Optical measurement device

Abstract

Provided is an optical measurement device in which the accuracy of measurement in two adjacent measurement regions is improved.　Provided is an optical measurement device, wherein a first probe has a first prism, a first lens system, and a first-visual-field diaphragm, the second probe has a second prism, a second lens system, and a second-visual-field diaphragm, the first prism and the second prism each have an incident surface facing a measurement region, a first reflection surface, a second reflection surface, and an emission surface, the incidence surface and the emission surface are parallel, and the first reflection surface and the second reflection surface are parallel, the first lens system and the second lens system are the same, the optical axes of the first lens system and the second lens system are parallel, the distance between the centers of the measurement regions of the first probe and the second probe is less than the distance between the optical axis of the first lens system and the optical axis of the second lens system, and the open area of the first-visual-field diaphragm is larger than the open area of the second-visual-field diaphragm.

Description

Optical Measurement Device

[0001] The present disclosure relates to optical metrology devices.

[0002] In recent years, a technology called Under Screen Camera (USC) has been developed in the field of displays. USC is a technology that places a camera module behind the display, and devices that use USC make it difficult to see the camera through the display. In such devices, the portion of the display that overlaps with the camera (the USC portion) and the normal portion of the display that does not overlap with the camera (the normal portion) have different structures. For example, gamma adjustment of the display requires gamma adjustment for both the USC portion and the normal portion.

[0003] In order to shorten the takt time for gamma adjustment, it is necessary to simultaneously measure the luminance of the USC section and the normal section. Furthermore, from the viewpoint of reducing the influence of the light emission distribution within the display surface, it is preferable that the measurement area of ​​the USC section and the measurement area of ​​the normal section are close to each other. An optical measurement device (Patent Document 1) is known that measures the light from the USC section and the normal section that are close to each other.

[0004] International Publication No. 2020 / 030292

[0005] The area of ​​the USC section on the display is very narrow, and therefore the measurement area of ​​the USC section is also very narrow. On the other hand, the area of ​​the normal section on the display is wide, so the measurement area of ​​the normal section does not necessarily need to be as narrow as the measurement area of ​​the USC section. Furthermore, from the viewpoint of obtaining a sufficient amount of light for measurement and improving accuracy, it is preferable that the measurement area of ​​the normal section be somewhat wide. By changing the shape, size, position, etc. of each component, such as the lens, inside the probe that measures luminance, the measurement areas of the USC section and the normal section can be changed to their appropriate measurement areas.

[0006] On the other hand, in gamma adjustment, from the viewpoint of focusing on the difference in luminance between the USC section and the normal section of the display, it is preferable that the measurement conditions for the USC section and the normal section are the same. If the shape, size, position, etc. of each component is significantly changed between the probe measuring the USC section and the probe measuring the normal section, the measurement conditions for each probe will change. In other words, the results for the same measurement target will differ depending on the probe used. As a result, it is difficult to accurately measure the difference in luminance between the USC section and the normal section of the display.

[0007] An object of the present disclosure is to provide an optical measurement device with improved measurement accuracy in two adjacent measurement regions.

[0008] In order to solve the above problems, the optical measurement device of the present disclosure is an optical measurement device comprising a first probe that measures light from a first measurement region of a measurement object, and a second probe that measures light from a second measurement region of the measurement object, wherein the first probe has a first prism, a first lens system, and a first field stop, the second probe has a second prism, a second lens system, and a second field stop, the first prism and the second prism each have an incident surface facing the measurement region, a first reflecting surface, a second reflecting surface, and an exit surface, the incident surface and the exit surface are parallel, and the first reflecting surface and the second reflecting surface are parallel, the first lens system and the second lens system are identical, the optical axes of the first lens system and the second lens system are parallel, the distance between the centers of the measurement regions of the first probe and the second probe is shorter than the distance between the optical axis of the first lens system and the optical axis of the second lens system, The opening area of ​​the first field stop is larger than the opening area of ​​the second field stop.

[0009] The invention of claim 2 is the invention of claim 1, wherein the following formula (1) is satisfied: Formula (1) 0.2≦(d1-d2) / (w1-w2)≦2.0 The symbols in the formula have the following meanings: d1: distance between the center point of the first measurement area and the intersection point when a perpendicular line is drawn from the tip position of the first prism closest to the second measurement area to the surface of the object to be measured d2: distance between the center point of the second measurement area and the intersection point when a perpendicular line is drawn from the tip position of the second prism closest to the first measurement area to the surface of the object to be measured w1: width of the first measurement area w2: width of the second measurement area

[0010] A third aspect of the present invention is the first or second aspect of the present invention, wherein the first prism and the second prism have the same shape, size, and are made of the same glass material.

[0011] The invention described in claim 4 is the invention described in claim 2, wherein the following formula (2) is satisfied: 0.2≦{d23 / (w1-w2)}×(w2 / s2)≦2.0 Formula (2) The symbols in the formula have the following meanings: d23: distance between the center of the aperture of the second field stop and the optical axis of the second lens system s2: aperture width of the second field stop

[0012] The invention of claim 5 is the invention of claim 2, wherein the following formula (3) is satisfied. Formula (3) 0.2≦(d24−d14) / (w1−w2)≦2.0 The symbols in the formula have the following meanings. d14: The distance between the intersection of a perpendicular line drawn from the tip position of the first prism closest to the second measurement region to the surface to be measured of the object, and the intersection of a perpendicular line drawn from the intersection line of the entrance surface and the first reflecting surface of the first prism to the surface to be measured of the object. d24: The distance between the intersection of a perpendicular line drawn from the tip position of the second prism closest to the first measurement region to the surface to be measured of the object, and the intersection of a perpendicular line drawn from the intersection line of the entrance surface and the first reflecting surface of the second prism to the surface to be measured of the object.

[0013] The invention described in claim 6 is the invention described in claim 2, wherein the first lens system has a first front lens, and the second lens system has a second front lens, and the following formula (4) is satisfied: 0.001≦|d15−d25| / w1≦1.0 Formula (4) The symbols in the formula have the following meanings: d15: distance between the first field stop and the exit surface of the first front lens d25: distance between the second field stop and the exit surface of the second front lens

[0014] The invention as set forth in claim 7 is the invention as set forth in claim 2, wherein the following formula (5) is satisfied: Formula (5) 0.001≦|wd1−wd2| / w1≦1.0 The symbols in the formula have the following meanings: wd1: optical path length from the surface to be measured of the object to the entrance surface of the lens closest to the object in the first probe wd2: optical path length from the surface to be measured of the object to the entrance surface of the lens closest to the object in the second probe

[0015] The invention described in claim 8 is the invention described in claim 1 or claim 2, wherein the first probe has a first aperture stop, the second probe has a second aperture stop, the first lens system has a first front lens, the second lens system has a second front lens, the distance between the first aperture stop and the entrance surface of the first front lens is the same as the distance between the second aperture stop and the entrance surface of the second front lens, and the aperture area and shape of the first aperture stop are the same as the aperture area and shape of the second aperture stop.

