JP7658377B2 - Photometric device - Google Patents

Description

The present invention relates to a photometric device that measures the characteristics of a light source to be measured, and in particular to a photometric device such as a colorimeter that measures the luminance and chromaticity of light emitted from a light source to be measured.

In photometric devices such as color luminance meters, measurement light is split into three and received by each sensor to measure color. For example, Patent Document 1 discloses a bundle fiber as a means for splitting measurement light into three, in which multiple fiber strands are bundled together, and light emitted from an objective optical system is incident on one end, and the multiple fiber strands are split at the other end. Each of the split ends of the bundle fiber is equipped with multiple colorimetric optical systems that detect the light emitted from the other end of the bundle fiber.

In addition, in Patent Document 2, the applicant proposed a photometric device that splits the measurement light into multiple beams using a light guide member and a relay optical system to branch the optical path, and receives the beams at each sensor. Specifically, the light guide member has been used to equalize the positional and angular variations of the object to be measured, and the beam is then irradiated onto multiple light receiving sensors using a relay optical system.

By the way, color measurement using a photometric device is performed by bringing the photometric device into contact with the surface of the object to be measured (the light source to be measured) or by bringing the photometric device close to the surface without contact and receiving light emitted from a predetermined area of the surface to be measured within a predetermined angle range. At this time, if there is unevenness (positional unevenness, angular unevenness) due to the emission position and emission angle in the emission intensity (emission brightness) of the surface to be measured, the photometric device is also affected by this. If the positional unevenness and angular unevenness of the measurement sensitivity on the photometric device side increase due to the above-mentioned influence, the difference in the measured value (measurement error) increases due to the difference in the measurement position and angle. Note that the positional unevenness of the measurement sensitivity refers to the difference in the measurement sensitivity for each light emitted in the same direction (for example, perpendicular to the surface) from different positions on the surface to be measured of the light source to be measured. Also, the angular unevenness of the measurement sensitivity refers to the difference in the measurement sensitivity for each light emitted in different directions from the same position on the surface to be measured of the light source to be measured.

Therefore, when measuring color, in order to reduce measurement errors due to differences in the measurement position and measurement angle, it is necessary to make the measurement less susceptible to positional and angular unevenness in the emission intensity of the light source being measured, and to reduce positional and angular unevenness in the measurement sensitivity.

Patent No. 5565458 Patent application No. 2018-135574

However, in Patent Document 1, the measurement light is guided using a light guide made of a bundle of many fibers, but in order to reduce the unevenness in the amount of light and the measurement error, it is necessary to randomly weave each fiber, which is expensive. In addition, because it is difficult to control the filling condition, bending state, stress state, etc. of the fibers, it is difficult to design a light guide that is less susceptible to the effects of positional and angular unevenness in the emission intensity of the light source to be measured, and as a result, there is an issue that it is difficult to reduce positional and angular unevenness in the measurement sensitivity.

In addition, in the photometric device proposed in Patent Document 2, when the light flux emitted from the exit end of the light guide member is irradiated onto the irradiation range R by the relay optical system, the area ratio of the light receiving sensors installed in the irradiation range R to the irradiation range R is approximately 10% per light receiving sensor. Therefore, if there are four light receiving sensors, the total becomes 40%, and approximately 60% of the light flux irradiated onto the irradiation range R is wasted, resulting in a problem of poor light efficiency.

The present invention has been made to solve the above problems, and its purpose is to provide a photometric device that is configured using inexpensive light-guiding members, can reduce positional and angular variations in measurement sensitivity, and has good light efficiency.

The above object can be achieved by the following means:
(1) A photometric device comprising: a light-guiding member having a circular or polygonal cross section; an objective optical system that collects a light beam from an object to be measured at the light-incident end face of the light-guiding member; a branching section having a plurality of branching members, each of which is a single member, that branch the light beam emitted from the light-emitting end face of the light-guiding member into a plurality of beams and guides them; and a plurality of light-receiving sensors that receive the light emitted from each of the plurality of branching members in the branching section and obtain data of two or more different characteristics , wherein the branching sections are arranged within the range of the light-emitting end face of the light-guiding member so as to be in close contact with each other along the contour of the light-emitting end face, and the light-emitting end face of the light-guiding member and the end face of the branching section are joined and connected by adhesive or fusion, or are formed as a single unit .
(2) The photometric device according to the preceding paragraph 1, wherein the objective optical system has a conjugate relationship between the object to be measured and a light-incident end surface of the light-guiding member.
(3) The photometric device according to the above item 1 or 2, wherein the plurality of light receiving sensors includes a light receiving sensor for obtaining light receiving data that is approximate to color matching functions XYZ.
(4) The photometric device according to any one of the preceding paragraphs 1 to 3, wherein the plurality of light receiving sensors includes a light receiving sensor for obtaining spectral data.
(5) A photometric device as described in any of paragraphs 1 to 4 above, wherein the plurality of light receiving sensors includes a light receiving sensor of an external measuring device that receives light from the branching member via an optical connector, the external measuring device is detachable from the branching member, and an arbitrary external measuring device selected by a user from a plurality of external measuring devices each having a light receiving sensor with different light receiving characteristics is connected to the branching member.
(6) A photometric device according to any one of the preceding paragraphs 1 to 5, wherein the plurality of branching members are each formed of an optical fiber.
(7) The photometric device according to the preceding paragraph 6, wherein the optical fiber is made of resin.
(8) The photometric device according to any one of the preceding paragraphs 1 to 7, wherein the light-guiding member is a polygonal prism or a polygonal truncated pyramid.

According to the invention described in the preceding paragraph (1), the light beam from the object to be measured is collected by the objective optical system on the light-incoming end face of the light-guiding member, and is incident on the light-guiding member from the light-incoming end face. The light-guiding member has a circular or polygonal cross section, and is therefore simpler in structure and less expensive than conventional light-guiding bodies that randomly weave multiple fibers to guide light. In addition, the light from the light source to be measured that is incident on the light-guiding member is totally reflected and guided by the side faces (faces other than the light-incoming end face and the light-emitting end face) of the light-guiding member a number of times according to the angle of incidence on the light-guiding member, reaches the light-emitting end face of the light-guiding member, is emitted from the light-emitting end face, and is branched into multiple branching members made of a single member. The light emitted from each of the multiple branching members is received by multiple light-receiving sensors to obtain data of two or more different characteristics.

Therefore, each sensor in the light receiving section receives a mixture of light emitted from various positions on the surface to be measured of the light source to be measured and light emitted at various angles from the surface to be measured. As a result, even if there is positional and angular unevenness in the emission intensity (emission brightness) of the surface to be measured of the light source to be measured, the light receiving section can be made less susceptible to such unevenness, thereby making it possible to reduce positional and angular unevenness in the measurement sensitivity.

