Optical characteristic measuring device and optical characteristic measuring method

Abstract

The present invention comprises: an illumination device (1) capable of illuminating a portion (110a) subject to measurement in an object (100) subject to measurement with illumination lights between which the illumination angle is changed to a plurality of angles; an imaging element (3) for receiving reflected light reflected by the portion subject to measurement from the respective illumination lights between which the illumination angle is changed; and an analysis means (4) for analyzing the optical characteristics of the portion subject to measurement on the basis of the result of receiving light in an analysis area when the portion subject to measurement is irradiated with the respective illumination lights, the analysis area being a specific area (32), from within the light-receiving area of the imaging element, located at a position that does not receive a component regularly reflected by the surface of the portion subject to measurement for any of the illumination lights between which the illumination angle is changed.

Description

[Technical field]

[0001] The present invention relates to an optical property measuring device and an optical property measuring method used to measure the optical properties of a measured portion such as a painted portion containing flake-like aluminum pieces or mica pieces called glittering materials. [Background technology]

[0002] Paints containing such lustrous materials appear to have different colors depending on the viewing angle, and are therefore widely used as metallic or pearlescent paints for automobiles and various other industrial products that require attractive designs.

[0003] Various measuring devices have been proposed to evaluate the characteristics of metallic or pearlescent coatings in terms of texture other than color.

[0004] For example, Patent Document 1 proposes a measuring device that sweeps a line light source in a direction perpendicular to the line light source, captures an image of a sample surface with a camera, and evaluates the optical characteristics of the sample near specular reflection.

[0005] Furthermore, Patent Document 2 proposes a device for more easily performing gonio-measurement of reflected light characteristics at multiple angles, in which the timing at which the object to be measured is imaged by the imaging unit is synchronized with at least one of the timing at which the illumination angle of the illumination unit changes or the timing at which the light receiving angle of the imaging unit changes, and the device measures the reflectance distribution of the object to be measured from an image captured in synchronization with at least one of the timing at which the illumination angle or the light receiving angle changes. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2018-9987 A [Patent Document 2] JP 2014-240830 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, the technique described in Patent Document 1 has a problem that it is difficult to accurately evaluate optical characteristics when the sample surface contains a glittering material, because it is affected by the regular reflection component from the sample surface. Also, the technique described in Patent Document 2 does not consider eliminating the influence of the regular reflection component from the surface of the measurement object.

[0008] This invention has been made in consideration of the above technical background, and aims to provide an optical property measuring device and an optical property measuring method that can accurately measure the optical properties of a measurement object having a surface containing reflective elements such as a shiny material contained in a painted area by eliminating the influence of the specular reflection component of the illumination light on the surface of the measurement object. [Means for solving the problem]

[0009] The above object can be achieved by the following means. (1) A method for measuring optical properties of a measured portion of an object to be measured, comprising: an illumination device capable of illuminating a measured portion of an object with illumination light having a plurality of different illumination angles; an imaging element that receives reflected light from the measured portion of each of the illumination lights having the different illumination angles; and an analysis means that defines a specific area of ​​the light receiving area of ​​the imaging element that is located at a position where no specular reflection component is received from a surface of the measured portion for any of the illumination lights having the different illumination angles as an analysis area, and analyzes optical properties of the measured portion based on a light receiving result in the analysis area when each of the illumination lights is irradiated onto the measured portion. The imaging element is a two-dimensional imaging element whose total light receiving area is larger than the light receiving area of ​​the specular reflection component on the surface of the measurement site due to one illumination light. Optical property measuring device. (2) an analysis means for analyzing the optical characteristics of the measured portion based on the light reception results in the analysis area when each of the illumination lights is irradiated onto the measured portion; and an illumination device for detecting the reflected light from the measured portion of the measured portion of each of the illumination lights having different illumination angles, the analysis means defining an analysis area as a specific area of ​​the light reception area of ​​the imaging element that is located at a position where no specular reflection component is received on the surface of the measured portion for any of the illumination lights having different illumination angles, the analysis means analyzing the optical characteristics of the measured portion based on the light reception results in the analysis area when each of the illumination lights is irradiated onto the measured portion; (3) an imaging element that receives reflected light from the measured part of the object with each of the illumination lights having a changed illumination angle; and an analysis means that defines an analysis area as a specific area of ​​the light receiving area of ​​the imaging element that is located at a position where no specular reflection component is received on the surface of the measured part for any of the illumination lights having a changed illumination angle, and analyzes the optical characteristics of the measured part based on the light receiving results in the analysis area when each of the illumination lights is irradiated onto the measured part, wherein two illumination lights are irradiated onto the measured part simultaneously at a plurality of changed illumination angles while maintaining a gap between them, and when the moving directions of the two light receiving positions on the imaging element side of the specular reflection component on the surface of the measured part moving in sequence in response to the change in illumination angles of both illumination lights are defined as a second direction and a third direction, the analysis area is set midway between the second direction and the third direction. (4) an optical property measuring device comprising: an illumination device capable of illuminating a measured portion of an object to be measured with illumination light having a plurality of altered illumination angles; an imaging element that receives reflected light from the measured portion of each of the illumination lights having altered illumination angles; and an analysis means that defines an analysis area as a specific area within the light receiving area of ​​the imaging element that is located at a position where no specular reflection component is received on the surface of the measured portion for any of the illumination lights having altered illumination angles, and analyzes optical properties of the measured portion based on the light receiving results in the analysis area when each of the illumination lights is irradiated onto the measured portion, wherein the optical properties of the measured portion are optical properties derived from a luster material contained in the object to be measured, and the optical properties derived from the luster material include at least one of information regarding the light distribution property, brightness, particle size, and dispersion and aggregation of the luster material, and the light distribution property is measured in two orthogonal directions. ( 5) The illumination device is a single illumination display device capable of changing the illumination angle to a plurality of angles by moving the display position of a specific illumination pattern, and the direction of movement of the illumination pattern is parallel and / or perpendicular to a plane formed by a normal line of the measurement site, a normal line of the illumination display device, and a normal line of the imaging element. ~4 The optical characteristic measuring apparatus according to claim 1 . ( 6 The specific illumination pattern is a single or multiple bright points or bright lines. 5 The optical characteristic measuring apparatus according to claim 1 . ( 7 ) The above-mentioned item, in which a moving direction in which a light receiving position on the imaging element side of a specular reflection component on the surface of the measurement site moves in sequence in response to a change in the illumination angle of the illumination light is defined as a first direction, the analysis area is set at a position shifted in a direction perpendicular to the first direction. 1 to The optical property measuring apparatus described herein. ( 8 The analysis area is two, and the receiving position of the specular reflection component moving in the first direction passes through the midpoint of the two analysis areas. 7 The optical characteristic measuring apparatus according to claim 1 . ( 9 ) The two illumination lights are configured to be irradiated onto the measurement site at a plurality of different illumination angles while maintaining an interval between them, and when the directions of movement of two light receiving positions on the imaging element side of the specular reflection components on the surface of the measurement site in sequence in response to the change in the illumination angles of the two illumination lights are defined as a second direction and a third direction, the analysis area is set midway between the second direction and the third direction. 1 to The optical property measuring apparatus described herein. ( 10 2. The method according to claim 1, further comprising: an exposure time determination unit that determines an exposure time of the illumination light to the imaging element before starting measurement. 9 13. The optical characteristic measuring apparatus according to claim 12 . ( 11 The exposure time determining means determines the exposure time based on luminance information obtained in the analysis area. 10 The optical characteristic measuring apparatus according to claim 1 . ( 12The exposure time determination means determines the exposure time based on the luminance information obtained in the analysis area and the exposure time at that time. 10 2. An optical characteristic measuring apparatus according to claim 1 . ( 13 ) The imaging element according to any one of the preceding paragraphs 1 to 4, wherein the spatial resolution of the imaging element is 10 to 100 μm. 12 13. The optical characteristic measuring apparatus according to claim 12 . ( 14 The illumination device, the image sensor, and the analysis means are provided in a single housing, and the housing is provided with an opening for irradiating the measurement site of the object with illumination light and for capturing reflected light from the measurement site, and a result display unit for displaying the measurement result. 13 13. The optical characteristic measuring apparatus according to claim 12 . ( 15 a step of an illumination device illuminating a measurement site of a measurement object with illumination light having a plurality of changed illumination angles; a step of an imaging element receiving reflected light from the measurement site of each of the illumination lights having the changed illumination angles; and a step of designating a specific area of ​​the light receiving area of ​​the imaging element, which is located at a position where no specular reflection component is received from the surface of the measurement site for any of the illumination lights having the changed illumination angles, as an analysis area, and analyzing optical characteristics of the measurement site based on a light receiving result in the analysis area when each of the illumination lights is irradiated onto the measurement site. When a moving direction in which a light receiving position on the imaging element side of a specular reflection component on the surface of the measurement site moves in sequence in response to a change in the illumination angle of the illumination light is defined as a first direction, the analysis area is set at a position shifted in a direction perpendicular to the first direction. Optical property measurement method. ( 16 The illumination device is a single illumination display device capable of changing the illumination angle to a plurality of angles by moving the display position of a specific illumination pattern, and the direction of movement of the illumination pattern is parallel and / or perpendicular to a plane formed by a normal line of the measurement site, a normal line of the illumination display device, and a normal line of the imaging element. 15 The optical characteristic measuring method according to claim 1 . ( 17 The spatial resolution of the imaging element is 10 to 100 μm. 15 or 16 The optical characteristic measuring method according to claim 1 . ( 18 The optical characteristics of the measurement site include at least one of the light distribution characteristics, brightness, particle size, and dispersion / aggregation information of the luminous material contained in the measurement object.15 ~ 17 13. The optical characteristic measuring method according to claim 12 . Effect of the Invention