[0016] According to the present disclosure, it is possible to improve the accuracy of measurements in two adjacent measurement regions.

[0017] 1 is a block diagram showing a schematic configuration of an optical measurement device. FIG. 1 is a block diagram showing a schematic configuration of an optical measurement device. FIG. 2 is a block diagram showing an example configuration of an optical unit and a photometry unit in a probe. FIG. 3 is a schematic diagram showing a configuration example (1) of a first optical unit and a second optical unit. FIG. 4 is a schematic diagram showing the positional relationship between a prism and a measurement region. FIG. 5 is a perspective view of a prism. FIG. 6 is an explanatory diagram of a state in which two parallelogram prisms are closely arranged. FIG. 7 is a perspective view of a chamfered prism. FIG. 8 is an explanatory diagram of a case in which a condenser lens is positioned between a measurement object and a prism. FIG. 9 is an explanatory diagram of the positional relationship of a lens system. FIG. 10 is an explanatory diagram of a measurement angle. FIG. 11 is an explanatory diagram of a measurement region controlled by an aperture stop and a field stop. FIG. 12 is a schematic diagram showing a configuration example (2) of a first optical unit and a second optical unit. FIG. 13 is a schematic diagram showing a configuration example (3) of a first optical unit and a second optical unit. FIG. 14 is a schematic diagram showing a configuration example (4) of a first optical unit and a second optical unit. FIG. 15 is a schematic diagram showing a configuration example (5) of a first optical unit and a second optical unit. FIG. 16 is a schematic diagram showing a configuration example (6) of a first optical unit and a second optical unit. FIG. 17 is a schematic diagram showing an example of a measurement object.

[0018] One or more embodiments of the present disclosure will be described below with reference to the drawings, however, the scope of the present disclosure is not limited to the disclosed embodiments.

[0019] [Configuration of Optical Measurement Device] Fig. 1 is a block diagram showing a schematic configuration of an optical measurement device 101 according to this embodiment. In Fig. 1, the object to be measured 1 is a light-emitting body that emits light, and may be, for example, a display, an electronic device equipped with a display, etc. A color luminance meter is an example of the optical measurement device 101, and can measure the color and luminance of the light-emitting body of the object to be measured 1.

[0020] The optical measurement device 101 includes a first probe 10A, a second probe 10B, and a control processing unit 50. Hereinafter, the probe having the larger width or area of ​​the measurement region will be referred to as the first probe 10A, and the probe having the smaller width or area will be referred to as the second probe 10B.

[0021] The first probe 10A includes a first optical unit 11A, a first photometer 12A, a first signal processor 13A, and a first calculator 14A. The first optical unit 11A receives light from a first measurement region of the object 1 and guides the light to the first photometer 12A. The first photometer 12A photoelectrically converts the light from the first measurement region of the object 1 and outputs an electrical signal (analog signal) having an intensity corresponding to the intensity of the light. The first signal processor 13A includes an amplifier (not shown) that amplifies the light from the first photometer 12A and an A / D converter (not shown) that converts the analog signal from the amplifier into a digital signal (measurement data). The first calculator 14A performs predetermined calculations using the digital signal (measurement data) output from the A / D converter. This allows calculation of tristimulus values ​​(X, Y, Z), xyY (chromaticity coordinates, luminance) established by the International Commission on Illumination (CIE), standard luminous efficiency established by the International Commission on Illumination (CIE), TΔuvY (correlated color temperature, color difference from the blackbody locus, luminance), etc.

[0022] The second probe 10B has the same functional configuration as the first probe 10A. Specifically, the second probe 10B has a second optical unit 11B, a second photometer 12B, a second signal processing unit 13B, and a second calculation unit 14B. The second optical unit 11B receives light from a second measurement region of the object to be measured 1 and guides the light to the second photometer 12B. As a result, the second photometer 12B receives light from the second measurement region of the object to be measured 1. The function of each block of the second probe 10B is the same as the function of the corresponding block of the first probe 10A, so the following description will not be repeated. Hereinafter, when there is no need to distinguish between probes A and B, the reference numerals A and B will be omitted.

[0023] The control processing unit 50 includes a control unit 51, a display unit 52, an operation unit 53, and a storage unit 54. The control processing unit 50 is realized by, for example, a personal computer. The control unit 51 controls the first probe 10A and the second probe 10B. The control unit 51 receives data from each of the first probe 10A and the second probe 10B and can perform processes such as displaying and managing the data. The display unit 52 displays the measurement data in the form of a graph, list, etc. under the control of the control unit 51. Various information related to the measurement (measurement instructions, display mode settings, measurement range, etc.) is input to the operation unit 53. The storage unit 54 stores various data including the measurement data.

[0024] The optical measurement device of this embodiment can also be applied to a colorimeter. Fig. 2 is a block diagram showing a schematic configuration of an optical measurement device 102 of this embodiment. The configuration of the optical measurement device 102 is basically the same as that of the optical measurement device 101, but differs from the configuration of the optical measurement device 101 in that it includes an illumination unit 40. The illumination unit 40 is a device that irradiates illumination light onto the measurement object 1 with, for example, a predetermined geometry. The geometry is not limited, but one example is 45°:0°.

[0025] Fig. 3 is a block diagram showing an example of the configuration of the optical unit 11 and the photometry unit 12 in the probe 10 according to this embodiment. Fig. 4 is a schematic diagram showing an example (1) of the configuration of the first optical unit 11A and the second optical unit 11B according to this embodiment. Fig. 5 is a schematic diagram showing the positional relationship between the prism 21 and the measurement region R. The first optical unit 11A and the second optical unit 11B have the same functional configuration.

[0026] As shown in Fig. 3, the first optical unit 11A has a first prism 21A, a first lens system 22A, and a first light guiding section 23A. Furthermore, as shown in Fig. 4, the first optical unit 11A has a field stop 46. Additionally, the first optical unit 11A may have an aperture stop 45 or an aperture stop 47. Because the aperture stop 47 has substantially the same function as the aperture stop 45 due to the conjugate positional relationship, the first optical unit 11A may have both aperture stops or only one of them.

[0027] 4, the first prism 21A deflects light from the first measurement region RA of the object 1 in the direction opposite to the second measurement region RB and guides it to the first lens system 22A. The second prism 21B deflects light from the second measurement region RB of the object 1 in the direction opposite to the first measurement region RA and guides it to the second lens system 22B. This makes it possible to make the distance between the center of the first measurement region RA and the center of the second measurement region RB, i.e., the measurement center distance D, shorter than the distance between the optical axis 43A of the first lens system 22A and the optical axis 43B of the second lens system 22B. As a result, it is possible to measure two adjacent regions.

