the direction 16b is condensed by the optical lens 17a and received at the position 15b of the light receiving element 15. . As a result, even when the brightness of the reflected light is low, the signal-to-noise ratio can be prevented from deteriorating, and as a result, the optical characteristics of the measurement target 11 can be measured with even higher accuracy.

[Example 2]
Next, Example 2 will be described. FIG. 2(1) is a schematic diagram showing a configuration example of a transmitted light measuring apparatus according to the second embodiment. This figure shows a cross section of the transmitted light measuring device as seen from the side. The same applies to FIG. 2(2), FIG. 5, FIG. 6, FIG. 9 and FIG. 10 which will be described later.

(Composition and arrangement)
This transmitted light measurement apparatus 2-1 includes a measurement object setting section 18 for setting the measurement object 11, an illumination light source 13, an optical lens 14, and a light receiving element 15. FIG. The measurement object installation section 18 has an opening 30 for illuminating the measurement object 11 with the illumination light source 13 . The illumination light source 13 is arranged at a position capable of illuminating the measurement object 11 and at a position where the light transmitted through the measurement object 11 is not blocked.

Comparing the reflected light measurement device 1-1 of Example 1 shown in FIG. They are common in that an optical lens 14 and a light receiving element 15 are provided. On the other hand, the transmitted light measurement apparatus 2-1 includes an illumination light source 13 that illuminates the measurement object 11 in a different direction from that of the reflected light measurement apparatus 1-1, and a measurement object installation section 18 having an opening 30. This is different from the reflected light measurement device 1-1.

Specifically, the illumination light source 13 provided in the reflected light measurement apparatus 1-1 is arranged at a position that illuminates the measurement object 11 from the side where the optical lens 14 is provided. On the other hand, the illumination light source 13 provided in the transmitted light measurement apparatus 2-1 is directed from the side of the measurement object 11 on which the optical lens 14 is not provided through the opening 30 of the measurement object installation portion 18. 11. In FIG. 2(1), parts common to those in FIG. 1(1) are assigned the same reference numerals as those in FIG. 1(1), and detailed description thereof will be omitted.

(optical path)
When the measurement target 11 is illuminated by the illumination light source 13 through the opening 30 of the measurement target installation section 18 , the light traveling in the direction of the optical lens 14 out of the light transmitted through the measurement target 11 passes through the optical lens 14 . After being refracted by the light receiving element 15 , the light is received by the light receiving element 15 .

Light passes through the measurement object 11 in various directions within the range of the solid angle 16a. The light refracted by the optical lens 14 reaches the light receiving element 15 as parallel light.

Except that the light received by the light-receiving element 15 is not the light reflected by the measurement object 11 but the light transmitted through the measurement object 11, its optical path is the same as the reflection light of the first embodiment shown in FIG. 1(1). It is the same as the case of the optical measurement device 1-1.

With such a configuration, the transmitted light measurement device 2-1 measures the transmission angles (θ, φ) of light transmitted in a plurality of directions (θ is the transmission angle of light in the vertical direction, and φ is the transmission angle of light in the horizontal direction). ) and the position of the light received by the light receiving element 15 are associated with each other, the luminance distribution L _obj (θ, φ) of the transmitted light can be measured.

Incidentally, the transmitted light measuring device 2-1 may measure the output value of each pixel constituting the light receiving element 15 as the luminance of the light transmitted in the direction of the transmission angle (θ, φ). Further, the transmitted light measuring device 2-1 may perform statistical processing such as calculating an average value on the measured values of a plurality of pixels forming the light receiving element 15. FIG.

Further, the transmitted light measuring device 2-1 may calculate a bidirectional transmittance distribution function representing the transmitted light characteristics of the measurement target 11. FIG. In order to calculate the bidirectional transmittance distribution function of the measurement object 11, a reference object whose bidirectional transmittance distribution function is known is prepared. The bidirectional transmittance distribution function of this reference object is defined as a function f _std (θ, φ) of the vertical light transmission angle θ and the horizontal light transmission angle φ.

A calculation unit (not shown in FIG. 2(1)) provided in the transmitted light measurement device 2-1 calculates the luminance distribution L Measure _std (θ, φ). Then, the calculation unit measures the luminance distribution L _obj (θ, φ) of the transmitted light for the measurement target 11 .

The calculation unit calculates the preset bidirectional transmittance distribution function f _std (θ, φ) of the reference object, the measured luminance distribution L _std (θ, φ) of the transmitted light of the reference object, and the measured luminance distribution of the measurement object 11 . Using the obtained luminance distribution L _obj (θ, φ) of the transmitted light, the bidirectional transmittance distribution function f _obj (θ, φ) of the measurement object 11 is calculated by the above equation (1). Thereby, the bidirectional transmittance distribution function f _obj (θ, φ) of the measurement target 11 can be obtained.

As described above, according to the transmitted light measurement apparatus 2-1 of the second embodiment, by using the optical lens 14 in the configuration shown in FIG. I made it

As a result, similarly to the reflected light measuring apparatus 1-1 of the first embodiment shown in FIG. never occur. Therefore, the loss of light quantity can be suppressed, and the optical characteristics of the measurement target 11 can be measured with high accuracy.

[Modification of Embodiment 2]
Next, a modified example of the second embodiment will be described. FIG. 2(2) is a schematic diagram showing a configuration example of a transmitted light measurement apparatus in a modified example of the second embodiment.

(Composition and arrangement)
This transmitted light measurement device 2-2 includes a measurement object installation section 18, an illumination light source 13, an optical lens 14, a light receiving element 15, and a condenser lens array 17. FIG.

The condenser lens array 17, like the condenser lens array 17 provided in the reflected light measuring apparatus 1-2 of the first embodiment shown in FIG. A light receiving element 15 is arranged at a position separated by the focal length of the optical lens 17a.

The transmitted light measuring device 2-2 has a condensing lens array 17 in addition to the configuration of the transmitted light measuring device 2-1 of the second embodiment shown in FIG. It differs from -1. Other configurations are the same. In FIG. 2(2), parts common to those in FIG. 2(1) are assigned the same reference numerals as those in FIG. 2(1), and detailed description thereof will be omitted.

(optical path)
When the object 11 to be measured is illuminated by the illumination light source 13, of the light transmitted through the object 11 to be measured, the light traveling in the direction of the optical lens 14 undergoes refraction by the optical lens 14 and becomes parallel light. , and advances in the direction of the condenser lens array 17 .

Of the light transmitted through the object 11 and traveling in the direction of the optical lens 14, the light having a solid angle 16c centered on the direction 16b is condensed by the optical lens 17a through the optical lens 14 and received. Light is received at position 15 b of element 15 .