In addition, the light beam emitted from the light-emitting end face of the light-guiding member is branched by multiple branching members and guided to each light-receiving sensor, so that the light emitted from the branching members can be used by each light-receiving sensor without waste. This improves light efficiency compared to a configuration in which the light beam emitted from the light-emitting end face of the light-guiding member is irradiated by a relay optical system and received by the light-receiving sensor.

According to the invention described in the preceding paragraph (2), the objective optical system has a conjugate relationship between the object to be measured and the light incident end face of the light-guiding member, thereby reducing positional and angular unevenness in the emission intensity of the measured surface of the measured light source.

According to the invention described in the preceding paragraph (3), a photometric device is provided that can obtain light reception data that is approximate to the color matching functions XYZ.

According to the invention described in the preceding paragraph (4), a photometric device capable of obtaining spectral data is provided.

According to the invention described in the preceding paragraph (5), the external measuring device can be used by having the light receiving sensor of the external measuring device receive light from the branching member via an optical connector, and the user can select and use any one of a number of external measuring devices, each having a different light receiving sensor characteristic.

According to the invention described in the preceding paragraph (6), each of the multiple branching members can be easily formed from optical fiber.

According to the invention described in the preceding paragraph (7), the optical fiber is made of resin, and therefore has advantages such as ease of bending, low cost, and a wide variety of types.

According to the invention described in the preceding paragraph (8), since the light-guiding member is a polygonal prism or a truncated polygonal pyramid, light emitted from various positions on the surface to be measured of the light source to be measured and light emitted at various angles from the surface to be measured can be efficiently mixed.

1 is an explanatory diagram showing a schematic configuration of a photometry device according to an embodiment of the present invention; FIG. 2 is a perspective view showing an example of a configuration of a light guiding member of the photometry device. FIG. 11 is a perspective view showing another configuration example of the light guide member. FIG. 11 is a perspective view showing still another configuration example of the light guide member. FIG. 11 is a perspective view showing still another configuration example of the light guide member. 2B is a plan view showing a schematic view of the light incident side end face of the light guiding member in FIG. 2A as viewed from the measurement range restricting aperture side. FIG. 5A to 5C are explanatory diagrams showing configuration examples of a light guide member and a branching member. 13A to 13C are explanatory diagrams showing other configuration examples of the light guide member and the branching member. FIG. 11 is a perspective view showing still another example of the configuration of the light guide member and the branching member. FIG. 11 is a perspective view showing still another example of the configuration of the light guide member and the branching member. 3 is an explanatory diagram showing a schematic configuration of a light guide member, a branching member, and a light receiving unit. FIG. 9 is an enlarged view of a connection portion between a branching member and a light receiving sensor in FIG. 8 . 13 is an enlarged view showing another configuration of the connection portion between the branching member and the light receiving sensor. FIG. FIG. 2 is a plan view showing a configuration of a light receiving section. FIG. 2 is a cross-sectional view showing a configuration of a light receiving section. FIG. 13 is an enlarged cross-sectional view showing a part of FIG. 12 . 5A and 5B are diagrams illustrating how light incident on a light-guiding member is reflected within the light-guiding member and then emitted. FIG. 11A and 11B are explanatory diagrams of light incident on a light guide member when there is no rear lens system. 11A and 11B are explanatory diagrams of light incident on a light guide member when a rear lens system is provided; 2 is an explanatory diagram illustrating a schematic optical path of a light ray guided inside a light-guiding member 2. FIG. 2E is an explanatory diagram showing an optical path of a light ray guided inside the light guiding member of FIG. 2D in a developed form; FIG. 13 is a diagram for explaining an example of a combination of light receiving sensors for obtaining data with different characteristics. FIG. 20 is an explanatory diagram of a configuration for obtaining spectroscopic data by the spectroscopic sensor of FIG. 19 . 13 is a diagram for explaining another example of a combination of light receiving sensors for obtaining data with different characteristics. FIG. 13 is a diagram for explaining still another example of a combination of light receiving sensors for obtaining data with different characteristics. FIG. 13 is a diagram for explaining still another example of a combination of light receiving sensors for obtaining data with different characteristics. FIG. 24 is a graph showing the transmittance of bandpass filters included in each of a plurality of light receiving sensors in the example of FIG. 23.

One embodiment of the present invention is described below with reference to the drawings.

1 is an explanatory diagram showing the general configuration of a photometric device 1 of this embodiment. The photometric device 1 is configured to include a light guiding member 2, an objective optical system 3, a branching section 4, and a light receiving section 5. In the configuration of the photometric device 1 described above, light emitted from a measurement target surface LS0 of a measurement target light source LS is guided to the light guiding member 2 via the objective optical system 3, guided inside the light guiding member 2, and then guided to the light receiving section 5 via the branching section 4. Each member that configures the photometric device 1 will be described below.
(Light guiding member)
2A is a perspective view showing one configuration example of the light guide member 2. The light guide member 2 is an optical element having a light incident side end face 2a and a light exit side end face 2b, which guides light incident from the light incident side end face 2a and emits it from the light exit side end face 2b. In this embodiment, the light guide member 2 is configured as a solid (filled) glass rod, but may be hollow (empty). In this embodiment, the light guide member 2 is in the shape of a quadrangular prism whose cross section is a quadrangle (e.g., a square) of the same size from the light incident side end face 2a to the light exit side end face 2b, but is not limited to this shape.

Figure 2B is a perspective view showing another configuration example of the light guide member 2. Also, Figure 2C is a perspective view showing yet another configuration example of the light guide member 2. As shown in these figures, the light guide member 2 may have a triangular prism shape in which the cross section is a triangle (e.g., an equilateral triangle) of the same size from the light incident side end face 2a to the light exit side end face 2b, or a hexagonal prism shape in which the cross section is a hexagon (e.g., a regular hexagon) of the same size from the light incident side end face 2a to the light exit side end face 2b. In other words, the light guide member 2 may have a polygonal prism shape in which the cross section is a polygon of the same size from the light incident side end face 2a to the light exit side end face 2b.

Also, FIG. 2D is a perspective view showing yet another configuration example of the light guide member 2. As shown in the figure, the light guide member 2 may be in the shape of a quadrangular pyramid truncated by having the light incident side end face 2a and the light exit side end face 2b in a quadrangular shape with a square cross section of different sizes. In addition, although not shown, the light guide member 2 may be in the shape of a triangular pyramid truncated by having the light incident side end face 2a and the light exit side end face 2b in a triangular shape with a triangular cross section of different sizes, or in the shape of a hexagonal pyramid truncated by having the light incident side end face 2a and the light exit side end face 2b in a hexagonal shape with a hexagonal cross section of different sizes. In other words, the light guide member 2 may be in the shape of a polygonal pyramid truncated by having the light incident side end face 2a and the light exit side end face 2b in a polygonal shape with a polygonal cross section of different sizes.