[0028] As shown in Figure 5, points PA and QA are points on the boundary of the first measurement area RA, and in Figure 5, point PA is the upper end of the first measurement area RA, and point QA is the lower end of the first measurement area RA. The distance between points PA and QA, i.e., the width of the first measurement area RA, is defined as w1. Similarly, points PB and QB are points on the boundary of the second measurement area RB, and in Figure 5, point PB is the lower end of the second measurement area RB, and point QB is the upper end of the second measurement area RB. The distance between points PB and QB, i.e., the width of the second measurement area RB, is defined as w2.

[0029] Point SA is the center point of the first measurement area RA, i.e., the point midway between points PA and QA. Point TA is the intersection point when a perpendicular line is drawn from the tip position of the first prism 21A closest to the second measurement area RB to the measurement surface of the object to be measured 1. The distance between points SA and TA is defined as d1. Similarly, point SB is the center point of the second measurement area RB, i.e., the point midway between points PB and QB. Point TB is the intersection point when a perpendicular line is drawn from the tip position of the second prism 21B closest to the first measurement area RA to the measurement surface of the object to be measured 1. The distance between points SB and TB is defined as d2.

[0030] FIG. 6 is a perspective view of the prism 21 according to this embodiment. The prism 21 is a parallelogram prism having surfaces 31 to 36. Surface 31 is an incident surface onto which light from the measurement region R is incident and faces the measurement region R. Surface 32 is an exit surface, is parallel to surface 31, and faces the lens system 22. Surfaces 33 and 34 are parallel to each other. Surfaces 35 and 36 are reflective surfaces arranged parallel to each other and facing each other. Surface 35 is a first reflective surface that reflects light incident on surface 31 (incident surface), and surface 36 is a second reflective surface that reflects light reflected by surface 35 (first reflective surface) and directs it to surface 32 (exit surface). In this embodiment, two surfaces being "parallel" means that the two surfaces are approximately parallel, specifically, parallel within a range of ±5°. The distance between surfaces 31 and 32 corresponds to the "thickness" of the parallelogram prism.

[0031] The end of the parallelogram prism connecting the incident surface (surface 31) and the first reflecting surface (surface 35) may be chamfered. FIG. 7 is an explanatory diagram of two parallelogram prisms arranged close to each other. The shorter the distance between the first measurement area RA and the second measurement area RB of the object 1, the closer the first prism 21A and the second prism 21B need to be. As shown in FIG. 7, by chamfering the opposing ends 37 of the first prism 21A and the second prism 21B, the first prism 21A and the second prism 21B can be brought even closer to each other. As a result, the first measurement area RA and the second measurement area RB can be brought even closer to each other.

[0032] 8 is a perspective view of the chamfered prism 21. In the chamfered prism 21, an end portion, i.e., a portion (cut portion 42) including an intersection line 41 between the incident surface (surface 31) and the first reflecting surface (surface 35), is cut away, forming a cut surface 38 that is tangent to both the incident surface (surface 31) and the first reflecting surface (surface 35). The incident surface (surface 31) and the cut surface 38 are tangent to each other at a first ridge line 391. The first reflecting surface (surface 35) and the cut surface 38 are tangent to each other at a second ridge line 392.

[0033] When the first prism 21A is not chamfered, the tip position of the first prism 21A closest to the second measurement region RB refers to the intersection line 41. When the first prism 21A is chamfered, the tip position of the first prism 21A closest to the second measurement region RB refers to the first ridge line 391 or the second ridge line 392. The tip position of the second prism 21B is the same as that of the first prism 21A.

[0034] In the example shown in FIG. 4, the distance between points QB and TB is the tip clearance d3 of the second prism 21B. By shortening the tip clearance d3, the measurement center distance D can be shortened. Note that a similar tip clearance can be defined for the first prism 21A. In the example shown in FIG. 5, in the first prism 21A, a first ridge 391 (not shown) corresponds to the tip position closest to the second measurement region RB. In the second prism 21B, a second ridge 392 (not shown) corresponds to the tip position closest to the first measurement region RA.

[0035] The optical unit 11 may have a condensing lens 60 between the object to be measured 1 and the prism 21. FIG. 9 is an explanatory diagram of a case where the condensing lens 60 is located between the object to be measured 1 and the prism 21. By having the condensing lens 60, the angle of light incident on the prism 21 from the measurement region R can be reduced. As a result, the distance (thickness) between the entrance surface (surface 31) and the exit surface (surface 32) of the prism 21 can be shortened, and the prism 21 can be made smaller. Furthermore, when the shape and size of the prism 21 are the same, having the condensing lens 60 can increase the angle of light incident on the prism 21 from the measurement region R. As a result, a larger amount of light can be obtained, improving the accuracy of measurement.

[0036] The prism 21 according to this embodiment may be a parallelogram prism formed by using a plurality of triangular prisms, for example.

[0037] The first prism 21A and the second prism 21B according to this embodiment may be identical. Specifically, the shape, size, and material of the prisms may be identical. When the prisms are chamfered, the shape of the cut portion 42 may also be identical. By using the same first prism 21A and the same second prism 21B, the first probe 10A and the second probe 10B can have similar structures. As a result, the measurement conditions for the first probe 10A and the second probe 10B can be made almost identical, thereby improving the accuracy of the measurement.

[0038] (Lens System) The lens system 22 has a lens with positive power, and collects the light totally reflected by the prism 21 and guides it to the light guide section 23. This allows the measurement of optical characteristics such as chromaticity and luminance in two adjacent measurement areas on the object 1 while taking in a large amount of light and maintaining brightness.

[0039] Fig. 10 is an explanatory diagram of the positional relationship of the lens system 22. The lens system 22 may have only one lens, or may have a combination of multiple lenses. Fig. 10 shows an example in which the lens system 22 combines two lenses, a front lens 221 and a rear lens 222. The front lens 221 is a lens located between the field stop 46 and the prism 21, and the rear lens 222 is a lens located between the field stop 46 and the light guiding unit 23.

[0040] As shown in Figure 10, in the front lens 221, the distance between the center of the incident surface where light enters and the center of the exit surface where light exits is defined as the thickness LD1 of the front lens 221. In the rear lens 222, the distance between the center of the incident surface where light enters and the center of the exit surface where light exits is defined as the thickness LD2 of the rear lens 222. The distance between the center of the exit surface of the front lens 221 and the center of the entrance surface of the rear lens 222 is defined as the lens spacing LD3. The distance between the perpendicular line drawn from the tip position of the prism 21 to the measurement surface of the object to be measured 1 and the optical axis 43 of the lens system 22 is defined as d11 or d12. The optical path length between the measurement surface of the object to be measured 1 and the entrance surface of the front lens 221 is defined as the working distance wd1 (wd2). The working distance refers to the optical path length to the entrance surface of the lens closest to the object to be measured 1, and will be described in detail later.