[0010] The preceding paragraph (1) ~(4) and ( 15 According to the invention described in (1), when a measurement site of a measurement object is illuminated with illumination light having a plurality of different illumination angles, the reflected light from the measurement site is received by an image sensor. A specific area of ​​the light receiving area of ​​the image sensor that is located at a position where the specular reflection component on the surface of the measurement site is not received for any of the illumination lights having different illumination angles is set as an analysis area, and the optical characteristics of the measurement site are analyzed based on the light receiving results in the analysis area when each illumination light is irradiated onto the measurement site.

[0011] In other words, in the analysis area of ​​the image sensor, reception of the specular reflection component on the surface of the measured part is avoided, and for each illumination light with a changed illumination angle, only the light reflected by the reflective elements such as the luminous material of the measured part irradiated with the illumination light and directed toward the analysis area is received in the analysis area, in other words, only the specular reflection light originating from the reflective elements. Therefore, from the light reception results in the analysis area for each illumination light with a changed illumination angle, the optical characteristics of the measured object can be measured with high accuracy while eliminating the influence of the specular reflection component on the surface of the measured object.

[0012] The previous paragraph ( 5 ) and ( 16 According to the invention described in (1), the lighting device is a single lighting display device that can change the lighting angle to a plurality of angles by moving the display position of a specific lighting pattern, and the direction of movement of the lighting pattern is parallel or perpendicular to a plane formed by the normal to the measurement site, the normal to the lighting display device, and the normal to the imaging element, so that the optical characteristics of the measurement object can be measured with a simple configuration.

[0013] The previous paragraph ( 6According to the invention described in (1), by moving a single bright point or bright line on a single lighting display device, illumination light with multiple changed lighting angles can be easily created.

[0014] The previous paragraph ( 1 According to the invention described in , by using a two-dimensional imaging element whose total light receiving area is larger than the light receiving area of ​​the specularly reflected light from a single illumination light as the imaging element, it becomes easy to set the analysis area.

[0015] The previous paragraph ( 2 ) 、(7) and ( 15 According to the invention described in (1), when the direction of movement of the receiving position on the imaging element side of the specular reflection component on the surface of the measured portion moves sequentially in response to a change in the illumination angle of the illumination light is defined as a first direction, the analysis area is set at a position shifted vertically to the first direction, so that it is possible to reliably prevent the specular reflection component of each illumination light on the surface of the measured portion from being received in the analysis area.

[0016] The previous paragraph ( 8 According to the invention described in , more detailed measurement results can be obtained based on the light reception results in the two analysis areas.

[0017] The previous paragraph ( 3 ) and (9) According to the invention described in the above, two illumination lights are irradiated onto the measured area at multiple different illumination angles simultaneously while maintaining a distance between them, and when the directions in which two light receiving positions on the imaging element side of the specular reflection component on the surface of the measured area move in sequence in response to the change in the illumination angles of both illumination lights are set to a second direction and a third direction, the analysis area is set midway between the second direction and the third direction, so that more detailed measurement results can be obtained using the two illumination lights.

[0018] The previous paragraph ( 10According to the invention described in , the exposure time of the illumination light for the imaging element is determined before measurement begins, so that optical characteristics can be measured with higher accuracy using an appropriate exposure time.

[0019] The previous paragraph ( 11 ) and ( 12 According to the invention described in , it is possible to determine a more appropriate exposure time.