Alternatively, the light guide member 2 may be in the shape of a cylinder whose cross section is a circle (including an ellipse) of the same size from the light incident end face 2a to the light exit end face 2b. Alternatively, the light incident end face 2a and the light exit end face 2b may be in the shape of a truncated cone whose cross section is also a circle (including an ellipse) of different sizes.

Light incident through the light-incident end face 2a into the light-guiding member 2 having such a configuration is totally reflected at the side face 2c (the interface between the light-guiding member 2 and the air) of the light-guiding member 2 a number of times according to the angle of incidence with respect to the light-incident end face 2a, and is guided and emitted from the light-exiting end face 2b. The side face 2c is a surface that connects the light-incident end face 2a and the light-exiting end face 2b.

For example, light that is incident at an angle perpendicular or close to the center of the light-incident end face 2a (the intersection of the light-incident end face 2a and the optical axis of the objective optical system 3) enters the inside of the light-guiding member 2 via the light-incident end face 2a, and is then guided without being totally reflected by the side surface 2c and emitted from the light-exiting end face 2b. Therefore, the above "number of times according to the incident angle" also includes 0 times.

The light guide member 2 may be formed of a hollow pipe (light pipe) having a circular or polygonal cross section, for example. In this case, by forming a reflective film made of metal on the inner surface of the pipe, the light incident on the light guide member 2 can be reflected by the inner surface (reflective film) and guided. The material constituting the light guide member 2 may be glass or a transparent resin such as acrylic.
(Objective optical system)
The objective optical system 3 is an optical system that reduces and forms an image of the light source LS to be measured on the light incident side end surface 2a of the light guiding member 2. This objective optical system 3 is configured to include a front lens system 31 located on the side of the light source LS to be measured, a rear lens system 32 located on the side of the light guiding member 2, an aperture AP1 (measurement angle restricting aperture) that restricts the spread angle of light emitted from one point of the light source LS to be measured, and an aperture AP2 (measurement range restricting aperture, field aperture) that restricts the measurement range of the light source LS to be measured.

Due to the arrangement of the objective lens system 3, the measured surface LS0 of the measured light source LS and the light incident side end surface 2a of the light guide member 2 are in a conjugate relationship. That is, light emitted from a point on the measured surface LS0 of the measured light source LS is focused at a point on the light incident side end surface 2a of the light guide member 2. In this embodiment, the front lens system 31 is composed of two lenses, and the rear lens system 32 is composed of three lenses, but the number of lenses in the front lens system 31 and the rear lens system 32 is not particularly limited as long as the configuration can realize the above conjugate relationship.

The aperture AP1 is disposed at the rear focal position of the front lens system 31. Each point on the surface of the aperture AP1 (aperture) corresponds to the emission angle of light from the light source LS to be measured at the measurement surface LS0. The positioning of the aperture AP1 makes it possible to appropriately regulate the measurement angle (emission angle) of the light emitted from the measurement surface LS0 without excess or deficiency, and to measure only the light within the angle range to be measured. In this embodiment, the shape of the aperture of the aperture AP1 is circular, but it may be rectangular or another shape.

The aperture AP2 is positioned immediately before the light-incident end surface 2a of the light-guiding member 2. Each point within the surface of the aperture AP2 (opening) corresponds to each point on the measurement surface LS0 of the measured light source LS. The positioning of the aperture AP2 makes it possible to appropriately regulate the measurement range (measurement area) of the measured light source LS without excess or deficiency, and to measure only the light in the range to be measured.

3 is a schematic diagram showing the light incident side end surface 2a of the light guide member 2 in FIG. 2A as viewed from the diaphragm AP2 side. In this embodiment, the opening AP2a of the diaphragm AP2 is circular, and its diameter is set to be slightly smaller than the diameter of the inscribed circle of the light incident side end surface 2a of the light guide member 2. The opening AP2a of the diaphragm AP2 may be rectangular or of another shape. It is also possible to omit the arrangement of the diaphragm AP2. In this case, the measurement range of the measurement surface LS0 of the measurement light source LS is similar to the shape of the light incident side end surface 2a of the light guide member 2.
(Branch)
The branching section 4 is a spectroscopic optical system that guides the light emitted from the light-emitting end surface 2b of the light-guiding member 2 to the light-receiving section 5, and is composed of a plurality of branching members 41. In this embodiment, each branching member 41 is composed of an optical fiber, although this is not limited thereto. The material constituting the optical fiber may be glass or a transparent resin such as acrylic, but a resin optical fiber is preferable from the viewpoints of being easily bent into a desired shape, being inexpensive, and being available in a wide variety of types. In addition, the cross-sectional shape of the branching member 41 may be a circle (including an ellipse) or a polygon.

The end face of each branching member 41 on the light guide member 2 side may be disposed close to the light output side end face 2b of the light guide member 2 through an air layer, or may be connected by a joining method such as adhesion or fusion without an air layer. If an air layer exists between the light guide member 2 and the branching member 41, a light amount loss occurs due to surface reflection. The light amount loss is about 4% each at the light output side end face 2b of the light guide member 2 and the face of the branching member 41 facing this face, and about 8% in total. If there is no air layer, the light amount loss is almost zero. Furthermore, if the light guide member 2 and the branching member 41 are separated, the light guide member 2 and each branching member 41 are likely to be misaligned due to the operating environment temperature or vibration, and the light amount change is likely to occur. Therefore, it is desirable to join the light guide member 2 and the branching member 41 without an air layer.

Figures 4 (A) to (C) show an example of the light guide member 2 and the branching portion 4. In the example shown in Figure 4 (B), the light guide member 2 is made of a solid triangular prism with a regular triangular cross section, and the ends of three optical fiber branching members 41 are joined to the light output side end face 2b of the light guide member 2 by bonding, fusion, or the like. As shown in Figure 4 (A), the relationship between the light input side end face 2a of the light guide member 2 and the aperture AP2 is such that the size of the aperture AP2a of the aperture AP2 as viewed from the aperture AP2 side is set to be approximately the same as or slightly smaller than the equilateral triangular inscribed circle of the light input side end face 2a of the light guide member 2. In this embodiment, the length of one side of the light guide member 2 is 2.8 mm, and the diameter of the aperture AP2a of the aperture AP2 is 1.5 mm.

