WO2016093130A1

WO2016093130A1 - Illumination device and reflection characteristics measurement device

Info

Publication number: WO2016093130A1
Application number: PCT/JP2015/083942
Authority: WO
Inventors: 貴志川崎; 利夫河野
Original assignee: コニカミノルタ株式会社
Priority date: 2014-12-10
Filing date: 2015-12-03
Publication date: 2016-06-16
Also published as: JPWO2016093130A1; JP6642450B2

Abstract

In order to improve the usage efficiency of light emitted by a light source for a light-radiating structure and in order to make more uniform the amount of light irradiated from the light-radiating structure towards each section of a reflection structure, an illumination device comprises: an integrating sphere arranged above the normal line of a surface to be illuminated; a straight-tube light source traversing the integrating sphere space, extending in the tube axial direction, and having a discharge segment extending in the tube axial direction; and a reflection structure provided between an emission port in the integrating sphere and the surface to be illuminated so as to surround the normal line, said reflection structure reflecting, towards the surface to be illuminated, light that has been radiated from the discharge segment, then diffusely reflected by a diffuse reflection surface, and irradiated from the emission port. The reflection structure has arranged therein at least one light-reflective area that reflects light towards the surface to be illuminated. The center of a section in the discharge segment that is contained in the space is outside an area in which at least some of the at least one light-reflective area in the space can be seen through the emission port.

Description

Illumination device and reflection characteristic measurement device

The present invention relates to an illumination device and a reflection characteristic measurement device including the illumination device.

For measurement of spectral reflection characteristics, an illumination light receiving system having a predetermined geometry, for example, a so-called 45: 0 degree geometry is used. The 45: 0 degree illumination light receiving system includes an illumination optical system that illuminates the sample surface from a direction at 45 ° from the normal line, and a light receiving optical system that receives reflected light from the sample surface from the normal direction. .

As an illumination optical system having such a geometry, Patent Document 1 discloses an illumination optical system including a light emission mechanism including an integrating sphere and a light source such as a xenon lamp. The xenon lamp is arranged at the periphery of the integrating sphere or outside. The light emitted from the xenon lamp is guided to the integrating sphere, diffused and reflected a plurality of times on the inner wall of the integrating sphere, and is made uniform and emitted outside through the opening of the integrating sphere. The light emitted to the outside is reflected by a mirror disposed so as to surround an axis connecting the opening and the surface to be illuminated, and is irradiated onto the surface to be illuminated. With this configuration, the angular distribution of the light emitted from the aperture is made to have a substantially cosine characteristic.

US Pat. No. 5,268,749

However, in the illumination optical system of Patent Document 1, since the xenon lamp is arranged outside the integrating sphere or at the peripheral edge of the integrating sphere, there is a problem that the apparatus becomes large, and the efficiency of use of light emitted from the light source is low. There is a problem that it is low.

As a method for solving this problem, for example, a configuration in which a light source such as a straight tube type xenon lamp is arranged inside the integrating sphere is conceivable. However, in this configuration, depending on the position and orientation of the lamp, the integrating sphere may emit light emitted from the opening toward the mirror arranged so as to surround the axis connecting the integrating sphere opening and the illuminated surface. There is a lot of direct light emitted from the opening without being reflected by the inner wall. Further, the ratio of the direct light included varies depending on the radiation direction from the opening.

In this case, the amount of light radiated from the opening of the integrating sphere to the mirror varies depending on each part of the mirror. For this reason, even in the illuminated surface irradiated with the light reflected by the mirror, the amount of light emitted from each direction varies. For this reason, when the surface to be irradiated is a sample surface having directionality in reflection characteristics such as a wrinkle pattern or a streak pattern, the amount of reflected light reflected from the surface to be irradiated is illuminated by the illumination optical system. There arises a problem that it fluctuates depending on the orientation of the surface.

The present invention has been made to solve these problems, and improves the utilization efficiency of light emitted from the light source of the light emission mechanism and surrounds an axis (normal line) connecting the light emission mechanism and the irradiated surface. An object of the present invention is to provide a technique capable of uniformizing the amount of light emitted from the light emission mechanism toward each part of the reflection mechanism arranged in this manner.

In order to solve the above-described problem, a lighting device according to a first aspect is disposed on a normal line of a surface to be illuminated, has an inner surface that defines a space, the inner surface has a diffuse reflection surface, and the space Integrating sphere formed on the illuminated surface side and having a round hole-shaped exit opening that connects the space and the outside, and the space and the exit opening have the normal as a common central axis And a straight tube light source extending in the tube axis direction across the space and having a discharge section extending in the tube axis direction, and the exit port and the illuminated object so as to surround the normal line A reflection mechanism that is provided between the surface and the light that is radiated from the discharge section and then diffused and reflected by the diffuse reflection surface and reflected from the exit port. The reflection mechanism reflects the light toward the illuminated surface at least. A region where one light reflection region is arranged, and a center of a portion of the discharge section included in the space is a region where at least a part of the at least one light reflection region can be seen through the emission port in the space. It is off.

The illumination device according to the second aspect is the illumination device according to the first aspect, wherein the at least one light reflection region is three or more light reflection regions, and the reflection mechanism includes the three light reflection regions. The light reflecting regions of the above light reflecting regions and the non-reflecting regions that do not reflect the light toward the illuminated surface are alternately arranged in the circumferential direction along the virtual cylindrical surface surrounding the normal line. Accordingly, three or more light reflecting areas and three or more non-reflecting areas are arranged, and the three or more non-reflecting areas are distributed in the circumferential direction so as to surround the normal line. Has been.

An illumination device according to a third aspect is the illumination device according to the second aspect, wherein the tube axis has the normal line so that the center of the space is not located on the tube axis of the straight tube light source. It is shifted in the crossing direction.

The illumination device according to the fourth aspect is the illumination device according to any one of the first to third aspects, and further includes a baffle between the discharge section and the emission port.

A lighting device according to a fifth aspect is the lighting device according to any one of the first to fourth aspects, wherein the inner surface of the integrating sphere is a first inner surface defining a hemispherical first space; A second inner surface that opposes the first inner surface and defines a hemispherical second space, wherein the first radius of the first space is smaller than the second radius of the second space, and the emission The mouth is open to the first inner surface.

The lighting device according to a sixth aspect is the lighting device according to the fifth aspect, wherein the second radius is 1.2 times or less of the first radius.

