JP2006145374A - Reflection characteristics measuring apparatus and multi-angle colorimeter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To monitor light that is as approximate as possible to the illumination light that is actually illuminating a sample surface, by constituting a reference system without using optical fibers or the like. <P>SOLUTION: A measurement area 1a and a reference area 3a are arranged in the vicinity of each other, and an illumination light is collectively irradiated to them. Sample luminous flux 1c and reference luminous flux 3c, reflected light from the measurement area 1a and the reference area 3a, are each converged to a slit 35a for samples and a slit 35b for reference arranged in parallel with each other via an objective lens 31 and made incident onto an image forming lens 36 and a diffraction grating 37 (dispersing element). Since a field lens 34 (intermediate lens) is arranged, at this time, all the sample luminous flux 1c and the reference luminous flux 3c are made incident to the image forming lens 36 and the diffraction grating 37 to contribute to the formation of dispersed images of an array 38a for samples and an array 38b for reference. It is thus possible to measure the spectral characteristics of the sample luminous flux 1c and the reference luminous flux 3c by using a common light-receiving system. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a reflection characteristic measuring apparatus for measuring a reflected light characteristic from a sample surface, and a special effect coating such as a metallic coating or a pearl color coating that exhibits different colors depending on the illumination or observation direction. The present invention relates to a multi-angle colorimeter that measures in an observation direction.

  Metallic paint and pearl color paint used for automobile painting and the like include a flake-like aluminum piece or mica piece called a glitter material in the paint film, and exhibits a so-called metallic effect or pearl effect. This is because the contribution of the glitter material to the reflection characteristics varies depending on the illumination and observation direction. For evaluation (color measurement) of such metallic coating and pearl color coating, illumination from multiple directions and reception from one direction (multidirectional illumination, one-way light reception), or illumination from one direction and from multiple directions A multi-angle colorimeter having a multi-angle geometry (optical arrangement) that receives light (one-way illumination multi-directional light reception) is used (for example, Patent Document 1).

  FIG. 13 is a schematic diagram showing an optical system S0 of a multi-angle colorimeter of the multi-directional illumination type unidirectional light receiving type according to the prior art. The optical system S0 includes light sources 220 to 260 (five illumination systems) arranged in five directions and a light receiving system 300 (one light receiving system) arranged in one direction. Each of the two light receiving systems is constituted by a transmission optical system. As shown in parentheses in the figure, the light receiving direction by the light receiving system 300 is 45 degrees from the normal of the sample surface 1 (normal angle), and the normal angle of the illumination direction by the light sources 220 to 260 is -30 degrees, -20 degrees, 0 degrees, 30 degrees, and 65 degrees (the direction with the light receiving direction with respect to the sample surface normal is positive). Since the normal angle of the illumination direction (regular reflection direction) that gives specularly reflected light in the light receiving direction is −45 degrees, the angle of each illumination direction from the regular reflection direction (regular reflection angle) is as shown in the figure. 15 degrees, 25 degrees, 45 degrees, 75 degrees, and 110 degrees. Therefore, the optical system S0 is a specular reflection angle of an optical arrangement recommended by two main standards of metallic and pearl paint measurement methods, ASTM E2194 and DIN6175-2-2 [15 degrees, 45 degrees, 110 degrees]. And [25 degrees, 45 degrees, 75 degrees].

  The operation of the multi-angle colorimeter equipped with such an optical system S0 will be described. First, the light sources 220 to 260 are sequentially turned on by a control unit (not shown). The light beams emitted from the light sources 220 to 260 are converted into parallel light beams by the collimator lenses 122 to 126, and the sample surface 1 is illuminated from the illumination direction described above. Then, the sample surface reflected light (sample light beam) in the direction of the normal angle of 45 degrees is converged on the sample slit 350a of the slit plate 350 by the light receiving lens 330 of the light receiving system 300, and becomes a parallel light beam by the imaging lens 360. The light enters the diffraction grating 370 and is dispersedly reflected for each wavelength component. Thereafter, the light is converged again by the imaging lens 360, and a dispersion image of the sample slit 350a shown in FIG. 14B is made incident on the sample array 380a of the sensor array 380 shown in FIG.

  In the optical system S0, it is necessary to provide a reference system for monitoring the fluctuation of the illumination light beam. For this reason, some of the output light beams of the light sources 220 to 260 constituting the five illumination systems are taken into the incident ends of the monitor fibers 220f to 260f as reference light beams, respectively. The exit ends of the five monitor fibers 220f to 260f are arranged side by side in the reference slit 350b of the slit plate 350 shown in FIG. The reference beam sequentially emitted from the five exit ends is incident on the reference array 380b of the sensor array 380 by forming a dispersed image of the slit 350b, similarly to the sample beam.

A signal corresponding to the spectral intensity of the sample light beam and the reference light beam incident on the sample array 380 is converted into spectral intensity data by a processing circuit (not shown), and is sent to control arithmetic means (not shown). The control calculation means obtains a spectral reflectance coefficient in each direction of the sample from the spectral intensity data of the sample light beam and the reference light beam by illumination from each direction, and further converts it into a color value or the like as necessary. is there.
JP 2001-50817 A

  According to the optical system S0 as described above, the illumination direction is switched by the light emission control of the light sources 220 to 260, and the measurement is performed by one light receiving system 300. Therefore, there is no mechanical movable part that moves the light source. There is an advantage of high stability. However, in order to monitor the fluctuation of the illumination light flux, it is necessary to guide the reference light to the spectroscopic means from the illumination systems (light sources 220 to 260) arranged in different directions. For this reason, the use of a light guide member (monitor fibers 220f to 260f) such as an optical fiber is inevitable, which not only leads to an increase in cost, but also requires a space for routing the optical fiber, thereby increasing the size of the apparatus. There is a problem of doing. Furthermore, since the transmission characteristics of the optical fiber fluctuate due to changes in temperature and the like, there is a problem that such temperature characteristics and the like cause an error.

  Therefore, according to the present invention, the reference system for monitoring the fluctuation of the illumination light beam is configured without using an optical fiber or the like, thereby reducing the size of the apparatus, eliminating an error factor, and reducing the cost. It is an object of the present invention to provide a reflection characteristic measuring apparatus and a multi-angle colorimeter capable of monitoring light that is as close as possible to the illumination light being irradiated.