With such a configuration, the transmitted light measuring device 2-2 can measure the luminance distribution L _obj (θ, φ) of the transmitted light in the same manner as the transmitted light measuring device 2-1. , the bidirectional transmittance distribution function f _obj (θ, φ) of the measurement target 11 can be calculated.

As described above, according to the transmitted light measuring device 2-2 of the modified example of the second embodiment, the loss of the light amount is suppressed and the optical characteristics of the measurement target 11 are measured with high precision, as in the transmitted light measuring device 2-1. can be measured to

Since the transmitted light measuring apparatus 2-1 of the second embodiment shown in FIG. It is associated with the transmission angle (θ, φ) of light transmitted in the direction. Therefore, there is an advantage that the transmission characteristics can be measured with high angular resolution, but if the brightness of the transmitted light is low, the signal-to-noise ratio will decrease, and it is assumed that the brightness measurement will become difficult.

On the other hand, in the transmitted light measuring device 2-2 of the modified example of the second embodiment, light having a solid angle 16c centered on the direction 16b is condensed by the optical lens 17a and received at the position 15b of the light receiving element 15. . As a result, even when the brightness of the transmitted light is low, the signal-to-noise ratio can be prevented from deteriorating, and as a result, the optical characteristics of the measurement target 11 can be measured with even higher accuracy.

[Example 3]
Next, Example 3 will be described. FIG. 3 is a schematic diagram showing a configuration example of a reflected light measuring device according to the third embodiment.

(Composition and arrangement)
This reflected light measurement device 3-1 includes a measurement object installation unit 12, an illumination light source 13, a parabolic mirror 19 for reflecting light reflected in a plurality of directions by the measurement object 11, and a parabolic mirror 19. A parabolic mirror 20 that further reflects light, an optical lens 21 that refracts the direction of the light reflected by the parabolic mirror 20, a shielding member 31 that shields part of the light reflected by the measurement target 11, and A light receiving element 15 for receiving light refracted by the optical lens 21 is provided.

FIG. 3 also shows a solid angle 16 a representing the range of light incident on the parabolic mirror 19 . The parabolic mirror 19 is configured in the shape of a paraboloid with an opening in the center. The parabolic mirror 20 is configured in the shape of a paraboloid. The shielding member 31 is composed of a circular flat plate.

The object 11 to be measured is arranged at the focal position of the parabolic mirror 19 . The illumination light source 13 is positioned so as to illuminate the object to be measured 11 through an opening 22 provided in the parabolic mirror 19, which will be described later, and not to block the light reflected by the object to be measured 11. are placed.

The parabolic mirror 19 has an annular opening 22 for allowing the light reflected by the parabolic mirror 20 to pass in the direction of the optical lens 21 . That is, the aperture 22 is an aperture through which the illumination light source 13 illuminates the measurement object 11 and the light reflected by the parabolic mirror 20 passes toward the optical lens 21 .

The parabolic mirror 20 and the optical lens 21 are in a state where the focal position of the parabolic mirror 20 and the focal position on the front side (the side opposite to the measurement object 11) of the optical lens 21 match (the matching position is the focal point 23). ). Optical lens 21 has a negative focal length.

The light-receiving element 15 is arranged on a plane perpendicular to the optical axis of the optical lens 21 on the opposite side of the measurement target 11 (with respect to the optical lens 21 ). The shielding member 31 is provided in the center of the ring-shaped opening 22 provided in the parabolic mirror 19, and prevents the light reflected by the measurement object 11 from proceeding directly to the optical lens 21. It is made of a material that shields and does not reflect the light.

FIG. 11(1) is a schematic diagram showing a first installation example of the shielding member 31 in Examples 3 and 4 and their modifications, and FIG. 11(2) shows a second installation example of the shielding member 31. 1 is a schematic diagram; FIG.

In the first installation example shown in FIG. 11(1), the shielding member 31 is installed so as to be held by the optical lens 21 by the holding member 33 that fixes the center of the shielding member 31 and the center of the optical lens 21 . be. The center of the shielding member 31 and one end of the holding member 33 are fixed with an adhesive, for example, and the center of the optical lens 21 and the other end of the holding member 33 are fixed with an adhesive, for example. The holding member 33 is installed at a position through which reflected light or transmitted light shown in FIGS. 5 and 6, which will be described later, does not pass.

In addition, in the second installation example shown in FIG. 11(2), the shielding member 31 is positioned so that the outer edge of the shielding member 31 and the parabolic mirror 19 are aligned on a straight line passing through the centers of the shielding member 31 and the parabolic mirror 19. It is installed so as to be held by the parabolic mirror 19 by two holding members 34-1 and 34-2 that fix the inner edge of the mirror. A predetermined portion of the outer edge of the shielding member 31 and one end of the holding member 34-1 are fixed by, for example, an adhesive, and a predetermined portion of the inner edge of the parabolic mirror 19 and the other end of the holding member 34-1 are fixed, for example. Fixed by glue. Similarly, the other portion of the outer edge of the shielding member 31 and one end of the holding member 34-2 are fixed by, for example, an adhesive, and the other portion of the inner edge of the parabolic mirror 19 and the other portion of the holding member 34-2 are fixed. The ends are fixed by, for example, an adhesive.

(optical path)
Returning to FIG. 3 , when the measurement object 11 is illuminated by the illumination light source 13 , among the light reflected by the measurement object 11 , the light traveling in the direction of the parabolic mirror 19 is reflected by the parabolic mirror 19 . After being reflected, it becomes parallel light and travels toward the parabolic mirror 20 . The light reflected by the parabolic mirror 20 travels in the direction of the focal point 23 of the parabolic mirror 20 through the opening 22 , but after receiving the refraction action of the optical lens 21 , light is received.

Light is reflected in various directions within the range of the solid angle 16 a on the measurement object 11 , and the reflected light is reflected by the parabolic mirror 20 . Since the optical lens 21 is arranged so as to coincide with the focal position, the light refracted by the optical lens 21 reaches the light receiving element 15 as parallel light. For example, in FIG. 3, the light reflected from the measurement object 11 through the parabolic mirrors 19 and 20 in the direction 16b of the optical lens 21 becomes parallel light due to the refraction action of the optical lens 21, and at the position 15a of the light receiving element 15 light is received.

With such a configuration, the reflected light measurement device 3-1 associates the reflection angles (θ, φ) of the light reflected in a plurality of directions by the measurement object 11 with the positions at which the light is received by the light receiving element 15. In this way, the luminance distribution L _obj (θ, φ) of the reflected light can be measured.