A reflection characteristic measurement device according to a seventh aspect is generated by the illumination device according to any one of the first to sixth aspects and the illuminated surface reflecting the light reflected by the reflection mechanism. A light receiving mechanism that receives the reflected light and outputs a measurement result of the reflected light.

According to the first aspect of the invention, any part of the at least one light reflection region cannot be seen from the center of the part included in the integrating sphere space in the discharge section of the straight tube light source. Therefore, it is possible to suppress the generation of light emitted from the discharge port without being emitted from the discharge section and reflected by the diffuse reflection surface of the integrating sphere. Therefore, it is possible to make uniform the amount of light applied to each part of the light reflection area of the reflection mechanism. Further, since the straight tube light source is provided across the space of the integrating sphere, it is possible to improve the utilization efficiency of light emitted from the straight tube light source.

According to the invention according to the second aspect, the three or more non-reflective regions are arranged in the circumferential direction so as to surround the normal line of the illuminated surface. Therefore, three or more reflective regions are also distributed and arranged in the circumferential direction. On the other hand, the wrinkle pattern and the stripe pattern on the illuminated surface often have two-fold rotational symmetry. For this reason, it is possible to suppress the occurrence of cases where the amount of reflected light is extremely reduced by irradiating illumination light from all directions with low reflectivity of the surface to be illuminated and not irradiating illumination light from all directions with high reflectivity. Is done. Further, it is possible to suppress the occurrence of a case in which the amount of reflected light is extremely increased by irradiating illumination light from all azimuths with low reflectivity and irradiating illumination light from all azimuths with high reflectivity. Therefore, it is possible to suppress fluctuations in the amount of light that is irradiated from the reflection mechanism to the illuminated surface having a directivity in the reflection characteristics and reflected from the illuminated surface.

According to the invention relating to the third aspect, the tube axis is shifted in the direction crossing the normal so that the center of the space is not located on the tube axis of the straight tube light source. Therefore, it becomes easy to arrange the straight tube light source so that the non-reflective area can be seen and the reflective area cannot be seen. Thereby, it can suppress that the light radiated | emitted from the straight tube | pipe type light source is directly radiated | emitted from an output port, without reflecting with the diffuse reflection surface of an integrating sphere.

According to the fourth aspect of the invention, since the baffle is further provided between the discharge section of the straight tube light source and the exit, the light emitted from the straight tube light source is reflected by the diffuse reflection surface of the integrating sphere. Without being done, it is possible to further suppress direct emission from the exit.

According to the fifth aspect of the invention, the first radius of the first space of the integrating sphere is smaller than the second radius of the second space, and the emission port is open to the first inner surface. The edge of the second inner surface that defines the second space has a large variation in reflectance, but the edge can be made difficult to see from the reflection mechanism by the first inner surface. As a result, the amount of light reflected from the inner wall of the integrating sphere and emitted from the emission port toward the reflection mechanism can be made uniform.

According to the sixth aspect of the invention, since the second radius is 1.2 times or less than the first radius, a difference in size between the first space and the second space can be suppressed. As a result, the amount of light reflected from the inner wall of the integrating sphere and emitted from the exit port toward the reflecting mechanism can be made more uniform.

According to the seventh aspect of the invention, even when the reflection characteristic measuring apparatus measures an illuminated surface having directionality in the reflection characteristics, it is possible to suppress fluctuations in the amount of light reflected from the illuminated surface, and thus stable. Measurements can be obtained.

It is a schematic diagram of a colorimeter. It is a top view of a measurement mechanism. It is a bottom view of a measurement mechanism. It is a cross-sectional view of a measurement mechanism. It is a figure which shows the part except each light-receiving mechanism for colorimetry and a correction | amendment from FIG. It is a longitudinal cross-sectional view of a measurement mechanism. It is sectional drawing of a light emission mechanism. It is a perspective view of a part of straight tube | pipe type xenon lamp and a part of baffle. It is a top view which shows the structure of a part of illumination mechanism. It is a perspective view which shows the structure of a part of illumination mechanism. It is a figure which shows the illumination light quantity with respect to the direction of a to-be-illuminated surface in a graph format.

<1. Colorimeter>
The schematic diagram of FIG. 1 shows a colorimeter.

The colorimeter 1000 shown in FIG. 1 measures the spectral reflectance of the sample. Reflection characteristics other than the spectral reflectance may be measured. For example, the color value may be measured. That is, the function of the spectrocolorimeter that the colorimeter 1000 has may be changed to the function of a reflection characteristic measuring device other than the spectrocolorimeter. For example, the spectral colorimeter function of the colorimeter 1000 may be changed to a colorimeter function.

Spectral reflectance is measured by a geometry with an illumination angle of 45 ° and a light receiving angle of 0 °. When the spectral reflectance is measured, the illuminated surface is illuminated by the annular illumination. The illuminated surface is the surface of the sample. Geometry and / or lighting may be changed.

The colorimeter 1000 includes a measurement mechanism 1010, a controller 1011 and a housing 1012. The measurement mechanism 1010 is responsible for color measurement. The controller 1011 controls the measurement mechanism 1010. The housing 1012 houses the measurement mechanism 1010, the controller 1011 and the like.

<2. Measuring mechanism>
The schematic diagram of FIG. 2 shows the top surface of the measurement mechanism. The schematic diagram of FIG. 3 shows the lower surface of the measurement mechanism. The schematic diagram of FIG. 4 shows a cross section of the measurement mechanism. The schematic diagram of FIG. 5 shows a cross section of the measuring mechanism excluding the light receiving mechanisms for colorimetry and correction. The schematic diagram of FIG. 6 shows a longitudinal section of the measurement mechanism.

The measurement mechanism 1010 shown in FIG. 2 to FIG. 5 includes an illumination mechanism 1032 for color measurement, a light reception mechanism 1033 for color measurement, a light reception mechanism 1034 for correction, and the like. The illumination mechanism 1032 for colorimetry illuminates the illuminated surface 1050 with illumination light 1042 from around the illuminated surface 1050. Illuminated surface 1050 is an illumination target region (also referred to as “measurement target region”) on the illuminated surface. The colorimetric light receiving mechanism 1033 receives the reflected light 1043 and outputs a measurement result for the reflected light 1043. The reflected light 1043 is light that is reflected by the illuminated surface 1050 in the direction of the normal 1120, that is, the direction in which the light receiving angle is 0 °, by the illuminated surface 1050. The correction light receiving mechanism 1034 receives the light 1045 and outputs a measurement result for the light 1045. The illumination mechanism 1032 for color measurement may be used for purposes other than color measurement. When the illumination mechanism 1032 for color measurement is used in an application other than color measurement, the illumination mechanism 1032 may be used alone, or the illumination mechanism 1032 may be incorporated in an apparatus other than the colorimeter 1000.