[0020] The previous paragraph ( 13 ) and ( 17 According to the invention described in , the spatial resolution of the imaging element is 10 to 100 μm, so that it is possible to measure realistic reflection angle characteristics suitable for the human eye.

[0021] The previous paragraph ( 4 According to the invention described in , it is possible to measure optical properties originating from the shiny material contained in the object to be measured.

[0022] The previous paragraph ( 4 ) and ( 18 According to the invention described in the above, it is possible to measure optical characteristics including at least one of the light distribution characteristics, brightness, particle size, and information regarding dispersion and aggregation of the lustrous material.

[0023] The previous paragraph ( 4 According to the invention described in , the light distribution characteristic is measured in two perpendicular directions.

[0024] The previous paragraph ( 14 According to the invention described in , the optical characteristics of an object to be measured can be measured anywhere by carrying the housing. [Brief description of the drawings]

[0025] [Figure 1] 1 is a block diagram showing a configuration of an optical characteristic measuring apparatus including an output device for optical characteristic measurement data according to an embodiment of the present invention. [Diagram 2]FIG. 2 is a perspective view of the appearance of an optical characteristic measuring device. [Diagram 3] 1 is a diagram for explaining the surface configuration of a measurement object having a coating containing a glittering material. FIG. [Figure 4] 1A and 1B are diagrams illustrating a moving state of the illumination pattern and an image captured by the imaging element at that time. [Diagram 5] 10A and 10B are diagrams for explaining a specific example of a range of illumination angles that can be changed by the illumination device. [Figure 6] 13(A) to 13(D) are diagrams showing schematic views of reflection from the metallic pigment when the illumination pattern is moved (scanned) in one direction. [Figure 7] Graphs (A) to (C) show examples of the brightness values ​​obtained for pixels located at positions receiving the specular reflection component on the surface of the measured area and pixels within the analysis area when the illumination angle is changed. [Figure 8] FIG. 11 is an explanatory diagram of light distribution information of a glittering material. [Figure 9] FIG. 1A is a schematic diagram showing a state in which a large number of luminous materials with small particle diameters are present, and FIG. 1B is a schematic diagram showing a state in which a luminous material with large particle diameters is present. [Figure 10] 1A is a schematic diagram showing a state in which the lustrous material is dispersed, and FIG. 1B is a schematic diagram showing a state in which the lustrous material is aggregated. [Figure 11] 13(A) and (B) are diagrams for explaining a method for determining an exposure time. [Figure 12] FIG. 13 is an explanatory diagram of a case where two analysis areas are set for one illumination pattern. [Figure 13] FIG. 13 is an explanatory diagram of a case where analysis areas are set for two illumination patterns. [Figure 14] FIG. 13 is an explanatory diagram of a case where an analysis area is set for two illumination patterns moving in two perpendicular directions. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0027] FIG. 1 is a block diagram showing the configuration of an optical characteristic measuring apparatus according to an embodiment of the present invention.

[0028] The optical property measuring device shown in FIG. 1 comprises a single illumination display device 1, an objective lens 2, a two-dimensional imaging element 3 consisting of a CCD sensor or the like, a calculation unit 4, and a measurement result display unit 5 consisting of a liquid crystal display device or the like.

[0029] The illumination display device 1 displays at least one illumination pattern, and irradiates illumination light L1 from the displayed illumination pattern onto a measurement site 100a of a measurement object (also simply referred to as a sample) 100.

[0030] The image sensor 3 has a large number of pixels, and receives reflected light L2 from the sample 100 for each pixel via the objective lens 2, converts it into image data, and outputs it.

[0031] In this embodiment, the lighting display device 1 and the image sensor 3 are disposed in a positional relationship that allows the image sensor 3 to receive reflected light of a regular reflection component that is a specular reflection from the surface of the measured portion 100a. In other words, they are disposed in a relationship in which the angle between the normal to the measured portion 100a of the sample 100 and the normal to the lighting display device 1 is approximately equal to the angle between the normal to the measured portion 100a of the sample 100 and the image sensor 3.

[0032] Image data, which is an electrical signal output from the imaging element 3, is converted into a digital signal through an IV conversion circuit and an AD conversion circuit (not shown) as necessary, and sent to a calculation unit (corresponding to an analysis means) 4. The calculation unit 4 uses the sent image data to perform calculation processing of the optical characteristics of the measurement site 100a, for example, the optical characteristics derived from the lustrous material, using a CPU or the like, and the measurement result display unit 5 displays the calculation results by the calculation unit 4, i.e., the measurement results. Note that the conversion of the image data output from the imaging element 3 into a digital signal may be performed by the calculation unit 4.

[0033] The calculation unit 4 may be a dedicated device or may be configured with a personal computer. Moreover, the image data output from the image sensor 3 and processed into a digital signal may be sent to the calculation unit 4 via a network. In this case, even if the calculation unit 4 is located at a place away from the measurement site, the optical characteristics can be measured.

[0034] Next, the spatial resolution of the image sensor 3 will be explained. In order for the image sensor 3 to detect a phenomenon that can be observed with the naked eye, the image sensor 3 needs to have a spatial resolution equivalent to that of the human eye. According to one study, the minimum width that the human eye can distinguish is said to be about 0.6 arc minutes. If the distance from the pupil to the object being observed is assumed to be 20 to 30 cm, the distance between two distinguishable points can be calculated to be 30 to 50 μm.

[0035] In addition, if the measurement target is a painted surface containing a luminous material of an automobile exterior material, the particle size of the luminous material contained inside the paint film is as small as 10 to 20 μm and as large as about 100 μm. It is more preferable that the imaging element 3 be able to spatially distinguish each luminous material.

[0036] For these reasons, it is desirable for the spatial resolution of the imaging element 3 to be approximately 10 to 100 μm.

[0037] 2 is a perspective view showing the appearance of an optical characteristic measuring device according to an embodiment of the present invention. In this embodiment, the optical characteristic measuring device is configured as a portable handy type.

[0038] Specifically, an illumination display device 1, an objective lens 2, an image sensor 3, and a calculation unit 4 are housed in a housing 8. A carrying handle 82 is provided on the top surface of the housing 8, as well as a measurement result display unit 5 for displaying the measurement results, and an opening 81 is formed on the bottom surface of the housing 8 for irradiating illumination light onto a measurement site 100a of the sample 100 and capturing reflected light from the measurement site.

[0039] 2, when in use, the gripping portion 82 is gripped and the opening 81 on the bottom surface is positioned at the measurement site 100a of the sample 100. In this state, illumination light is irradiated onto the sample 100 from the illumination display device 1 housed inside the housing 8, the reflected light is received by the image sensor 3, and the optical properties are measured by performing calculations in the calculation unit 5 using the image data output from the image sensor 3, and the measurement results are displayed on the measurement result display unit 5.