[0041] In this embodiment, the first lens system 22A and the second lens system 22B are identical. This allows the first probe 10A and the second probe 10B to have similar structures. As a result, the measurement conditions for the first probe 10A and the second probe 10B can be made almost the same, thereby improving the accuracy of measurement.

[0042] Specifically, "being the same" means that the curvature, thickness, spacing, and glass material of the first lens system 22A and the second lens system 22B are the same. When the lens system 22 has a front lens 221 and a rear lens 222, the curvature, thickness LD1, and glass material of the first front lens 221A and the second front lens 221B are the same, and the curvature, thickness LD2, and glass material of the first rear lens 222A and the second rear lens 222B are the same. Furthermore, the lens spacing LD3 between the first front lens 221A and the first rear lens 222A is the same as the lens spacing LD3 between the second front lens 221B and the second rear lens 222B. When the lens system 22 has only the front lens 221, the lens spacing LD3 does not exist and need not be considered.

[0043] In this embodiment, the optical axes 43 of the first lens system 22A and the second lens system 22B are parallel to each other. When the lens system 22 has a front lens 221 and a rear lens 222, the front lens 221 and the rear lens 222 are positioned so that their optical axes coincide with each other.

[0044] When the lens system 22 has only one lens, it has only the front lens 221. The lens system 22 may have three or more lenses, and for example, a lens may be provided between the aperture stop 45 and the field stop 46. Furthermore, the front lens 221 may be made up of multiple lenses instead of a single lens, and the rear lens 222 may be made up of multiple lenses instead of a single lens.

[0045] (Field stop and aperture stop) The field stop 46 is located near a position conjugate with the measurement surface of the object 1 with respect to the entire lens located closer to the object 1 than the field stop 46. The shape and area of ​​the measurement region R can be controlled by the aperture shape and aperture area of ​​the field stop 46. In this embodiment, by making the aperture area of ​​the first field stop 46A larger than the aperture area of ​​the second field stop 46B, a larger amount of light can be obtained from the first measurement region RA, improving the signal-to-noise ratio and measurement accuracy.

[0046] The position of field stop 46 in the optical axis direction of lens system 22 can be expressed by the distance from front lens 221. For example, as shown in Fig. 10, the distance between the opening plane of field stop 46 and the exit surface of front lens 221 is set to d15 (d25).

[0047] The shape and size of the measurement region R are appropriately selected depending on the measurement purpose, conditions, etc. The shape of the measurement region R may be, for example, circular or rectangular. In accordance with the shape of the measurement region R, the opening shape of the field stop 46 may be circular or rectangular.

[0048] Aperture stop 45 is located near the focal point on the light guiding unit 23 side of the entire lens located closer to the object to be measured 1 than aperture stop 45. Aperture stop 47 is located at a position conjugate to aperture stop 45 with respect to the entire lens located between aperture stop 45 and aperture stop 47. Aperture stop 45 and aperture stop 47 can control the angle of light from measurement region R, i.e., the measurement angle. Aperture stop 45 will be described below, but aperture stop 47 has the same function.

[0049] FIG. 11 is an explanatory diagram of the measurement angle. The "measurement angle" refers to the maximum angle between the light to be measured from the light from the object 1, i.e., the measurement light 5, and the normal to the object 1. Generally, many light-emitting devices such as displays have orientation characteristics, i.e., differences in light emission intensity depending on the angle, so if the measurement angle conditions are different, a large discrepancy will occur in the measurement results. Therefore, if the measurement conditions for the first measurement area RA and the second measurement area RB are the same, it is preferable that the measurement angle conditions are also the same. By making the measurement angle conditions the same, stable measurements can be made regardless of the orientation characteristics of the light-emitting device, such as a display.

[0050] FIG. 12 is an explanatory diagram of the measurement region R controlled by the aperture stop 45 and the field stop 46. Points P and Q are points on the boundary of the measurement region R, and in FIG. 12, point P is the upper end of the measurement region R and point Q is the lower end of the measurement region R. Light LP1 is light from point P in the normal direction to the measurement region R. In FIG. 12, light LP1 passes through the lower end of the opening region of the field stop 46. Light LQ1 is light from point Q in the normal direction to the measurement region R. In FIG. 9, light LQ1 passes through the upper end of the opening region of the field stop 46. In other words, the measurement region R is controlled by the opening shape, opening area, and position of the field stop 46.

[0051] The width of the opening region of the field stop 46 (opening width) is expressed by the following formula (a), where w is the distance between points P and Q, i.e., the width of the measurement region R, and β is the magnification of the field stop 46 with respect to the object to be measured 1 with respect to the entire lens located between the object to be measured 1 and the field stop 46. Formula (a) Width of the opening region of the field stop = w × β

[0052] Light LQ2 is light from point Q that is directed in a direction that forms a certain angle with the normal direction of measurement region R. In FIG. 12 , light LQ2 passes through the lower end of the aperture region of aperture stop 45 and also passes through the upper end of the aperture region of field stop 46. Light LQ3 is light from point Q that is directed in a direction that forms a certain angle with the normal direction of measurement region R. In FIG. 12 , light LQ3 passes through the upper end of the aperture region of aperture stop 45 and also passes through the upper end of the aperture region of field stop 46. In other words, the measurement angle is controlled by the aperture shape, aperture area, and position of aperture stop 45.

[0053] It is preferable that the first aperture stop 45A and the second aperture stop 45B have the same aperture shape, aperture area, and position. Here, "the same position" means that the distance between the first aperture stop 45A and the entrance surface of the first front lens 221A is the same as the distance between the second aperture stop 45B and the entrance surface of the second front lens 221B. By having the same aperture shape, aperture area, and position, the measurement angle in the first measurement region RA and the measurement angle in the second measurement region RB can be made the same.

[0054] It is preferable that the prism 21, the lens system 22, the field stop 46, and the measurement region R satisfy the relationships of the following formulas (1) to (7).

[0055] Equation (1) 0.2≦(d1−d2) / (w1−w2)≦2.0 The symbols in the equation have the following meanings: d1: the distance between the center point of the first measurement area RA and the intersection point of a perpendicular line drawn from the tip position of the first prism 21A closest to the second measurement area RB to the surface to be measured of the object 1; d2: the distance between the center point of the second measurement area RB and the intersection point of a perpendicular line drawn from the tip position of the second prism 21B closest to the first measurement area RA to the surface to be measured of the object 1; w1: the width of the first measurement area RA; w2: the width of the second measurement area RB

[0056] Fig. 13 is a schematic diagram showing a configuration example (2) of the first optical unit and the second optical unit. Compared to the configuration example (1) shown in Fig. 4, in the configuration example (2) shown in Fig. 13, the position of the second prism 21B is moved to the opposite side from the first prism 21A.