  A reflection characteristic measuring apparatus according to claim 1 of the present invention includes a measurement opening for irradiating a sample surface with illumination light, a reference surface provided in the vicinity of the measurement opening, the sample surface, and the reference surface. Illuminating means for collectively illuminating, an objective lens to which reflected light from the sample surface and the reference surface illuminated by the illuminating means is incident, and reflection from the sample surface converged by at least the objective lens A sample slit into which light is incident, a reference slit juxtaposed with the sample slit and into which reflected light from the reference surface is incident, a sample surface reflected light that has passed through the sample slit and the reference slit, and The spectral reflection characteristic of the sample is obtained from the spectral means including a dispersive element that disperses the reference surface reflected light for each wavelength and the sample surface reflected light and the reference surface reflected light measured by the spectral means. A reflection characteristic measuring apparatus configured to include a control arithmetic unit that includes an intermediate lens that forms an image of the objective lens in the vicinity of the dispersion element in the vicinity of the sample slit and the reference slit. It is characterized by.

  According to this configuration, the sample surface and the reference surface are adjacent to each other, and these are collectively illuminated by the illuminating means, and the sample surface reflected light and the reference surface reflected light generated by the illumination are respectively supplied to the sample slit and the reference slit. Therefore, the approximation of the illumination light beam and the reference light beam applied to the sample surface and the reference surface, respectively, is improved, and fluctuations in the illumination light irradiated on the sample surface are obtained. On the other hand, measurement can be performed while correcting with high accuracy. In addition, an intermediate lens for creating an image of the objective lens in the vicinity of the dispersive element of the spectroscopic means is disposed in the vicinity of the sample slit and the reference slit, so that the sample light beam and the reference light beam are separated by a common light receiving system. Characteristics can be measured. Therefore, even in a reflection characteristic measuring apparatus employing a multi-directional illumination / light-receiving optical system, a reference system is constructed without providing reference monitor fibers 220f to 260f as in the conventional example shown in FIG. it can.

  In the above-mentioned configuration, the sample slit and the reference slit are juxtaposed on the focal plane of the objective lens, and a light flux limiting means is disposed between the objective lens and the reference slit, and the light flux limiting means is The sample-surface reflected light beam traveling from the objective lens toward the sample slit is not shielded, while a part of the reference-surface reflected light beam traveling from the objective lens toward the reference slit is shielded, and is shielded by the light beam limiting means. It is desirable that a part of the reference surface reflected light beam is a part in a direction far from the sample surface reflected light beam.

  When a configuration in which the reference surface is arranged in the vicinity of the sample surface is adopted, a predetermined distance required to separate the reference light beam and the sample light beam reflected from each surface is set between the objective lens and the sample surface. Need to do. However, according to the above configuration, the reference light beam reflected from the portion near the sample surface of the reference surface can be partially removed by the light beam limiting means. Therefore, the distance between the sample surface and the objective lens necessary for separating the illumination light beam and the reference light beam can be reduced, and the light receiving system can be made compact.

  In the above configuration, in the case where the illumination unit illuminates the sample surface and the reference surface in a lump from a plurality of directions in a measurement plane including the optical axis of the objective lens and a sample surface normal line. Preferably, the reference surface is an anisotropic diffuse reflection surface that diffuses and reflects largely in a direction parallel to the measurement plane and diffuses and reflects small in a direction perpendicular to the measurement plane. ). According to this configuration, since the reference surface is an anisotropic diffuse reflection surface, the reflected light from the reference surface can be concentrated in a direction close to the measurement plane, and the reference light beam can be efficiently directed to the objective lens. It becomes possible to make it enter.

  A multi-angle colorimeter according to a fourth aspect of the present invention includes a measurement aperture for irradiating the sample surface with illumination light, a reference surface provided in the vicinity of the measurement aperture, and a normal line of the sample surface A toroidal mirror that is orthogonal to a measurement plane including the rotation plane and rotationally symmetric with respect to an axis that is in contact with the sample surface, and a plurality of light source units arranged in the vicinity of a focal circle composed of a focal group of the toroidal mirror, A light beam emitted from a plurality of light source parts is reflected by the toroidal mirror to be a parallel light beam, and the illumination unit illuminates the sample surface and the reference surface from different directions in the measurement plane, and the illumination unit. An objective lens to which the reflected light from the illuminated sample surface and reference surface is incident, and a sample slit to which the reflected light from the sample surface converged by at least the objective lens is incident; A reference slit that is juxtaposed to the sample slit and receives reflected light from the reference surface, and dispersion that disperses the sample surface reflected light and the reference surface reflected light that have passed through the sample slit and the reference slit, for each wavelength. The spectral means including the element and the plurality of light source units are sequentially turned on, and the spectral reflection characteristic of the sample is obtained from the spectral intensity of the sample surface reflected light and the reference surface reflected light measured by the spectral means in each illumination direction. And an arithmetic lens for forming an image of the objective lens in the vicinity of the dispersive element in the vicinity of the sample slit and the reference slit.

  According to this structure, while exhibiting the effect | action of the reflection characteristic measuring apparatus mentioned above, while using a toroidal mirror for an illumination system, the return optical path which turns the optical path of an illumination system with a toroidal mirror is employ | adopted, and the illumination system of 2 adjacent directions Since it is possible to share the reflecting surface of the toroidal mirror, the illumination system can be greatly reduced in size.

  According to the reflection characteristic measuring apparatus according to claim 1, since the closeness between the illumination light beam and the reference light beam respectively applied to the sample surface and the reference surface becomes high, the fluctuation of the illumination light irradiated on the sample surface is increased. Thus, measurement can be performed while correcting with high accuracy. In addition to adopting an objective lens and an intermediate lens, the sample surface reflected light and the reference surface reflected light are introduced into the sample slit and the reference slit, respectively, to measure the spectral reflection characteristics. Thus, a reference system can be constructed without providing a reference monitor fiber, and various problems arising from the use of an optical fiber in the reference system (for example, an optical fiber routing space that is easily affected by temperature, etc. is required, and cost is low. Can be avoided.

  According to the reflection characteristic measuring apparatus of the second aspect, the distance between the sample surface and the objective lens necessary for separating the illumination light beam and the reference light beam can be reduced, and the light receiving system can be made compact. The reflection characteristic measuring device can be downsized.

  According to the reflection characteristic measuring apparatus of the third aspect, since the reference light beam can be efficiently incident on the objective lens, for example, even when a part of the reference light beam is shielded by the light beam limiting unit. The remaining reference light beam can be efficiently incorporated into the light receiving system, and the necessary reference light beam can be easily secured.