<3. Lighting mechanism for color measurement>
The color measurement illumination mechanism 1032 shown in FIGS. 2 to 6 includes a light emission mechanism 1190, a reflection mechanism 1191, and the like, as shown in FIGS. The light emitting mechanism 1190 emits light 1044, light 1045, and the like. The reflection mechanism 1191 turns the light 1044 into illumination light 1042. The light emitting mechanism 1190 may be used in applications other than colorimetry. When the light emission mechanism 1190 is used in applications other than color measurement, the light emission mechanism 1190 may be used alone, or the light emission mechanism 1190 may be incorporated in an apparatus other than the colorimeter 1000.

<4. Light emission mechanism>
FIG. 7 shows a cross section of the light emitting mechanism.

4 to 7 includes a straight tube type xenon lamp 1200, an integrating sphere 1201, a baffle 1202, and the like. The straight tube type xenon lamp 1200 emits light. The integrating sphere 1201 makes the light uniform. The baffle 1202 prevents light from being emitted without being made uniform.

A spherical space 1210 formed in the integrating sphere 1201 is defined on the inner surface 1220 of the integrating sphere 1201. The integrating sphere 1201 is formed by integrating integrating

hemispheres

1205 and 1206 with screws. In order to say that the space 1210 is spherical, it is only necessary to grasp a sphere having a spherical surface along the main part of the inner surface 1220. The

hemispherical spaces

1207 and 1208 formed in the integrating

hemispheres

1205 and 1206 are defined by hemispherical

inner surfaces

1217 and 1218. The

inner surfaces

1217 and 1218 are each coated with a white matte paint (light diffusion material). In order for the

spaces

1207 and 1208 to be said to be hemispherical, it is sufficient if the respective hemispheres having the respective hemispherical surfaces along the main portions of the

inner surfaces

1217 and 1218 can be grasped. The diameter of the hemisphere along the main part of the inner surface 1217 is smaller than the diameter of the hemisphere along the main part of the inner surface 1218. The space 1210 includes an inner surface 1217 that defines a hemispherical space 1207 and an inner surface 1218 that faces the inner surface 1217 and defines a hemispherical space 1208. The radius of the space 1207 is smaller than the radius of the space 1208. The space 1207 is open to one end surface of the integrating hemisphere 1205. The other end surface of the integrating hemisphere 1206 is in contact with the one end surface. The space 1208 opens to the other end surface of the integrating hemisphere 1206. The opening diameters of the

openings

1227 and 1228 in the

spaces

1207 and 1208 are equal to the diameters of the respective hemispheres along the main portions of the

inner surfaces

1217 and 1218, respectively. The integrating

hemispheres

1205 and 1206 are coupled to each other with the one end surface of the integrating hemisphere 1205 and the other end surface of the integrating hemisphere 1206 in contact with each other so that the centers of the

openings

1227 and 1228 coincide with each other. The centers of the

openings

1227 and 1228 are the center 1240 of the integrating sphere 1201.

A round hole-shaped exit port 1211 formed in the integrating sphere 1201 is defined on the inner surface 1217 of the integrating hemisphere 1205. The emission port 1211 communicates the space 1210 and the outside of the integrating sphere 1201. The diameter of the emission port 1211 is constant. The exit 1211 may be divergent from one end on the space 1210 side toward the other end on the outside of the integrating sphere 1201. In order to say that the exit port 1211 has a round hole shape, it is only necessary to grasp the rotationally symmetric body.

The space 1210, that is, the

spaces

1207 and 1208, and the emission port 1211 have a common central axis 1230. The symmetry axes of the sphere and the hemisphere along the main parts of the

inner surfaces

1220, 1217, and 1218, and the symmetry axis of the rotationally symmetric body grasped from the exit port 1211 are on the central axis 1230. The center 1240 of the integrating sphere 1201 is also on the central axis 1230. Center axis 1230 coincides with normal 1120 passing through the center of illuminated surface 1050. That is, the light emitting mechanism 1190 is disposed on the normal line 1120 of the illuminated surface 1050.

In order to say that the space 1210 has a spherical shape, a rotationally symmetric body having a central axis 1230 as a symmetry axis from a main portion of the inner surface 1220, that is, a space where the respective hemispheres grasped from the main portions of the

inner surfaces

1217 and 1218 are combined. It is enough if you can grasp it. The inner surface 1220 may have some unevenness, and some holes may be exposed on the inner surface 1220. The emission port 1211 exposed to the inner surface 1220 also corresponds to the hole.

As described above, the diameter of the hemisphere along the main part of the inner surface 1217, that is, the diameter of the opening 1227 is smaller than the diameter of the hemisphere along the main part of the inner surface 1218, that is, the diameter of the opening 1228. As a result, a line connecting each point on each reflection surface 1340 described later included in the reflection mechanism 1191 and each point on the periphery of the opening 1228 is blocked by the periphery of the opening 1227. For this reason, the periphery of the opening 1228 of the space 1208 cannot be seen from each reflecting surface 1340.

For example, when the diameters of the

openings

1227 and 1228 are equal to each other, the white matte paint is easily peeled off at the connection portion between the openings. Due to the peeling of the paint, the reflectance of the light at the connection portion is lower than the surrounding portion. For this reason, when the said connection part is visible from each reflective surface 1340 through the output port 1211, the light quantity of the light inject | emitted from the output port 1211 to each reflective surface 1340 arises.

On the other hand, when the diameter of the opening 1227 is smaller than the diameter of the opening 1228, the peripheral edge of the opening 1227 does not hit the other end surface of the integrating hemisphere 1206, and thus the reflectance of the peripheral edge of the opening 1227 is the same as that of other parts. It will be about. On the other hand, the peripheral edge of the opening 1228 is a corner where one end surface of the integrating hemisphere 1205 and the inner surface 1218 contact each other at an angle of approximately 90 degrees, and thus the reflectance is lower than the other portions. However, as described above, the periphery of the opening 1227 is visible from each reflecting surface 1340, but the periphery of the opening 1228 is not visible from each reflecting surface 1340. Accordingly, it is possible to suppress unevenness in the amount of light emitted from the emission port 1211 to each reflection surface 1340 due to a decrease in reflectance at the periphery of the opening 1228.