[0040] According to such an optical characteristic measuring device, the housing can be carried around, allowing the optical characteristics to be measured regardless of location. (Embodiment 1) Next, specific measurements of optical characteristics will be described.

[0041] The optical characteristic is a characteristic of the reflection angle at which the measurement site 100a reflects the illumination light L1, and as described below, is evaluated in a specific analysis area among the entire light receiving area of ​​the imaging element 3. In this embodiment, a case will be described in which the optical characteristic is information related to the light distribution of the lustrous material (for example, the light distribution angle).

[0042] A typical layer structure of an automobile surface coated with paint containing a lustrous material is shown in Fig. 3, in which a lustrous material-containing layer 102 containing a lustrous material 110 is painted and laminated on a base layer 101, which is a substrate, and a clear layer 103 made of a clear coat layer or the like is further laminated on top of that. Consider an optical model for measuring the optical properties of such a layer structure.

[0043] The lustrous material 110 in the coating exists with a certain inclination (orientation). The orientation distribution generally has a peak at the horizontal direction (0 degrees) of the coating surface, and the number of lustrous material decreases as the angle increases.

[0044] The state of orientation is said to depend on design factors such as the type of glittering material 110 and paint, as well as coating conditions such as the paint spray speed, pressure, and film thickness.

[0045] When illumination light L1 is incident on the measurement site 100a of the sample 100 having such a lustrous material-containing layer 102, part of it is specularly reflected (regularly reflected) on the surface of the clear layer 103, and part of it is transmitted through the surface of the clear layer 103. Part of the transmitted light is specularly reflected (regularly reflected light L12) by the lustrous material 110 inside the coating.

[0046] The glittering material reflects light in a direction according to the inclination of the glittering material 110 from the horizontal direction of the coating surface. Usually, the orientation angle θ of most glittering materials 110 is within 5° with respect to the normal direction of the sample. This corresponds to |θas|≦15° when expressed as the as angle in FIG. 2, when the refractive index of the clear layer is n=1.4 and the incident angle is 45°.

[0047] A case will be described in which the optical characteristics of the measurement site 100a of the sample 100 having such a shiny material-containing layer 102 and clear layer 103 are measured using the optical characteristic measuring device according to this embodiment.

[0048] It is assumed that the resolution on the sample surface is sufficiently high and that the spatial resolution is sufficient to capture the bright spots originating from each luster material in the automobile exterior paint. As explained above, the spatial resolution of the imaging element 3 is preferably about 10 to 100 μm.

[0049] The lighting display device 1 displays a predetermined lighting pattern and moves the displayed lighting pattern in one direction. An example of a lighting pattern is a single bright spot. Fig. 4(A) shows how this single bright spot is displayed and moved on the lighting display device 1, and Fig. 4(B) shows an image captured by the imaging element 3 when the bright spot is moved. In this example, the direction of movement of the bright spot 11 is parallel to the plane formed by the normal to the measurement site 100a, the normal to the lighting display device 1, and the normal to the imaging element 3 (the horizontal direction in Fig. 4(A)).

[0050] In Fig. 4(A), the white parts of the rectangle are bright points 11 and the black parts are non-luminous areas. The illumination display device 1 has a rectangular display surface, and in screen number A1, a bright point 11 is displayed in the middle of the vertical direction at one horizontal end of the display surface (the left end in Fig. 4(A)). This bright point 11 moves (scans) in sequence to the other horizontal end side of the display surface (the right end side in Fig. 34A) as shown by arrow H1 on screen A1. Screen numbers A1 → A2 →... → An →... indicate the display surfaces along which the bright point 11 is moving.

[0051] On the other hand, the two-dimensional image sensor 3 has a rectangular light receiving area consisting of many pixels as shown in Fig. 4(B). Image number B1 shows an image captured by the image sensor 3 when illuminated by the display screen of screen number A1, and the white dots indicate that the light receiving section 30 at one end in the horizontal direction (the left end in Fig. 4(A)) of the entire rectangular light receiving area has high brightness. The reason why the brightness of this light receiving section 30 is high is because it receives the regular reflection component specularly reflected by the surface of the clear layer 103 when the illumination light from the bright point 11 shown in screen number A1 is irradiated to the measurement site 100a. In other words, the arrival point of the regular reflection component specularly reflected by the surface of the clear layer 103 to the image sensor 3 is the light receiving section 30.

[0052] When the bright spot 11 of the lighting display device 1 moves (scans) as shown in screen numbers A2 →... →An →..., the illumination angle with respect to the measurement site 100a changes sequentially, but the angle of the light-receiving image sensor 3 is fixed. From the position of the bright spot 11 and the geometry of the image sensor 3, the incident light direction and the outgoing light direction at each measurement site 100a can be uniquely identified.

[0053] Therefore, the position of the light receiving unit 30, which receives the specular reflection component on the surface of the clear layer 103 when the illumination light from the moved bright spot 11 is irradiated onto the measurement area 100a, also moves sequentially to the other end side in the horizontal direction (the right end side in Figure 4(B)), as shown in image numbers B2 →... → Bn →...

[0054] Here, a specific example will be given to supplement the changeable illumination angle range of the illumination display device 1. For example, as shown in Fig. 5, when the distance between the illumination display device 1 and the measurement site 100a of the measurement object 100 is 65.0 mm, the illumination display device 1 is 2.4 inch QVGA, and the length of the long side is 48.8 mm, the illumination angle of the bright spot 11 can be realized up to 21.8° as angle. As mentioned above, this is an illumination angle width sufficient for evaluating the luminous material 110.

[0055] For the luminous material 110 contained in the luminous material-containing layer 102, when the illumination angle and light receiving angle are equal with respect to the surface normal of the luminous material 110, the imaging element 3 receives the specularly reflected light from the luminous material 110, and the obtained luminance is maximized. On the other hand, since the reflected luminance decreases as the relationship deviates from that of specular reflection, moving the bright point 11 results in a distribution with a luminance peak in a certain pattern (=specific illumination angle).

[0056] This state is shown in Figures 6(A) to (D). These figures show a schematic diagram of the state of reflection from the luminous material 110 when the bright spot 11 of the lighting display device 1 is moved in the width direction of the display surface. Moreover, each of the figures on the bottom shows the luminous material 111 of interest sandwiched between two + signs.