  According to the multi-angle colorimeter according to the fourth aspect, the measurement can be performed while accurately correcting the fluctuation of the illumination light, and it is not necessary to use an optical fiber for the reference system, and the light receiving system can be made compact. In addition, it is possible to share the reflecting surface of the toroidal mirror with the adjacent two-way illumination system by adopting a folding optical path in which the optical path of the illumination system is folded back with a toroidal mirror. Can be greatly reduced in size. Accordingly, it is possible to achieve miniaturization of a multi-angle colorimeter incorporating such an illumination system.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, a multi-angle colorimeter to which the reflected light measurement device according to the present invention is preferably applied will be described as an example.

(Description of overall configuration of multi-angle colorimeter)
FIG. 1A is a perspective view schematically showing the appearance of the multi-angle colorimeter MS according to the present embodiment. The multi-angle colorimeter MS is configured in its entirety by a main body case 2e having an elongated box shape in which each component such as an optical system including an illumination system and a light receiving system described later is housed. A bottom wall surface of the case 2e is a measurement opening surface 2, and a measurement opening 2a having an appropriate shape (for example, an ellipse) is formed in the measurement opening surface 2. In addition, the main body case 2e has a finder 2b for making the target sample surface visible, a display unit 2c composed of an LCD or the like arranged on the top surface for displaying measurement results, etc., and an operator can easily grasp it. A grip portion 2d and the like are provided so that they can be handled.

  Then, as shown in FIG. 1 (b), the measurement opening 2a of the multi-angle colorimeter MS is formed on the sample surface 1 of the measurement sample d (for example, the body of an automobile subjected to metallic coating or pearl color coating). When the body of the automobile is the measurement sample d, the surface of the coating film corresponds to the measurement sample d), and color measurement evaluation of the sample surface 1 (for example, color measurement evaluation for metallic color management) is performed. .

  In the multi-angle colorimeter MS having such a schematic configuration, in this embodiment, the optical system S is provided with a toroidal mirror 11 in order to make the multi-angle colorimeter MS compact. The toroidal mirror is a concave mirror having different radii of curvature in two axial directions orthogonal to each other. In this embodiment, the radius of curvature in one of the axial directions (the measurement plane 10p direction) is shown in FIG. As shown in the figure, it is rotationally symmetric on the measurement plane 10p with the axis 11x perpendicular to the measurement plane 10p including the sample plane normal 1n (θ = 90 °) and in contact with the sample plane 1 as the central axis. A toroidal mirror 11 having a radius of curvature r is used.

  FIG. 2 is a block diagram showing the internal structure of the multi-angle colorimeter MS according to the present embodiment, and FIG. 3 is a side sectional view taken along the sample surface normal 1n of FIG. This multi-angle colorimeter MS is illuminated by the illumination system 10 as an optical system S1 and an illumination system 10 (illuminating means) that illuminates the sample surface 1 placed in the measurement aperture 2a of the sample aperture surface 2. A light receiving system 30 (spectral means) for measuring the spectral characteristics of the sample reflected light, further controlling the illumination system 10 and the light receiving system 30, and based on the measurement data output from the light receiving system 30, the sample surface 1 The control calculation means 40 is provided as a control processing system that obtains and outputs the reflection characteristics of the light. Note that the measurement plane 10p and the axis 11x drawn in FIG. 2 (shown as dots in FIG. 2 because they are in the direction perpendicular to the paper surface) correspond to the measurement plane 10p and the axis 11x in FIG.

(Lighting system)
The illumination system 10 includes the above-described toroidal mirror 11 and angles (normal angle) from the normal 1n of the sample surface 1 shown in () of FIG. 2 -30 degrees, -20 degrees, 0 degrees, 30 degrees, And first to fifth illumination systems 102 to 106 arranged in a direction of 65 degrees. By adopting such an arrangement relationship, the standard reflection angle of the optical arrangement (geometry) recommended by ASTM E2194 and DIN6175-2, 2001, which are two major standards in the evaluation method of metallic coating and pearl color coating, is used. Multi-angle colorimeter suitable for evaluation of metallic paint and pearl color paint because it includes 15 degree, 45 degree, 110 degree arrangement and 25 degree, 45 degree, 75 degree arrangement. MS.

  The toroidal mirror 11 covers the direction of the normal angle of −30 degrees to 65 degrees in which the first to fifth illumination systems 102 to 106 are arranged on the measurement plane 10p with the axis 11x as the central axis. It has a concave curved surface 111 that is rotationally symmetric. As shown in FIG. 3, the toroidal mirror 11 includes a concave curved surface 112 having a predetermined curvature in the extending direction of the shaft 11x. The focal point 110b of the curved surface 112 is at approximately a half position in the radial direction of the curved surface 111, and is in contact with the edge of the measurement opening 2a (the edge that defines a predetermined measurement region on the sample surface 1). It is set outside the plane parallel to the measurement plane.

  The curved surface 112 is a parabolic curved surface having a perpendicular line dropped from the focal point 110b to the axis 11x as an axis of symmetry. As a result, the illumination light beam (or reflected light beam) in each direction in the measurement plane 10p is parallel to the radius in the measurement plane 10p and along a plane perpendicular to the radius, and has a highly direction-dependent metallic paint surface or pearl paint surface. Can be measured with high accuracy. The position of the focal point 110b can be appropriately adjusted by setting the curved surface 112, but from the viewpoint of further increasing the parallelism of the illumination light beam (or reflected light beam) in each direction within the measurement plane 10p, as shown in FIG. It is desirable to set the radius within the measurement plane 10p as close as possible.

  The toroidal mirror 11 is provided with such a focal point 110b at each point in the circumferential direction, and a focal group composed of the focal point 110b forms a circumference corresponding to the curvature of the curved surface 111. In FIG. 2, the circumference formed by the focus group is depicted as a focus circumference 11b. As described above, the focal point 110b is set at a position close to the measurement plane 10p, and the curvature of the curved surface 112 is constant in the circumferential direction of the curved surface 111. As a result, the focal point circumference 11b is also measured. It exists in a plane 110p (see FIG. 3) close to 10p and parallel to the measurement plane 10p.