Incidentally, the reflected light measurement device 3-1 may measure the output value of each pixel constituting the light receiving element 15 as the luminance of the light reflected in the direction of the reflection angle (θ, φ). Further, the reflected light measurement device 3-1 may perform statistical processing such as calculating an average value on the output values of a plurality of pixels forming the light receiving element 15. FIG.

In addition, the reflected light measurement device 3-1 illuminates the measurement object 11 with the illumination light source 13 through the opening 22 of the parabolic mirror 19. , the illumination light source 13 may be arranged to illuminate the object 11 to be measured.

Further, the reflected light measurement device 3-1, similarly to the reflected light measurement device 1-1 of the first embodiment shown in FIG. You may make it calculate. In this case, a calculation unit (not shown in FIG. 3) provided in the reflected light measurement device 3-1 obtains a preset bidirectional reflectance distribution function f _std (θ, φ) of the reference object, Using the measured luminance distribution L _std (θ, φ) of the reflected light and the measured luminance distribution L _obj (θ, φ) of the reflected light of the measurement object 11, the measurement object 11 , the bidirectional reflectance distribution function f _obj (θ, φ) is calculated.

As described above, according to the reflected light measurement apparatus 3-1 of the third embodiment, by using the parabolic mirrors 19 and 20 and the optical lens 21 in the configuration shown in FIG. is led to the light receiving element 15.

As a result, similarly to the reflected light measuring apparatus 1-1 of the first embodiment shown in FIG. never occur. Therefore, the loss of light quantity can be suppressed, and the optical characteristics of the measurement target 11 can be measured with high accuracy.

Further, in the reflected light measurement apparatus 1-1 of the first embodiment shown in FIG. 1(1), the size of the optical lens 14 must be increased when measuring reflected light over a wide range. On the other hand, in the reflected light measurement device 3-1 of Example 3, the size of the optical lens 21 can be smaller than that of the optical lens 14. FIG. In other words, the reflected light measurement device 3-1 can measure reflected light over a wide range without increasing the size of the optical lens 21, so that cost reduction and space saving can be realized.

[Modification of Embodiment 3]
Next, a modification of Example 3 will be described. FIG. 4 is a schematic diagram showing a configuration example of a reflected light measuring device in a modified example of the third embodiment.

(Composition and arrangement)
This reflected light measurement device 3-2 includes a measuring object setting portion 12, an illumination light source 13, parabolic mirrors 19 and 20, an optical lens 21, a shielding member 31, a light receiving element 15, and the optical lens 21 and the light receiving element 15. A condenser lens array 17 is provided between.

The condenser lens array 17 is configured with a plurality of optical lenses 17 a having a positive focal length and arranged parallel to the light receiving element 15 . A light receiving element 15 is arranged at a position separated by the focal length of the optical lens 17a.

The reflected light measurement device 3-2 differs from the reflected light measurement device 3-1 in that it includes a condenser lens array 17 in addition to the configuration of the reflected light measurement device 3-1 of the third embodiment shown in FIG. differ. Other configurations are the same. In FIG. 4, parts common to those in FIG. 3 are assigned the same reference numerals as those in FIG. 3, and detailed description thereof will be omitted.

(optical path)
After the illumination light source 13 illuminates the measurement object 11, the light reflected by the measurement object 11 is reflected by the parabolic mirrors 19 and 20, undergoes the refraction action of the optical lens 21, and becomes parallel light. The optical path is the same as that of the reflected light measuring device 3-1 of Example 3 shown in FIG.

Of the light reflected by the measurement object 11, reflected by the parabolic mirrors 19 and 20, and traveling in the direction of the optical lens 21 through the opening 22, a solid angle (not shown) around the direction 16b (Fig. 1 (corresponding to the solid angle 16c of 2)) is condensed by the optical lens 17a through the optical lens 21 and received by the light receiving element 15 at the position 15b.

With such a configuration, the reflected light measurement device 3-2 can measure the luminance distribution L _obj (θ, φ) of the reflected light in the same manner as the reflected light measurement device 3-1. , the bidirectional reflectance distribution function f _obj (θ, φ) of the measurement object 11 can be calculated.

As described above, according to the reflected light measurement device 3-2 of the modified example of the third embodiment, the loss of the light amount is suppressed and the optical characteristics of the measurement target 11 are measured with high precision, as in the reflected light measurement device 3-1. can be measured to

In the reflected light measuring device 3-2 of the modification of the third embodiment, the optical lens 17a collects light having a solid angle (not shown) centering on the direction 16b, and the light receiving element 15 receives the light at the position 15b. As a result, as in the modification of the first embodiment, even when the luminance of the reflected light is low, the signal-to-noise ratio can be prevented from lowering than the reflected light measurement apparatus 3-1 of the third embodiment. As a result, the optical properties of the object 11 to be measured can be measured with higher accuracy.

[Example 4]
Next, Example 4 will be described. FIG. 5 is a schematic diagram showing a configuration example of a transmitted light measuring device according to the fourth embodiment.

(Composition and arrangement)
This transmitted light measurement device 4-1 includes a measurement object setting section 18 for setting the measurement object 11, an illumination light source 13, parabolic mirrors 19 and 20, an optical lens 21, a shielding member 31, and a light receiving element 15. FIG. The measurement object installation section 18 has an opening 30 for illuminating the measurement object 11 with the illumination light source 13, as in FIG. 2(1).

Comparing the reflected light measurement device 3-1 and the transmitted light measurement device 4-1 of the third embodiment shown in FIG. They are common in that mirrors 19 and 20, an optical lens 21, a shielding member 31 and a light receiving element 15 are provided. On the other hand, the transmitted light measuring device 4-1, like the transmitted light measuring device 2-1 of the second embodiment shown in FIG. is different from the reflected light measurement apparatus 3-1 in that it has a different illumination light source 13 and a measurement object installation section 18 having an opening 30. FIG. 5, the same reference numerals as in FIG. 3 denote the same parts as in FIG. 3, and detailed description thereof will be omitted.

(optical path)
When the measurement object 11 is illuminated by the illumination light source 13 through the opening 30 of the measurement object installation section 18, the light that has passed through the measurement object 11 and travels toward the parabolic mirror 19 is emitted. After being reflected by the object mirror 19 , it becomes parallel light and travels toward the parabolic mirror 20 . Then, similarly to the reflected light measuring device 3-1 of the third embodiment shown in FIG. After receiving the refraction action of the lens 21 , the light is received by the light receiving element 15 .

Except that the light received by the light-receiving element 15 is not the light reflected by the measurement object 11 but the light transmitted through the measurement object 11, the optical path is the same as that of the reflected light measurement apparatus of the third embodiment shown in FIG. Same as 3-1.