However, even when the diameters of the

openings

1227 and 1228 are equal to each other, the function of the integrating sphere 1201 for making the light uniform is not lost, and the usefulness of the light emission mechanism 1190 is not lost.

The inner surface 1220, that is, the

inner surfaces

1217 and 1218 has a diffuse reflection surface 1245. Desirably, the entire inner surface 1220 becomes the diffuse reflection surface 1245, but the inner surface 1220 may have a slight surface that is not the diffuse reflection surface 1245. The diffuse reflection surface 1245 is a surface painted with a white matte paint. The white matte paint includes a resin, a white pigment, a matte material, and the like. The resin is an acrylic resin or the like. The white pigment is a powder of titanium oxide, zinc oxide, barium sulfate, calcium carbonate or the like. The matting material is fine particles such as silica, calcium carbonate, calcium phosphate. The white matte paint may be replaced with an achromatic matte paint other than white. The diffuse reflection surface 1245 may be formed by roughening the inner surface 1220.

The schematic diagram of FIG. 8 is a perspective view of a part of a straight tube type xenon lamp and a part of a baffle.

A straight tube type xenon lamp (also referred to as “straight tube light source”) 1200 shown in FIGS. 4, 5, 7 and 8 includes an arc tube 1250, an electrode 1251, and an electrode 1252, as shown in FIG. , A sealed gas 1253, and the like. The electrode 1251 is sealed to one end of the arc tube 1250. The electrode 1252 is sealed to the other end of the arc tube 1250. The sealed gas 1253 is sealed in the arc tube 1250. The main component of the sealed gas 1253 is xenon gas. The straight tube type xenon lamp 1200 extends in the tube axis direction in which the tube shaft 1310 extends. The straight tube xenon lamp 1200 has a discharge section 1260. The discharge section 1260 is between the electrode 1251 and the electrode 1252. When a voltage is applied between the electrode 1251 and the electrode 1252, a discharge occurs in the discharge section 1260, and light is emitted from the straight tube xenon lamp 1200. The straight tube type xenon lamp 1200 has an advantage that it is inexpensive and has a large amount of light emitted over the entire visible range. This advantage contributes to lowering the manufacturing cost of the colorimeter 1000 and improving the colorimetric signal-to-noise ratio. Further, as a straight tube type light source replacing the straight tube type xenon lamp 1200, for example, a straight tube type HID lamp (High-intensity-discharge lamp) such as a metal halide lamp UCM manufactured by Ushio Lighting Co., Ltd. may be used.

Integral hemispheres

1205 and 1206 have a concavo-convex structure that can be fitted to the concavo-convex structure at both ends of the xenon lamp 1200 at one end and the other end in the tube axis 1310 direction. The

integration hemispheres

1205 and 1206 are fixed to each other in a state where the xenon lamp 1200 is sandwiched between the

integration hemispheres

1205 and 1206 so that these fitting structures are fitted to each other. Thereby, the xenon lamp 1200 is fixed to the integrating sphere 1201. The straight tube type xenon lamp 1200 traverses the space 1210. When the straight tube type xenon lamp 1200 crosses the space 1210, it is easy to make both the straight tube type xenon lamp 1200 larger and the integrating sphere 1201 smaller. Increasing the size of the straight tube type xenon lamp 1200 contributes to increasing the amount of light emitted by the straight tube type xenon lamp 1200 and extending the life of the straight tube type xenon lamp 1200.

The baffle 1202 is between the discharge section 1260 and the outlet 1211. The baffle 1202 prevents a part or all of the exit port 1211 from being seen through the discharge section 1260, and desirably prevents the whole exit port 1211 from being seen through the discharge section 1260. One position is seen from another position (also referred to as “visible”) means that there is no light shielding object on a straight line connecting one position and another position, and the light beam is directly from one position to another position. To reach the target. On the other hand, if one position is not seen from another position (also referred to as “invisible”), there is a light shielding object on a straight line connecting the one position and the other position. This means that the light beam cannot reach the position of. The baffle 1202 shields the light beam that travels directly from the discharge section 1260 to the exit port 1211, and suppresses the light emitted from the discharge section 1260 from exiting from the exit port 1211 without being diffusely reflected by the diffuse reflection surface 1245. As a result, stray light is suppressed and the accuracy of colorimetry is improved. When the light emitted from the discharge section 1260 is diffused and reflected by the diffuse reflection surface 1245 and then emitted from the emission port 1211, the uniformed light 1045 is received by the light receiving mechanism 1034 for correction, and the emission port 1211. The fluctuation of the light 1044 emitted from the light source is appropriately monitored. Conversely, when the light emitted from the discharge section 1260 exits from the exit 1211 without being diffusely reflected by the diffuse reflection surface 1245, the disadvantage of the straight tube xenon lamp 1200 that the horizontal light distribution characteristic is not uniform. The fluctuation of the light 1045 emitted from the emission port 1211 is not properly monitored. However, even when the baffle 1202 is omitted, the function of the integrating sphere 1201 for making the light uniform is not lost, and the usefulness of the light emitting mechanism 1190 is not lost.

The baffle 1202 has a partial cylindrical shape and extends in a direction parallel to the direction in which the discharge section 1260 extends. The partial cylinder refers to a shape obtained by cutting a part from one circumferential position of the cylinder to another circumferential position. In order to say that the shape is a partial cylindrical shape, it is sufficient that the shape is along the partial cylinder, and the shape may have some unevenness with respect to the partial cylinder. An inner peripheral surface 1275 of the baffle 1202 is directed to the discharge section 1260. The outer peripheral surface 1276 of the baffle 1202 is directed to the emission port 1211. The shape of the baffle 1202 may be changed.

The surface 1280 of the baffle 1202 has a diffuse reflection surface 1290. Desirably, the entire surface 1280 is the diffuse reflection surface 1290, but the surface 1280 may have a slight surface that is not the diffuse reflection surface 1290. However, even when the surface of the baffle 1202 does not have the diffuse reflection surface 1290, the function of the integrating sphere 1201 for making the light uniform is not lost, and the usefulness of the light emitting mechanism 1190 is not lost.