  The 1st-5th illumination systems 102-106 (light source part) are arrange | positioned close to the incident ends 12b-16b of the small right-angle prisms 12-16 which have the emission ends 12a-16a, and this small right-angle prisms 12-16. And flash light sources 22 to 26 made of xenon lamps. FIG. 3 illustrates the side structures of the right-angle prism 14 and the flash light source 24 in the third illumination system 104. The flash light source 24 is a light source in which a pair of electrodes 24d and 24d are disposed at both ends of an elongated xenon tube 24g, and is a generation source of illumination light that illuminates the sample surface 1. The incident end 14b of the right-angle prism 14 is in contact with the central portion of the xenon tube 24g, and the light emitted from the flash light source 24 is incident on the right-angle prism 14 through the incident end 14b. .

  The light (illumination light) incident on the right-angle prism 14 is changed in direction by the internal reflection surface 14 c and emitted from the emission end 14 a toward the toroidal mirror 11. Here, the exit end 14 a is disposed at the focal point 110 b position of the curved surface 112 in the toroidal mirror 11, that is, on the focal circumference 11 b of the toroidal mirror 11. The exit end 14 a has an exit area that is sufficiently smaller than the focal length of the curved surface 112. According to this configuration, since the exit area of the exit end 14a is sufficiently smaller than the focal length, illumination light with high parallelism can be irradiated onto the sample surface 1. The other illumination systems 102, 103, 105, 106 also have the same configuration as above.

  As shown in FIG. 1, light beams 22 a to 26 a emitted from the first to fifth illumination systems 102 to 106 are reflected by the toroidal mirror 11, and an angle from the sample surface normal 1 n within the measurement plane 10 p. The sample surface 1 is illuminated with light beams 22a to 26a parallel to -20, -30, 0, 30 and 65 radii. Here, the light source itself may be arranged to face the toroidal mirror 11, but since the illumination light is emitted from the emission ends 12a to 16a set in the small right angle prisms 12 to 16 as described above, The flash light sources 22 to 26 do not block the illumination light beams 22a to 26a. Therefore, since the focal circumference 11b can be set close to the measurement plane 10p, there is an advantage that the aberration of the toroidal mirror 11 can be suppressed and the parallelism of the illumination light beams 22a to 26a can be increased.

  Adjacent to the sample surface 1 (in the vicinity of the measurement aperture 2a), a reference surface 3 for monitoring fluctuations in illumination light flux in the first to fifth illumination systems 102 to 106 is provided. In this embodiment, it is adjacent to the sample surface 1 in a direction orthogonal to the measurement plane 10p. In order to illuminate the reference surface 3 in each of the first to fifth illumination systems 102 to 106, the toroidal mirror 11 is provided with an extension portion 11c in the extending direction of the rotationally symmetric axis 11x. ing. That is, the reference surface 3 adjacent to the sample surface 1 is illuminated by the light beams 22a to 26a reflected by the extension portion 11c. Note that the light beam that illuminates the reference surface 3 is a surface away from the surface that forms the focal circumference of the toroidal mirror 11, so that although the aberration slightly increases, it is not a big problem because it is a reference system.

  With the illumination system 10 having the above-described configuration, the light beams 22a to 26a emitted from the first to fifth illumination systems 102 to 106 are reflected by the toroidal mirror 11 and pass through a folded optical path to the sample surface. For this reason, the illumination system 10 is greatly reduced in size as compared with the configuration in which the light source and the collimator lens are linearly arranged around the sample surface. Moreover, since the toroidal mirror 11 has a continuous annular reflecting surface, like the first illumination system 102 (−30 degrees) and the second illumination system 103 (−20 degrees) shown in FIG. It is possible to share the reflecting surface of the toroidal mirror 11 between adjacent two-way illumination systems (the common part is indicated by a symbol W in the figure), and even if two-way illumination systems are arranged close to each other. The illumination system 10 can be further reduced in size because the problem of collimator lens interference does not occur as in the prior art.

(Light receiving system)
Next, the light receiving system 30 (spectral means) will be described with reference to FIGS. The light receiving system 30 includes an objective lens 31, a light beam diaphragm plate 33, a field lens 34 (intermediate lens), an entrance slit plate 35, an imaging lens 36, a diffraction grating 37 (dispersion element), a sensor array 38, and a light beam regulating plate 39 (light beam). Limiting means) and the like. The light receiving system 30 has an optical axis 30x having a normal angle of 45 degrees passing through the center of the sample surface 1 in the measurement plane 10p. Since the direction of regular reflection with respect to the light receiving direction with a normal angle of 45 degrees is −45 degrees, the normal angles of the first to fifth illumination systems 102 to 106 are −30 degrees, −20 degrees, 0 degrees, The angles of the illumination direction of 30 degrees and 65 degrees from the regular reflection direction (regular reflection angles) are 15 degrees, 25 degrees, 45 degrees, 75 degrees, and 110 degrees, respectively.

  The incident slit plate 35, the imaging lens 36, the diffraction grating 37, and the sensor array 38 constitute a polychromator. That is, the imaging lens 36 and the diffraction grating 37 generate a dispersion image of the slit 35a (and the slit 35b) of the entrance slit plate 35, and the sensor array 38 is placed at the image formation position of the entrance slit dispersion image. ing. The polychromator is for simultaneously measuring all wavelengths in the measurement wavelength range in order to separate the reflected light from the sample surface 1 received by the light receiving system 30 for each wavelength and create spectral data according to the light intensity. Is.

  The objective lens 31 is disposed in the opening portion 11a provided in the toroidal mirror 11 and having a normal angle of 45 degrees, and converges the reflected light along the direction of the optical axis 30x onto the incident slit plate 35. Specifically, as shown in FIG. 4, the objective lens 31 reflects reflected light in the direction of a normal angle of 45 degrees from the sample surface 1 and the reference surface 3 that are collectively illuminated by the illumination system 10 (hereinafter referred to as “normal angle”). The sample light beam 1 c and the reference light beam 3 c) are converged on the slit plate 35 placed on the focal plane of the objective lens 31.

  The light beam diaphragm plate 33 includes an opening 33 a through which the light beam passes, and is disposed in the vicinity of the back side of the objective lens 31. The beam stop plate 33 is for restricting the diameters of the sample light beam 1c and the reference light beam 3c to a predetermined size, and the opening 33a is selected to have a predetermined size according to the size to be controlled.

  As shown in FIGS. 4 and 5B, the incident slit plate 35 includes a sample slit 35a and a reference slit 35b juxtaposed therewith. These slits 35a and 35b function as entrance slits of the polychromator. That is, the sample light beam 1c collected by the objective lens 31 is guided to the sample slit 35a as a convergent light beam 1c ', and the reference light beam 3c is guided to the reference slit 35b as a convergent light beam 3c'.