[0057] In FIG. 1A, the bright spot 11 does not move, and the illumination angle with respect to the measured portion 100a is θ1. In this state, the luminance of the luminous material 110 with a downward sloping angle to the right is maximum, as shown in the target luminous material 111. In FIG. 1B, the bright spot 11 moves, and the illumination angle with respect to the measured portion 100a is θ2. In this state, the luminance of the luminous material 110 arranged substantially horizontally is maximum, as shown in the target luminous material 111. In FIG. 1C, the bright spot 11 moves further, and the illumination angle with respect to the measured portion 100a is θ3. In this state, the luminance of the luminous material 110 with a downward sloping angle to the left is maximum, as shown in the target luminous material 111. In FIG. 1D, the bright spot 11 moves further, and the illumination angle with respect to the measured portion 100a is θ4. In this state, the luminance of the luminous material 110 with a further downward sloping angle to the left is maximum, as shown in the target luminous material 111.

[0058] In this way, the angle at which the luminance is maximum differs for each pixel and depends on the reflection angle and therefore the orientation angle of the luminous material 110. In other words, it is possible to estimate the orientation angle of each luminous material from the position of the peak luminance.

[0059] However, as mentioned above, if a specular reflection component is included on the surface of the clear layer 103, a brightness peak will appear at a position different from that due to the lustrous material, making it difficult to estimate the optical characteristics due to the lustrous material.

[0060] Therefore, in this embodiment, a specific area within the light receiving area of ​​the imaging element 3 that does not receive the specular reflection component on the surface of the clear layer 103 is set as the analysis area, and the optical characteristics of the lustrous material 110 are analyzed based on the light receiving results in this analysis area.

[0061] To explain this analysis area, as shown in image number B1 in FIG. 4B, a dashed rectangular area 31 and a solid rectangular area 32 are provisionally set among the entire light receiving area of ​​the image sensor 3. As described above, the position of the light receiving unit 30 that receives the specular reflection component on the surface of the clear layer 103, in other words the position where the specular reflection component on the surface of the clear layer 103 reaches the image sensor 3, also moves in the horizontal direction in response to the lateral movement of the bright point 11 of the illumination display device 1, but the dashed rectangular area 31 is located on a line in the movement direction (corresponding to the first direction) of the light receiving unit 30, and receives the specular reflection component on the surface of the clear layer 103 depending on the position of the bright point 11. On the other hand, the solid rectangular area 32 is located in a position that is shifted vertically from the movement direction of the light receiving unit 30 accompanying the movement of the bright point 11, and does not receive any specular reflection component on the surface of the clear layer 103 due to each bright point 11 even if the bright point 11 moves.

[0062] For this reason, the solid-line rectangular area 32 that receives only the specularly reflected light from the lustrous material and does not receive the specularly reflected component from the surface of the clear layer 103 is used as the analysis area, and the light reception results of the pixels within this analysis area 32 are analyzed to determine the optical characteristics of the lustrous material 110.

[0063] A specific example will be described. As shown in FIG. 4(A), the bright spot 11 is moved from left to right 31 times to change the illumination angle 31 times, and 31 images captured at the positions of the bright spots 11 are designated as images (image-number) 1 to 31. An example of the luminance value obtained for each pixel in the solid rectangular area (analysis area) 32 and the dashed rectangular area 31 for each of the 31 images is shown in FIG. 7(A), (B), and (C). The upper graph in the figure shows the pixel value for the pixel in the dashed rectangular area 31, and the lower graph shows the pixel value for the pixel (pixel of interest) in the solid rectangular area 32. The horizontal axis of each graph is the image number, and the vertical axis is the luminance value. The luminance value is held in 8 bits, with the maximum value being 255 and the minimum value being 0.

[0064] Also, Figs. 7(A), (B), and (C) show cases where the peaks of specularly reflected light from the glittering material 110 are present in the first half of the image, the image near the center, and the second half of the image, respectively.

[0065] In the upper graph, in all of (A) to (C), a peak always exists near image number 15. This is the peak of the regular reflection component on the surface of the clear layer 103. Due to the presence of this peak, it is difficult to directly associate the peak position with the orientation of the luster material 110. In particular, the luminance component originating from the luster material, which has a peak near image number 15, is buried in the regular reflection component on the surface of the clear layer 103, as in the upper graph of FIG. 7(B), making it difficult to detect the peak of the luminance component originating from the luster material. In addition, the luster material reflection that shows a peak at this position is due to the luster material 110, which has a small slope, and is usually the case due to the orientation distribution of the luster material 110.

[0066] In contrast, in the graph at the bottom, such a peak structure is not seen, and only peaks due to the reflection of the luminous material are seen regardless of the position of the peak in (A), (B), or (C) of the figure. Therefore, the orientation information of the luminous material 110 can be calculated from the peak position. In other words, highly accurate light distribution information can be calculated based on the luminance position of the pixels in the solid-line rectangular area (analysis area) 32.

[0067] The calculated orientation information will be described.

[0068] 8, the horizontal direction of the measurement area 100a is the x direction, the vertical direction is the y direction, the x direction of the luminous material 110 is the central axis and the inclination in the y direction is θx, and the y direction is the central axis and the inclination in the x direction is θy, and the bright spot 11 of the lighting display device 1 is moved in the x direction. In the normal direction of the measurement area 100a, θx=θy=0.

[0069] The orientation information of the luminous material 110 obtained by the measurement method of this embodiment corresponds to θx=θx', θy=θy'. Here, θx' is the amount of shift from the moving direction line of the analysis area 32 in which the moving bright spot 11 analyzes the specularly reflected light by the luminous material 110, and an angle that is uniquely determined by the geometry of the image sensor 3. Meanwhile, θy' corresponds to the peak position obtained by the above measurement.

[0070] Automobile exteriors, etc., often have a surface structure as shown in Figure 2, and the illumination light incident on the measurement target portion 100a of the measurement object 100 is refracted on the surface of the clear layer 103. By taking this effect into account, accurate orientation information of the lustrous material 110 can be calculated from the above information.

[0071] Furthermore, the peak brightness value obtained within the analysis area 32 does not contain any specular reflection components on the surface of the clear layer 103, and is derived purely from the reflection of the lustrous material 110, so that brightness information of the lustrous material 110 can be calculated from the obtained peak value.

[0072] In addition, since pixels other than the pixel of interest within the analysis area 32 do not contain regular reflection components due to the clear layer 200, by performing a similar analysis on the entire analysis area, statistical information such as brightness distribution and orientation distribution can also be obtained.

[0073] In addition, in order to analyze a location shifted vertically from the movement direction line of the light receiving unit 30 of the regular reflection component by the clear layer 200, an orientation distribution with respect to θy, including θy=0, for the lustrous material 110 at θx=θx' can be obtained.