With such a configuration, the transmitted light measuring device 4-1 can measure transmitted light in a form in which the transmission angles (θ, φ) of light transmitted in a plurality of directions are associated with the positions at which the light is received by the light receiving element 15. A light luminance distribution L _obj (θ, φ) can be measured.

The transmitted light measurement device 4-1 may measure the output value of each pixel constituting the light receiving element 15 as the luminance of light transmitted in the direction of the transmission angle (θ, φ). Further, the transmitted light measurement device 4-1 may perform statistical processing such as calculating an average value on the measured values of a plurality of pixels forming the light receiving element 15. FIG.

Further, the transmitted light measuring device 4-1, like the transmitted light measuring device 2-1 of the second embodiment shown in FIG. You may make it calculate. In this case, a calculation unit (not shown in FIG. 5) provided in the transmitted light measurement device 4-1 is used to obtain a preset bidirectional transmittance distribution function f _std (θ, φ) of the reference object, Using the measured luminance distribution L _std (θ, φ) of the transmitted light and the measured luminance distribution L _obj (θ, φ) of the measured object 11, the measurement object 11 to calculate the bidirectional transmittance distribution function f _obj (θ, φ) of

As described above, according to the transmitted light measurement apparatus 4-1 of the fourth embodiment, by using the parabolic mirrors 19 and 20 and the optical lens 21 in the configuration shown in FIG. is led to the light receiving element 15.

As a result, similarly to the reflected light measuring apparatus 1-1 of the first embodiment shown in FIG. never occur. Therefore, the loss of light quantity can be suppressed, and the optical characteristics of the measurement target 11 can be measured with high accuracy.

In the transmitted light measurement apparatus 2-1 of the second embodiment shown in FIG. 2(1), the size of the optical lens 14 must be increased when measuring transmitted light over a wide range. On the other hand, in the transmitted light measuring device 4-1 of Example 4, the size of the optical lens 21 can be smaller than that of the optical lens 14. FIG. In other words, the transmitted light measuring device 4-1 can measure transmitted light over a wide range without increasing the size of the optical lens 21, so that cost reduction and space saving can be realized.

[Modification of Embodiment 4]
Next, a modification of Example 4 will be described. FIG. 6 is a schematic diagram showing a configuration example of a transmitted light measuring device in a modified example of the fourth embodiment.

(Composition and arrangement)
This transmitted light measurement device 4-2 includes a measurement object setting portion 18, an illumination light source 13, parabolic mirrors 19 and 20, an optical lens 21, a light receiving element 15, and a condenser lens array 17. FIG.

The condenser lens array 17 has a plurality of optical lenses having a positive focal length, similar to the condenser lens array 17 provided in the transmitted light measurement apparatus 2-2 of the modification of the second embodiment shown in FIG. A light receiving element 15 is arranged at a position separated by the focal length of the optical lens 17a.

The transmitted light measuring device 4-2 is different from the transmitted light measuring device 4-1 in that it has a condensing lens array 17 in addition to the configuration of the transmitted light measuring device 4-1 of the fourth embodiment shown in FIG. differ. Other configurations are the same. In FIG. 6, parts common to those in FIG. 5 are denoted by the same reference numerals as those in FIG. 5, and detailed description thereof will be omitted.

(optical path)
When the measurement object 11 is illuminated by the illumination light source 13 through the opening 30 of the measurement object installation section 18, the light traveling in the direction of the parabolic mirror 19 out of the light transmitted through the measurement object 11 is reflected in the figure. 5, after being reflected by the parabolic mirror 19, it becomes parallel light and travels toward the parabolic mirror 20. The light reflected by the object mirror 20 travels in the direction of the focal point 23 of the parabolic mirror 20 , but after undergoing the refraction action of the optical lens 21 , becomes parallel light and travels in the direction of the condenser lens array 17 . proceed.

Except that the light received by the light-receiving element 15 is not the light reflected by the measurement object 11 but the light transmitted through the measurement object 11, its optical path is similar to the reflection of the modification of the third embodiment shown in FIG. It is the same as the light measuring device 3-2.

With such a configuration, the transmitted light measuring device 4-2 can measure the luminance distribution L _obj (θ, φ) of the transmitted light in the same manner as the transmitted light measuring device 4-1. , the bidirectional transmittance distribution function f _obj (θ, φ) of the measurement object 11 can be calculated.

As described above, according to the transmitted light measuring device 4-2 of the modified example of the fourth embodiment, similarly to the transmitted light measuring device 4-1, the loss of light quantity is suppressed, and the optical characteristics of the measurement object 11 are measured with high accuracy. can be measured to

Further, in the transmitted light measuring device 4-2 of the modified example of the fourth embodiment, as in the modified example of the second embodiment, even when the luminance of the transmitted light is low, the transmitted light measuring device 4-2 of the fourth embodiment A signal-to-noise ratio lower than that of 1 can be avoided, and as a result, the optical properties of the measurement object 11 can be measured with higher accuracy.

Further, in the transmitted light measuring device 4-2 of the modification of the fourth embodiment, transmitted light in a wide range can be measured without increasing the size of the optical lens 21 as compared with the optical lens 14 of the modification of the second embodiment. Therefore, cost can be reduced and space can be saved.

[Example 5]
Next, Example 5 will be described. FIG. 7 is a schematic diagram showing a configuration example of a reflected light measuring device according to the fifth embodiment.

(Composition and arrangement)
This reflected light measurement device 5-1 includes a measurement object installation unit 12, an illumination light source 13, parabolic mirrors 19 and 20, optical lenses 24 and 25 for refracting directions of light reflected in a plurality of directions from the measurement object 11, An optical lens 26 that refracts the direction of the light reflected by the parabolic mirror 20, a shielding member 32 that shields part of the light reflected by the measurement target 11, and the optical lenses 24, 25, and 26. A light receiving element 15 for receiving light is provided.

7 also shows a solid angle 16a representing the range of light incident on the parabolic mirror 19, a solid angle 16c representing the range of light incident on the optical lens 24, and a range of light incident on the optical lens 25. A solid angle 16d representing . The parabolic mirrors 19, 20 are configured in the same shape as the parabolic mirrors 19, 20 shown in FIG. The optical lenses 24, 25, 26 are constructed integrally. The shielding member 32 is composed of a ring-shaped flat plate with an opening 27 in the center.

The object 11 to be measured is arranged at the focal position of the parabolic mirror 19 . The illumination light source 13 is arranged at a position where it is possible to illuminate the measurement object 11 through the opening 22 provided in the parabolic mirror 19 and where the light reflected by the measurement object 11 is not blocked. ing.