In the example shown in Figure 4, the light efficiency at the connection between the light-guiding member 2 and the branching member 41, in other words, the area ratio between the light-guiding member 2 and the three branching members 41, will be explained.

If the length of one side of the equilateral triangle in the cross section of the light guide member 2 is 2.8 mm and the branching member 41 is an optical fiber with a diameter of 1 mm, as shown in the positional relationship in Fig. 4(C), the three branching members 41 can be arranged in a form that fits within the range of the equilateral triangular light output side end face 2b of the light guide member 2. The light efficiency (area rate) per branching member 41 is
Area of branching member 41 (0.5 ² ×π)÷area of light guide member 2 (2.8×2.42÷2)=0.23
On the other hand, the optical efficiency of the three-branched bundle fiber described in Patent Document 1 described as a conventional example is as follows:
Bundle filling rate (ratio of effective area of fiber wire to bundle diameter = approx. 70%) ÷ 3 = 0.23
4, the optical efficiency of the branching portion 4 according to the embodiment shown in Fig. 4 is comparable to that of the three-branched bundle fiber type. On the other hand, the present embodiment has a simpler configuration than the three-branched bundle fiber type, and is therefore less expensive and has more stable optical characteristics (less variation due to the product).

5A to 5C show further examples of the light guide member 2 and the branching portion 4. In the example shown in FIG. 5B, the light guide member 2 is a solid regular rectangular prism with a square cross section, and the ends of four optical fiber branching members 41 are joined to the light output side end face 2b of the light guide member 2 by bonding, fusion, or the like. The relationship between the light input side end face 2a of the light guide member 2 and the aperture AP2 is such that, as shown in FIG. 5A, the size of the aperture AP2a of the aperture AP2 as viewed from the aperture AP2 side is set to be approximately the same as or slightly smaller than the square inscribed circle of the light input side end face 2a of the light guide member 2. In this embodiment, the length of one side of the light guide member 2 is 1.5 mm, and the diameter of the aperture AP2a of the aperture AP2 is also 1.5 mm.

In the example shown in Figure 5, the light efficiency at the connection between the light-guiding member 2 and the branching member 41, in other words, the area ratio between the light-guiding member 2 and the three branching members 41, will be explained.

If the length of one side of the square cross section of the light guide member 2 is 1.5 mm and the branching member 41 is an optical fiber with a diameter of 0.75 mm, as shown in the positional relationship in Fig. 5(C), the four branching members 41 can be arranged in a form that fits within the range of the square light output side end surface 2b of the light guide member 2. The light efficiency (area ratio) per branching member 41 is
Area of branching member 41 (0.375 ² ×π)÷area of light guide member 2 (1.5×1.5)=0.20
On the other hand, the optical efficiency of the four-branched bundle fiber explained in the conventional example is as follows: bundle packing factor (effective area ratio of fiber wires to bundle diameter = about 70%) ÷ 4 = 0.18 per branch
In addition, when branching into four using a light guiding member and a relay lens as in Patent Document 2, the optical efficiency per branch is about 10%, and the optical efficiency of the branching unit 4 according to this embodiment is higher than that of a conventional four-branch bundle fiber type and that of a light guiding member and a relay lens type.

6 and 7 show other examples of the light-guiding member 2 and the branching portion 4. In this example, the light-guiding member 2 and each branching member 41 are formed as an integral structure using the same material.

In Figures 6 and 7, each light-guiding member 2 is made of a solid equilateral triangular prism with an equilateral triangular cross section, and three branching members 41 with circular cross sections formed integrally with the light-guiding member 2 are shown protruding forward from the light-emitting end face 2b of the light-guiding member 2.

In Fig. 6, a step is formed between the peripheral edge of the light-emitting end face 2b of the light-guiding member 2 and the branching member 41. On the other hand, in Fig. 7, there is no step between the peripheral edge of the light-emitting end face 2b of the light-guiding member 2 and the branching member 41, and the light-guiding member 2 and the branching member 41 are smoothly connected to each other. Even when the light-guiding member 2 and each branching member 41 are formed as an integral structure using the same material in this way, the advantage of not having an air layer between the light-guiding member 2 and each branching member 41 can be taught.
(Light receiving section)
8, the light receiving unit 5 receives light that enters the light guide member 2 from the measured light source LS via the objective optical system 3, exits from the light exit side end surface 2b of the light guide member 2, and is guided by the plurality of branching members 41 of the branching unit 4. The light receiving unit 5 is composed of a plurality of light receiving sensors 51 with different characteristics that are arranged opposite the exit ends of the respective branching members 41. In this embodiment, the plurality of sensors 51 of the light receiving unit 5 have measurement sensitivities that correspond to the color matching functions X, Y, and Z, respectively.

Each light receiving sensor 51 is composed of a light receiving element 52 and an optical color filter 53 arranged in front of the light receiving element 52. The light receiving element 52 is composed of, for example, a silicon photodiode, and an electrical signal corresponding to the amount of light received is output to a downstream electrical circuit (not shown). In this example, the light receiving surface of the light receiving element 52 is a square or rectangle, but the light receiving surface may be a polygon other than a square (for example, a triangle) or may be a circle.

As shown in Fig. 9, it is desirable for all light beams emitted from each branching member 41 to be received by the light receiving element 52 via the optical color filter 53 in order to achieve 100% light efficiency. Also, as shown in Fig. 10, depending on the diameter and NA (numerical aperture) of the branching member 41, the size and positional relationship of the light receiving element 52, a condenser lens 55 may be interposed between each branching member 41 and each optical color filter 53 so that all light beams emitted from each branching member 41 are received by the light receiving element 52.

Figure 11 is a plan view showing a specific configuration of the light receiving unit 5. In this example, the light receiving unit 5 has four light receiving sensors 51 (51a to 51d) corresponding to the four branching members 41. As described above, each light receiving sensor 51 is composed of a light receiving element 52 and an optical color filter 53. Each light receiving element 52 is composed of, for example, a silicon photodiode, and an electrical signal corresponding to the amount of light received is output to a subsequent electrical circuit (not shown). In this example, the light receiving surface 5a of each light receiving element 52 is a square or a rectangle, and is located at each of the four corners of a rectangle. From this, it can be said that the multiple light receiving sensors 51 of the light receiving unit 5 have a square light receiving surface 5a located at each of the four corners of a rectangle. As described above, each light receiving surface 5a may be a polygon other than a rectangle (for example, a triangle) or may be a circle. In addition, the number of light receiving sensors 51 is the same as the number of branching members 41.