[0074] As described above, in this embodiment, the measurement site 100a of the measurement object 100 is illuminated with illumination light whose illumination angle has been changed by moving and scanning the bright spot 11 in one direction, and a specific area among the light receiving areas in the image sensor 3 that does not receive any specular reflection components from the surface of the clear layer 103 of each of the illumination lights whose illumination angles have been changed is set as the analysis area 32, and the optical characteristics of the shining material 110 are analyzed based on the light receiving result of only the specular reflection light from the shining material 110 in the analysis area 32. Therefore, the optical characteristics such as the luminance and light distribution characteristics of the shining material 110 can be accurately measured by eliminating the influence of the specular reflection components from the surface of the clear layer 103.

[0075] In addition, the optical characteristics that can be obtained in this embodiment are not limited to luminance and orientation information. By analyzing the two-dimensional spatial luminance distribution, it is also possible to quantify the particle size of the contained luminous material 202 and the dispersion and aggregation of the luminous material.

[0076] For example, Fig. 9(A) shows a case where there are many small particle diameter luminous materials 110, and Fig. 9(B) shows a case where there are large particle diameter luminous materials 110. The particle diameter of the luminous materials 110 can be calculated by analyzing the two-dimensional spatial luminance distribution, since the light distribution angle and horizontal length of the luminous materials 110 are known.

[0077] Similarly, by analyzing the two-dimensional spatial luminance distribution, it is possible to quantify the presence or absence of unevenness in the luminous material from place to place (whether it is uniformly dispersed or there are areas where it is aggregated). Figure 10 (A) shows the dispersed state of the luminous material 110, and (B) shows the aggregated state.

[0078] By analyzing and evaluating the optical characteristics in this manner, it is possible to measure a great deal of information relating to the paint properties, such as at least one of the brightness, chromaticity, orientation, particle size, dispersion, aggregation, etc. of the lustrous material 110.

[0079] Furthermore, in this embodiment, since a single illumination display device 1 is used, the overall configuration of the optical characteristic measuring device can be made less complicated than when a plurality of light sources are used.

[0080] In this embodiment, the movement direction of the bright spot 11 may be the vertical direction in Figure 4 (A), i.e., a direction perpendicular to the plane formed by the normal to the measurement site 100a, the normal to the lighting display device 1, and the normal to the imaging element 3. (Embodiment 2) In this embodiment, a method for determining the exposure time in the analysis area 32 will be described.

[0081] Since the optical characteristics differ depending on the measurement object 100, the appropriate exposure time differs for each measurement object 100. From the viewpoint of shortening the overall measurement time, it is desirable to first perform a preliminary measurement to determine the exposure time, and then perform a series of main measurements using the optimal exposure time calculated using the obtained information.

[0082] From the viewpoint of signal-to-noise ratio (S / N), a longer exposure time is preferable, but from the viewpoint of luminance value calculation and luminance change analysis, it is necessary not to exceed the maximum measured luminance value. Therefore, it is preferable to select an exposure time that allows the luminance value of the bright spot of the luminous material 110 when the illumination light is specularly reflected to fall within the desired luminance range.

[0083] A process for determining such exposure times is described.

[0084] The analysis area 32 that is actually used in the measurement is used, and the illumination pattern (for example, bright spots) that is actually used in the measurement is used. It is preferable that the illumination pattern illuminates a location close to the analysis area 32, but this is not limited to the above.

[0085] Using the above illumination pattern, an image is captured for a certain short time t1 set in advance, as shown in Fig. 11(B). Of the captured luminance images in the analysis area 32, the luminance value of a characteristically bright one, as shown in Fig. 11(A), is used. The characteristically bright one may be, but is not limited to, the one with the highest luminance value in the analysis area 32.

[0086] Normally, there is a linear relationship between the exposure time and the acquired luminance value, so once the luminance value at a certain exposure time is measured, it is possible to calculate an exposure time that falls within a desired luminance range. Therefore, as shown in Figure 11(B), the above linearity is used to calculate t2, which is an appropriate exposure time for this illumination image.

[0087] In the main measurement after the preliminary measurement, this exposure time t2 is used as the standard, and measurements are performed with exposure times appropriate for each lighting.

[0088] It is desirable to determine such exposure time t2 each time the illumination pattern is moved, in other words, for each illumination angle of the illumination light, but this is not limited to the above.

[0089] In this manner, in the second embodiment, the exposure time for the image sensor 3 is determined for each illumination angle of the illumination light before starting the main measurement, so that the optical characteristics can be measured with higher accuracy using an appropriate exposure time. (Embodiment 3) 12, in this embodiment, the analysis areas 32, 32 in the image sensor 3 are set at positions shifted in the perpendicular directions V2 and V3, respectively, to the moving direction H of the light receiving section 30 of the specular reflection component on the surface of the clear layer 103. In other words, the light receiving section 30 passes through the midpoint of the analysis areas 32, 32. The positions of both analysis areas 32, 32 do not need to be the same in each captured image when the bright point 11 is moved.

[0090] In many cases, the distribution of the luminous material 110 depends only on the angle between the normal of the luminous material 110 and the normal direction of the measurement site 100a. Therefore, the orientation distribution of the luminous material 110 with θx=θx' and the orientation distribution of the luminous material 110 with θy=0 are the same.

[0091] By taking advantage of this property and setting analysis areas 32, 32 on both sides of the movement direction H2 of the light receiving unit 30 with respect to the bright point 11, the analysis range can be enlarged while keeping the light receiving angle width small, and more shiny materials can be observed at once.

[0092] In addition, if the analysis area 32 is made large, the illumination and light receiving angle width will also increase, so it is better for the analysis area 32 to be small, but on the other hand, if the analysis area 32 is not sufficiently large, it will be impossible to obtain statistical information on the shiny material 110, so from this point of view it is better for the analysis area 32 to be large. By setting two analysis areas 32, 32 as in the third embodiment, the above trade-off relationship can be resolved at the same time. (Embodiment 4) In the first to third embodiments, the illumination pattern is a bright point 11 that is moved. In the fourth embodiment, however, the illumination pattern is two bright lines that are moved.

[0093] As shown in FIG. 13(A), vertically elongated bright lines 12, 12 are displayed at both ends of the rectangular display surface of the lighting display device 1 except for the vertical middle portion, and these bright lines 12, 12 are moved and scanned horizontally as indicated by arrow H3 to change the illumination angle of the illumination light relative to the measurement area 100a.