The parabolic mirror 19 has an annular aperture for allowing the light reflected by the object 11 to pass through to the optical lens 25 and the light reflected by the parabolic mirror 20 to pass through the optical lens 26 . A portion 22 is provided. That is, the aperture 22 allows the illumination light source 13 to illuminate the measurement object 11, the light reflected by the measurement object 11 to pass through the optical lens 25, and the light reflected by the parabolic mirror 20 to pass through the optical lens 25. It is an opening for passing toward the lens 26 .

The parabolic mirror 20 and the optical lens 26 are arranged so that the focal position of the parabolic mirror 20 and the front focal position of the optical lens 26 match (the matching position is the focal point 23). Optical lens 26 has a negative focal length.

The optical lens 24 is arranged so that the measurement object 11 and the light receiving element 15 are in an optically conjugate relationship. The optical lens 25 is arranged so that the front focal position of the optical lens 25 and the position of the object 11 to be measured match. Optical lenses 24, 25 have a positive focal length.

The light-receiving element 15 is arranged on a plane orthogonal to the optical axes of the optical lenses 24 , 25 , 26 on the opposite side of the measurement object 11 (with respect to the optical lenses 24 , 25 , 26 ). The shielding member 32 is provided in the center of the ring-shaped opening 22 provided in the parabolic mirror 19 and blocks the light reflected by the measurement object 11 from proceeding directly to the optical lens 26 . It is made of a material that shields and does not reflect the light.

FIG. 11(3) is a schematic diagram showing a first installation example of the shielding member 32 in Examples 5 and 6 and their modifications, and FIG. is a schematic diagram showing a second installation example of the shielding member 32 in FIG.

In the first installation example shown in FIG. 11(3), the shielding member 32 is installed at a location near the opening 27 provided in the shielding member 32 and a location at which the optical lenses 24 and 26 are connected (or any of the optical lenses 24 and 26). The optical lenses 24, 25 and 26 are held by the two holding members 33-1 and 33-2 that fix the above points. The holding members 33-1 and 33-2 are installed at positions through which reflected light or transmitted light shown in FIGS. 9 and 10, which will be described later, do not pass.

In addition, in the second installation example shown in FIG. 11(4), the shielding member 32 is arranged so that the outer edge of the shielding member 32 and the parabolic mirror 19 are aligned on a straight line passing through the centers of the shielding member 32 and the parabolic mirror 19. It is installed so as to be held by the parabolic mirror 19 by two holding members 34-1 and 34-2 that fix the inner edge of the mirror.

In the first installation example shown in FIG. 11(3), similar to FIG. 11(1), the shielding member 32, the optical lenses 24 and 26 and the ends of the holding members 33-1 and 33-2 are attached by an adhesive, for example. Fixed. Further, in the second installation example shown in FIG. 11(4), similarly to FIG. fixed by an agent.

(optical path)
Returning to FIG. 7 , when the measurement object 11 is illuminated by the illumination light source 13 , the light traveling toward the parabolic mirror 19 among the lights reflected by the measurement object 11 is reflected by the parabolic mirror 19 . After being reflected, it becomes parallel light and travels toward the parabolic mirror 20 . The light reflected by the parabolic mirror 20 travels in the direction of the focal point 23 of the parabolic mirror 20 through the opening 22, but after being refracted by the optical lens 26, becomes parallel light. is received by the light receiving element 15. For example, of the light reflected by the object 11 to be measured, the light in the direction 16b that travels to the parabolic mirror 19 and is reflected and travels to the parabolic mirror 20 and is reflected is subjected to the refraction action of the optical lens 26. After that, the light is received at the position 15 a of the light receiving element 15 .

In addition, although the measurement object 11 reflects light in various directions within the range of the solid angle 16d, since the front focal position of the optical lens 25 and the position of the measurement object 11 are aligned, The light refracted by the optical lens 25 reaches the light receiving element 15 as parallel light. For example, of the light reflected by the measurement object 11 , the light in the direction 16 e is refracted by the optical lens 25 and then received at the position 15 b of the light receiving element 15 .

Among the light reflected by the object 11 to be measured, the light having a solid angle of 16 c that has passed through the opening 27 provided in the shielding member 32 travels toward the optical lens 24 and is refracted by the optical lens 24 . After that, the light is received at the position 15 c of the light receiving element 15 .

With such a configuration, the reflected light measurement device 5-1 associates the reflection angles (θ, φ) of the light reflected in a plurality of directions by the measurement object 11 with the positions at which the light is received by the light receiving element 15. In this way, the luminance distribution L _obj (θ, φ) of the reflected light can be measured.

Incidentally, the reflected light measurement device 5-1 may measure the output value of each pixel constituting the light receiving element 15 as the luminance of the light reflected in the direction of the reflection angle (θ, φ). Further, the reflected light measuring device 5-1 may perform statistical processing such as calculating an average value on the output values of a plurality of pixels forming the light receiving element 15. FIG.

In addition, the reflected light measurement device 5-1 illuminates the measurement object 11 with the illumination light source 13 through the opening 22 of the parabolic mirror 19. , the illumination light source 13 may be arranged to illuminate the object 11 to be measured.

Further, the reflected light measurement device 5-1, like the reflected light measurement device 1-1 of the first embodiment shown in FIG. You may make it calculate. In this case, a calculation unit (not shown in FIG. 7) provided in the reflected light measurement device 5-1 obtains a preset bidirectional reflectance distribution function f _std (θ, φ) of the reference object, Using the measured luminance distribution L _std (θ, φ) of the reflected light and the measured luminance distribution L _obj (θ, φ) of the reflected light of the measurement object 11, the measurement object 11 , the bidirectional reflectance distribution function f _obj (θ, φ) is calculated.

As described above, according to the reflected light measuring apparatus 5-1 of the fifth embodiment, the parabolic mirrors 19 and 20 and the optical lenses 24, 25 and 26 are used in the configuration shown in FIG. 11 is guided to the light receiving element 15. As shown in FIG.

As a result, similarly to the reflected light measuring apparatus 1-1 of the first embodiment shown in FIG. never occur. Therefore, the loss of light quantity can be suppressed, and the optical characteristics of the measurement target 11 can be measured with high accuracy.

In addition, since the shielding member 31 is installed in the reflected light measuring apparatus 3-1 of the third embodiment shown in FIG. 3, it is impossible to measure reflected light with a shallow angle. On the other hand, in the reflected light measuring device 5-1 of the fifth embodiment, since the opening 27 is provided in the shielding member 32, it is possible to measure reflected light with a shallow angle.

[Modification of Example 5]
Next, a modification of Example 5 will be described. FIG. 8 is a schematic diagram showing a configuration example of a reflected light measuring device in a modified example of the fifth embodiment.