[0057] By adjusting the position of the prism 21, the relationship of formula (1) can be satisfied. From the viewpoint of narrowing the distance between points SA and SB, i.e., the measurement center distance D, it is preferable that the value expressed by (|d1-d2|) / (w1-w2) be 0.2 or more. From the viewpoint of preventing the measured light from going beyond the second prism 21B and obtaining a sufficient amount of measurement light without making the size of the first prism 21A too large, it is preferable that the value expressed by (|d1-d2|) / (w1-w2) be 2.0 or less.

[0058] In the example shown in Fig. 13, the cut portions 42A and 42B of the first prism 21A and the second prism 21B have the same shape and size.

[0059] d1 and d2 are respectively expressed by the following formulas (1-1) and (1-2): Formula (1-1) d1 = (w1 / 2) + clearance at the tip of the first prism 21A Formula (1-2) d2 = (w2 / 2) + clearance at the tip of the second prism 21B d3 Therefore, (d1 - d2) / (w1 - w2) can also be expressed as 0.5 + {(clearance at the tip of the first prism 21A - clearance at the tip of the second prism 21B) / (w1 - w2)}.

[0060] When the clearance d3 at the tip of the first prism 21A and the clearance d3 at the tip of the second prism 21B are the same, the value expressed by (d1-d2) / (w1-w2) is 0.5. When the clearance d3 at the tip of the second prism 21B is greater than the clearance d3 at the tip of the first prism 21A, the value expressed by (d1-d2) / (w1-w2) is less than 0.5. Conversely, when the clearance d3 at the tip of the second prism 21B is smaller than the clearance d3 at the tip of the first prism 21A, the value expressed by (d1-d2) / (w1-w2) is greater than 0.5.

[0061] It is preferable that the values ​​represented by d1 and d2 are not too small, i.e., the margin at the tip of the prism 21 is not too small. This prevents the light to be measured 5 from the object to be measured 1 from going beyond the prism 21, and a sufficient amount of light can be obtained for measurement. It is also preferable that the values ​​represented by d1 and d2 are not too large, i.e., the margin at the tip of the prism 21 is not too large. This ensures that the position of the first reflecting surface (surface 35) that reflects the light to be measured 5 from the object to be measured 1 is not too far from the measurement region R, and the prism 21 can be made appropriately small. As a result, the device can be made more compact.

[0062] Here, for example, the following settings are used: Width w1 of the first measurement region RA: 6 mm Width w2 of the second measurement region RB: 5 mm Minimum clearance at the tip of the prism: 2.5 mm In this case, from the above viewpoint, it is preferable that the clearance at the tip of the first prism 21A is within the range of 2.5 to 4.0 mm. It is preferable that the clearance at the tip of the second prism 21B is within the range of 2.5 to 2.8 mm. Furthermore, in this case, the value expressed by (d1-d2) / (w1-w2) can be within the range of 0.2 to 2.0. By having the value expressed by (d1-d2) / (w1-w2) within the range of 0.2 to 2.0, the measurement accuracy can be improved and the device can be made more compact. From the same viewpoint, it is more preferable that the value expressed by (d1-d2) / (w1-w2) is within the range of 0.25 to 1.0.

[0063] Equation (2) 0.2≦{d23 / (w1−w2)}×(w2 / s2)≦2.0 The symbols in the equation have the following meanings: d23: distance between the center of the aperture of second field stop 46B and the optical axis of second lens system 22B s2: aperture width of second field stop 46B

[0064] Figure 14 is a schematic diagram showing a configuration example (3) of the first optical unit and the second optical unit. Compared to the configuration example (1) shown in Figure 4, in the configuration example (3) shown in Figure 14, the position of the second field stop 46B is moved to the opposite side from the first probe 10A. In Figure 14, light passing through the upper end of the second field stop 46B overlaps with the optical axis 43B of the second lens system 22B. The distance between the center of the aperture of the second field stop 46B and the optical axis 43B is d23, and the distance between the upper and lower ends of the opening of the second field stop 46B is the aperture width s2.

[0065] By adjusting the position of second field stop 46B, the relationship of formula (2) can be satisfied. From the viewpoint of narrowing the distance between points SA and SB, i.e., the measurement center distance D, it is preferable that the value expressed by {d23 / (w1-w2)} x (w2 / s2) be 0.2 or more. From the viewpoint of preventing the light to be measured from going beyond second prism 21B and obtaining a sufficient amount of measurement light without making first prism 21A too large, it is preferable that the value expressed by {d23 / (w1-w2)} x (w2 / s2) be 2.0 or less.

[0066] From the above formula (a), the magnification β can be expressed as s2 / w2. When the center of the aperture of second field stop 46B moves away from first optical unit 11A by the value represented by d23 from the optical axis of second lens system 22B, the position of second measurement region RB moves toward first measurement region RA. This allows the clearance d3 at the tip of second prism 21B to be reduced by (d23 / β) = {d23 × (w2 / s2)}, thereby reducing the value represented by d2.

[0067] Equation (3) 0.2≦(d24−d14) / (w1−w2)≦2.0 The symbols in the equation have the following meanings. d14: The distance between the intersection of a perpendicular line drawn from the tip position of the first prism 21A closest to the second measurement region RB to the surface to be measured of the object 1, and the intersection of a perpendicular line drawn from an intersection line 41A between the incident surface (surface 31A) and the first reflecting surface (surface 35A) of the first prism 21A to the surface to be measured of the object 1. d24: The distance between the intersection of a perpendicular line drawn from the tip position of the second prism 21B closest to the first measurement region RA to the surface to be measured of the object 1, and the intersection of a perpendicular line drawn from an intersection line 41B between the incident surface (surface 31B) and the first reflecting surface (surface 35B) of the second prism 21B to the surface to be measured of the object 1.

[0068] In this case, the second prism 21B is chamfered by cutting out a portion including the intersection line 41B. The first prism 21A may or may not have a portion including the intersection line 41A cut out, i.e., may or may not be chamfered. If the first prism 21A is not chamfered, the tip position and the intersection line 41A coincide, so d14 = 0.