When the straight tube type xenon lamp 1200 emits light, the light sequentially proceeds through the space 1210 and the emission port 1211 and finally exits from the integrating sphere 1201. The light is diffusely reflected on the diffuse reflection surface 1245 at least once while traveling through the space 1210. Most of the light is diffusely reflected by the diffuse reflection surface 1245 repeatedly while traveling through the space 1210. The light is diffused and reflected by the diffuse reflection surface 1245 and then emitted from the emission port 1211, whereby the light emitted from the light emission mechanism 1190 becomes uniform, and the light emission mechanism 1190 is substantially vertically distributed according to Lambert's cosine law. It has characteristics. When the light emitting mechanism 1190 has a vertical light distribution characteristic according to Lambert's cosine law, the luminous intensity of light emitted in a direction that forms an angle θ with the central axis 1230 is proportional to the cosine cos θ of the angle θ.

The straight tube type xenon lamp 1200 has a drawback that the vertical light distribution characteristic does not follow Lambert's cosine law. Further, the straight tube type xenon lamp 1200 has a drawback that the horizontal light distribution characteristic is not uniform. However, these disadvantages are alleviated to such an extent that they are not substantially problematic by integrating sphere 1201.

<5. Arrangement of straight tube xenon lamp>
One end 1301 and the other end 1302 of the discharge section 1260 are along the inner surface 1220, preferably on the spherical surface of the grasped sphere. When one end 1301 and the other end 1302 of the discharge section 1260 are along the inner surface 1220, the protrusion of the straight tube type xenon lamp 1200 from the space 1210 is reduced, and the light emission mechanism 1190 is reduced in size. Further, most of the discharge section 1260 is accommodated in the space 1210, and most of the light emitted from the straight tube xenon lamp 1200 is emitted to the space 1210, so that the efficiency of the light emission mechanism 1190 is improved.

In order for the one end 1301 and the other end 1302 of the discharge section 1260 to be along the inner surface 1220, the one end 1301 and the other end 1302 of the discharge section 1260 are on the spherical surface of the grasped sphere or the one end 1301 and the other end 1301 of the discharge section 1260 It suffices if the other end 1302 is close to the inner surface 1220 at a distance from the inner surface 1220.

More specifically, the center 1300 of the discharge section 1260 is the center of the portion included in the space 1210 in the discharge section 1260. The center 1300 is on the tube axis 1310 of the straight tube type xenon lamp 1200 and at the same distance from the electrode 1251 and the electrode 1252. The tube axis 1310 is arranged so as to be shifted in a direction crossing the normal line 1120 of the illuminated surface 1050 so that the center 1240 of the integrating sphere 1201 is not positioned on the tube axis 1310 of the xenon lamp 1200. When the reflecting mechanism 1191 includes an even number of mirror blocks 600, the amount of light emitted from the xenon lamp 1200 to each mirror can be made uniform by setting the straight tube extension direction of the xenon lamp 1200 as a bridge. When the reflection mechanism 1191 includes an odd number of mirror blocks 600, as described above, the xenon lamp 1200 is shifted from the center 1240 so that the amount of light radiated from the emission port 1211 to each mirror block 600 can be easily obtained. Can be made uniform.

The center 1300 of the portion included in the space 1210 in the discharge section 1260 is desirably outside the region where at least a part of the three reflection regions can be seen through the emission port 1211 in the space 1210.

The exit 1211 is in the tube radial direction 1320 that is away from the tube axis 1310 when viewed from the discharge section 1260. The discharge section 1260 preferably extends in a plane perpendicular to the direction of the central axis 1230, that is, the axial direction 1330 and parallel to the illuminated surface 1050. The center 1300 of the discharge section 1260 may be on the central axis 1230. Further, since the LED light source is also a surface light source, an LED light source may be used instead of the light emitting mechanism 1190.

<6. Reflection mechanism>
The schematic diagrams of FIGS. 9 and 10 are a top view and a perspective view showing a part of the structure of the illumination mechanism 1032.

The reflection mechanism 1191 is provided between the light emission mechanism 1190 and the illuminated surface 1050 so as to surround the normal 1120. The reflection mechanism 1191 reflects the light 1044 emitted from the light emission mechanism 1190 toward the illumination target surface 1050 as illumination light 1042.

The reflection mechanism 1191 includes three or more (three in the illustrated example) mirror blocks 600. The mirror blocks 600 are arranged in a distributed manner in the circumferential direction 1350 along the virtual cylindrical surface K1 surrounding the normal 1120. Each mirror block 600 is a partially cylindrical plate member along the virtual cylindrical surface K1. From both end faces in the normal 1120 direction of each mirror block 600, a protrusion N1 (FIG. 5) protrudes in the normal 1120 direction. A plurality of protrusions N1 are provided on at least one end face of the both end faces.

The measurement mechanism 1010 further includes

cylindrical members

810 and 820 that are provided with the normal 1120 as an axis.

The cylindrical member 810, the reflection mechanism 1191, and the cylindrical member 820 are provided in this order from the illuminated surface 1050 side. The

cylindrical members

810 and 820 and the reflection mechanism 1191 are located between the illuminated surface 1050 and the light emission mechanism 1190. The diameters of the

cylindrical members

810 and 820 and the virtual cylindrical surface K1 are equal to each other.

The cylindrical member 820 includes a cylindrical side wall 823 having a normal line 1120 as a central axis, and a disk-shaped lid 822 that closes an opening of the side wall 823 on the light emission mechanism 1190 side. A round hole-shaped opening 821 centering on the normal 1120 is formed at the center of the lid 822. The opening 821 has a larger diameter than the exit port 1211 of the integrating sphere 1201. The space 1210 of the integrating sphere 1201 and the internal space of the cylindrical member 820 communicate with each other via the emission port 1211 and the opening 821.

Of the both end faces of the cylindrical member 810, one end face on the light emitting mechanism 1190 side and the other end face on the illuminated surface 1050 side of both end faces in the normal 1120 direction of each mirror block 600 are in contact with each other. One end surface of the cylindrical member 810 is provided with a hole that can be fitted to the protrusion N <b> 1 provided on the other end surface of the mirror block 600. The cylindrical member 810 and the mirror block 600 are fixed to each other by fitting the hole and the protrusion N1 of the mirror block 600.

Of the both end surfaces of each mirror block 600, one end surface on the light emitting mechanism 1190 side and the other end surface on the illuminated surface 1050 side of both end surfaces of the side wall 823 of the cylindrical member 820 are in contact with each other. The other end surface of the side wall 823 is provided with a hole that can be fitted to the protrusion N1 provided on one end surface of the mirror block 600. The mirror block 600 and the cylindrical member 820 are fixed to each other by fitting the hole and the protrusion N1.