(Composition and arrangement)
This reflected light measuring device 5-2 includes a measuring object installation section 12, an illumination light source 13, parabolic mirrors 19 and 20, optical lenses 24, 25 and 26, a shielding member 32, a light receiving element 15, an optical lens 24, A condenser lens array 17 is provided between 25 and 26 and the light receiving element 15 .

The condenser lens array 17 is configured with a plurality of optical lenses 17 a having a positive focal length and arranged parallel to the light receiving element 15 . A light receiving element 15 is arranged at a position separated by the focal length of the optical lens 17a.

The reflected light measurement device 5-2 differs from the reflected light measurement device 5-1 in that it includes a condenser lens array 17 in addition to the configuration of the reflected light measurement device 5-1 of the fifth embodiment shown in FIG. differ. Other configurations are the same. In FIG. 8, parts common to those in FIG. 7 are assigned the same reference numerals as those in FIG. 7, and detailed description thereof will be omitted.

(optical path)
After the illumination light source 13 illuminates the object 11 to be measured, the light reflected by the object 11 is reflected by the parabolic mirrors 19 and 20, undergoes refraction by the optical lens 26, and becomes parallel light. An optical path, an optical path from the light reflected by the measurement object 11 undergoing the refraction action of the optical lens 25 until it becomes parallel light, and the light reflected by the measurement object 11 undergoes the refraction action of the optical lens 24 and is received. The optical path traveling in the direction of the element 15 is the same as that of the reflected light measuring device 5-1 of Example 5 shown in FIG.

Of the light reflected by the object 11 to be measured, reflected by the parabolic mirrors 19 and 20, passed through the opening 22 and traveling toward the optical lens 26, light having a solid angle (not shown) is reflected by the optical lens. The light is refracted by 26, condensed by the optical lens 17a, and received by the light receiving element 15. FIG.

Among the light reflected by the measurement object 11 and passing through the aperture 22, light having a solid angle (not shown) is refracted by the optical lens 25, condensed by the optical lens 17a, and received by the light receiving element 15. light is received.

Among the light reflected by the measurement object 11 and passing through the aperture 27 , light having a solid angle (not shown) is refracted by the optical lens 24 and received by the light receiving element 15 .

With such a configuration, the reflected light measurement device 5-2 can measure the luminance distribution L _obj (θ, φ) of the reflected light in the same manner as the reflected light measurement device 5-1. , the bidirectional reflectance distribution function f _obj (θ, φ) of the measurement object 11 can be calculated.

As described above, according to the reflected light measuring device 5-2 of the modified example of the fifth embodiment, the loss of light quantity is suppressed and the optical characteristics of the measurement target 11 are measured with high precision, as in the reflected light measuring device 5-1. can be measured to

Further, the reflected light measuring device 5-2 of the modified example of the fifth embodiment is similar to the modified example of the first embodiment, even when the luminance of the reflected light is low, the reflected light measuring device 5-2 of the fifth embodiment A signal-to-noise ratio lower than that of 1 can be avoided, and as a result, the optical properties of the measurement object 11 can be measured with higher accuracy.

[Example 6]
Next, Example 6 will be described. FIG. 9 is a schematic diagram showing a configuration example of a transmitted light measuring device according to the sixth embodiment.

(Composition and arrangement)
This transmitted light measurement device 6-1 includes a measurement object setting section 18 for setting the measurement object 11, an illumination light source 13, parabolic mirrors 19 and 20, optical lenses 24, 25 and 26, a shielding member 32, and a light receiving element 15. I have. The measurement object installation section 18 has an opening 30 for illuminating the measurement object 11 with the illumination light source 13, as in FIG. 2(1).

Comparing the reflected light measurement device 5-1 of Example 5 shown in FIG. They are common in that mirrors 19 and 20, optical lenses 24, 25 and 26, a shielding member 32 and a light receiving element 15 are provided. On the other hand, the transmitted light measuring device 6-1, like the transmitted light measuring device 2-1 of the second embodiment shown in FIG. is different from the reflected light measurement device 5-1 in that it has a different illumination light source 13 and a measurement object installation section 18 having an opening 30. FIG. In FIG. 9, parts common to those in FIG. 7 are assigned the same reference numerals as those in FIG. 7, and detailed description thereof will be omitted.

(optical path)
When the measurement object 11 is illuminated by the illumination light source 13 through the opening 30 of the measurement object installation section 18, the light that has passed through the measurement object 11 and travels toward the parabolic mirror 19 is emitted. After being reflected by the object mirror 19 , it becomes parallel light and travels toward the parabolic mirror 20 . 7, the light reflected by the parabolic mirror 20 travels in the direction of the focal point 23 of the parabolic mirror 20. After receiving the refraction action of the lens 26 , it becomes parallel light and is received by the light receiving element 15 .

In addition, among the light transmitted through the measurement object 11, the light traveling in the direction of the optical lens 25 through the opening 22 provided in the parabolic mirror 19 undergoes the refraction action of the optical lens 25, and then becomes parallel. It becomes light and is received by the light receiving element 15 . Further, among the light transmitted through the measurement object 11 , the light traveling in the direction of the optical lens 24 through the opening 27 provided in the shielding member 32 is subjected to the refraction action of the optical lens 24 , and then is received at

Except that the light received by the light-receiving element 15 is not the light reflected by the measurement object 11 but the light transmitted through the measurement object 11, the optical path is the same as that of the reflected light measurement apparatus of the fifth embodiment shown in FIG. Same as 5-1.

With such a configuration, the transmitted light measurement device 6-1 can measure transmitted light in a form in which the transmission angles (θ, φ) of light transmitted in a plurality of directions are associated with the positions at which the light is received by the light receiving element 15. A light luminance distribution L _obj (θ, φ) can be measured.

Incidentally, the transmitted light measuring device 6-1 may measure the output value of each pixel constituting the light receiving element 15 as the luminance of the light transmitted in the direction of the transmission angle (θ, φ). Further, the transmitted light measuring device 6-1 may perform statistical processing such as calculating an average value on the measured values of a plurality of pixels forming the light receiving element 15. FIG.

Further, the transmitted light measuring device 6-1, like the transmitted light measuring device 2-1 of the second embodiment shown in FIG. You may make it calculate. In this case, a calculation unit (not shown in FIG. 9) provided in the transmitted light measurement device 6-1 is used to obtain a preset bidirectional transmittance distribution function f _std (θ, φ) of the reference object, Using the measured luminance distribution L _std (θ, φ) of the transmitted light and the measured luminance distribution L _obj (θ, φ) of the measured object 11, the measurement object 11 to calculate the bidirectional transmittance distribution function f _obj (θ, φ) of

As described above, according to the transmitted light measuring apparatus 6-1 of the sixth embodiment, the parabolic mirrors 19, 20 and the optical lenses 24, 25, 26 are used in the configuration shown in FIG. 11 is guided to the light receiving element 15. FIG.