[0094] On the other hand, as shown in Fig. 1B, in the image obtained by the imaging element 3, both ends of the rectangular light receiving area excluding the vertical middle part become light receiving sections 30 that receive the regular reflection component of the illumination light of the bright lines 12, 12 on the surface of the clear layer 103. Then, in response to the lateral movement (scanning) of the bright lines 12, 12, the two light receiving sections 30, 30 move in the lateral directions (corresponding to the second and third directions) H4, H4.

[0095] In this embodiment, an analysis area 32 is set in the light receiving area of ​​the image sensor 30 at a position halfway between the two moving directions H4, H4 of the two light receiving sections 30, 30, and approximately in the horizontal center. In this analysis area 32, the specular reflection component from the surface of the clear layer 103 is not received, and only the specular reflection light originating from the luminous material is received. Therefore, similarly to the case of the bright spot 11, the optical characteristics such as the brightness and orientation characteristics of the luminous material 110 can be measured.

[0096] In addition, since the analysis area is set to a region where the two light receiving sections 30 corresponding to the two bright lines 12, 12 do not pass through, it is possible to obtain the orientation distribution with respect to θy including θy=0 for the luminous materials 110 having a wide range of orientation angles within |θx|<θx'max, where θx'max is determined by the configuration of the lighting display device 1. In the configuration shown in Fig. 5, θx'max=21.8°, and as described above, most luminous materials 110 are usually inside this illumination angle width.

[0097] In the fourth embodiment, the two bright lines 12, 12 may be replaced by two bright points. (Embodiment 5) In this embodiment, the two bright lines 12, 12 used in the fourth embodiment are moved in the horizontal direction (x direction) and vertical direction (y direction) of the display surface of the lighting display device 1, respectively.

[0098] As shown in FIG. 14(A), vertically elongated bright lines 12, 12 are displayed on both ends of the rectangular display surface of the lighting display device 1, excluding the vertical middle part of the left end, and these bright lines 12, 12 are moved horizontally as indicated by arrows H5, H5 to change the illumination angle of the illumination light relative to the measurement area 100a.

[0099] Also, as shown in the same figure (B), horizontally elongated bright lines 12, 12 are displayed at both ends of the lower end of the rectangular display surface of the lighting display device 1, excluding the horizontal middle part, and these bright lines 12, 12 are moved vertically as shown by arrows V4, V4, thereby changing the illumination angle of the illumination light relative to the measurement area 100a.

[0100] 14(C) shows an image of the image sensor 3 corresponding to the bright lines 12, 12 shown in Fig. 14(A). In this image, both ends of the entire rectangular light receiving area, excluding the vertical middle part, become light receiving sections 30, 30 that receive the specular reflection component of the illumination light by the bright lines 12, 12 on the surface of the clear layer 103. Then, in response to the lateral movement of the bright lines 12, 12, the two light receiving sections 30, 30 move horizontally as indicated by arrows H6, H6.

[0101] 14(D) shows an image of the image sensor 3 corresponding to the bright lines 12, 12 shown in Fig. 14(B). In this image, both ends of the entire rectangular light receiving area, excluding the horizontal middle part, become light receiving sections 30, 30 that receive the specular reflection component of the illumination light by the bright lines 12, 12 on the surface of the clear layer 103. Then, in response to the vertical movement of the bright lines 12, 12, the two light receiving sections 30, 30 move vertically as indicated by arrows V5 and V6.

[0102] In this embodiment, an analysis area 32 is set in the center of the light receiving area of ​​the imaging element 3, where the specular reflection component from the surface of the clear layer does not pass through any of the light receiving sections 30 when the bright lines 12, 12 are moved in two directions, vertically and horizontally. In this analysis area 32, the specular reflection component from the surface of the clear layer 103 is not received, and only the specular reflection light originating from the lustrous material is received, so that the optical characteristics of the lustrous material 110, such as the luminance and orientation characteristics, can be measured.

[0103] In addition, by moving the two bright lines 12, 12 in two perpendicular directions, it is possible to obtain the orientation angles in two perpendicular directions for each lustrous material 110. Therefore, it is possible to estimate the orientation angle (or surface normal vector) in any two-dimensional direction from both values.

[0104] In the fourth embodiment, instead of the two bright lines 12, two bright points may be moved vertically and horizontally. (Modification) Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments.

[0105] For example, the lighting device has been described as being configured as a lighting display device 1 that moves a lighting pattern consisting of bright spots 11 and bright lines 12 on a screen, but a single point light source or line light source may be moved, or a lighting device may be configured to change the lighting angle of the illumination light by arranging a plurality of point light sources or line light sources and controlling the lighting in sequence.

[0106] Furthermore, the imaging element 3 does not have to be a two-dimensional imaging element, and a line sensor or the like may be used that is arranged so that at least one or a plurality of pixels are positioned on the analysis area 32 .

[0107] In addition, the sample 100 is exemplified as having a coating containing the luminous material 110 on its surface, but even if the sample does not contain the luminous material 110, when a treatment such as anodizing is applied, minute irregularities and gradients exist on the surface in a micro region of the order of several μm to several tens of μm. The minute structure is the driving force behind the expression of high designability, such as when illuminated and observed from a certain direction, a part of the surface appears to sparkle, and when illuminated and observed from another direction, another part appears to shine. Therefore, even if the luminous material 110 is not present, the optical properties can be measured in the same way for the sample 100 having minute irregularities and gradients on its surface, such as an anodized sample.

[0108] This application claims priority from Japanese Patent Application No. 2020-160338, filed on September 25, 2020, the disclosure of which is incorporated herein by reference in its entirety. [Industrial Applicability]

[0109] The present invention can be used as an optical property measuring device for measuring the optical properties of a measured portion such as a painted portion containing flake-like aluminum pieces or mica pieces, which are called glittering materials. [Explanation of symbols]

[0110] 1 Lighting display device 2 Objective Lenses 3. Image sensor 4 Arithmetic section 5 Measurement result display section 8. Cabinet 81 Opening 11 bright point 12. Light Line 30 Light receiving section for regular reflection component 32 Analysis Area 100 Measurement object (sample) 100a Measured area 110 Bright material 111 Featured lustrous materials

Claims

1. a lighting device capable of illuminating a portion to be measured of an object to be measured with illumination light having a plurality of different lighting angles; an image pickup element that receives reflected light from the measurement site of each of the illumination lights whose illumination angles have been changed; an analysis means for analyzing optical characteristics of the measured site based on a light receiving result in the analysis area when each illumination light is irradiated onto the measured site, the analysis means defining a specific area of ​​the light receiving area in the image sensor at a position where the specific reflection component on the surface of the measured site is not received for each illumination light having an altered illumination angle; Equipped with The imaging element is a two-dimensional imaging element whose total light receiving area is larger than the light receiving area of ​​a specular reflection component on the surface of the measurement site due to a single illumination light.