  The imaging lens 36 changes the sample light beam 1c and the reference light beam 3c (sample surface reflected light and reference surface reflected light) that have passed through the sample slit 35a and the reference slit 35b, respectively, from a diffused light beam to a parallel light beam, thereby changing the diffraction grating. 37. The diffraction grating 37 diffuses and reflects the parallel light beam guided by the imaging lens 36 for each wavelength component. The light beam dispersedly reflected by the diffraction grating 37 is converged again by the imaging lens 36 and imaged on the sensor array 38.

  The sensor array 38 outputs a signal corresponding to the spectral intensity of the sample light beam 1c and the reference light beam 3c to the signal processing unit 43 described later. As shown in FIG. 5A, the sensor array 38 includes a sample array 38a and a reference array 38b. Each of the sample array 38a and the reference array 38b is configured by a photodiode array of, for example, 40 pixels arranged in a predetermined size section set in accordance with the size of the sample slit 35a and the reference slit 35b. can do. A dispersion image of the sample slit 35a is incident on the sample array 38a, and a dispersion image of the reference slit 35b is incident on the reference array 38b.

  A field lens 34 (intermediate lens) is disposed immediately before the entrance slit plate 35 (the sample slit 35a and the reference slit 35b) (in the vicinity of the surface of the entrance slit plate 35 on the objective lens 31 side). The field lens 34 functions to create an image of the aperture 33 a of the light beam diaphragm plate 33 at the position of the imaging lens 36. By arranging such a field lens 34, the sample light beam 1c and the reference light beam 3c that have passed through the sample slit 35a and the reference slit 35b are all incident on the imaging lens 36 and the diffraction grating 37. This contributes to the formation of a dispersed image on the sample array 38a and the reference array 38b. Therefore, the spectral characteristics of the sample light beam 1c and the reference light beam 3c can be efficiently measured with a common light receiving system.

  FIG. 6 is an optical path diagram for explaining the utility of the field lens 34. In the optical path from the measurement area 1a and the reference area 3a to the imaging lens 36 in FIG. It is equivalent. As described above, the sample light beam 1c and the reference light beam 3c are converged by the objective lens 31 to the juxtaposed sample slit 35a and the reference slit 35b, respectively, but the field lens 34 is provided in the vicinity of the entrance slit plate 35. Otherwise, the reference light beam 3c that has passed through the entrance slit plate 35 changes from convergence to diffusion, but has an optical axis 3x that is inclined at a predetermined angle with respect to the optical axis 1x of the sample light beam 1c (the optical axis of the imaging lens 36). For this reason, a part of the light flux comes out of the cover range of the imaging lens 36 (the allowable incidence range of the imaging lens 36).

  That is, in the example shown in FIG. 6, the slit passing light beam 300x corresponding to the light beam reflected from the vicinity of the optical axis 3x of the reference area 3a can be incident on the imaging lens 36, but is a portion away from the measurement area 1a of the reference area 3a. The slit passing light beam 300 c corresponding to the light beam reflected from the light beam cannot enter the imaging lens 36 and the diffraction grating 37. As a result, a dispersion image of the reference slit 35b by the accurate reference light beam 3c cannot be formed in the reference array 38b, and a sufficient reference light beam cannot be obtained. As a result, the correction accuracy of the illumination light fluctuation is deteriorated and the measurement accuracy is also improved. The problem of deteriorating arises.

  However, by disposing the field lens 34 in the vicinity of the entrance slit plate 35, the light flux 300c passing through the slit is refracted and converged to the allowable incidence range of the imaging lens 36. As a result, not only the sample light beam 1 c but also the reference light beam 3 c are all incident on the imaging lens 36 and the diffraction grating 37. Therefore, an accurate dispersion image of the reference slit 35b can be formed with a sufficient reference light beam, and the correction accuracy of illumination light fluctuation is improved.

  The light beam restricting plate 39 is disposed between the entrance slit plate 35 and the objective lens 34, and serves to shield a part of the reference light beam 3c 'in FIG. The light flux restricting plate 39 is installed to shorten the optical path length of the light receiving system 30 as much as possible in the optical system S1 according to this embodiment in which the sample surface 1 and the reference surface 3 are disposed adjacent to each other. This point will be described with reference to FIG. 4, FIG. 7, and FIG.

As shown in FIG. 4, the distance on the sample surface 1 (reference surface 3) between the optical axis 1x of the sample light beam 1c and the optical axis 3x of the reference light beam 3c is D, and the distance between the sample slit 35a and the reference slit 35b. When the interval is d, the interval between the entrance slit plate 35 and the objective lens 31 is a, and the interval between the sample surface 1 (and the reference surface 3) and the objective lens 31 is b.
b = a · D / d (1)
The relationship is established.

Here, as shown in FIG. 7, when both the measurement aperture 10a and the measurement diameter of the reference surface 3 (reference region 30a) are circular, for example, the measurement aperture 10a has a diameter of 12 mm and the reference region 3a. If the diameter is 8 mm, the distance D ₀ between the optical axis 10x of the sample light beam 10c and the optical axis 30x of the reference light beam 30c is about 12 mm in order to allow a margin according to the above equation (1). (Note that since the measurement aperture 10a is covered with the sample surface, if the two overlap, the reference beam 30c cannot be accurately monitored). In this case, if the slit interval d is 3 mm and the interval a between the entrance slit plate 35 and the objective lens 31 is 25 mm, the interval b ₀ between the sample surface 1 and the objective lens 31 is 100 mm, which requires a relatively long distance. Therefore, it is inevitable to increase the size of the device.

  Therefore, in the present embodiment, as shown in FIG. 4, a light beam restricting plate 39 is disposed between the entrance slit plate 35 and the objective lens 31, and a half of the reference light beam 3c ′ far from the sample light beam 1c ′ in this portion. Shielded. In other words, the light beam restricting plate 39 prevents the reflected light reflected from the region of the sample surface 1 from entering the reference slit 35b of the incident slit plate 35. If the sample light beam 1c is shielded, the original purpose of the reflected light measurement is hindered. Therefore, the light beam restricting plate 39 does not interfere with the sample light beam 1c incident on the objective lens 1 (the sample light beam 1c is not reflected in the position). (Position not to be shielded). Thereby, as shown in FIG. 4, the reference area 3a on the reference surface 3 becomes a semicircular shape whose diameter is directed to the circular measurement area 1a (on the sample surface 1), and only the semicircular portion that shields the interval D is formed. Can be shortened.