[0069] Fig. 15 is a schematic diagram showing a configuration example (4) of the first optical unit and the second optical unit. Compared to the configuration example (1) shown in Fig. 4, in the configuration example (4) shown in Fig. 15, a larger amount of the second prism 21B is cut away, and the second cut portion 42B is larger than the first cut portion 42A. In Fig. 15, the intersection line 41A of the first prism 21A and the intersection line 41B of the second prism 21B overlap. In the first prism 21A, the distance between the intersection point when a perpendicular line is drawn from the second ridge line 392A (not shown) to the measurement surface of the object 1 and the intersection point when a perpendicular line is drawn from the intersection line 41A to the measurement surface of the object 1 is defined as d14. In the second prism 21B, the distance between the intersection point when a perpendicular line is drawn from the second ridge 392B (not shown) to the measurement surface of the object 1 and the intersection point when a perpendicular line is drawn from the intersection line 41B to the measurement surface of the object 1 is d24.

[0070] The relationship of formula (3) can be satisfied by adjusting the amount of cutting away of prism 21. From the viewpoint of narrowing the distance between points SA and SB, i.e., the measurement center distance D, it is preferable that the value expressed by (d24-d14) / (w1-w2) be 0.2 or more. From the viewpoint of preventing the measured light from going beyond second prism 21B and obtaining a sufficient amount of measurement light without making first prism 21A too large, it is preferable that the value expressed by (d24-d14) / (w1-w2) be 2.0 or less.

[0071] Equation (4) 0.001≦|d15−d25| / w1≦1.0 The symbols in the equation have the following meanings: d15: distance between first field stop 46A and the exit surface of first front lens 221A d25: distance between second field stop 46B and the exit surface of second front lens 221B Note that d15 and d25 are shown in Figures 10 and 13.

[0072] The first field stop 46A and the second field stop 46B have different aperture areas. Therefore, the imaging performance and aberrations differ between the aperture boundary of the first field stop 46A and the aperture boundary of the second field stop 46B. By changing the positions of the first field stop 46A and the second field stop 46B, aberrations can be effectively corrected. The value represented by |d15-d25| / w1 is not particularly limited and can be any value. However, from the viewpoint of sufficient aberration correction and device miniaturization, the value represented by |d15-d25| / w1 is preferably 0.001 or greater. From the viewpoint of reducing overcorrection, the value represented by |d15-d25| / w1 is preferably 1.0 or less.

[0073] Equation (5) 0.001≦|wd1−wd2| / w1≦1.0 The symbols in the equation have the following meanings: wd1: optical path length from the measurement surface of the object 1 to the entrance surface of the lens closest to the object 1 in the first probe 10A wd2: optical path length from the measurement surface of the object 1 to the entrance surface of the lens closest to the object 1 in the second probe 10B

[0074] As shown in Figure 10, when only the prism 21 is located between the object to be measured 1 and the front lens 221, the lens closest to the object to be measured 1 is the front lens 221. Therefore, the working distances wd1 and wd2 are the optical path lengths from the surface to be measured of the object to be measured 1 to the incident surface of the front lens 221. The optical path length of the prism 21 is calculated as the air-equivalent optical path length. The air-equivalent optical path length is calculated using the following formula (b). Formula (b) Air-equivalent optical path length = Physical optical path length ÷ Refractive index of the prism 21

[0075] 9 , when the condenser lens 60 is located between the object to be measured 1 and the prism 21, the lens closest to the object to be measured 1 is the condenser lens 60. Therefore, the working distances wd1 and wd2 are the optical path lengths from the measurement surface of the object to be measured 1 to the incident surface of the condenser lens 60.

[0076] The value expressed by |wd1-wd2| / w1 is not particularly limited and can be any value. However, from the viewpoint of sufficient aberration correction and miniaturization of the device, the value expressed by |wd1-wd2| / w1 is preferably 0.001 or more. From the viewpoint of reducing overcorrection, the value expressed by |wd1-wd2| / w1 is preferably 1.0 or less.

[0077] Equation (6) 1.4≦s12 / s22≦5000 The symbols in the equation have the following meanings: s12: opening area of ​​the first field stop 46A; s22: opening area of ​​the second field stop 46B.

[0078] From the viewpoint of obtaining a sufficient amount of light in the first probe 10A and achieving a high S / N ratio, the value expressed by s12 / s22 is preferably 1.4 or more. From the viewpoint of reducing the error sensitivity without making the aperture area of ​​the second field stop 46B too small, the value expressed by s12 / s22 is preferably 5000 or less.

[0079] Here, for example, the following settings are made: Width w1 of the first measurement region RA: 6 mm Width w2 of the second measurement region RB: 5 mm The value expressed by s12 / s22 is (w1) ２ / (w2) ２ In this case, s12 / s22 is 1.44.

[0080] Equation (7) 0.2≦(d11−d12) / (w1−w2)≦2.0 The symbols in the equation have the following meanings: d11: the distance between the optical axis of the first lens system 22A and a perpendicular line drawn from the tip position of the first prism 21A closest to the second measurement region RB to the surface to be measured of the object 1; d12: the distance between the optical axis of the second lens system 22B and a perpendicular line drawn from the tip position of the second prism 21B closest to the first measurement region RA to the surface to be measured of the object 1.

[0081] Fig. 13 is a schematic diagram showing a configuration example (2) of the first optical unit and the second optical unit. Compared to the configuration example (1) shown in Fig. 4, in the configuration example (2) shown in Fig. 13, the position of the second prism 21B is moved to the opposite side of the first prism 21A, i.e., in the direction of the arrow in Fig. 13.

[0082] By adjusting the position of the prism 21, the relationship of formula (7) can be satisfied. From the viewpoint of narrowing the distance between points SA and SB, i.e., the measurement center distance D, it is preferable that the value expressed by (d11-d12) / (w1-w2) be 0.2 or more. From the viewpoint of preventing the measured light from going beyond the second prism 21B and obtaining a sufficient amount of measurement light without making the size of the first prism 21A too large, it is preferable that the value expressed by (d11-d12) / (w1-w2) be 2.0 or less.

[0083] The lens system 22 may be composed of only one lens (front lens 221). Fig. 16 is a schematic diagram showing a configuration example (5) of the first optical unit 11A and the second optical unit 11B. Compared to the configuration example (1) shown in Fig. 4, in the configuration example (5) shown in Fig. 16, the lens system 22 is composed of only one lens. In addition, the position of the second prism 21B is moved to the opposite side of the first prism 21A, i.e., in the direction of the arrow in Fig. 16.

[0084] By adjusting the position of the prism 21, it is possible to narrow the measurement center distance D. Furthermore, other than the position of the prism 21, the first probe 10A and the second probe 10B can have the same structure, which reduces measurement errors caused by the two probes.

[0085] The shapes of the first prism 21A and the second prism 21B may be different. Fig. 17 is a schematic diagram showing a configuration example (6) of the first optical unit 11A and the second optical unit 11B. Compared to the configuration example (1) shown in Fig. 4, in the configuration example (6) shown in Fig. 17, the width of the second prism 21B, i.e., the distance between the first reflecting surface (surface 35) and the second reflecting surface (surface 36), is narrower.

[0086] By varying the shape of the prism 21, it is possible to narrow the measurement center distance D. Furthermore, other than the shape of the prism 21, the first probe 10A and the second probe 10B can have the same structure, which reduces measurement errors caused by the two probes.

[0087] (Light Guide Section) The light guide section 23 guides the light beam transmitted through the lens system 22 to the photometry section 12. The light guide section 23 may mix the light beam transmitted through the lens system 22 or may split it into three light beams. For example, a fiber bundle, a light pipe, a diffusion plate, etc. can be used as the mixing member of the light guide section 23. For example, a fiber bundle, a lens, a diffraction grating, etc. can be used as the light beam splitting member of the light guide section 23.

[0088] The light guide section 23 can function as an aperture stop 47 by controlling the range in which the light beam transmitted through the lens system 22 can be received at the opening.

[0089] (Photometric Unit) The photometric unit 12 includes filters 24A-1, 24A-2, and 24A-3 and sensors 25A-1, 25A-2, and 25A-3. The filters 24A-1, 24A-2, and 24A-3 are color filters that transmit light emitted from the light guide unit 23 with predetermined transmittance characteristics. Specifically, the filters 24A-1, 24A-2, and 24A-3 are filters, such as interference film filters, that have spectral transmittance characteristics corresponding to the color matching functions X, Y, and Z defined by the International Commission on Illumination (CIE). The sensors 25A-1, 25A-2, and 25A-3 receive light that has passed through the filters 24A-1, 24A-2, and 24A-3, respectively, and output electrical signals corresponding to the intensity of the received light. The signals from the sensors 25A-1, 25A-2, and 25A-3 are input to the signal processing unit 13.

[0090] In another embodiment, the photometry unit 12 may include a filter corresponding to the standard luminosity defined by the International Commission on Illumination (CIE) and a sensor that receives light transmitted through the filter. The photometry unit 12 may also include a spectroscopic unit having a diffraction grating and a line sensor.

[0091] 18 is a schematic diagram showing an example of an object to be measured 1. The object to be measured 1 is, for example, a smartphone, and has a display 2 that employs USC. A camera (not shown) is placed behind the display 2. As described above, when performing gamma adjustment of the display 2, for example, luminance and the like are measured in the USC section 3 and the normal section 4. The USC section 3 corresponds to the second measurement area RB, and the normal section 4 corresponds to the first measurement area RA.

[0092] In a display 2 that employs a USC, the first measurement area RA and the second measurement area RB are close to each other. The distance between the centers of the first measurement area RA and the second measurement area RB, i.e., the measurement center distance D, is, for example, 10 mm.

[0093] 18, the shape of the measurement region R is circular, but the shape of the measurement region R is not limited to this and may be rectangular. The width w1 of the first measurement region RA is, for example, 6 mm. The width w2 of the second measurement region RB is, for example, 5 mm.

[0094] In this embodiment, the optical measurement device 101 includes a first probe 10A that measures light from a first measurement region RA of the object to be measured 1, and a second probe 10B that measures light from a second measurement region RB of the object to be measured 1. The first probe 10A has a first prism 21A, a first lens system 22A, and a first field stop 46A. The second probe 10B has a second prism 21B, a second lens system 22B, and a second field stop 46B. The first prism 21A and the second prism 21B each have an incident surface (surface 31) facing the measurement region R, a first reflecting surface (surface 35), a second reflecting surface (surface 36), and an exit surface (surface 32). The incident surface (surface 31) and the exit surface (surface 32) are parallel to each other, and the first reflecting surface (surface 35) and the second reflecting surface (surface 36) are parallel to each other. The first lens system 22A and the second lens system 22B are identical. The optical axes of the first lens system 22A and the second lens system 22B are parallel. The distance between the centers of the measurement regions R of the first probe 10A and the second probe 10B (measurement center distance D) is shorter than the distance between the optical axes of the first lens system 22A and the second lens system 22B. The aperture area of ​​the first field stop 46A is larger than the aperture area of ​​the second field stop 46B. This improves the accuracy of measurements in the adjacent first measurement region RA and second measurement region RB.

[0095] In this embodiment, the following formula (1) is satisfied. This makes it possible to narrow the measurement center distance D. Furthermore, a sufficient amount of measurement light can be obtained without the measurement light going beyond the second prism 21B and without making the size of the first prism 21A too large. Formula (1) 0.2≦(d1−d2) / (w1−w2)≦2.0 The symbols in the formula have the following meanings. d1: Distance between the center point of the first measurement region RA and the intersection point when a perpendicular line is drawn from the tip position of the first prism 21A closest to the second measurement region RB to the measurement surface of the object 1. d2: Distance between the center point of the second measurement region RB and the intersection point when a perpendicular line is drawn from the tip position of the second prism 21B closest to the first measurement region RA to the measurement surface of the object 1. w1: Width of the first measurement region RA w2: Width of the second measurement region RB

[0096] In this embodiment, the first prism 21A and the second prism 21B have the same shape, size, and glass material, which makes it easier to make the measurement conditions for the first measurement area RA and the second measurement area RB the same, thereby improving the accuracy of the measurement.

[0097] In this embodiment, the following formula (2) is satisfied. This allows the measurement center distance D to be narrowed. Furthermore, a sufficient amount of measurement light can be obtained without the measured light going beyond the second prism 21B and without making the size of the first prism 21A too large. Formula (2) 0.2≦{d23 / (w1-w2)}×(w2 / s2)≦2.0 The symbols in the formula have the following meanings: d23: distance between the center of the aperture of the second field stop 46B and the optical axis 43B of the second lens system 22B s2: aperture width of the second field stop 46B

[0098] In this embodiment, the following formula (3) is satisfied. This makes it possible to narrow the measurement center distance D. Furthermore, the light to be measured does not extend beyond the second prism 21B, and a sufficient amount of measurement light can be obtained without making the size of the first prism 21A too large. Formula (3) 0.2≦(d24−d14) / (w1−w2)≦2.0 The symbols in the formula have the following meanings. d14: The distance between the intersection point when a perpendicular line is drawn from the tip position of the first prism 21A closest to the second measurement region RB to the surface to be measured of the object 1, and the intersection point when a perpendicular line is drawn from the intersection line 41 of the incident surface (surface 31) and the first reflecting surface (surface 35) of the first prism 21A to the surface to be measured of the object 1. d24: The distance between the intersection point when a perpendicular line is drawn from the tip position of the second prism 21B closest to the first measurement region RA to the surface to be measured of the object 1, and the intersection point when a perpendicular line is drawn from the intersection line 41 of the incident surface (surface 31) and the first reflecting surface (surface 35) of the second prism 21B to the surface to be measured of the object 1.