As a result, similarly to the reflected light measuring apparatus 1-1 of the first embodiment shown in FIG. never occur. Therefore, the loss of light quantity can be suppressed, and the optical characteristics of the measurement target 11 can be measured with high accuracy.

Further, in the transmitted light measuring apparatus 4-1 of the fourth embodiment shown in FIG. 5, since the shielding member 31 is installed, it is impossible to measure transmitted light with a shallow angle. On the other hand, in the transmitted light measuring device 6-1 of the sixth embodiment, since the opening 27 is provided in the shielding member 32, it is possible to measure even transmitted light with a shallow angle.

[Modification of Embodiment 6]
Next, a modification of Example 6 will be described. FIG. 10 is a schematic diagram showing a configuration example of a transmitted light measuring device in a modified example of the sixth embodiment.

(Composition and arrangement)
This transmitted light measuring device 6-2 includes a measuring object installation section 18, an illumination light source 13, parabolic mirrors 19 and 20, optical lenses 24, 25 and 26, a shielding member 32, a light receiving element 15, an optical lens 24, A condenser lens array 17 is provided between 25 and 26 and the light receiving element 15 .

The condenser lens array 17 is configured with a plurality of optical lenses 17 a having a positive focal length and arranged parallel to the light receiving element 15 . A light receiving element 15 is arranged at a position separated by the focal length of the optical lens 17a.

The transmitted light measuring device 6-2 is different from the transmitted light measuring device 6-1 in that it has a condensing lens array 17 in addition to the configuration of the transmitted light measuring device 6-1 of the sixth embodiment shown in FIG. differ. Other configurations are the same. In FIG. 10, the same reference numerals as in FIG. 9 denote the same parts as in FIG. 9, and detailed description thereof will be omitted.

(optical path)
After the measurement object 11 is illuminated by the illumination light source 13, the light transmitted through the measurement object 11 is reflected by the parabolic mirrors 19 and 20, undergoes the refraction action of the optical lens 26, and becomes parallel light. An optical path, an optical path until the light transmitted through the measurement object 11 undergoes the refraction action of the optical lens 25 and then becomes parallel light, and the light transmitted through the measurement object 11 undergoes the refraction action of the optical lens 24 and is received. The optical path traveling in the direction of the element 15 is the same as that of the transmitted light measurement device 6-1 of Example 6 shown in FIG.

Of the light that passes through the measurement object 11, is reflected by the parabolic mirrors 19 and 20, passes through the opening 22 and travels toward the optical lens 26, the light having a solid angle (not shown) passes through the optical lens. The light is refracted by 26, condensed by the optical lens 17a, and received by the light receiving element 15. FIG.

Among the light that has passed through the measurement object 11 and passed through the aperture 22, light having a solid angle (not shown) is refracted by the optical lens 25, condensed by the optical lens 17a, and received by the light receiving element 15. light is received.

Among the light that has passed through the measurement target 11 and passed through the aperture 27 , light having a solid angle (not shown) is refracted by the optical lens 24 and received by the light receiving element 15 .

With such a configuration, the transmitted light measuring device 6-2 can measure the luminance distribution L _obj (θ, φ) of the transmitted light in the same manner as the transmitted light measuring device 6-1. , the bidirectional transmittance distribution function f _obj (θ, φ) of the measurement target 11 can be calculated.

As described above, according to the transmitted light measuring device 6-2 of the modified example of the sixth embodiment, similarly to the transmitted light measuring device 6-1, the loss of light quantity is suppressed, and the optical characteristics of the object 11 to be measured can be measured with high accuracy. can be measured to

Further, the transmitted light measuring device 6-2 of the modified example of the sixth embodiment is similar to the modified example of the second embodiment, even when the luminance of the transmitted light is low, the transmitted light measuring device 6-2 of the sixth embodiment A signal-to-noise ratio lower than that of 1 can be avoided, and as a result, the optical properties of the measurement object 11 can be measured with higher accuracy.

Although the present invention has been described above with reference to Examples 1 to 6, the present invention is not limited to Examples 1 to 6, and can be variously modified without departing from the technical idea thereof.

For example, in Examples 1, 3, and 5 and their modifications, the measurement object 11 is illuminated by the illumination light source 13, and the reflection characteristics of the measurement object 11 are measured by measuring the light reflected by the measurement object 11. I made it In Examples 2, 4, and 6 and their modifications, the measurement object 11 is illuminated by the illumination light source 13, and the transmission characteristics of the measurement object 11 are measured by measuring the light transmitted through the measurement object 11. I made it

On the other hand, the present invention is also applicable when the object 11 to be measured is a self-luminous body. Specifically, the optical characteristic measuring device measures the light distribution of the self-luminous body, which is the measurement target 11, without using the illumination light source 13, according to the configurations of Examples 1 to 6 and their modifications. , to measure the optical properties of the object 11 to be measured.

Specifically, the optical characteristic measuring apparatus corresponding to Examples 1 and 2 includes an optical lens 14 and a light receiving element 15 that refract light emitted in a plurality of directions from the object 11 to be measured. Moreover, the optical characteristic measuring apparatus corresponding to the modifications of Examples 1 and 2 further includes a condenser lens array 17 .

An optical characteristic measuring apparatus corresponding to Examples 3 and 4 includes a parabolic mirror 19, a parabolic mirror 20, an optical lens 21, and a light receiving element 15 that reflect light emitted in a plurality of directions from the measurement object 11. . Moreover, the optical characteristic measuring apparatus corresponding to the modifications of the third and fourth embodiments further includes a condenser lens array 17 .

The optical characteristic measuring apparatus corresponding to Examples 5 and 6 includes a parabolic mirror 19 and a parabolic mirror 20 that reflect light emitted in a plurality of directions by the measurement object 11, and a parabolic mirror 20 that reflects the light emitted in the measurement object 11 in a plurality of directions. It has optical lenses 24 and 25 for refracting emitted light, an optical lens 26 for refracting light reflected by the parabolic mirror 20 , and a light receiving element 15 . Moreover, the optical characteristic measuring apparatus corresponding to the modifications of the fifth and sixth embodiments further includes a condenser lens array 17 .