  This point will be described in detail with reference to FIG. 8. As shown in FIG. 7, the measurement area 10a and the reference area 30a are considered as circles that do not overlap (or close to each other) (in this case, the distance D = 12 mm is inevitably required). As shown in FIG. 8, the measurement area 1a and the reference area 3a are set as overlapping circles, and the light flux corresponding to the overlapping portion 31a in the reference area 3a is set so as not to affect the measurement afterwards. 31c is shielded by the light flux restricting plate 39. In order to avoid such duplication, the light beam shielded by the light beam restricting plate 39 is between the objective lens 31 and the field lens 34, and the sample light beam 1c out of the convergent light beam 3c ′ (reference surface reflected light beam). A part (light beam 31c ′ corresponding to the overlapping portion 31a) located in a direction far from the convergent light beam 1c ′ (sample-surface reflected light beam). As a result, the distance D can be reduced from 12 mm to 8 mm, and the distance b can be reduced from 100 mm to 66 mm. Thus, the optical path length of the light receiving system 30 is greatly shortened.

  By arranging the light flux restricting plate 39 as described above, the area of the reference area 3a is halved, and the reference light flux necessary for monitoring may be insufficient. In this case, it is desirable to arrange a reflector having anisotropic diffusion characteristics as shown in FIG. That is, as shown in FIG. 9A, the incident illumination light beams 22a to 26a are largely diffusely reflected in the direction within the measurement plane 10p to form diffuse reflected light 3p, while FIG. As shown, it is an anisotropic diffuse reflector that diffuses and reflects small in the direction perpendicular to the measurement plane 10p to form diffusely reflected light 3q. By using such an anisotropic diffuse reflector, the illumination light beams 22a to 26a can be efficiently incident on the light receiving system 30, and a necessary reference light beam can be obtained. As such an anisotropic diffuse reflector, for example, an elliptic profile LSD (Light Shaping Diffuser) manufactured by POC of the United States can be used.

  Note that the sample slit 35a and the reference slit formed in the sample array 38a and the reference array 38b if the reference beam and the sample beam are different in the diffraction grating irradiation area by shielding the reference beam with the beam restricting plate 39. There is a concern that the imaging characteristics of the dispersion image of 35b are different and the illumination light fluctuation cannot be accurately corrected. However, in the configuration shown in FIG. 4, the light flux restricting plate 39 shields half of the direction orthogonal to the dispersion direction, and as shown in FIG. 10, the irradiation area (S1 + S2) of the diffraction grating 37 by the sample light and the reference light Since the irradiation region (S2) of the diffraction grating 37 is equal in the width in the dispersion direction, the imaging characteristics of the dispersion images of the sample slit 35a and the reference slit 35b formed by the sample light beam 1 and the reference light beam 3c are the illumination light. It is not so different as to be a problem in correcting for variations.

  According to the light receiving system 30 configured as described above, since the reference surface 3 is adjacent to the sample surface 1 in the direction orthogonal to the measurement plane 10p, the approximation between the illumination light beam 1c and the reference light beam 3c is improved. The measurement becomes higher, and the measurement can be performed while accurately correcting the fluctuation of the illumination light applied to the sample surface 1. Further, by using the light beam restricting plate 39, the distance b between the sample surface 1 and the objective lens 31 necessary for separating the illumination light beam 1c and the reference light beam 3c can be reduced, and the light receiving system can be made compact. Furthermore, the spectral characteristics of the sample light beam 1 c and the reference light beam 3 c can be measured by the common light receiving system 30 by the arrangement of the field lens 34. In particular, in the case of the multi-directional illumination to unidirectional light receiving optical system S0 as in this embodiment, there is no need to provide the reference monitor fibers 220f to 260f as in the conventional example shown in FIG. Since the reference light beam 3c can also be monitored by the light receiving system 30 common to the system, various problems caused by using the optical fiber (for example, the influence of the temperature and the like, the necessity of a drawing space for the optical fiber, etc.) can be avoided.

(Control processing system)
Returning to FIG. 2, the control calculation unit 40 obtains and outputs the reflection characteristic of the sample surface 1 based on the measurement data output from the light receiving system 30 described above, and is a control processing unit including a CPU, a memory, and the like. 41, a flash control unit 42, a signal processing unit 43, a measurement control unit 44, and a display unit (corresponding to the display unit 2c shown in FIG. 1).

  The control processing unit 41 transmits a control signal to each unit to control the measurement operation when measuring the color of the sample surface 1. Specifically, when receiving the measurement start signal from the measurement control unit 44, the control processing unit 41 gives a drive signal corresponding to the operation sequence to the flash control unit 42, and controls the light emission of the flash light sources 22 to 26. Further, it receives the spectral intensity data output from the signal processing unit 43 that receives the spectral intensity signals of the sample light beam 1c and the reference light beam 3c, obtains the spectral reflectance coefficient for each illumination direction, and determines the color value and other values as necessary. It is converted into an index and output and displayed on the display unit 2c.

  The flash control unit 42 generates a control signal for actually sequentially emitting the flash light sources 22 to 26 of the first to fifth illumination systems 102 to 106 based on the drive signal given from the control processing unit 41.

  In the signal processing unit 43, the illumination light emitted from the illumination system 10 is reflected by the sample surface 1 and the reference surface 3, and the intensity of the reflected light received by the light receiving system 30 (the spectral intensity of the sample light beam 1c and the reference light beam 3c). The spectral reflection characteristic of the sample surface 1 is calculated based on (signal) (spectral intensity data is obtained). That is, the signal processing unit 43 uses the spectral intensity signal output from the sensor array 38 to calculate spectral reflection characteristics corresponding to the illumination directions of the first to fifth illumination systems 102 to 106 on the measurement plane 10p. The signal processing unit 43 can be configured by a signal processing circuit including, for example, a current-voltage conversion circuit, a feedback resistor, a multiplexer, a variable gain amplifier, an analog-digital converter, and the like.

  The measurement control unit 44 controls the overall operation of the multi-angle colorimeter MS, and gives a measurement start signal corresponding to the measurement menu selected by the user to the control processing unit 41 to execute the measurement operation. The unit 2c displays measurement result data such as color values, graphs, measurement menus, and the like.