The inner peripheral surface of the mirror block 600, that is, the surface facing the normal 1120 is a reflection region 500 that reflects the light 1044 toward the illuminated surface 1050. Further, among the three or more mirror blocks 600, the adjacent mirror blocks 600 are provided at intervals from each other along the virtual cylindrical surface K1. A portion between the adjacent mirror blocks 600 is a non-reflective region 502 that does not reflect the light 1044 toward the illuminated surface 1050.

That is, in the reflection mechanism 1191, three or more (three in the illustrated example) reflective regions 500 and three or more (three in the illustrated example) non-reflective regions 502 are arranged. The reflective region 500 and the non-reflective region 502 are alternately arranged in the circumferential direction 1350 along the virtual cylindrical surface K1 surrounding the normal 1120.

Each reflective region 500 is a partial cylindrical region along the virtual cylindrical surface K1, and three or more non-reflective regions 502 are arranged in the circumferential direction 1350 along the virtual cylindrical surface K1 so as to surround the normal 1120. It is distributed. Accordingly, the three or more reflective regions 500 are also distributed in the circumferential direction 1350 along the virtual cylindrical surface K1 so as to surround the normal 1120. The three or more non-reflective regions 502 are preferably arranged at equal intervals in the circumferential direction 1350. The shape of the plurality of reflection regions 500 in the reflection mechanism 1191 preferably has a rotational symmetry of three or more times (three times in the example of FIG. 9) with the central axis 1230 as a rotation axis.

Each reflection region 500 of each mirror block 600 is provided with a plurality (four in the illustrated example) of reflection surfaces 1340 that reflect the light 1044 toward the surface 1050 to be illuminated. The plurality of reflection surfaces 1340 are arranged in the circumferential direction 1350 along the virtual cylindrical surface K1.

Each reflection surface 1340 is a mirror surface and reflects light 1044. Each reflecting surface 1340 is formed in a curved shape extending in the direction of the normal 1120, and a cross section perpendicular to the normal 1120 is an arc-shaped curve convex toward the normal 1120 side. The cross section may be an arcuate curve convex on the opposite side of the normal line 1120. Moreover, each reflective surface 1340 may be a planar reflective surface.

Each reflective surface 1340 faces the radially inner side approaching the central axis 1230. Each reflecting surface 1340 is arranged such that the light 1044 becomes incident light and the reflected light becomes illumination light 1042. The illumination light 1042 enters the illuminated surface 1050 from a direction with an illumination angle of 45 °. The direction of the illumination angle of 45 ° is a direction that forms a 45 ° with the normal line 1120 of the surface to be illuminated 1050.

The vertical light distribution characteristic of the light emitting mechanism 1190 follows Lambert's cosine law, and the light 1044 emitted from the emission port 1211 in the direction of 45 ° with the central axis 1230 enters the illuminated surface 1050 from the direction of the illumination angle of 45 °. In the case of light, the illuminance does not vary greatly even when the illuminated surface 1050 moves in the axial direction 1330 from the reference position, and the stability of colorimetry is improved.

Each mirror block 600 includes a plurality of plate-like members (5 in the illustrated example) 340 arranged in a line in the circumferential direction 1350. That is, the reflection mechanism 1191 includes a plurality of members 340 arranged in a line in the circumferential direction 1350 for each of the plurality of reflection regions 500. Each of the plurality of members 340 has a facing surface that faces the normal 1120. The plurality of reflecting surfaces 1340 are formed on opposing surfaces of at least a part (four in the illustrated example) of the plurality of members 340. Adjacent members of the plurality of members 340 are preferably coupled to each other such that the directions of the plurality of reflecting surfaces 1340 are fixed to each other. The plurality of members 340 are combined in this manner, so that the mirror block 600 is formed.

A non-reflective portion 1342 that does not reflect the light 1044 toward the illuminated surface 1050 is preferably disposed in a part of each of the three or more reflective regions 500. That is, three or more non-reflective portions 1342 are arranged in the reflection mechanism 1191. Each non-reflective portion 1342 is formed, for example, by applying black paint or flocking paper to a part of the reflective region 500. In addition, a non-reflective portion 1342 may be realized by providing a through hole or the like in a part of the reflective region 500. The three or more non-reflective portions 1342 are distributed in the circumferential direction 1350 so as to surround the normal 1120. The three or more non-reflective portions 1342 are preferably arranged at equal intervals in the circumferential direction 1350.

Each non-reflective portion 1342 preferably occupies a range in the reflective region 500 that is greater than or equal to the range occupied by one reflective surface in the reflective region 500 among the plurality of reflective surfaces 1340 of each reflective region 500.

The portion other than the non-reflective portion 1342 in the reflective region 500 is preferably provided to be larger than the non-reflective portion 1342.

The non-reflective portion 1342 includes a portion painted black as described above or a portion to which flocked paper is attached. In this case, for example, the reflectance of the non-reflective portion is preferably set to 10% or less, more preferably 5% or less. Even if a low reflection portion having a reflectance of about 10% to 30% is employed instead of the non-reflection portion 1342, the usefulness of the present invention is not impaired. Moreover, even if all the inner peripheral surfaces of the members 340 included in the reflection region 500 are the reflection surfaces 1340, the usefulness of the present invention is not impaired.

In the illustrated example, the non-reflective region 502 is preferably a region in the space between the adjacent mirror blocks 600. However, it is non-reflective due to the area where black coating or flocking paper is applied to the inner peripheral surface of the partially cylindrical plate so that the reflectance is 10% or less, more preferably 5% or less. Even if the region 502 is realized, the usefulness of the present invention is not impaired. Instead of the non-reflective region 502, a low-reflective region whose reflectivity for reflecting the light 1044 toward the illuminated surface 1050 is lower than that of the reflective region 500 may be employed. The reflectance of the low reflection region is, for example, 10% to 30%.

<7. Light-receiving mechanism for color measurement>
The colorimetric light receiving mechanism 1033 shown in FIGS. 2 to 4 includes a mirror 1360, a lens 1361, a spectroscopic measurement mechanism 1362, and a lens barrel 1363, as shown in FIG. The mirror 1360 and the lens 1361 are held by the inner wall of the lens barrel 1363, and the spectroscopic measurement mechanism 1362 is attached to the end of the lens barrel 1363. The mirror 1360 reflects the reflected light 1043. The lens 1361 converges the light beam of the reflected light 1043. The spectroscopic measurement mechanism 1362 outputs a signal corresponding to the light amount of each wavelength component of the reflected light 1043.