2. A lighting device capable of illuminating a measurement target portion of a measurement object with illumination light having a plurality of different illumination angles; an image pickup element that receives reflected light from the measurement site of each of the illumination lights whose illumination angles have been changed; an analysis means for analyzing optical characteristics of the measured site based on a light receiving result in the analysis area when each illumination light is irradiated onto the measured site, the analysis means defining a specific area of ​​the light receiving area in the image sensor at a position where the specific reflection component on the surface of the measured site is not received for each illumination light having an altered illumination angle; Equipped with An optical property measuring device in which, when a moving direction of the light receiving position on the imaging element side of the specular reflection component on the surface of the measured portion moves sequentially in response to a change in the illumination angle of the illumination light is defined as a first direction, the analysis area is set at a position shifted vertically to the first direction.

3. A lighting device capable of illuminating a measurement target portion of a measurement object with illumination light having a plurality of different illumination angles; an image pickup element that receives reflected light from the measurement site of each of the illumination lights whose illumination angles have been changed; an analysis means for analyzing optical characteristics of the measured site based on a light receiving result in the analysis area when each illumination light is irradiated onto the measured site, the analysis means defining a specific area of ​​the light receiving area in the image sensor at a position where the specific reflection component on the surface of the measured site is not received for each illumination light having an altered illumination angle; Equipped with An optical property measuring device in which two illumination lights are irradiated onto the measured area by changing the illumination angle simultaneously while maintaining a distance between them, and when the directions of movement of two light receiving positions on the imaging element side of the specular reflection component on the surface of the measured area moving in sequence in response to the change in the illumination angles of both illumination lights are set to a second direction and a third direction, the analysis area is set halfway between the second direction and the third direction.

4. A lighting device capable of illuminating a measurement target portion of a measurement object with illumination light having a plurality of different illumination angles; an image pickup element that receives reflected light from the measurement site of each of the illumination lights whose illumination angles have been changed; an analysis means for analyzing optical characteristics of the measured site based on a light receiving result in the analysis area when each illumination light is irradiated onto the measured site, the analysis means defining a specific area of ​​the light receiving area in the image sensor at a position where the specific reflection component on the surface of the measured site is not received for each illumination light having an altered illumination angle; Equipped with The optical characteristic of the measurement site is an optical characteristic derived from a glittering material contained in the measurement object, The optical characteristics derived from the shining material include at least one of information regarding the light distribution characteristics, luminance, particle size, and dispersion and aggregation of the shining material, An optical characteristic measuring apparatus in which the light distribution characteristic is measured in two orthogonal directions.

5. the lighting device is a single lighting display device capable of changing a lighting angle to a plurality of angles by moving a display position of a specific lighting pattern; An optical characteristic measuring device according to any one of claims 1 to 4, wherein the direction of movement of the illumination pattern is parallel and / or perpendicular to a plane formed by the normal of the measurement portion, the normal of the illumination display device, and the normal of the imaging element.

6. 6. The optical characteristic measuring apparatus according to claim 5, wherein the specific illumination pattern is a single or multiple bright points or bright lines.

7. 2. The optical characteristic measuring device according to claim 1, wherein when a moving direction of the light receiving position on the imaging element side of the specular reflection component on the surface of the measured portion moves sequentially in response to a change in the illumination angle of the illumination light is defined as a first direction, the analysis area is set at a position shifted perpendicularly to the first direction.

8. 8. The optical characteristic measuring device according to claim 7, wherein there are two analysis areas, and a receiving position of the specular reflection component moving in the first direction passes through a midpoint of the two analysis areas.

9. 2. The optical characteristic measuring device of claim 1, wherein two illumination lights are irradiated onto the measured portion at multiple different illumination angles simultaneously while maintaining a distance therebetween, and when the directions of movement of two light receiving positions on the imaging element side of the specular reflection component on the surface of the measured portion moving in sequence in response to the change in illumination angle of both illumination lights are defined as a second direction and a third direction, the analysis area is set midway between the second direction and the third direction.

10. 10. The optical characteristic measuring apparatus according to claim 1, further comprising an exposure time determining means for determining an exposure time for said imaging element to said illumination light before starting measurement.

11. 11. The optical characteristic measuring apparatus according to claim 10, wherein the exposure time determining means determines the exposure time based on luminance information obtained in the analysis area.

12. 11. The optical characteristic measuring apparatus according to claim 10, wherein the exposure time determining means determines the exposure time based on luminance information obtained in the analysis area and the exposure time at that time.

13. 13. The optical characteristic measuring apparatus according to claim 1, wherein the spatial resolution of the imaging element is 10 to 100 μm.

14. The illumination device, the imaging element, and the analyzing means are provided in one housing, An optical characteristic measuring device as described in any one of claims 1 to 13, wherein the housing is provided with an opening for irradiating illumination light onto the measured portion of the object to be measured and capturing reflected light from the measured portion, and a result display unit for displaying the measurement results.

15. A lighting device illuminates a measurement site of a measurement object with illumination light having a plurality of different illumination angles; receiving, by an image sensor, reflected light of each of the illumination lights having the changed illumination angle from the measurement site; a step of setting a specific area of ​​the light receiving area of ​​the image sensor, which is located at a position where no specular reflection component is received from the surface of the measured site for any of the illumination lights having changed illumination angles, as an analysis area, and analyzing optical characteristics of the measured site based on the light receiving results in the analysis area when each illumination light is irradiated onto the measured site; Equipped with An optical characteristic measurement method in which, when a moving direction of a light receiving position on the imaging element side of a specular reflection component on the surface of the measured portion moves sequentially in response to a change in the illumination angle of the illumination light is defined as a first direction, the analysis area is set at a position shifted vertically to the first direction.

16. the lighting device is a single lighting display device capable of changing a lighting angle to a plurality of angles by moving a display position of a specific lighting pattern; The optical characteristic measuring method according to claim 15, wherein the direction of movement of the illumination pattern is parallel and / or perpendicular to a plane formed by a normal to the measurement portion, a normal to the illumination display device, and a normal to the imaging element.

17. 17. The optical characteristic measuring method according to claim 15, wherein the spatial resolution of the imaging element is 10 to 100 μm.

18. The optical characteristic measuring method according to any one of claims 15 to 17, wherein the optical characteristics of the measured portion include at least one of the following information: light distribution characteristics, luminance, particle size, and dispersion / aggregation information of the luminous material contained in the measured object.

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