The optical color filter 53 of each sensor 51 has optical properties that transmit light in a predetermined wavelength range, is formed in a size larger than the light receiving element 52, and is arranged on the light incident side of the light receiving element 52. In this embodiment, the optical color filters 53 of three of the four sensors 51 (for example, sensors 51a to 51c) are composed of optical color filters 53X, 53Y, and 53Z that transmit light in wavelength ranges corresponding to the color matching functions X, Y, and Z, respectively. As a result, the three sensors 51 have measurement sensitivities corresponding to the color matching functions X, Y, and Z, respectively. The light that has passed through the optical color filters 53X, 53Y, and 53Z of the three sensors 51 is received by the corresponding light receiving element 52. The electrical signals output from each light receiving element 52 can be processed by an electrical circuit to measure color and brightness.

In other words, since the multiple light receiving sensors 51 of the light receiving unit 5 each have a measurement sensitivity corresponding to the color matching functions X, Y, and Z, it is possible to obtain luminance (Lv) and chromaticity (x, y) in an electrical circuit based on the electrical signals (corresponding to the tristimulus values of XYZ) output from each sensor 51 (each light receiving element 52). This makes it possible to realize a color luminance meter (colorimeter) that determines color and luminance.

The optical color filter 53 of the remaining sensor 51 (e.g., sensor 51d) of the four sensors 51 is composed of an optical color filter 53Y that transmits light in a wavelength range corresponding to the color matching function Y. The light receiving element 52 that receives the light transmitted through the optical color filter 53Y is connected to, for example, an electrical circuit for detecting flicker. This makes it possible to detect flicker based on the electrical signal output from the light receiving element 52.

In addition, one of the two optical color filters 53Y may be configured as an optical color filter that transmits, for example, infrared light. In this case, four types of optical color filters 53 are arranged, making it possible to simultaneously measure four types of optical characteristics.

In this embodiment, the optical characteristics of three of the four optical color filters 53, 53X, 53Y, and 53Z, are different from each other, but it is sufficient that the characteristics of at least two of the optical color filters 53 are different from each other (it is sufficient that all of the optical color filters 53 do not have the same characteristics, and it is sufficient that data of two or more different characteristics is obtained from the multiple light receiving sensors 51). The multiple sensors 51 of the light receiving unit 5 each include a light receiving element 52 whose light receiving surface 5a is square or rectangular, and an optical color filter 53 arranged on the light incident side of the light receiving element 52, and at least two characteristics of the optical color filters 53 are different from each other, so that it is possible to easily arrange sensors 51 with multiple characteristics together as shown in FIG.

Figure 12 is a cross-sectional view of the light receiving unit 5 facing the branching member 41, and Figure 13 is a cross-sectional view showing an enlarged portion of it.

Each light receiving sensor 51 is accommodated and held in a recess 54a of a holding member 54 so that the optical color filter 53 is located closer to the branching member 41 than the light receiving element 52, and the light receiving element 52 and the optical color filter 53 are arranged with a gap between them. The recess 54a has a stepped shape in which the opening diameter gradually narrows from the arrangement side of the optical color filter 53 toward the arrangement side of the light receiving element 52, and this allows the optical color filter 53 and the light receiving element 52 to be accommodated in the recess 54a so as to have the above-mentioned positional relationship.

The holding member 54 also serves as a light-shielding wall that separates adjacent light-receiving sensors 51. In other words, because the holding member 54 exists between two adjacent sensors 51 as a light-shielding wall, light that has passed through the optical color filter 53 of one adjacent sensor 51 is prevented from entering the light-receiving element 52 of the other adjacent sensor 51, making it possible to reduce measurement errors.

In addition, as the optical color filter 53 described above, it is possible to use an interference film filter in which an interference film is formed on a glass substrate. When an interference film filter is used, the transmission characteristics change depending on the angle of incidence of the light beam to the interference film. However, in this embodiment, the characteristics (positional unevenness, angular unevenness) of the measured light source LS are mixed at the light emission side end surface 2b of the light guide member 2, so that the emitted light from the light guide member 2 does not depend on the characteristics of the measured light source LS. Therefore, it is sufficient to design the film according to the angle of incidence (cone angle) to the interference film filter.

Interference film filters are polarization dependent (transmittance varies depending on polarization conditions), but by passing through the light-guiding member 2, the polarized light is mixed (becoming non-polarized), so it is not dependent on the characteristics of the light source LS to be measured (LCD monitors emit polarized light).

In addition, the optical color filter 53 may be a colored glass filter that absorbs light in a specific wavelength range, a neutral density (ND) filter that attenuates light in a wide wavelength range, a linear polarizing plate, a wave plate, or the like. In addition, multiple optical color filters 53 may be arranged on the light incident side of one light receiving element 52.

The optical color filters 53 may all be composed of the same filter. In this case, however, in order to make the characteristics of the multiple sensors 51 different, it is necessary to use different sensors as the light receiving elements 52. For example, by combining a silicon photodiode for visible light with an InGaAs photodiode for infrared light, or by combining a light receiving element capable of high-sensitivity measurement with a light receiving element capable of high-speed measurement, it is possible to simultaneously measure a variety of optical characteristics while using the same optical color filters 53.

The number of sensors 51 constituting the light receiving unit 5 is not limited to four in this embodiment. Depending on the number of branching members 41, for example, nine light receiving sensors 51 are used and arranged in three rows and three columns, or 16 sensors are used and arranged in four rows and four columns. By appropriately arranging more sensors 51, it is possible to simultaneously measure more optical characteristics.

A calculation unit (not shown) calculates the luminance Lv and chromaticity x, y from the received light data corresponding to the color matching functions XYZ converted into electrical signals output from each light receiving sensor 31. The calculation results are displayed on the display unit or sent to an external personal computer.
(Effect of light guide members on reducing positional and angular variations in measurement sensitivity)
Next, the effect of reducing positional and angular variations in measurement sensitivity by using the light guiding member 2 of this embodiment will be described.

In the configuration using the light-guiding member 2 having a polygonal prism or a polygonal truncated pyramid shape as described above, the light emitted from the light source LS to be measured and incident inside the light-guiding member 2 is repeatedly totally reflected at the side surface 2c of the light-guiding member 2 a number of times according to the angle of incidence at the light-incident end surface 2a, and is emitted from the light-exiting end surface 2b. In this configuration, when considering a certain point on the light-exiting end surface 2b, the point is illuminated by light from various points on the light-incident end surface 2a of the light-guiding member 2. In addition, since the measured surface LS0 of the light source LS to be measured and the light-incident end surface 2a of the light-guiding member 2 are conjugate by the objective optical system 3, light from various points of the light source LS to be measured illuminates each sensor 51 of the light-receiving unit 5 through the light-guiding member 2 and the branching member 41.