Further, the reflected light measuring devices 1-1 and the like of Examples 1 to 6 and their modifications may be provided with an arbitrary polarizing filter between the illumination light source 13 and the measurement object 11, and the light receiving element 15 and the optical lens 14 or the like may be provided with an arbitrary polarizing filter. If the object 11 to be measured is a self-luminous body, the self-luminous measurement device may be provided with an arbitrary polarizing filter between the self-luminous body that is the object 11 to be measured and the optical lens 14 or the like. and the optical lens 14 or the like may be provided with an arbitrary polarizing filter.

1-1, 1-2, 3-1, 3-2, 5-1, 5-2, 100, 110 Reflected light measuring device 2-1, 2-2, 4-1, 4-2, 6-1 , 6-2 Transmitted light measurement devices 11, 101, 111 Measurement objects 12, 18 Measurement object installation parts 13, 114 Illumination light sources 14, 17a, 21, 24, 25, 26 Optical lens 15 Light receiving elements 15a, 15b, 15c Position 16a , 16c, 16d Solid angles 16b, 16e, 118 Direction 17 Collecting lens arrays 19, 20 Parabolic mirrors 22, 27, 30, 117 Opening 23 Focal points 31, 32 Shielding members 33, 33-1, 33-2, 34-1, 34-2 Holding member 102 Elliptical mirror 103 Projector 104, 115 Camera 105 Semitransparent mirror 106 Image plane 112 Elliptical transmission mirror dome 113 Specular reflector 116 Cylindrical member

Claims (10)

In an optical property measuring device for measuring optical properties of a measurement target,
an illumination light source that irradiates the object to be measured;
an optical lens that refracts light reflected in a plurality of directions by the object to be measured;
a light receiving element that receives light refracted by the optical lens,
The measurement object is arranged at a front focal position of the optical lens,
the optical lens has a positive focal length,
The optical characteristic measuring apparatus, wherein the light receiving element is arranged on a plane orthogonal to an optical axis of the optical lens on a side opposite to the object to be measured with respect to the optical lens. In the optical characteristic measuring device according to claim 1,
The optical characteristic measuring apparatus, wherein the optical lens refracts light transmitted through the object to be measured in a plurality of directions. 3. In the optical property measuring device according to claim 1 or 2,
Furthermore, a condenser lens array for condensing light refracted by the optical lens is provided between the optical lens and the light receiving element,
The condenser lens array comprises a plurality of lenses having a positive focal length and is arranged parallel to the light receiving element,
The optical characteristic measuring apparatus, wherein the light receiving element is arranged at a position separated by the focal length of the plurality of lenses, and receives light condensed by the condensing lens array. In an optical property measuring device for measuring optical properties of a measurement target,
an illumination light source that irradiates the object to be measured;
a first parabolic mirror that reflects light reflected in a plurality of directions by the measurement object;
a second parabolic mirror that reflects the light reflected by the first parabolic mirror;
an optical lens that refracts the light reflected by the second parabolic mirror;
a light receiving element that receives light refracted by the optical lens,
The measurement object is arranged at the focal position of the first parabolic mirror,
The first parabolic mirror has an annular opening through which the light reflected by the second parabolic mirror passes toward the optical lens,
The second parabolic mirror and the optical lens are arranged so that the focal position of the second parabolic mirror and the front focal position of the optical lens are aligned,
the optical lens has a negative focal length,
The optical characteristic measuring apparatus, wherein the light receiving element is arranged on a plane orthogonal to an optical axis of the optical lens on a side opposite to the object to be measured with respect to the optical lens. In the optical characteristic measuring device according to claim 4,
The optical characteristic measuring apparatus, wherein the first parabolic mirror reflects light transmitted in a plurality of directions through the object to be measured. 6. In the optical property measuring device according to claim 4 or 5,
Furthermore, a condenser lens array for condensing light refracted by the optical lens is provided between the optical lens and the light receiving element,
The condenser lens array comprises a plurality of lenses having a positive focal length and is arranged parallel to the light receiving element,
The optical characteristic measuring apparatus, wherein the light receiving element is arranged at a position separated by the focal length of the plurality of lenses, and receives light condensed by the condensing lens array. In an optical property measuring device for measuring optical properties of a measurement target,
an illumination light source that irradiates the object to be measured;
a first parabolic mirror that reflects light reflected in a plurality of directions by the measurement object;
a second parabolic mirror that reflects the light reflected by the first parabolic mirror;
a first optical lens and a second optical lens that refract light reflected in a plurality of directions by the object to be measured;
a third optical lens that refracts the light reflected by the second parabolic mirror;
a light receiving element that receives light refracted by each of the first optical lens, the second optical lens, and the third optical lens,
The measurement object is arranged at the focal position of the first parabolic mirror,
The first parabolic mirror passes the light reflected by the second parabolic mirror toward the third optical lens, and transmits the light reflected by the measurement object to the second optical lens. with an annular opening for passage towards the lens,
The second parabolic mirror and the third optical lens are arranged so that the focal position of the second parabolic mirror and the front focal position of the third optical lens are aligned,
The first optical lens has a positive focal length and is arranged so that the measurement target and the light receiving element are in an optically conjugate relationship,
The second optical lens has a positive focal length, and is arranged so that the front focal position of the second optical lens and the position of the measurement object match,
the third optical lens has a negative focal length;
The light-receiving element includes the first optical lens, the second optical lens, and the third optical lens on the opposite side of the measurement target with respect to the first optical lens, the second optical lens, and the third optical lens. An optical characteristic measuring device, characterized in that it is arranged on a plane perpendicular to the optical axis of the third optical lens. In the optical characteristic measuring device according to claim 7,
The first parabolic mirror reflects light transmitted in a plurality of directions by the measurement object,
The optical characteristic measuring apparatus, wherein the first optical lens and the second optical lens refract light transmitted through the object to be measured in a plurality of directions. 9. In the optical property measuring device according to claim 7 or 8,
Further, light refracted by the second optical lens and the third optical lens is collected between the first optical lens, the second optical lens and the third optical lens, and the light receiving element. Equipped with a light collecting lens array,
The condenser lens array comprises a plurality of lenses having a positive focal length and is arranged parallel to the light receiving element,
The light receiving element is arranged at a position separated by the focal length of the plurality of lenses, and receives light refracted by the first optical lens and light condensed by the condenser lens array. An optical characteristic measuring device characterized by: In an optical property measuring device for measuring optical properties of a measurement target,
The measurement object is a self-luminous body,
an optical lens that refracts light emitted in a plurality of directions from the object to be measured;
a light receiving element that receives light refracted by the optical lens,
The measurement object is arranged at a front focal position of the optical lens,
the optical lens has a positive focal length,
The optical characteristic measuring apparatus, wherein the light receiving element is arranged on a plane orthogonal to an optical axis of the optical lens on a side opposite to the object to be measured with respect to the optical lens.

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