[0099] In this embodiment, the first lens system 22A has a first front lens 221A, and the second lens system 22B has a second front lens 221B, and the following formula (4) is satisfied. This allows for sufficient aberration correction and downsizing of the device. Also, overcorrection can be reduced. Formula (4) 0.001≦|d15−d25| / w1≦1.0 The symbols in the formula have the following meanings. d15: distance between the first field stop 46A and the exit surface of the first front lens 221A d25: distance between the second field stop 46B and the exit surface of the second front lens 221B

[0100] In this embodiment, the following formula (5) is satisfied. This allows for sufficient aberration correction and downsizing of the device. Also, overcorrection can be reduced. Formula (5) 0.001≦|wd1−wd2| / w1≦1.0 The symbols in the formula have the following meanings. wd1: Optical path length from the surface to be measured of the object 1 to the entrance surface of the lens closest to the object 1 in the first probe 10A. wd2: Optical path length from the surface to be measured of the object 1 to the entrance surface of the lens closest to the object 1 in the second probe 10B.

[0101] In this embodiment, the first probe 10A has a first aperture stop 45A or 47A, and the second probe 10B has a second aperture stop 45B or 47B. The first lens system 22A has a first front lens 221A, and the second lens system 22B has a second front lens 221B. The distance between the first aperture stop 45A or 47A and the entrance surface of the first front lens 221A is the same as the distance between the second aperture stop 45B or 47B and the entrance surface of the second front lens 221B. The aperture area and shape of the first aperture stop 45A or 47A are the same as those of the second aperture stop 45B or 47B. This allows the measurement angle of the first measurement region RA and the measurement angle of the second measurement region RB to be the same, improving measurement accuracy.

[0102] In addition, the detailed configuration and detailed operation of each device constituting the optical measurement device can be modified as appropriate within the scope that does not deviate from the spirit of the present disclosure.

[0103] The present disclosure makes it possible to provide an optical measurement device with improved measurement accuracy in two adjacent measurement regions, and by using this optical measurement device, it is possible to accurately measure, for example, the USC portion and normal portion of a display.

[0104] REFERENCE SIGNS LIST 1 Object to be measured 2 Display 3 USC section 4 Normal section 5 Light to be measured 10 Probe 11 Optical unit 12 Photometric section 13 Signal processing section 14 Calculation section 21 Prism 22 Lens system 221 Front lens 222 Rear lens 23 Light guide section 24 Filter 25 Sensor 31 Incident surface 32 Exit surface 35 First reflecting surface 36 Second reflecting surface 37 End section 38 Cutting surface 391 First ridge line 392 Second ridge line 40 Illumination section 41 Intersection line 42 Cutting section 43 Optical axis 45 Aperture stop 46 Field stop 47 Aperture stop 50 Control processing section 51 Control section 52 Display section 53 Operation section 54 Memory section 60 Condenser lens 101 Optical measurement device 102 Optical measurement device R Measurement area wd Working distance

Claims

1. An optical measurement device comprising a first probe that measures light from a first measurement area of ​​a measurement object, and a second probe that measures light from a second measurement area of ​​the measurement object, wherein the first probe has a first prism, a first lens system, and a first field stop, the second probe has a second prism, a second lens system, and a second field stop, the first prism and the second prism each have an incident surface facing the measurement area, a first reflecting surface, a second reflecting surface, and an exit surface, the incident surface and the exit surface are parallel, and the first reflecting surface and the second reflecting surface are parallel, the first lens system and the second lens system are identical, the optical axes of the first lens system and the second lens system are parallel, the distance between the centers of the measurement areas of the first probe and the second probe is shorter than the distance between the optical axis of the first lens system and the optical axis of the second lens system, An optical measurement device, wherein the opening area of ​​the first field stop is larger than the opening area of ​​the second field stop.

2. The optical measurement device according to claim 1, which satisfies the following formula (1): Formula (1) 0.2≦(d1-d2) / (w1-w2)≦2.0 The symbols in the formula have the following meanings: d1: distance between the center point of the first measurement area and the intersection point when a perpendicular line is drawn from the tip position of the first prism closest to the second measurement area to the surface of the object to be measured d2: distance between the center point of the second measurement area and the intersection point when a perpendicular line is drawn from the tip position of the second prism closest to the first measurement area to the surface of the object to be measured w1: width of the first measurement area w2: width of the second measurement area 3. An optical measurement device according to claim 1 or claim 2, wherein the first prism and the second prism are identical in shape, size and made of the same glass material.

4. The optical measurement device according to claim 2, which satisfies the following formula (2): 0.2≦{d23 / (w1-w2)}×(w2 / s2)≦2.0 Formula (2) The symbols in the formula have the following meanings: d23: distance between the center of the aperture of the second field stop and the optical axis of the second lens system s2: aperture width of the second field stop 5. The optical measurement device according to claim 2, which satisfies the following formula (3): Formula (3) 0.2≦(d24−d14) / (w1−w2)≦2.0 The symbols in the formula have the following meanings. d14: The distance between the point of intersection when a perpendicular line is drawn from the tip position of the first prism closest to the second measurement region to the surface to be measured of the object to be measured, and the point of intersection when a perpendicular line is drawn from the intersection line of the entrance surface and the first reflecting surface of the first prism to the surface to be measured of the object to be measured. d24: The distance between the point of intersection when a perpendicular line is drawn from the tip position of the second prism closest to the first measurement region to the surface to be measured of the object to be measured, and the point of intersection when a perpendicular line is drawn from the intersection line of the entrance surface and the first reflecting surface of the second prism to the surface to be measured of the object to be measured.

6. The optical measurement device according to claim 2, wherein the first lens system has a first front lens, and the second lens system has a second front lens, and the following formula (4) is satisfied: Formula (4) 0.001≦|d15-d25| / w1≦1.0 The symbols in the formula have the following meanings: d15: distance between the first field stop and the exit surface of the first front lens d25: distance between the second field stop and the exit surface of the second front lens 7. The optical measurement device according to claim 2, which satisfies the following formula (5): Formula (5) 0.001≦|wd1−wd2| / w1≦1.0 The symbols in the formula have the following meanings: wd1: optical path length from the surface to be measured of the object to the entrance surface of the lens closest to the object in the first probe wd2: optical path length from the surface to be measured of the object to the entrance surface of the lens closest to the object in the second probe 8. An optical measurement device according to claim 1 or claim 2, wherein the first probe has a first aperture stop, the second probe has a second aperture stop, the first lens system has a first front lens, the second lens system has a second front lens, the distance between the first aperture stop and the entrance surface of the first front lens is the same as the distance between the second aperture stop and the entrance surface of the second front lens, and the aperture area and shape of the first aperture stop are the same as the aperture area and shape of the second aperture stop.

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