That is, as shown in FIG. 14(A), the light ray incident on the light guide member 2 from the position S1 at the center of the light incident side end face 2a of the light guide member 2, and as shown in FIG. 14(B), the light ray incident on the light guide member 2 from the position S2 at the end of the light incident side end face 2a of the light guide member 2 are emitted with approximately uniform intensity from the light output side end face 2b of the light guide member 2, and even if there is positional unevenness in the emission intensity (brightness) of the measured surface LS0 of the measured light source LS, each sensor 51 receives light in which light from various positions on the measured surface LS0 is mixed by the light guide member 2, and is therefore less susceptible to positional unevenness on the measured surface LS0. This makes it possible to reduce positional unevenness in the measurement sensitivity of each sensor 51, enabling stable measurement.

In addition, in a configuration using a light-guiding member 2 in the shape of a polygonal prism or a polygonal truncated pyramid, the angle of incidence on the light-incident end face 2a of the light-guiding member 2 changes depending on the emission angle of the light emitted from the measured light source LS. The light that enters the inside of the light-guiding member 2 through the light-incident end face 2a repeats total reflection on the side face 2c of the light-guiding member 2 a number of times depending on the angle, and reaches various positions on the light-exiting end face 2b (positions depending on the incidence angle to the light-guiding member 2). Therefore, if one point on the light-exiting end face 2b is considered in the same manner as above, the one point is illuminated by light at various angles. Since the emission angle of light from the measured light source LS corresponds to the incidence angle of light at the light-incident end face 2a of the light-guiding member 2, the light emitted at various angles from the measured light source LS will eventually illuminate each sensor 51 of the light-receiving unit 5 through the light-guiding member 2 and the branching member 41.

That is, the light ray (shown by a solid line) L1 incident on the light incident side end face 2a at an incident angle of 0° shown in Figures 14(A) and 14(B) travels straight whether the incident position on the light incident side end face 2a is the central position S1 or the end position S2, and is uniformly emitted from the light output side end face 2b. On the other hand, the light ray incident on the light incident side end face 2a at an incident angle other than 0° is reflected, and the emission position from the light output side end face 2b is biased. For example, the light ray (shown by a wavy line) L2 incident at an angle at the central position S1 of the light incident side end face 2a as shown in Figure 14(A) gathers at the center of the light output side end face 2b, and the light ray L2 incident at the same angle at the end position S2 of the light incident side end face 2a as shown in Figure 14(B) gathers at the end of the light output side end face 2b. This phenomenon occurs when the number of reflections in the light guide member 2 is smaller, the degree of bias becomes greater, and when the number of reflections is larger, the bias is alleviated and approaches uniformity.

In this way, even if there is angular unevenness in the emission intensity (brightness) of the measured surface LS0 of the measured light source LS, each sensor 51 is less susceptible to the influence of angular unevenness on the measured surface LS0 by receiving, via the branching member 41, light that is mixed by the light-guiding member 2 from the light emitted from the measured surface LS0 at various angles. This makes it possible to reduce angular unevenness in the measurement sensitivity in each sensor 51, enabling stable measurements.

Moreover, since the light-guiding member 2 has a simple polygonal prism or polygonal truncated pyramid shape (see Figures 2A to 2D), it has a simpler configuration and is less expensive than conventional light-guiding bodies in which multiple fibers are randomly woven together to guide light. Therefore, with a simple configuration using the inexpensive light-guiding member 2, it is possible to obtain the effect of reducing positional and angular unevenness in measurement sensitivity. In particular, in this embodiment, as described above, the light-receiving unit 5 has multiple sensors 51 with different characteristics, which makes it possible to measure color and brightness, and therefore the above-mentioned effect can be obtained in a colorimeter that measures such color and brightness.

Next, we will explain the difference in mixing effect depending on the incidence conditions on the light-guiding member 2 depending on whether or not the rear lens system 32 is present.

15, when the light-incident end face 2a of the light-guiding member 2 is located at the position of the aperture AP1, i.e., when the rear lens system 32 is not present, the position of the light-incident end face 2a correlates with the angular distribution (directivity) of the measurement surface LS0. Only the light rays (indicated by the dashed line) emitted from the measurement light source LS at an upward angle are concentrated at the incidence position S3 on the light-incident end face 2a.

The angle of incidence on the light-incident end surface 2a of the light-guiding member 2 correlates with the spatial distribution (measurement position) of the measurement surface LS0. All light rays from point P1 on the measurement surface LS0 are incident on the light-guiding member 2 in a diagonally downward direction.

In other words, the spatial distribution (positional unevenness) of the measured surface LS0 depends on the number of reflections by the light-guiding member 2; the more the number of reflections, the higher the mixing ability; whereas the angular distribution (directional unevenness) of the measured surface LS0 has good mixing ability regardless of the number of reflections.

16, when the measurement surface LS0 and the light-incident end surface 2a of the light-guiding member 2 are conjugated using the rear lens system 32, the position of the light-incident end surface 2a of the light-guiding member 2 correlates with the spatial distribution (measurement position) of the measurement surface LS0. The light rays from point P2 on the measurement surface LS0 are concentrated at the incidence position S4 of the light-incident end surface 2a.

The angle of incidence on the light-incident end surface 2a of the light-guiding member 2 correlates with the angle distribution (directivity) of the measured surface LS0. All light rays (dashed lines) emanating from the measured surface LS0 at an upward angle enter the light-guiding member 2 at an oblique downward angle.

In other words, the spatial distribution (positional unevenness) of the measured surface LS0 has good mixing properties regardless of the number of reflections by the light-guiding member 2, and the angular distribution (directional unevenness) of the measured surface LS0 depends on the number of reflections, with the greater the number of reflections, the higher the mixing properties.

As mentioned above, the more reflections there are in the light-guiding member 2, the better the mixing performance. Therefore, an additional effect of the rear lens system 32 is that it can focus light smaller than the field stop size, allowing a smaller light-guiding member 2 to be used, thereby increasing the number of reflections, or that it increases the angle of incidence on the light-guiding member 2, thereby increasing the number of reflections.

Incidentally, LCD and OLED monitors have uneven light emission across the monitor screen due to variations in the RGB display elements. When the measurement range is narrow, the RGB light-emitting elements are also discretely arranged, so the measured values are easily affected by spatial distribution (unevenness in measurement position). In addition, many recent PC monitors, home TVs, and smartphones have wide directivity (light distribution characteristics), so it can be said that mixing spatial distribution (unevenness in measurement position) is a higher priority for colorimeters.