  The operation of the multi-angle side colorimeter MS configured as described above will be briefly described. First, when a measurement start signal is generated from the measurement control unit 44, a predetermined drive signal is given from the control processing unit 41 to the flash control unit 42, and the flash control unit 42 receives the first to fifth illumination systems 102 to 102. The flash light sources 22 to 26 of 106 are made to emit light sequentially. Light beams emitted from the respective flash light sources 22 to 26 are reflected by the toroidal mirror 11 and applied to the sample surface 1 and the reference surface 3.

  This point will be described with respect to the third illumination system 104 shown in FIG. 3, for example. After being incident on the incident end 14b of the small right-angle prism 14 and reflected by the internal reflecting surface 14c, the direction is changed, and then the toroidal from the exit end 14a. It is emitted toward the mirror 11. The emitted light beam is reflected by the toroidal mirror 11 and is irradiated onto the sample surface 1 and the reference surface 3 after being converted into a parallel illumination light beam 24a. The other illumination systems 102, 103, 105, 106 operate in the same manner.

  Of the reflected light from the sample surface 1 and the reference surface 3, reflected light (sample light beam 1 c and reference light beam 3 c) parallel to the radius of the normal angle of 45 degrees in the measurement plane 10 p is received by the light receiving system 30. Is received. Specifically, the sample light beam 1c and the reference light beam 3c are converged to the sample slit 35a and the reference slit 35b of the entrance slit plate 35 through the objective lens 31, respectively. At this time, a predetermined aperture is applied to the light beam by the light beam stop plate 33, and the semicircular portion of the reference light beam 3c is shielded by the light beam restricting plate 39.

  The sample light beam 1 c and the reference light beam 3 c that have passed through the sample slit 35 a and the reference slit 35 b are converted into a parallel light beam through the imaging lens 36 and then guided to the diffraction grating 37. Each wavelength component is dispersedly reflected. This light beam that has been dispersed and reflected is again converged by the imaging lens 36 and imaged on the sensor array 38. Since the field lens 30 is disposed in the optical path of the light receiving system 30, the sample light beam 1c and the reference light beam 3c that have passed through the sample slit 35a and the reference slit 35b are all formed by the imaging lens 36 and the diffraction grating. 37 is incident.

  Thereafter, the sensor array 38 outputs a spectral intensity signal corresponding to the received sample light beam 1 c and reference light beam 3 c to the signal processing unit 43. Then, the signal processing unit 43 obtains the spectral intensity data of the sample surface 1 based on the spectral intensity signal, and then the control processing unit 41 calculates the spectral reflectance coefficient for each illumination direction based on the spectral intensity data. It is obtained, converted to a color value or other index as required, and output and displayed on the display unit 2c.

(Description of other embodiments)
FIG. 11 is a cross-sectional configuration diagram showing an example in which the present invention is applied to a reflected light measurement apparatus employing an integrating sphere illumination system, and FIG. 12 is a cross-sectional configuration diagram in the direction of arrow C in FIG. This reflected light measuring apparatus includes an integrating sphere 100, a light receiving system 300 (spectral means) and a control calculation means 400 that constitute an illumination system.

  The integrating sphere 100 has an inner wall with high reflectivity and high diffusion, and a flash light source 122 composed of a xenon lamp or the like is provided therein. The integrating sphere 100 includes a measurement aperture 100a, and diffuses and multi-reflects the light beam emitted from the flash light source 122 on the inner wall of high reflectivity and high diffusion to form a secondary light source having uniform brightness, and measures. The sample placed in the opening 100a is illuminated uniformly from all directions. Further, the integrating sphere 100 has a light receiving opening 100b provided substantially in the counter electrode direction with respect to the measurement opening 100a so that reflected light from the sample can be taken out. A reference surface 103 is set in the vicinity of the measurement opening 100a (the inner wall of the integrating sphere in the vicinity of the measurement opening 100a functions as the reference surface 103).

  The light receiving system 300 and the control calculation means 400 have substantially the same configuration as the light receiving system 30 and the control calculation means 40 described in the above embodiment, and detailed description of each element is omitted. The light receiving system 300 has an optical axis 30x tilted 8 degrees from the sample surface normal 1n, and constitutes a so-called d / 8 illumination light receiving system.

  In the above configuration, when the flash light source 122 emits light through the flash control unit 42 by the control processing unit 41 of the control calculation unit 400, the light beam emitted from the flash light source 122 is multiple-reflected by the inner wall of the integrating sphere 100, and diffuse illumination is performed. The sample surface 1 placed in the sample opening 100a as light is diffusely illuminated. Then, in the objective lens 31 of the light receiving system 300, the sample light beam 101c and the reference light beam 103c, which are reflected light in the direction of the optical axis 30x from the diffusely illuminated sample surface 1 and the reference surface 103, are received by the light receiving aperture of the integrating sphere 100. Incident through 100b. The diameter of the received light beam is limited by the opening 33a of the beam stop plate 33 disposed in the vicinity of the objective lens 31.

  By the objective lens 31, the sample light beam 101c and the reference light beam 103c are converged on the sample slit 35a and the reference slit 35b juxtaposed on the incident slit plate 35. Hereinafter, in the same manner as in the previous embodiment, the spectral intensity data of the sample surface 1 is obtained by the imaging lens 36, the diffraction grating 37 (dispersing element) and the sensor array 38 constituting the polychromator, and the control calculation means 400 is used. The spectral reflectance coefficient and the like are obtained by the (control processing unit 41).

  Also in this embodiment, the field lens 34 (intermediate lens) that creates an image of the objective lens 31 limited by the opening 33a at the position of the imaging lens 36 is disposed in the vicinity (immediately before) of the slit plate 35. The sample light beam 101 c and the reference light beam 103 c that have passed through the sample slit 35 a and the reference slit 35 b are all incident on the imaging lens 36 and the diffraction grating 37. In addition, a light beam restricting plate 39 that blocks a part of the reference light beam 103c is disposed between the incident slit plate 35 and the objective lens 34 at a position that does not interfere with the sample light beam 101c incident on the objective lens 31. Of the reference light beam 103c, a portion of the light beam 103c ′ far from the sample light beam 101c is shielded. Thereby, the distance between the objective lens 31 and the sample surface 1 is reduced.

As mentioned above, although embodiment of this invention was described, this invention is not limited to the said structure, For example, a structure as shown to following (1)-(3) can also be taken.
(1) In the optical system S1 in the embodiment shown in FIG. 2, the example in which the reference surface 3 is adjacent to the sample surface 1 in the direction orthogonal to the measurement plane 10p is shown. It can also be set as the structure which adjoins. In this case, it is not necessary to provide the extension 11c that extends the toroidal mirror 11 in the direction of the axis 11x, and the size of the toroidal mirror 11 in the direction of the axis 11x can be reduced.