Mirror 1360 is on normal 1120. The reflecting surface 1380 of the mirror 1360 faces the middle direction between the direction toward the illuminated surface 1050 and the direction toward the spectroscopic measurement mechanism 1362. The lens 1361 is between the reflecting surface 1380 and the spectroscopic measurement mechanism 1362.

The reflected light 1043 travels along the optical axis 1112. The reflected light 1043 is generated when the illuminated surface 1050 reflects the illuminated light 1042, exits from the illuminated surface 1050 in the direction of the light receiving angle of 0 °, is reflected by the mirror 1360, passes through the lens 1361, and is measured spectroscopically. Light is received by mechanism 1362. The direction of the light receiving angle of 0 ° is a direction that forms 0 ° with the normal line 1120 of the illuminated surface 1050. The spectroscopic measurement mechanism 1362 outputs a signal corresponding to the light amount of each wavelength component of the reflected light 1043. A signal output from the spectroscopic measurement mechanism 1362 becomes a result of measurement with respect to the reflected light 1043. The reflected light 1043 is reflected by the mirror 1360 so that the optical axis 1112 is bent. When the reflected light 1043 passes through the lens 1361, the light flux of the reflected light 1043 is converged.

The reflected light 1043 travels from the illuminated surface 1050 to the reflecting surface 1380 along the optical axis 1112 in the direction of the light receiving angle of 0 °, and is reflected by the reflecting surface 1380. The reflected reflected light 1043 travels along the optical axis 1112 from the reflecting surface 1380 and reaches the spectroscopic measurement mechanism 1362 through the lens 1361.

Mirror 1360 may be replaced with another type of bending optical element. For example, the mirror 1360 may be replaced with a prism. A bending optical element other than the mirror 1360 may be added, and the optical axis 1112 may be further bent. The optical system including the mirror 1360 and the lens 1361 may be replaced with another type of optical system that bends the optical axis 1112 and converges the light beam of the reflected light 1043. For example, an optical system including the mirror 1360 and the lens 1361 may be replaced with an optical system including a mirror having a concave reflecting surface. When the spectrocolorimeter provided in the colorimeter 1000 is changed to a colorimeter, the spectroscopic measurement mechanism 1362 may be replaced with a mechanism that measures tristimulus values.

<8. Light receiving mechanism for correction>
The correction light receiving mechanism 1034 shown in FIGS. 2 and 4 includes a mirror 1390, an optical fiber 1391, and a spectroscopic measurement mechanism 1392 as shown in FIG. The spectroscopic measurement mechanism 1392 is shared with the spectroscopic measurement mechanism 1362.

The light 1045 travels along the optical axis 1113. Light 1045 exits from the exit port 1211 in a direction that forms 0 ° with the central axis 1230, is reflected by the mirror 1390, is guided to the optical fiber 1391, and is received by the spectroscopic measurement mechanism 1392. The spectroscopic measurement mechanism 1392 outputs a signal corresponding to the light amount of each wavelength component of the light 1045.

Mirror 1390 may be replaced with another type of bending optical element. For example, the mirror 1390 may be replaced with a prism. A bending optical element other than the mirror 1390 may be added. The optical fiber 1391 may be replaced with another type of light guide mechanism. For example, the optical fiber 1391 may be replaced with a bending optical element. The optical fiber 1391 may be omitted, and the light 1045 may travel straight from the reflection surface 1400 to the spectroscopic measurement mechanism 1392.

When measurement for correction is performed on the light 1045 emitted from the emission port 1211 in the direction of 0 ° with the central axis 1230, what is the emission port 1211 in order to obtain light for which measurement for correction is performed? It is not necessary to form another exit port in the integrating sphere 1201, and the efficiency of the light emitting mechanism 1190 is improved.

<9. Controller>
The controller 1011 illustrated in FIG. 1 includes an embedded computer, a control circuit, and the like, and causes the embedded computer to execute firmware. All or part of the processing by the embedded computer may be realized by hardware that does not execute the program.

The controller 1011 controls the measurement mechanism 1010. The controller 1011 controls lighting of the straight tube type xenon lamp 1200 and acquires the measurement result from the spectroscopic measurement mechanism 1362 and the spectroscopic measurement mechanism 1392. The controller 1011 obtains colorimetric information from the measurement result acquired from the spectroscopic measurement mechanism 1362. The controller 1011 performs correction to reflect the measurement result acquired from the spectroscopic measurement mechanism 1392 when obtaining colorimetric information. Thereby, the influence which the fluctuation | variation of the light which the light emission mechanism 1190 radiates has on colorimetric information is mitigated. The colorimetric information is a spectral spectrum, a color value, and the like.

<10. Reflected light reflected from illuminated surface with directionality in reflection characteristics>
FIG. 11 is a diagram showing the illumination light quantity with respect to the direction of the illuminated surface 1050 in a graph format. On the horizontal axis of the graph, the illumination direction of the illumination light 1042 with respect to the illuminated surface 1050 is shown. On the vertical axis, the amount of illumination light 1042 in each illumination direction is shown. The twelve peaks in the graph indicate the amount of light emitted from a total of twelve reflecting surfaces 1340 arranged in four in each of the three reflecting regions 500. In the case of the illumination light amount shown in this graph, the illuminated surface 1050 is irradiated from the reflection mechanism 1191 to the illuminated surface 1050 having the directionality due to the wrinkles or the like, even when the reflection property has the directionality. Thus, fluctuations in the amount of light reflected from the illuminated surface 1050 can be suppressed.

According to the illumination mechanism according to the present embodiment configured as described above, at least one reflection region 500 from the center 1300 of the portion included in the space 1210 of the integrating sphere 1201 in the discharge section 1260 of the xenon lamp 1200. Neither part is visible. Therefore, generation of light emitted from the discharge section 1260 and irradiated from the exit 1211 without being reflected by the diffuse reflection surface 1245 of the integrating sphere 1201 can be suppressed. Accordingly, the amount of light applied to each part of the reflection region 500 of the reflection mechanism 1191 can be made uniform. Further, since the xenon lamp 1200 is provided across the space 1210 of the integrating sphere 1201, the utilization efficiency of the light emitted by the xenon lamp 1200 can be improved.