Figure 17 is an explanatory diagram showing the optical path of the light guided inside the light guide member 2. The objective optical system 3 (see Figure 1) reduces and forms an image of the measured surface LS0 of the measured light source LS on the light incident side end face 2a of the light guide member 2, making it possible to use a thin light guide member 2 (a light guide member with a small diameter D1 of the inscribed circle of the light incident side end face 2a and a small diameter D2 of the inscribed circle of the light exit side end face 2b), and the incident angle θ of the light at the light incident side end face 2a of the light guide member 2 is larger than the exit angle of the light emitted from the measured light source LS (hence, the refraction angle θP inside the light guide member 2 is also larger). From Figure 17, it can be seen that the larger the incident angle θ of the light at the light incident side end face 2a (the larger the refraction angle θP), or the smaller the diameters D1 and D2, the more the number of reflections on the side surface 2c of the light entering the inside of the light guide member 2 increases.

In this embodiment, D=D. The approximate number of times that the light ray LT that is emitted from the measured light source LS and enters the light incident side end surface 2a of the light guide member 2 and that forms the maximum angle θ with the optical axis AX is reflected by the side surface 2c of the light guide member 2 is
(L tan θ P )/D 1 , or (L tan θ P )/D 2
where nP is the refractive index of the light-guiding member 2, the refraction angle θP is an angle that satisfies nP sin θP = sin θ. The optical axis AX is an axis that connects the center of the inscribed circle of the light-incident side end face 2a of the light-guiding member 2 and the center of the inscribed circle of the light-emitting side end face 2b, and is coaxial with the optical axis of the objective optical system 3.

As described above, in the configuration of this embodiment, when considering a certain point on the light-emitting end surface 2b of the light-guiding member 2, the above-mentioned point is illuminated by light emitted from the light source LS to be measured at various angles, and the influence of the angular unevenness of the light source LS to be measured can be reduced. When a light ray is reflected inside the light-guiding member 2, the angle of the light ray is inverted, so that as the number of times the light ray is reflected increases, the above-mentioned point is illuminated by light at more various angles. Therefore, it is possible to more effectively reduce the influence of the angular unevenness of the light source LS to be measured and reduce the angular unevenness of the measurement sensitivity, enabling more stable measurements.

Furthermore, when the number of reflections in the light guiding member 2 is constant, the length L of the light guiding member 2 in the optical axis AX direction can be reduced as the refraction angle θP increases and D1 or D2 decreases. In this case, the photometric device 1 can be made smaller.
(Number of reflections when using a polygonal pyramid light-guiding member)
18 is an explanatory diagram showing, in a developed form, the optical paths of light rays guided inside the light-guiding member 2 when the light-guiding member 2 having the polygonal pyramid truncated shape shown in Fig. 2D is used as the light-guiding member 2. In the light-guiding member 2 described above, the light-incident end face 2a and the light-emitting end face 2b have square shapes, but the area of the light-emitting end face 2b is larger than the area of the light-incident end face 2a.

Here, the number of reflections of light guided inside the light guide member 2 having a truncated polygonal pyramid shape can be considered as follows. That is, when the light guide member 2 having a truncated polygonal pyramid shape is used, the approximate number of times that the light ray LT, which is emitted from the measured light source LS and enters the light incident side end face 2a of the light guide member 2 and has the maximum angle θ with the optical axis AX, is reflected by the side surface 2c of the light guide member 2 is expressed as α/β. In FIG. 18, α is the angle (°) between the straight line connecting points A and O and the optical axis AX, and β is the angle (°) twice the angle between the side surface 2c of the light guide member 2 and the optical axis AX in the cross section including the optical axis AX. Here, point O refers to the point at which the side surface 2c of the light-guiding member 2 intersects with the optical axis AX when extended in a cross section including the optical axis AX, and point A is the point at which a straight line (dashed line LP) extending the light ray LT after it is refracted at the light-incident end surface 2a of the light-guiding member 2 (the angle it makes with the optical axis AX is θP) intersects with a circle whose center is point O and whose radius is L0. Specifically, α and β are angles that satisfy the following relational expressions. That is,
L0sinα={L−L0(1−cosα)}tanθP
tan(β/2)=(D2-D1)/2L
L0=D2L/(D2-D1)
nPsinθP=sinθ
and
L: Length of the light guide member 2 in the optical axis AX direction (mm)
θ: the maximum angle (°) between a light ray incident on the center of the light incident side end surface 2a of the light guide member 2 and a normal line of the light incident side end surface 2a
D1: diameter of the inscribed circle of the light incident side end surface 2a of the light guide member 2 (mm)
D2: diameter of the inscribed circle of the light emitting end surface 2b of the light guide member 2 (mm)
nP: the refractive index of the light guide member 2.

If α/β>1, that is, if the light ray LT is reflected at least once on the side surface 2c of the light-guiding member 2, the light emitted from various positions on the measured surface LS0 and the light emitted at various angles from the measured surface LS0 can be mixed in the light-guiding member 2 by reflecting the light ray LT on the side surface 2c. Therefore, the influence of the positional and angular unevenness of the measured light source LS can be reduced, and the positional and angular unevenness of the measurement sensitivity can be reduced. In particular, it is desirable that α/β>2, because the light ray LT can be reflected multiple times on the side surface 2c to reliably reduce the influence of the positional and angular unevenness of the measured light source LS and reliably reduce the positional and angular unevenness of the measurement sensitivity.

In addition, when α<<1, β<<1,
α≒(L/L0)tanθP={(D2-D1)/D2}/tanθP
β ≈ (D2 - D1) / L
And then,
α/β≒(LtanθP)/D2
That is, in this case, α/β roughly coincides with the number of reflections in the above-mentioned case where D1 = D2.
(Combination of light receiving sensors in light receiving unit 5)
As described above, the light receiving unit 5 has a plurality of light receiving sensors 51 for obtaining data of two or more different characteristics. In the case where there are four light receiving sensors 41, three of the light receiving sensors 51 (e.g., light receiving sensors 51a to 51c) have measurement sensitivity corresponding to the color matching functions X, Y, and Z and are light receiving sensors for obtaining luminance (Lv) and chromaticity (x, y), and the remaining sensor 51 (e.g., sensor 51d) is a light receiving sensor for detecting flicker, for example, as has already been described.

Below are other examples of combinations of light receiving sensors 51 to obtain data with different characteristics.

In the embodiment shown in FIG. 19, the light-guiding member 2 is a regular rectangular prism with a square cross section and a side length of 1.5 mm, the branching section 4 has four branching members 41 made of optical fibers with a diameter of 0.75 mm, and the light-receiving section 5 has four light-receiving sensors 51. Of the four light-receiving sensors 51, three are light-receiving sensors 51a to 51c composed of an optical color filter 53 and a light-receiving element 52, and are used for calculating chromaticity and luminance with the light-receiving sensitivity of the color matching function XYZ. The other is light-receiving sensor 51e, which acquires spectral data using a diffraction grating, prism, bandpass filter, etc., and is used for calculating spectral radiance, chromaticity, and luminance. Note that in FIG. 19, only one light-receiving sensor is shown as a representative of the three light-receiving sensors 51a to 51c.

As shown in Figures 20 (A) and (B), the light receiving sensor 51e that obtains the spectral data is arranged such that the output end of a branching member 41 made of an optical fiber with a diameter of 0.75 mm is placed on an entrance slit 61 with an aperture size of 0.4 x 0.75 mm provided in the housing 6, and the light beam from the entrance slit 61 is made into approximately parallel light by a lens 62 and irradiated onto a diffraction grating 63 with 600 lines/mm. The light beam dispersed in wavelength by the diffraction grating 63 is then collected by the lens 62 and received by the light receiving sensor 51e consisting of a line sensor. The line sensor that constitutes the light receiving sensor 51e has 100 cells with each element being 0.2 x 1 mm, and obtains spectral data with a wavelength range of 380 to 780 nm, a wavelength resolution of 4 nm pitch, and a wavelength half-value width of 8 nm.

The light quantity efficiency (area ratio) at the entrance slit 61 is slit area (0.4×0.6)÷optical fiber area (0.375 ² ×π)=0.54.

Figure 21 illustrates yet another combination of multiple light receiving sensors 51. In this example, the light guide member 2 is a regular rectangular prism with a square cross section and sides each 1.5 mm long, the branching section 4 includes four branching members 41 made of optical fiber with a diameter of 0.75 mm, and the light receiving section 5 includes four light receiving sensors 51. Each of the four light receiving sensors 51 is composed of spectroscopic sensors 51f-51i, and each of the spectroscopic sensors 51f-51i is designed to obtain spectroscopic data in a different wavelength band. Note that in Figure 21, two of the four light receiving sensors 51f-51i overlap in the depth direction of the page, so only two light receiving sensors are shown.

Figure 22 illustrates yet another combination of multiple light receiving sensors 51. In this example, the light guide member 2 is a regular rectangular prism with a square cross section and sides each having a length of 1.5 mm, the branching section 4 includes four branching members 41 made of optical fiber with a diameter of 0.75 mm, and the light receiving section 5 includes four light receiving sensors 51. Of the four light receiving sensors 51, three are light receiving sensors 51a to 51c each composed of an optical color filter 53 and a light receiving element 52, and the remaining one is light receiving sensor 51j provided in the external measuring device 593.

The light receiving sensor 51j of the external measuring device 593 is connected to the branching member 41 via optical connectors (exit side and entrance side) 591, 592, and receives the light output from the branching member 41 via the optical connectors 591, 592. In this embodiment, multiple external measuring devices 593, each of which has a different light receiving sensor built in, can be detachably connected to the branching member 41 via the optical connectors 591, 592. The user selects an arbitrary external measuring device 593 from the multiple external measuring devices 593, connects it, and uses it or replaces it. Examples of the external measuring device 593 include a flicker measuring device and a spectrometer equipped with polychrome.

Figure 23 illustrates another example of a combination of multiple light receiving sensors 51. In this example, the shape of the light guide member 2 and the number of branching members 41 (number of branches) are arbitrary.

For example, as shown in Fig. 23, 19 branching members 41 made of optical fibers are connected to a light-guiding member 2 in the form of a regular hexagonal prism with a cross-sectional shape of a regular hexagon, and 19 light-receiving sensors 51 (not shown) corresponding to each branching member 41 are arranged. Each of the 19 light-receiving sensors 51 has an arbitrary light-receiving sensitivity. For example, as shown in the graph of the transmittance of bandpass filters in Fig. 24, a configuration can be achieved in which spectral data from 400 to 760 nm can be obtained by providing 19 types of bandpass filters with center wavelengths of 400 nm, 420 nm, ... 500 nm, ... 760 nm, each shifted by 20 nm, and each with a half-width of 30 nm.

This application claims priority from Japanese Patent Application No. 2020-155610, filed on September 16, 2020, the disclosure of which is incorporated herein by reference in its entirety.

The present invention can be used in colorimeters that measure the brightness and chromaticity of light emitted from a light source to be measured.

REFERENCE SIGNS LIST 1 Photometric device 2 Light guide member 2a Light incident end surface 2b Light exit end surface 2c Side surface 3 Objective optical system 4 Branching section 41 Branching member 5 Light receiving section 5a Light receiving surface 31 Front lens system 32 Rear lens system 51 Sensor 52 Light receiving element 53 Optical color filter AP1, AP2 Aperture LS Light source to be measured

Claims (8)

A light guiding member having a circular or polygonal cross section;
an objective optical system that collects a light beam from the object to be measured on a light incident end surface of the light guiding member;
a branching unit including a plurality of branching members each made of a single member, which branch a light beam emitted from a light exit end surface of the light guide member into a plurality of beams and guides the beams;
a plurality of light receiving sensors for receiving light emitted from each of the plurality of branching members in the branching section and obtaining data of two or more different characteristics;
Equipped with
the branching portions are disposed within a range of the light-emitting end surface of the light guide member along a contour of the light-emitting end surface so as to be in close contact with each other,
A photometric device, characterized in that the light-emitting end face of the light-guiding member and the end face of the branching portion are joined and connected by adhesion or fusion, or are formed integrally with each other . The photometric device according to claim 1, wherein the objective optical system is in a conjugate relationship between the object to be measured and the light-incident end surface of the light-guiding member. The photometric device according to claim 1 or 2, wherein the plurality of light receiving sensors includes a light receiving sensor for obtaining light receiving data that is approximate to color matching functions XYZ. The photometric device according to any one of claims 1 to 3, wherein the plurality of light receiving sensors includes a light receiving sensor for obtaining spectroscopic data. The photometric device according to any one of claims 1 to 4, wherein the plurality of light receiving sensors includes a light receiving sensor of an external measuring device that receives light from the branching member via an optical connector, the external measuring device is detachable from the branching member, and an arbitrary external measuring device selected by a user from among a plurality of external measuring devices each having a light receiving sensor with different light receiving characteristics is connected to the branching member. The photometric device according to any one of claims 1 to 5, wherein each of the multiple branching members is formed from an optical fiber. The photometric device according to claim 6, wherein the optical fiber is made of resin. The photometric device according to any one of claims 1 to 7, wherein the light guiding member is a polygonal prism or a polygonal truncated pyramid.

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