(2) In the above embodiment, the field lens 34 (intermediate lens) is disposed just before the slit plate 35. However, the field lens 34 only needs to be positioned in the vicinity of the slit plate 35 and is incident. The slit plate 35 may be disposed in the vicinity of the surface on the imaging lens 36 side.

(3) In the multi-angle colorimeter MS shown in FIG. 2, the example in which the folded optical path type illumination system using the toroidal mirror 11 is employed as the illumination system has been described. However, the measurement apparatus is not required to be downsized. In use, an illumination system in which a light source and a collimator lens are linearly arranged around the sample surface as shown in FIG.

FIG. 1A is a perspective view schematically showing the appearance of the multi-angle colorimeter MS according to the present invention, and FIG. 1B is a perspective view schematically showing the main part of its internal structure. . It is a block diagram which shows the internal structure of multi-angle colorimeter MS concerning this embodiment. FIG. 3 is a side sectional view in a direction perpendicular to a sample surface normal line 1 n of FIG. 2. It is sectional drawing of the direction perpendicular | vertical to the measurement plane 10p which shows the structure of the light reception system 30 in FIG. FIG. 5A is a front view of the sensor array 38, and FIG. 5B is a front view of the sample slit 35. It is an optical path diagram for demonstrating the utility of a field lens (intermediate lens). It is an optical path diagram for demonstrating the utility of a light beam restricting plate (light beam restricting means). It is an optical path diagram for demonstrating the utility of a light beam restricting plate (light beam restricting means). It is a schematic diagram which shows the reflective characteristic of an anisotropic diffused reflection board. It is explanatory drawing about the irradiation area | region of a diffraction grating. It is a cross-sectional block diagram which shows embodiment which applied this invention to the reflected light measuring apparatus which employ | adopted the integrating sphere illumination system. It is a cross-sectional block diagram of the arrow C direction of FIG. It is a block diagram which shows optical system S0 of the multi-angle illumination unidirectional light reception type multi-angle colorimeter concerning a prior art. 14A is a front view of the sensor array 380 in FIG. 13, and FIG. 14B is a front view of the sample slit 350.

Explanation of symbols

1 Sample surface 1n Sample surface normal line 10 Illumination system (illumination means)
10p measurement plane 102-106 1st-5th illumination system (light source part)
11 Toroidal mirror 11b Focal circumference 11c, 11d Extension 11x (Toroidal mirror) axis 2 Measurement aperture 2a Measurement aperture 22-26 Flash light source (light source)
3 Reference surface 30 Light receiving system (spectral means)
31 Objective lens 34 Field lens (intermediate lens)
35 Entrance slit plate 35a Sample slit 35b Reference slit 36 Imaging lens 37 Diffraction grating (dispersion element)
38 Sensor array 39 Light flux restricting plate (light flux limiting means)
40 Control operation means MS Multi-angle colorimeter S1 Optical system

Claims (4)

A measurement aperture for illuminating the sample surface with illumination light;
A reference surface provided in the vicinity of the measurement opening;
Illuminating means for collectively illuminating the sample surface and the reference surface;
An objective lens on which reflected light from the sample surface and the reference surface illuminated by the illumination means is incident;
A sample slit into which the reflected light from the sample surface converged by at least the objective lens is incident; a reference slit juxtaposed with the sample slit and into which the reflected light from the reference surface is incident; and the sample A spectroscopic means including a dispersion element that disperses the sample surface reflected light and the reference surface reflected light that have passed through the slit and the reference slit, for each wavelength, and
A reflection characteristic measuring apparatus comprising control arithmetic means for obtaining a spectral reflection characteristic of the sample from the spectral intensity of the sample surface reflected light and the reference surface reflected light measured by the spectroscopic means,
An apparatus for measuring reflection characteristics, comprising an intermediate lens for producing an image of the objective lens in the vicinity of the dispersion element in the vicinity of the sample slit and the reference slit. The sample slit and the reference slit are juxtaposed on the focal plane of the objective lens, and a light flux limiting means is disposed between the objective lens and the reference slit,
The light beam limiting means shields a part of the reference surface reflected light beam from the objective lens toward the reference slit while not shielding the sample surface reflected light beam from the objective lens toward the sample slit,
2. The reflection characteristic measuring apparatus according to claim 1, wherein a part of the reference surface reflected light beam shielded by the light beam limiting means is a part in a direction far from the sample surface reflected light beam. In the case where the illumination means illuminates the sample surface and the reference surface in a lump from a plurality of directions in a measurement plane including the optical axis of the objective lens and a sample surface normal,
2. The anisotropic diffusion reflecting surface according to claim 1, wherein the reference surface is diffused and reflected greatly in a direction parallel to the measurement plane and diffusely reflected in a direction perpendicular to the measurement plane. Or the reflection characteristic measuring apparatus of 2 description. A measurement aperture for illuminating the sample surface with illumination light;
A reference surface provided in the vicinity of the measurement opening;
A toroidal mirror that is orthogonal to a measurement plane including a normal line of the sample surface and is rotationally symmetric with respect to an axis in contact with the sample surface, and a plurality of light sources arranged in the vicinity of a focal circle composed of a focal group of the toroidal mirror And illuminating means for collectively illuminating the sample surface and the reference surface from different directions in the measurement plane by reflecting light beams emitted from the plurality of light source units by the toroidal mirror to form parallel light beams. When,
An objective lens on which reflected light from the sample surface and the reference surface illuminated by the illumination means is incident;
A sample slit into which the reflected light from the sample surface converged by at least the objective lens is incident; a reference slit juxtaposed with the sample slit and into which the reflected light from the reference surface is incident; and the sample A spectroscopic means including a dispersion element that disperses the sample surface reflected light and the reference surface reflected light that have passed through the slit and the reference slit, for each wavelength, and
A plurality of light source units that are sequentially turned on, and a control calculation unit that obtains a spectral reflection characteristic of the sample from the spectral intensity of the sample surface reflected light and the reference surface reflected light measured by the spectroscopic unit in each illumination direction; The multi-angle colorimeter further comprising an intermediate lens for forming an image of the objective lens in the vicinity of the dispersion element in the vicinity of the sample slit and the reference slit.

Images