Further, according to the illumination mechanism according to the present embodiment configured as described above, the three or more non-reflective regions 502 are arranged in the circumferential direction 1350 so as to surround the normal line 1120 of the illuminated surface 1050. Has been. Therefore, three or more reflective regions are also distributed in the circumferential direction 1350. On the other hand, the wrinkle pattern and the stripe pattern on the illuminated surface 1050 often have two-fold rotational symmetry. For this reason, there is a case in which illumination light is irradiated from all orientations with low reflectivity of the surface to be illuminated 1050, and the amount of reflected light is extremely reduced by not illuminating illumination light from all orientations with high reflectivity. It is suppressed. Further, it is possible to suppress the occurrence of a case in which the amount of reflected light is extremely increased by irradiating illumination light from all azimuths with low reflectivity and irradiating illumination light from all azimuths with high reflectivity. Therefore, it is possible to suppress a variation in the amount of light that is irradiated from the reflection mechanism 1191 to the illuminated surface 1050 having the directionality in the reflection characteristics and reflected from the illuminated surface 1050. That is, when the plurality of reflective regions 500 do not have the same number of rotational symmetries as the number of rotational symmetry such as the wrinkle pattern of the illuminated surface 1050, the direction and illumination with high reflectance of the illuminated surface 1050 The azimuth with the large incident light quantity of the light 1042 is suppressed to exactly match, and the azimuth with low reflectance and the azimuth with the small incident light quantity are also prevented from matching exactly. Thereby, the fluctuation | variation of the light quantity of the reflected light 1043 is suppressed.

Further, according to the illumination mechanism according to the present embodiment configured as described above, the tube axis 1310 crosses the normal line 1120 so that the center 1300 of the space 1210 is not positioned on the tube axis of the xenon lamp 1200. It is off. Therefore, it becomes easy to arrange the xenon lamp 1200 so that the non-reflective area 502 can be seen and the reflective area cannot be seen. Thereby, it is possible to suppress light emitted from the xenon lamp 1200 from being directly emitted from the emission port without being reflected by the diffuse reflection surface 1245 of the integrating sphere 1201.

In addition, according to the illumination mechanism according to the present embodiment configured as described above, since the baffle is further provided between the discharge section 1260 of the xenon lamp 1200 and the exit, the light emitted from the xenon lamp 1200 is Direct reflection from the diffuse reflection surface 1245 of the integrating sphere 1201 can be further suppressed.

Further, according to the illumination mechanism according to the present embodiment configured as described above, the radius of the space 1207 of the integrating sphere 1201 is smaller than the radius of the space 1208, and the emission port is open to the first inner surface. . The edge of the second inner surface that defines the space 1208 has a large variation in reflectance, but the edge can be made difficult to see from the reflection mechanism 1191 by the first inner surface. As a result, the amount of light reflected from the inner wall of the integrating sphere 1201 and emitted from the emission port toward the reflection mechanism 1191 can be made uniform.

Further, according to the illumination mechanism according to the present embodiment configured as described above, the radius of the space 1208 is 1.2 times or less than the radius of the space 1207, so that the size of the space 1207 and the space 1208 is the same. The difference can be suppressed. As a result, the amount of light reflected from the inner wall of the integrating sphere 1201 and emitted from the emission port 1211 toward the reflection mechanism 1191 can be made more uniform.

Further, according to the reflection characteristic measuring apparatus according to the present embodiment configured as described above, the amount of light reflected from the illuminated surface 1050 even when measuring the illuminated surface 1050 having directivity in the reflection characteristics. Therefore, stable measurement values can be obtained.

Although the present invention has been shown and described in detail, the above description is illustrative in all aspects and not limiting. Therefore, embodiments of the present invention can be modified or omitted as appropriate within the scope of the invention.

1000 Colorimeter 1010 Measuring mechanism (reflection characteristic measuring device)
1011 Controller 1032 Color measuring illumination mechanism (lighting device)
1033 Light-receiving mechanism for colorimetry (light-receiving mechanism)
1034 Light-receiving mechanism for correction 1340 Reflecting surface 1342 Non-reflecting portion 1050 Illuminated surface 1120 Normal 1190 Light emission mechanism (surface light source)
1191 Reflection mechanism 1200 Straight tube xenon lamp 1201 Integrating sphere 1202 Baffle 500 Reflection area (light reflection area)
502 Non-reflective area 600 Mirror block K1 Virtual cylindrical surface

Claims

Arranged on the normal line of the illuminated surface, has an inner surface that defines the space, the inner surface has a diffuse reflection surface, and is formed on the illuminated surface side with respect to the space to connect the space and the outside An integrating sphere having a round hole-shaped exit port, the space and the exit port having the normal as a common central axis;
A straight tube light source extending in the tube axis direction across the space and having a discharge section extending in the tube axis direction;
The light that is provided between the exit port and the surface to be illuminated so as to surround the normal line, is diffused and reflected by the diffuse reflection surface after being emitted from the discharge section, and is emitted from the exit port, A reflection mechanism that reflects toward the illuminated surface;
With
In the reflection mechanism, at least one light reflection region that reflects the light toward the illuminated surface is disposed,
The lighting device, wherein a center of a portion included in the space in the discharge section is deviated from a region where at least a part of the at least one light reflection region is visible through the emission port in the space.
The lighting device according to claim 1,
The at least one light reflecting region is three or more light reflecting regions;
In the reflection mechanism,
The light reflecting regions of the three or more light reflecting regions and the non-reflecting regions that do not reflect the light toward the illuminated surface are alternately arranged in the circumferential direction along a virtual cylindrical surface surrounding the normal line. By being arranged, three or more light reflecting areas and three or more non-reflecting areas are arranged,
The illuminating device, wherein the three or more non-reflective regions are distributed in the circumferential direction so as to surround the normal.
The lighting device according to claim 2,
The illuminating device, wherein the tube axis is shifted in a direction crossing the normal so that a center of the space is not located on a tube axis of the straight tube light source.
The lighting device according to any one of claims 1 to 3,
A lighting device further comprising a baffle between the discharge section and the exit.
A lighting device according to any one of claims 1 to 4,
The inner surface of the integrating sphere includes a first inner surface that defines a hemispherical first space, and a second inner surface that faces the first inner surface and defines a hemispherical second space;
A first radius of the first space is smaller than a second radius of the second space;
The said exit is an illuminating device opened to the said 1st inner surface.
The lighting device according to claim 5,
The lighting device, wherein the second radius is 1.2 times or less of the first radius.
The lighting device according to any one of claims 1 to 6,
A light receiving mechanism that receives reflected light generated by reflecting the light reflected by the reflecting mechanism and that outputs a measurement result of the reflected light; and
A reflection characteristic measuring apparatus comprising: