JP2009085600A - Optical characteristic measuring instrument and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable measurement at an arbitrary light receiving open angle while keeping the interchangeability of an apparatus. <P>SOLUTION: An optical characteristic measuring instrument includes an illumination part for illuminating a measuring target, a light receiving part for receiving the reflected light reflected by the measuring target under the illumination state by the illumination part, a light receiving control part for allowing the light receiving part to receive the reflected light at a plurality of the light receiving angles within a predetermined angle range containing a preset light receiving angle, and an arithmetic part for performing not only predetermined weighting operation but also predetermined adding and subtracting operation with respect to the photometric values at the respective light receiving angles obtained by the light receiving part. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical characteristic measuring apparatus and an optical characteristic measuring method used for measuring optical characteristics of special effect coatings such as metallic paint and pearl paint having different colors depending on illumination direction and observation direction.

  Conventionally, metallic paints and pearl color paints used for, for example, automobile body painting, include glitter materials made of flaky aluminum or mica, and due to variations in reflected light due to the orientation of the glitter materials. The reflected light intensity from the glittering material varies depending on the viewing direction, and thereby a metallic effect and a pearl effect can be obtained. When measuring the optical properties of materials such as metallic and pearl color coatings that have such properties, the difference in optical properties due to variations in glittering materials can be evaluated even if measurements are made using only reflected light viewed from one angle. In general, the difference in optical characteristics is evaluated by measuring reflected light at a plurality of angles. Here, as an optical characteristic measuring device capable of measuring reflected light at a plurality of angles, a multi-angle colorimeter using a multi-directional illumination one-way light reception or a one-way illumination multi-directional light reception method has been used.

As a characteristic of the coating film, since the spectral reflectance changes according to the incident angle, there is a problem that the measurement reproducibility is poor due to the influence of the posture difference or the like. In order to solve this problem, for example, in Patent Document 1, an attitude error amount that is a basis of correction is estimated by estimating the attitude error by function approximation of the direction dependency of the reflection characteristic with respect to illumination in the 45 ° direction, and based on this estimated value. A technique for performing error correction is disclosed. For example, Patent Document 2 includes an attitude error detection illumination system (detection-dedicated light source) configured by a measurement system different from the illumination optical system, and is directed toward the measurement surface by the attitude error detection illumination system. A technique for illuminating illumination light from a substantially normal angle direction in a plane orthogonal to the measurement surface and detecting an attitude error based on the intensity of the reflected light is disclosed.
JP 2001-50817 A JP 2006-10508 A

  In order to perform more advanced (high accuracy) color measurement, it is necessary to increase the point (angle) for photometry and to increase the angle purity of the light receiving optical system (narrow the light receiving angle distribution characteristics). The angle purity is different from the angle purity of the light receiving optical system of the apparatus used in the measurement (multi-angle colorimeter; the same colorimeter or another colorimeter), causing a problem that the light reception opening angle changes. When the light reception opening angle changes, the obtained optical characteristic (light reception angle distribution characteristic) value also differs, and the compatibility of the devices (between devices) cannot be maintained.

  In addition, a problem with the compatibility of devices is when the light-receiving angle distribution characteristic has wavelength dependency. In other words, even if the light receiving optical system is designed so that the light receiving angle distribution characteristics are the same at a certain wavelength, if the wavelength is changed, the obtained optical characteristic value will be different, so that the compatibility of the apparatus cannot be maintained. .

  The present invention has been made in order to solve the above-mentioned problems, and the light reception opening angle can be made variable, that is, measurement at an arbitrary light reception opening angle is possible, and the light reception angle distribution characteristic is wavelength-dependent. Be compatible with measured values from other devices or previous measured values from the same device (maintain device compatibility). An object of the present invention is to provide an optical characteristic measuring apparatus and an optical characteristic measuring method capable of performing the above.

  An optical characteristic measuring apparatus according to the present invention includes an illumination unit that illuminates an object to be measured, a light receiving unit that receives reflected light reflected by the object under illumination by the illumination unit, and a preset setting A light receiving control unit that causes the light receiving unit to receive the reflected light at a plurality of light receiving angles within a predetermined angle range including a light receiving angle, and a predetermined photometric value at each light receiving angle obtained by the light receiving unit. And a calculation unit for performing a predetermined addition / subtraction calculation.

  According to the above configuration, the object to be measured is illuminated by the illumination unit, and the reflected light reflected by the object to be measured under the illumination state by the illumination unit is received by the light receiving unit. Then, the light receiving control unit receives reflected light at a plurality of light receiving angles within a predetermined angle range including a preset set light receiving angle by the light receiving unit, and the calculation unit receives each light receiving angle obtained by the light receiving unit. A predetermined weighting calculation and a predetermined addition / subtraction calculation are performed on the photometric value at.

  Further, the optical characteristic measuring method according to the present invention illuminates the object to be measured and is reflected light reflected by the object to be measured under the illumination state, and includes a predetermined angle including a preset set light receiving angle. Reflected light at a plurality of light receiving angles within a range is received, and a predetermined weighting operation and a predetermined addition / subtraction operation are performed on a photometric value at each light receiving angle obtained by the light reception. .

  According to the above configuration, the object to be measured is illuminated, and is reflected light reflected by the object to be measured under the illumination state, and a plurality of light receiving angles within a predetermined angle range including a preset set light receiving angle. Reflected light is received, and a predetermined weighting operation and a predetermined addition / subtraction operation are performed on the photometric values at the respective light receiving angles obtained by the light reception.

  As described above, reflected light at a plurality of light receiving angles within a predetermined angle range including a preset set light receiving angle is received by the light receiving unit, and for each photometric value obtained by this light reception, a predetermined value is obtained. Since a weighting operation and a predetermined addition / subtraction operation are performed, a desired (target) photometric value can be obtained from each photometric value, that is, a certain light receiving opening angle (light receiving angle range; angle) in the light receiving unit. An arbitrary (other) photometric value, that is, another light receiving opening angle can be obtained from the light measuring value in the range), that is, the light receiving opening angle can be made variable. Therefore, it is possible to measure at an arbitrary light receiving opening angle. Further, since it becomes possible to obtain an arbitrary photometric value based on the certain photometric value, compatibility with a measured value by another device or a previous measured value by the same device is maintained (the compatibility of the device is reduced). Can be maintained). In addition, even when the photometric value (light-receiving angle distribution characteristic) has wavelength dependency, it is possible to obtain an arbitrary photometric value from a certain photometric value by weighting for each wavelength. Can be maintained.

  In the above configuration, it is preferable that the light receiving control unit causes the light receiving unit to receive reflected light at the plurality of light receiving angles at predetermined angular pitch positions within the angle range.

  According to this, since the reflected light at the plurality of light receiving angles at the predetermined angle pitch positions within the predetermined angle range including the set light reception angle is received by the light receiving unit by the light receiving control unit, the plurality of light beams at the predetermined angle pitch positions are received. The desired (desired) desired photometric value (second received light angle distribution characteristic) can be easily obtained from the measured photometric value (first received light angle distribution characteristic). In addition, it becomes possible to obtain | require arbitrary target photometry value more accurately and more accurately by making this angle pitch smaller and increasing a light-receiving position (photometry value).

  In the above configuration, the light receiving unit is orthogonal to a geometry plane including an optical axis of incident light incident on the object to be measured and an optical axis of reflected light from the object to be measured, and the optical axis of the incident light. And an axis passing through the intersection of the reflected light and the optical axis of the reflected light. The light receiving control unit is configured to rotate within the predetermined angle range including the set light receiving angle by rotating the light receiving unit. Reflected light at a plurality of light receiving angles may be received by the light receiving unit.

  According to this, the light receiving unit is orthogonal to the geometry plane including the optical axis of the incident light incident on the object to be measured and the optical axis of the reflected light from the object to be measured, and the optical axis of the incident light and the light of the reflected light. It is configured to be rotatable about an axis passing through the intersection with the axis, and the light receiving control unit rotates the light receiving unit so that the reflected light at a plurality of light receiving angles within a predetermined angle range including the set light receiving angle is obtained. Since the light receiving unit receives the light, the configuration in which the reflected light at the plurality of light receiving angles is received by the light receiving unit can be realized with a simple configuration.

  Further, in the above configuration, the light receiving unit is rotatable about a toroidal mirror having a reflection surface rotationally symmetric with respect to a central axis in contact with the measurement surface of the object to be measured, and a rotational axis that coincides with the central axis. A rotating optical system configured to reflect reflected light corresponding to a rotation angle among reflected light reflected by the reflecting surface of the toroidal mirror, and a light receiving sensor that receives light guided by the rotating optical system. The light receiving control unit may cause the light receiving unit to receive reflected light at a plurality of light receiving angles within a predetermined angle range including the set light receiving angle by rotating the rotating optical system.

  According to this, the light receiving part is configured to be rotatable about a toroidal mirror having a reflection surface rotationally symmetric with respect to the central axis in contact with the measurement surface of the object to be measured, and a rotational axis that coincides with the central axis. Of the reflected light reflected by the reflecting surface of the mirror, it is provided with a rotating optical system that reflects the reflected light corresponding to the rotation angle, and a light receiving sensor that receives the light guided by the rotating optical system. As the rotating optical system is rotated by the control unit, reflected light at a plurality of light receiving angles within a predetermined angle range including a set light receiving angle is received by the light receiving unit, so that reflection at the plurality of light receiving angles is performed. A configuration in which light is received by the light receiving unit can be realized with a compact configuration (the device can be miniaturized).

  In the above configuration, the weight value in the weighting calculation is based on the known first light reception angle distribution characteristic that is the characteristic of the photometric value at the light reception opening angle of the light receiving unit, and the first light reception angle distribution characteristic. It is preferable that the light reception angle distribution characteristic is calculated from the relationship with the known second light reception angle distribution characteristic in the optical characteristic measurement apparatus or another optical characteristic measurement apparatus different from the apparatus.

  According to this, the weight value in the weighting calculation is calculated based on the known first light reception angle distribution characteristic which is the characteristic of the photometric value at the light reception opening angle of the light receiving unit and the first light reception angle distribution characteristic. Since the angle distribution characteristic is a value obtained from the relationship with the known second light receiving angle distribution characteristic in the optical characteristic measurement device or another optical characteristic measurement device different from the device, the weight value is used, Obtaining a desired (target) photometric value (second light receiving angle distribution characteristic) from the photometric value (first light receiving angle distribution characteristic) at each light receiving angle obtained by the light receiving unit with high accuracy and ease. It becomes possible.

In the above configuration, the relationship between the first light receiving angle distribution characteristic and the second light receiving angle distribution characteristic is preferably the following expression (1) when the angle range and the angle pitch are fixed.
Σ (first acceptance angle distribution characteristic × weight value) = second acceptance angle distribution characteristic (1)
However, the symbol “Σ” indicates that a sum is obtained for each first light receiving angle distribution characteristic obtained by photometry at the predetermined angular pitch position, and the symbol “×” indicates multiplication.

  According to this, since the relationship between the first light reception angle distribution characteristic and the second light reception angle distribution characteristic is the above expression (1) when the angle range and the angle pitch are fixed, the expression (1) The weight value can be easily obtained by using a simple expression. In other words, a desired photometric value (second light receiving angle distribution characteristic) can be easily obtained from the photometric value (first light receiving angle distribution characteristic) at each light receiving angle obtained by the light receiving unit using the weight value. Can do.

  In the above configuration, it is preferable that the weight value is a value calculated as a weight value satisfying the equation (1) for each wavelength of light received by the light receiving unit.

  According to this, since the weight value is a value calculated as a weight value satisfying Equation (1) for each wavelength of light received by the light receiving unit, even if the photometric value has wavelength dependency, Therefore, a desired photometric value (second light receiving angle distribution characteristic) can be obtained from the photometric value (first light receiving angle distribution characteristic), and further, between devices (between the photometric value and the light receiving angle distribution characteristic). ) Compatibility can be maintained.

  Further, in the above configuration, the calculation unit further performs a calculation using a predetermined value for calculating reflection characteristics on a calculated photometric value obtained by performing a predetermined weighting calculation and a predetermined addition / subtraction calculation on the photometric value. Thus, it is preferable to calculate the reflection characteristic value of the object to be measured.

  According to this, a calculation using the predetermined value for calculating the reflection characteristic is further performed by the calculation unit on the calculated photometric value obtained by performing the predetermined weighting calculation and the predetermined addition / subtraction calculation on the photometric value. Thus, the reflection characteristic value of the object to be measured is calculated, so that the reflection characteristic value can be easily calculated based on the photometric value at each light receiving angle obtained by the light receiving unit.

  According to the present invention, the reflected light at a plurality of light receiving angles within a predetermined angle range including a preset set light receiving angle is received by the light receiving unit, and for each photometric value obtained by this light reception, a predetermined value is obtained. Since a predetermined addition / subtraction calculation is performed, a desired (target) photometric value can be obtained from each photometric value, that is, a certain light reception opening angle (light reception angle range; An arbitrary (other) photometric value, that is, another light receiving opening angle can be obtained from the light measuring value in the angle range), that is, the light receiving opening angle can be made variable. Therefore, it is possible to measure at an arbitrary light receiving opening angle. Further, since it becomes possible to obtain an arbitrary photometric value based on the certain photometric value, compatibility with a measured value by another device or a previous measured value by the same device is maintained (the compatibility of the device is reduced). Can be maintained). In addition, even when the photometric value (light-receiving angle distribution characteristic) has wavelength dependency, it is possible to obtain an arbitrary photometric value from a certain photometric value by weighting for each wavelength. Can be maintained.

  FIG. 1 is a diagram illustrating an external appearance example of a multi-angle colorimeter that is an example of an optical characteristic measuring apparatus according to an embodiment of the present invention. As shown in FIG. 1, the multi-angle colorimeter 1 includes a holding unit 1a held by an operator, an operation display unit 1b provided on one end side of the holding unit 1a, and the other end of the holding unit 1a. It comprises a contact portion 1c provided on the side, and has a portable structure (handy type) that can be carried.

  The holding unit 1 a is provided with a measurement trigger button 1 a-1 for performing an input for instructing start of a measurement operation for the object to be measured. The measurement trigger button 1a-1 is installed at a position where the thumb abuts when the measurer grips the holding unit 1a in consideration of the operability of the measurement operation start instruction input, for example. The operation display unit 1b includes a display unit 1b-1 for displaying measurement results, a power button for switching on / off of the power source, a display switching button for switching on / off of the display operation by the display unit 1b-1, and the like. 1b-2. The abutting portion 1c is a portion having a bottom surface 1c-1 that is brought into contact with the measurement surface of the object to be measured, and a measurement opening 3 is formed in the bottom surface 1c-1.

  FIG. 2 is a cross-sectional view showing a configuration in the vicinity of the measurement opening 3. As shown in FIG. 2, the bottom surface 1 c-1 of the contact portion 1 c has a flat surface, and the measurement opening 3 has an elliptical shape, for example, in this flat surface. Hereinafter, this plane is referred to as an aperture plane X, the center of the measurement aperture 3 is referred to as an aperture center O, and a straight line that is orthogonal to the aperture plane X and passes through the aperture center O is referred to as a normal G. In FIG. 2, the bottom surface 1 c-1 of the contact portion 1 c and the measurement surface of the measurement object S are illustrated separately from each other to show the opening plane X, but the measurement surface of the measurement object S is uniform. In the case of a flat surface, the bottom surface 1c-1 of the contact portion 1c and the measurement surface of the object S to be measured are in close contact.

  FIG. 3 is a diagram illustrating an example (first embodiment) of the internal configuration of the multi-angle colorimeter 1. FIG. 4 is a block diagram showing a control system of the multi-angle colorimeter 1. As shown in FIGS. 3 and 4, the multi-angle colorimeter 1 includes an illumination unit 10, a light receiving unit 20, and a control unit 30. The illuminating unit 10 includes a light source 11 composed of a halogen lamp, a xenon flash lamp, or the like, a light emitting circuit 12 that drives the light source 11, a light beam restricting plate 13 that restricts a light beam output from the light source 11, and a collimating lens 14. Configured. The light source is installed at a position having a predetermined angle (for example, 45 °) with respect to the normal G. The light beam restricting plate 13 is arranged so that its opening 13 a coincides with the focal position of the collimating lens 14. The light beam from the light source 11 that has passed through the opening 13 a of the light restricting plate 13 is collimated (collected) by the collimating lens 14. Light) is converted into a parallel light beam and guided to the measurement surface of the object S to be measured.

  The light receiving unit 20 is disposed at a light receiving optical system 21 that focuses the parallel light beam reflected from the object S to be measured, and an image forming position of the light receiving optical system 21, and restricts light that has passed through the light receiving optical system 21. And a light receiving sensor 23 that outputs spectral data corresponding to the light intensity, and a light receiving sensor 23 that outputs spectral data corresponding to the light intensity. The spectral intensity of the light beam that has passed through the light receiving optical system 21 and entered the entrance slit 22a is measured. FIG. 5 is a configuration diagram illustrating an example of the spectroscopic unit 22.

  As shown in FIG. 5, the spectroscopic unit 22 includes a lens 22b and a diffraction grating 22c in a case 22d in which the entrance slit 22a is formed at an appropriate position. The lens 22 b converts the measured light that has passed through the incident slit 22 a into parallel light and guides it to the diffraction grating 22 c, and forms a dispersed image of the incident slit 22 a dispersed by the diffraction grating 22 c on the light receiving surface of the light receiving sensor 23. The diffraction grating 22c has a function of reflecting and dispersing incident measurement light according to the wavelength, and forms a dispersion image of the incident slit 22a on the light receiving sensor 23. The light receiving sensor 23 includes a plurality of light receiving channels (pixels) arranged at a predetermined interval, and is constituted by, for example, a silicon photodiode array in which silicon photodiodes are arranged in one line in one direction. The dispersed light (incident slit dispersion image) incident on each light receiving channel of the light receiving sensor 23 is converted into a current by the photoelectric conversion action of each photodiode.

  3 and 4, the analog light reception signal output from each light receiving channel of the light receiving sensor 23 is subjected to amplification processing by an unillustrated amplifier circuit and A / D conversion processing by the A / D conversion unit 24. Thereafter, the light is taken in by the control unit 30, and the control unit 30 calculates the spectral intensity of the light to be measured and the reflection characteristic value based on the spectral intensity.

  The spectroscopic unit 22 is connected to an arm 26 as an example of a driving force transmission member that receives a driving force from the motor 25. The spectroscopic unit 22 and the light receiving sensor 23 are integrated. When the arm 26 receives a driving force from the motor 25, the spectroscopic unit 22 and the light receiving sensor 23 cause the optical axis L1 of the incident light incident on the measurement object S and the optical axis of the reflected light from the measurement object S to be measured. Rotate an axis that is orthogonal to a plane R including L2 (paper surface in FIG. 1; hereinafter referred to as a geometry plane) and that passes through the intersection (opening center O) of the optical axis of the incident light and the optical axis of the reflected light. As an axis, it rotates in the direction of arrow Q shown in FIG. With this configuration, the light receiving unit 20 can change the light receiving position of the reflected light, and can receive the reflected light at a plurality of light receiving positions. The light receiving position is defined by a light receiving angle, and in the present embodiment, the light receiving angle is an angle formed between the normal G and the optical axis of the light receiving unit 20 (light receiving optical system 21). .

  The control unit 30 is a storage unit such as a CPU (Central Processing Unit), a ROM (Read Only Memory) that stores a program that defines the operation of the CPU, and a RAM that temporarily stores data. Etc., and controls the overall operation of the multi-angle colorimeter 1. The control unit 30 is functionally based on an illumination control unit 31 that controls the light emission operation of the light source 11, a light reception control unit 32 that controls the light reception operation of the light reception sensor 23, and an output signal from the light reception sensor 23. An arithmetic processing unit 33 for obtaining the reflection characteristic value of the object S and a drive control unit 34 for controlling the driving of the motor 25 are provided.

  Here, the light reception angle distribution characteristics of a multi-angle colorimeter (hereinafter referred to as a measuring device as appropriate) will be described. In general, a light reception opening angle or light reception angle distribution characteristic in light reception has a certain width, and the characteristic is different for each measuring device (or even in the same measuring device, for example, in the previous measurement and the current measurement). It will be different. FIG. 6A is a diagram schematically showing an example of the light receiving angle distribution characteristic of a certain optical characteristic measuring device (multi-angle colorimeter), and the horizontal axis represents the light receiving angle (light receiving angle; The vertical axis indicates the relative sensitivity of light reception. FIG. 6B schematically shows an example of the light receiving angle distribution characteristic of a so-called target optical property measuring device (multi-angle colorimeter) that is compatible with the optical property measuring device of FIG. FIG. Here, a case is considered in which the light reception angle distribution characteristic of FIG. 6B is a so-called wide light reception angle distribution characteristic compared to the light reception angle distribution characteristic of FIG.

  FIGS. 7A and 7B are schematic diagrams for explaining that the measured value (photometric value) varies depending on the difference in the light-receiving angle distribution characteristics. FIG. 7A is a diagram of FIG. FIG. 7B corresponds to the case where the light reception angle distribution characteristic of FIG. 6B is obtained when the light reception angle distribution characteristic is obtained. However, in FIG. 7, when the measurement surface of the object to be measured S is illuminated by the illumination system (light source 11), the intensity distribution of reflected light reflected by the measurement surface, that is, the reflection intensity M for each angle, is measured from the opening center O. The distance is shown in magnitude. The protruding portion (peak position) in the reflection intensity M indicates specularly reflected light (specularly reflected light component), and the other portion indicates diffused light (diffused light component).

  Specifically, FIGS. 7A and 7B show the specularity from the reflection intensity M (reflection characteristic) of a certain object S to be measured and the position of specular reflection light indicated by symbol A under 45 ° illumination. The state of light reception at the measurement position indicated by the symbol B moved by the angle + 15 ° is shown. However, in the figure, the angle indicated by the symbol J, that is, the angle from the normal G to the measurement surface of the object S to be measured is the light receiving angle (light receiving angle J), and the angle indicated by the symbol K or K ′ is the measurement. With a light receiving opening angle (light receiving opening angles K ′, K; this light receiving opening angle is also expressed as “light receiving opening angle”) with respect to the light receiving system at the position B (the light receiving unit 20, specifically, the light receiving optical system 21). is there. As shown in the figure, the light receiving opening angle K ′ is larger than the light receiving opening angle K, and the larger the light receiving opening angle, the larger the area (photometric value) of the shaded portion in the reflection intensity M, that is, the light receiving opening. When the light reception angle distribution characteristic (FIG. 6A) when the angle K is obtained and when the light reception angle distribution characteristic (FIG. 6B) when the light reception opening angle K ′ is obtained, In other words, it can be seen that the measurement results are different between a measuring instrument with a narrow acceptance angle distribution characteristic and a measuring instrument with a wide acceptance angle distribution characteristic. In addition, since the photometric value includes various reflected light components from the glitter material, the fact that the photometric value is different does not mean that the amount of light is different, but so-called “color”. It shows changing.

  By the way, the light receiving angle distribution characteristic varies depending on the wavelength. FIG. 8A shows an example in which the peak positions of the light reception angle distribution characteristics differ according to the difference in wavelength, for example, according to the difference in wavelength of 400 nm, 500 nm, and 600 nm. Similar to FIG. 6, the horizontal axis represents the light receiving angle, and the vertical axis represents the relative sensitivity. Such a characteristic appears when, for example, the so-called mixing property of the light receiving optical system of the measuring instrument is poor, and the light condensing characteristic on the incident slit surface (incident slit 22a) changes for each light receiving angle. Further, FIG. 8B shows how the light reception angle distribution characteristic spreads (a portion with a low relative sensitivity or a light reception angle) according to the difference in wavelength, and here again, for example, according to the difference between the wavelengths of 400 nm, 500 nm, and 600 nm. An example in which the spread at the bottom of the distribution characteristic graph is different is shown. Such characteristics occur, for example, when an optical fiber is used in the light receiving optical system of the measuring instrument, because the NA of the optical fiber changes depending on the wavelength.

  As described above, the light reception angle distribution characteristic varies depending on the difference between the measuring instruments and the difference in wavelength. In the present embodiment, so-called so-called difference in the received light angle distribution characteristics is obtained by actually measuring a photometric value of a desired received light angle distribution characteristic (arbitrary received light angle distribution characteristic) in order to interpolate the difference in the received light angle distribution characteristics. The main characteristic point is to obtain the measured value (photometric value) of the received light angle distribution characteristic by performing a predetermined calculation.

  FIGS. 9A and 9B show a case where a predetermined calculation is performed on the reception angle distribution characteristic obtained by measuring with a measuring instrument, specifically, a calculation for multiplying a predetermined weight (weight) is performed. It is a schematic diagram illustrating that it is possible to obtain a photometric value of a target light reception angle distribution characteristic (referred to as a target light reception angle distribution characteristic) by further performing addition / subtraction calculation. The horizontal axis and the vertical axis represent the light receiving angle and the relative sensitivity as described above.

  FIG. 9A assumes the case where the spread of the light reception angle distribution characteristic of the measuring device is changed, and the original light reception angle distribution characteristic (the light reception angle distribution characteristic obtained by measuring with the measurement device is referred to as “original This indicates that it is possible to create a light receiving angle distribution characteristic that is broader than "light receiving angle distribution characteristic". Here, a plurality of so-called small reception angle distribution characteristics at each reception angle indicated by dotted lines (broken lines) in the figure are synthesized to obtain one reception angle distribution characteristic H (so-called pseudo reception angle distribution characteristic). Specifically, each sensitivity of the discrete light receiving angles indicated by the dotted lines (the light receiving angle distribution characteristics are expressed as “sensitivity” because the light receiving angle distribution characteristics are relative sensitivities at a certain light receiving angle. The original light receiving angle distribution characteristic is also expressed as “original sensitivity”), for example, by multiplying a weight that is symmetrical with respect to the center (a predetermined center position determined when the plurality of original sensitivities are viewed as a whole) as a boundary. By adding together, it is possible to obtain a light receiving angle distribution characteristic H (also expressed as “combined sensitivity H” obtained by combining the original sensitivities). Therefore, if the angle range (light reception angle range) and pitch (for example, the movement angle pitch of the light receiving unit 20 described later; 0.4 ° pitch) and the weight are set appropriately for each wavelength, the desired light reception is achieved. Angular distribution characteristics (sensitivity) can be obtained.

  FIG. 9B shows that the light receiving angle distribution characteristic in which the peak position of the light receiving angle distribution characteristic of the measuring device is shifted can be created. In this case as well, one light reception angle distribution characteristic I (pseudo light reception angle distribution characteristic) is obtained by synthesizing a plurality of so-called small light reception angle distribution characteristics at the respective light reception angles indicated by dotted lines. In other words, the distribution of the received light angle with the peak position shifted by adding each asymmetrical weight from the center to each sensitivity (original sensitivity, original received light angle distribution characteristic) of the discrete received light angle shown by the dotted line. Characteristic I (synthesis sensitivity I) can be obtained. In this case as well, desired angle distribution characteristics (sensitivity) can be obtained if the angle range, pitch, and weight are set appropriately for each wavelength.

  In general, even if the arrangement is similar, for example, the light receiving angle distribution characteristic (photometric value) varies depending on the characteristics of the light receiving optical system, so that compatibility between measuring instruments cannot be achieved. . However, if a combined light reception angle distribution characteristic can be created from a certain original light reception angle distribution characteristic as described above, compatibility between measuring instruments is maintained, that is, the light reception angle distribution characteristic (photometric value) is Even with different measuring instruments (including the same measuring instrument), compatibility can be maintained.

  By the way, the “weight” refers to the light reception angle distribution characteristic (light reception angle distribution characteristic st1) of its own measuring device that has been obtained in advance and the target measuring device that has been obtained in advance (the own measuring device). Alternatively, it may be obtained by so-called reverse calculation from the light receiving angle distribution characteristic (light receiving angle distribution characteristic st2) of another measuring device. That is, a weight value that can create a desired desired reception angle distribution characteristic in a pseudo manner by using the known reception angle distribution characteristic of itself (the measurement values of these two reception angle distribution characteristics can be combined). It is. The control unit 30 (for example, the arithmetic processing unit 33) stores the weight data obtained in advance. However, only this weight value may be stored and this value may be used as it is, or each of the known light receiving angle distribution characteristic data may be stored, and if necessary (every measurement), a required value may be obtained. The weight may be calculated.

  Further, the weight for the light reception angle distribution characteristic in its own measuring device is, for example, an angle range at a certain standard measurement position when it is desired to convert a certain light reception angle distribution characteristic into an arbitrary light reception angle distribution characteristic in the same measuring device. This is a weight value used for the former acceptance angle distribution characteristic when it is desired to convert the acceptance angle distribution characteristic at ± 5 ° to the acceptance angle distribution characteristic in the angle range ± 10 ° at the same standard measurement position. The method using this weight can also be applied to the reception angle distribution characteristics for each wavelength described later in its own measuring device (same measuring device).

As a specific calculation method of the weight, when the weight is “Wt”,
Σ (light receiving angle distribution characteristic st1 × Wt) = light receiving angle distribution characteristic st2
The weight Wt that satisfies the following equation may be obtained. However, Σ (light receiving angle distribution characteristic st1 × Wt) is obtained in a state in which values of an angle range (for example, ± 1 °) and an angle pitch (for example, 0.4 °) are fixed. If the desired accuracy cannot be obtained, the optimum solution may be obtained by changing the angle range and the angle pitch.

  Further, by obtaining the weight Wt from the above formula for each wavelength, it is possible to cope with the case where the light reception angle distribution characteristic has wavelength dependency. Normally, although the wavelength dependence is not considered in the light receiving angle distribution characteristic (the measuring instrument is not designed considering that much), the weight per wavelength (weight for one wavelength) is used as in this embodiment. Therefore, it is possible to cope with the difference in the reception angle distribution characteristic due to the difference in wavelength. That is, the reception angle distribution characteristic at another target wavelength can be created from the reception angle distribution characteristic at a certain wavelength. This makes it possible to increase the measurement accuracy and the degree of freedom of measurement between the same measuring devices or different measuring devices, and the compatibility is increased. Note that the “wavelength” indicates, for example, a wavelength for every 10 nm pitch in a wavelength range after spectral separation by the spectroscopic unit 22, for example, in a visible range of 400 nm to 700 nm in a reflected color.

  Note that the generation of the light reception angle distribution characteristic st2 from the light reception angle distribution characteristic st1 is actually performed by preparing the measuring instrument of this embodiment and, for example, an industry standard measuring instrument, and measuring the same measurement sample. The weights are multiplied so that the measurement results match. In principle, the light reception angle distribution characteristic st2 is obtained by multiplying the light reception angle distribution characteristic st1 by weight as in the above equation.

  In the above description, the light receiving angle distribution characteristics H and I are symmetric (laterally symmetric), but may be asymmetric. In practice, the light is measured with the light receiving unit 20 tilted in the rotation direction with respect to the object S to be measured. In addition, so-called so-called conversion of the respective light reception angle distribution characteristics to obtain a desired light reception angle distribution characteristic, multiplying the weight or performing addition / subtraction calculation is expressed as “light reception angle distribution characteristic conversion calculation”.

  In each of the cases shown in FIGS. 9A and 9B, the exposure time (exposure amount) of the light receiving sensor 23 at the time of measurement may be changed instead of applying a weight. In this case, it is equivalent to multiplying all wavelengths uniformly, so if there is no need to change the weight for each wavelength (using different weights), the extra calculation can be omitted (calculation Time can be shortened), and the measurement efficiency by the multi-angle colorimeter 1 can be improved.

  In this embodiment, the functional units 31 to 33 in the control unit 30 perform the following processing with respect to obtaining a desired light reception angle distribution characteristic as described above. FIG. 10 is a flowchart showing a series of processing by the control unit 30. As shown in FIG. 10, the control unit 30 first performs dark photometry (step S1). In this dark photometry, the light source 11 is turned off in order to cancel offset values (output values obtained when light is not substantially incident on the light receiving sensor 23) of various circuits provided in the light receiving sensor 23 and the light receiving unit 20. In this state, the light receiving operation of the light receiving sensor 23 is performed to obtain an output value. The output value (offset value) is stored in a storage unit such as a RAM or a ROM in the control unit 30. However, this dark metering may be omitted when the electrical stability is achieved.

  Next, the control unit 30 turns on the light source 11 (step S2) and sets the light receiving unit 20 in the vicinity of the measurement position, specifically, when the measurement position is zero, a position deviated from the measurement position by a predetermined angle, for example, −1 °. (Step S3). By the way, the “measurement position” here is a standard of DIN (German Industrial Standard), for example, when performing color measurement of metallic coating, + 15 °, +25 from the position of regular reflection light toward the normal G side. A position moved by an angle of each of °, + 45 °, + 75 °, and + 110 ° (hereinafter, referred to as an aspecular angle) is set as a measurement position. A measurement position of + 15 ° is shown. Accordingly, in step S3, the light receiving unit 20 (the optical axis position thereof) moves to a position moved by -1 ° from this + 15 °, that is, a position of the aspecular angle + 14 °.

  The control unit 30 causes the light receiving unit 20 to perform a photometric operation at the moved measurement position. At this time, a counter (not shown) that counts the number of times of photometry by the light receiving unit 20 is operated to set the count value N to N = 0 (step S4). Next, the light receiving unit 20 is rotated and moved to the normal G side in the arrow Q direction shown in FIG. 1 by a predetermined relatively small angular pitch (for example, 0.4 °) (step S5). The light receiving unit 20 is caused to perform the next photometric operation (step S6). At this time, the current count value N of the photometry count is incremented by 1 (N = N + 1) (step S7). The controller 30 determines whether or not the count value N has reached a predetermined value (Nt), for example, “5” (N = Nt). Step S5 returns to Step S5, and Steps S5 to S7 are repeated until “5” is reached. Thereby, the rotational movement with the minute angle pitch of 0.4 ° is performed five times in order, and the photometric operation at each position is performed six times in total. In addition, by the rotational movement from N = 0 to N = 5, the range from −1 ° to + 1 ° centered on + 15 ° (angle range of ± 1 ° of 15 °; 0.4 ° × 5 = 2) ° range) will be moved.

  When the count value reaches “5”, that is, when the measurement operation is completed at all positions of 0.4 ° pitch in the 15 ° ± 1 ° angle range (YES in step S8), the control unit 30 It is determined whether or not measurement is completed at all angular positions of + 15 °, + 25 °, + 45 °, + 75 °, and + 110 °. If not completed (NO in step S9), the process returns to step S3. Then, the light receiving unit 20 is rotated and moved to the next measurement position, that is, the position of + 25 °, specifically, the position moved by −1 ° from + 25 ° (the position of + 24 °) as described above, and 0.4 similarly. The measurement is performed by rotating and moving in increments of degrees, and the operations of steps S4 to S8 are repeated at the measurement positions + 45 ° ± 1 °, + 75 ° ± 1 °, and + 110 ° ± 1 °. In addition, this can be said to measure finely the set light reception angle and a plurality of light reception angles in the vicinity thereof for each measurement. When the measurement at all the positions is completed (YES in step S9), the control unit 30 turns off the light source 11 (step S10) and moves the light receiving unit 20 to a predetermined initial position, for example, a position of regular reflection light. (Step S11).

  And the control part 30 (arithmetic processing part 33) is each measurement position (pitch measurement) in each +15 degree measurement position (it expresses as a standard measurement position) +15 degrees by said DIN standard (it expresses as a standard measurement position). Based on each output value obtained from the light receiving sensor 23 by a photometric operation at (expressed as a position), a photometric value of a target light receiving angle distribution characteristic is calculated. Specifically, after subtracting the offset value stored in step S1 from each output value, a light receiving angle distribution characteristic conversion calculation is performed, that is, each output value is multiplied by a predetermined weight ( By performing addition / subtraction calculation (weighting is performed), a photometric value corresponding to a desired light receiving angle distribution characteristic is obtained (step S12). Further, the control unit 30 (calculation processing unit 33) uses (multiplies) the photometric value obtained in step S12 and other calibration coefficients necessary for the calculation of the reflection characteristic value to reflect the reflection characteristic value at each standard measurement position. Is calculated (step S13). The calculation for calculating the reflection characteristic value is expressed as “reflection characteristic value calculation calculation”.

  The angle range is not limited to ± 1 °, and may be an arbitrary angle range such as ± 5 °. The moving angle pitch is not limited to 0.4 °, but may be any pitch such as 0.1 °, 0.2 °, or 1 °. In this case, for example, a range of ± 1 ° at a pitch of 0.2 °, or a range of ± 5 ° at a pitch of 1 ° when so-called coarse measurement is performed may be used. The standard measurement position may be an angle other than + 15 °,... + 110 °, or the measurement position according to the DIN standard may not be adopted. In short, the evaluation may be performed at an arbitrarily set angular position.

In this case, the following modifications may be employed instead of or in addition to the above embodiments.
[1] The configuration for changing the light receiving angle for receiving the reflected light reflected from the object S to be measured is that the spectroscopic unit 22 and the light receiving sensor 23 integrated as in the above-described embodiment are moved by the motor 25 to the arrow Q shown in FIG. In addition to the configuration of driving in this direction, the following configuration can also be adopted. 11 is a cross-sectional view showing another example of the internal configuration of the multi-angle colorimeter, FIG. 12 is a side cross-sectional view taken along the normal line G in FIG. 11, and FIG. 13 is a side cross-sectional view taken at the position of the light source shown in FIG. FIG. 14 and FIG. 14 are perspective views showing the internal configuration of the multi-angle colorimeter in three dimensions.

  As shown in FIGS. 11 to 14, the multi-angle colorimeter 100 of the present embodiment includes a toroidal mirror having a reflection surface that is rotationally symmetric with respect to a central axis Z (see FIGS. 12 to 14) that is in contact with the measurement surface Sa. 110, an illumination unit 120 that emits illumination light to the measurement surface Sa, a light receiving unit 130 that receives reflected light from the measurement surface Sa, and a control unit 30. The control unit 30 is the same as the control unit 30 in the first embodiment.

  The toroidal mirror 110 is a concave mirror having different cross sections in planes orthogonal to each other. The toroidal mirror 110 illustrated in the present embodiment has a central axis Z, and the cross-sectional shape in a plane orthogonal to the central axis Z is a relatively large arc 111 as shown in FIG. 12 is a semi-circular optical member whose in-plane cross-sectional shape is a relatively small arc 112 as shown in FIG. That is, when a plane including the normal G at the center P of the measurement surface Sa is defined as a measurement plane R (see FIG. 11), the toroidal mirror 110 has a central axis Z perpendicular to the measurement plane R and in contact with the measurement plane Sa. Have. The toroidal mirror 110 has a large arc-shaped cross section (arc 111) centered on the central axis Z in a plane orthogonal to the central axis Z, and a parabolic shape in the plane including the central axis Z. The cross section (arc 112). However, the arc 112 (parabola) is centered on a central axis Z in a plane parallel to the measurement plane R and separated by a predetermined distance, and is on a focal circumference 111f having a radius approximately half that of the arc 111. It is a parabola having a focal point F and having a perpendicular line h from the focal point F to the central axis Z as a symmetry axis.

  By providing such a toroidal mirror 110, the reflected light reflected from the measurement surface Sa, which is parallel to the measurement plane R perpendicular to the central axis Z and reflected on the central axis Z, is toroidal. Reflected by the mirror 110. Then, the light flux is converged at a position corresponding to the reflection direction of the reflected light reflected by the measurement surface Sa on the focal circumference 111f of the toroidal mirror 110.

  The illuminating unit 120 includes a light source 121 disposed on the focal circumference 111f of the toroidal mirror 110 and inclined at 45 ° with respect to the normal G. The illumination light beam output from the light source 121 is not directly irradiated onto the measurement surface Sa, but is once reflected by the toroidal mirror 110 and converted into a parallel light beam, as shown in FIGS. The measurement surface Sa is irradiated. By adopting such a configuration, the illumination unit 120 can be greatly increased compared to a configuration in which the light source 121 and the collimating lens 14 (see FIG. 3) as in the first embodiment are installed around the measurement surface Sa. It becomes possible to reduce the size.

  The light receiving unit 130 includes a light receiving optical system having a plane mirror 131 that functions as a rotating optical system and a relay lens 132 as a relay optical system, and a spectroscopic unit 22 and a light receiving sensor 23 that are substantially the same as those in the above embodiment. The relay lens 132 is a fixed optical system that does not rotate. Since the spectroscopic unit 22 and the light receiving sensor 23 are substantially the same as those in the above embodiment, the description thereof is omitted, and the same numbers as those in the above embodiment are given.

  The plane mirror 131 is an optical component having an elliptical shape (see FIG. 14) and a reflective surface with a high reflectance, and has a rotation axis 131x (see FIG. 12) that coincides with the central axis Z of the toroidal mirror 110. Yes. Specifically, the plane mirror 131 is installed at a predetermined angle with respect to the rotation axis 131x, and is rotated around the rotation axis 131x (in the direction of the arrow c shown in FIGS. 11 and 14) by the control unit 30. It is designed to be driven. The rotation range of the plane mirror 131 is set to rotate about 180 ° around the rotation axis 131x so as to face the entire range of the arc 111 in the toroidal mirror 110.

  That is, the plane mirror 131 reflects the light beam at a position where all the light beams reflected by the toroidal mirror 110 and converged on the focal circumference 111f can enter, and in the direction of the central axis Z (rotation axis 131x). It is arranged so as to be rotatable at a possible predetermined inclination angle. Then, the convergence position of the light beam on the focal circumference 111f is selected according to the rotation angle of the plane mirror 131, and only the light beam in a specific direction is guided to the entrance slit 22a (incident aperture) of the spectroscopic unit 22. Thus, by the rotation of the plane mirror 131, the reflected light to be received among the reflected light reflected from the measurement object S can be changed, and as a result, the reflected light can be received at a plurality of light receiving angles. In the present embodiment, the light receiving angle refers to an angle formed by the normal line G and the optical axis of a light beam (reflected light beam 121c described later) reflected by the measurement surface Sa and incident on the toroidal mirror 110.

  FIG. 15 is a diagram for explaining the function of the plane mirror 131, and schematically shows a cross section in a plane that passes through the intersection T between the reflection surface of the plane mirror 131 and the central axis Z shown in FIG. 14 and is orthogonal to the central axis Z. FIG. As indicated by the solid line in FIG. 15, when the ridgeline of the cross section of the plane mirror 131 is parallel to the measurement surface Sa, the component parallel to the radius RP1 that coincides with the normal line G among the reflected light from the measurement surface Sa is toroidal. The light is reflected by the reflection surface portion A1 facing the measurement surface Sa in the mirror 110, converged at the point F1 on the focal circumference 111f, and selectively refocused on the entrance slit 22a.

  On the other hand, when the ridgeline of the cross section of the plane mirror 131 is rotated by a predetermined angle θ from the state parallel to the measurement surface Sa as shown by the dotted line in FIG. 15, the component parallel to the radius RP2 rotated from the normal G by the angle θ. Is reflected by the reflecting surface portion A2 facing the measurement surface Sa in the toroidal mirror 110, converged at a point F2 on the focal circumference 111f, and selectively refocused on the entrance slit 22a. Thus, the plane mirror 131 can select the direction of the reflected light according to the rotation angle, and can enter the incident slit 22a. That is, the angle of the light receiving direction with respect to the illumination direction of the plane mirror 131 is variable according to the rotation angle of the plane mirror 131. The relay lens 132 is an optical lens having a positive optical power, and converges the reflected light in the direction of the central axis Z (rotation axis 131x) reflected by the plane mirror 131 to the entrance slit 22a. Thereby, the light beam converged at a predetermined position on the focal circumference 111f selected in accordance with the rotation angle of the plane mirror 131 enters the entrance slit 22a.

  The operation (optical path) of the multi-angle colorimeter 100 configured as described above will be described with reference to FIGS. 11, 12, and 14. A light beam 121a output from the light source 121 disposed at a position inclined by 45 degrees with respect to the normal G toward the toroidal mirror 110 is reflected by the toroidal mirror 110, is parallel to the measurement plane R, and is a normal line. The measurement surface Sa is irradiated with a parallel light beam 121b having a direction of an angle of 45 degrees. The parallel light beam 121b is reflected by the measurement surface Sa according to the reflection characteristics of the measurement surface Sa.

  Of this reflected light, a reflected light beam 121c (components parallel to the measurement plane R) is reflected by the toroidal mirror 110 (FIGS. 11 and 12 show only the light beam in the normal G direction). The Then, since the arc 112 of the toroidal mirror 110 is a parabola with the perpendicular h as the target axis, the reflected light beam 121d is reflected by the measurement surface Sa on the focal circumference 111f. It is converged to a position corresponding to the reflection direction (a point depending on the reflection direction at the toroidal mirror 110).

  Each point on the focal circumference 111 f has an imaging relationship with the entrance slit 22 a of the spectroscopic unit 22 by the plane mirror 131 and the relay lens 132. Further, the light beam converged at each point on the focal circumference 111f is selected by the rotation of the plane mirror 131. Therefore, an optical path from the toroidal mirror 110 to the entrance slit 22a is formed according to the rotation angle of the plane mirror 131. That is, the diffused light beam 121e from the focal point F selected by the plane mirror 131 is reflected by the plane mirror 131 in the direction of the central axis Z (rotation axis 131x) and enters the relay lens 132. And it is made into the light beam 121f converged by this relay lens 132, and injects into the entrance slit 22a.

  At this time, the spectral intensity measured by the light receiving sensor 23 is the spectral intensity of the reflected light in the direction determined by the rotation angle of the plane mirror 131. In the example of FIG. 11, since the rotation angle of the plane mirror 131 is the rotation angle at which the reflected light in the normal G direction is selected, the spectral intensity of the reflected light in the direction of 0 ° to the normal angle with respect to the illumination light is Will be measured.

  Similarly to the above-described embodiment (measurement operation in the flowchart of FIG. 10), this modified embodiment [1] is sequentially controlled by the control unit 30, for example, + 15 °, + 25 °, + 45 °, + 75 °, and + 110 °. The photometry operation is performed at a pitch measurement position of every 0.4 ° in the ± 1 ° angle range, and based on each output value obtained from the light receiving sensor 23 by this photometry operation, the target photo acceptance angle distribution characteristic Calculates the photometric value (performs the acceptance angle distribution characteristic conversion calculation) and calculates the reflection characteristic value at each standard measurement position using the calculated photometric value and other calibration coefficients necessary for the calculation of the reflection characteristic value (Reflection characteristic value calculation calculation is performed). In the embodiment, the light receiving sensor 23 (the light receiving unit 20) is configured to receive light from an arbitrary light receiving angle by rotating the light receiving sensor 23. However, in the modification [1], the light receiving sensor 23 is fixed. The plane mirror 131 is rotated so that reflected light from each direction of the toroidal mirror 110 is incident on the light receiving sensor 23 to receive light from an arbitrary light receiving angle. In other words, the movement of the measurement position (standard measurement position, pitch measurement position) is realized by rotating the plane mirror 131 and changing the angle of the light receiving direction according to the rotation angle. This measurement operation (calculation method) is the same in the following modified embodiment [2].

[2] In putting the modified embodiment [1] into practical use, it is desirable to solve the following points (1) to (3).
(1) Since the rotation axis 131x of the plane mirror 131, the optical axis of the relay lens 132, and the incident slit 22a of the spectroscopic unit 22 are configured to coincide with the central axis Z of the toroidal mirror 110 in contact with the measurement surface Sa, the plane mirror 131, A part of the relay lens 132 and the spectroscopic unit 22 are arranged below the measurement surface Sa (see FIG. 12), and the measurement surface Sa and a part of the multi-angle colorimeter 100 interfere with each other, so that a large measurement target is obtained. Things cannot be measured.
(2) Since the light beam reflected by the toroidal mirror 110 converges at each point on the focal circumference 111f and then diffuses again and enters the plane mirror 131 and the relay lens 132, the plane mirror 131 or relay having a large effective diameter. There is a concern that the lens 132 is required and the multi-angle colorimeter 100 is increased in size.
(3) It is necessary to incorporate a reference optical system that monitors fluctuations in the light source 11.

  FIG. 16 is a front view showing the configuration of the multi-angle colorimeter 200 considering the points (1) to (3), and FIG. 17 is a side sectional view of FIG. The multi-angle colorimeter 200 is different from the multi-angle colorimeter 100 of the modification [1] described above in that the actual toroidal mirror 110 is disposed between the toroidal mirror 110 and the object S to be measured. This is the point that a reflecting mirror 201 is provided that bends the measurement plane R (see FIGS. 11 and 12) at a predetermined angle with the central axis Z. Thereby, the problem (1) can be solved, and the optical characteristics of the measurement surface Sa having a large size such as an automobile body can be measured. The multi-angle colorimeter 100 is different from the multi-angle colorimeter 100 in that the second relay lens 202 is disposed between the plane mirror 131 and the focal point circumference 111f as a relay optical system and the reference optical system 250 is provided. Thereby, the problems (2) and (3) are solved. Hereinafter, these differences will be mainly described. In addition, about the member which has a function similar to the said modification [1], the description is abbreviate | omitted and shall attach | subject the same number as the said modification [1].

  The reflecting mirror 201 is a flat mirror having an elongated rectangular shape, and is fixed between the central axis Z of the toroidal mirror 110 and the reflecting surface of the toroidal mirror 110 and is fixed at an inclination angle that bends the measurement plane R by 90 °. (See FIG. 17). The position of the measurement surface Sa is substantially equivalent to the position in contact with the central axis Z of the toroidal mirror 110, although the optical path is bent by the reflecting mirror 201. Thus, regarding the relationship between the toroidal mirror 110 and the measurement surface Sa, even if the measurement surface Sa is arranged so as to actually touch the central axis Z of the toroidal mirror 110 as in the previous multi-angle colorimeter 100, By interposing the reflecting mirror 201 as in the multi-angle colorimeter 200, the measurement surface Sa can be arranged in an aspect equivalent to an aspect that is not actually in contact with the central axis Z but is in contact therewith.

  The relay optical system includes a second relay lens 202 disposed between the plane mirror 131 and the focal circumference 111f in addition to the first relay lens 132 disposed between the plane mirror 131 and the entrance slit 22a. It is configured. Although the illustration of the second relay lens 202 is simplified, when the plane mirror 131 is driven to rotate, the second relay lens 202 rotates integrally with the plane mirror 131. By adding the second relay lens 202, it is possible to suppress the diffusion of the light beam converged at each point on the focal circumference 111f, and thereby the light beam incident on the plane mirror 131 and the first relay lens 132 is reduced. The effective diameters of the plane mirror 131 and the first relay lens 132 can be suppressed. Therefore, the multi-angle colorimeter 100 can be made compact.

  The reference optical system 250 includes a diffusing plate 251 and a reference fiber 252, and the reference light beam 260 r (output from the light source 11) reflected by the extension 110 x extending in the central axis Z direction of the toroidal mirror 110. It is installed at a position where a part of the luminous flux enters. The diffusing plate 251 constitutes an incident surface of the reference optical system 250, is made of an optical member having a property of diffusing and transmitting incident light, and is disposed on the central axis Z of the toroidal mirror 110. Note that the diffusion plate 251 is installed at a position where it does not interfere with the reflecting mirror 201, as shown in FIG. The reference fiber 252 has an incident end 252a disposed on the back side of the diffuser plate 251, and a reference light beam 251r of the reference light beam 260r incident on the diffuser plate 251 and diffused and transmitted through the diffuser plate 251 is used for reference. The light enters the incident end 252a of the fiber 252 as reference light.

  Instead of installing the diffuser plate 251, the incident end 252 a of the reference fiber 252 may be arranged directly on the central axis Z of the toroidal mirror 110 to take in the reference light. However, if the configuration is such that the reference light is introduced into the incident end 252a of the reference fiber 252 via the diffuser plate 251 as in this embodiment, a part of the reference light beam 260r diffused by the diffuser plate 251 is incident on the incident end 252a. For example, even when a plurality of light sources are arranged on the focal circumference 111f, the reference light for the light source in each direction can be taken into the incident end 252a of the reference fiber 252. There are advantages.

  The spectroscopic unit 22 according to the present embodiment includes a dual channel type including two incident slits, the above-described incident slit 22a through which the reflected light passing through the relay optical system enters and a reference light slit 22e for allowing the reference light to enter. It has the composition of. The entrance slit 22a is disposed on an extension line of the central axis Z, and the output end 252b of the reference fiber 252 is connected to the reference light slit 22e.

  As a mechanism for driving the plane mirror 131 to rotate, the present embodiment shows an example in which a motor unit 253 including a pulse motor and a pulse motor drive circuit is used (see FIG. 17). The output shaft of the pulse motor is directly connected to the rotation shaft 253a of the plane mirror 131, and a predetermined drive pulse is applied to the pulse motor from the pulse motor drive circuit, so that the plane mirror 131 is rotated around the rotation shaft 253a. It is configured as follows. The operation of the motor drive circuit is controlled by the control unit 30.

  The operation (optical path) of the multi-angle colorimeter 200 configured as described above will be described with reference to FIGS. The light beam 121a output from the light source 11 disposed at a position inclined by 45 degrees with respect to the normal line G is reflected by the toroidal mirror 110 to become a parallel light beam 121b in the direction of the normal line angle of 45 degrees. A parallel light beam 121c that is incident on 201 and reflected by the reflecting mirror 201 is irradiated onto the measurement surface Sa. On the measurement surface Sa, the parallel light beam 121c is reflected according to the reflection characteristics of the measurement surface Sa, and the reflected light beam 121d is incident on the reflection mirror 201 again and reflected.

  Of the reflected light, a reflected light beam 121e, which is a component parallel to the measurement plane R perpendicular to the central axis Z, is reflected by the toroidal mirror 110. Since the arc 112 of the toroidal mirror 110 is a parabola with the perpendicular h as the target axis, the reflected light beam 121f is reflected by the measurement surface Sa on the focal circumference 111f. The light is converged to a position 121g corresponding to the reflection direction. The convergence position 121g is selected according to the rotation angle of the plane mirror 131 as described above. Thereafter, the diffused light beam 121h from the convergence position 121g selected by the plane mirror 131 is narrowed down by the second relay lens 202, and the transmitted light beam 121i is reflected by the plane mirror 131 in the central axis Z direction. Incident to Then, the light is converged by the relay lens 132, and the light beam 121j enters the entrance slit 22a.

  On the other hand, with respect to the reference light, a part of the light beam output from the light source 121 and the reference light beam 260r reflected by the extension 110x of the toroidal mirror 110 is applied to the diffusion plate 251 and diffused and transmitted through the diffusion plate 251. Is incident on the incident end 252a of the reference fiber 252 as reference light. The reference light is transmitted by the reference fiber 252 and enters the reference light slit 22e.

  [3] In the modified embodiments [1] and [2], the example in which the light source 121 is disposed on the focal circumference 111f is illustrated. However, instead of this embodiment, the illumination unit having the configuration shown in FIG. 120 'may be installed. FIG. 18 is a diagram in which the configuration of the present embodiment is applied to the configuration of the modification [2]. As shown in FIG. 18, the illumination unit 120 ′ includes a light source 121, a light source reflecting mirror 122, and a condenser lens 123. The light source reflecting mirror 122 is disposed at a predetermined angle on the focal circumference 111f of the toroidal mirror 110, reflects the light beam 124a output from the light source 121 and converged by the condenser lens 123, and reflects the reflecting surface of the toroidal mirror 110. Are emitted as a diffused light beam 124b. The diffused light beam 124b is reflected by the toroidal mirror 110 to be converted into a parallel light beam 124c. The diffused light beam 124b is directly reflected on the measurement surface Sa (in the case of the modification [1], directly on the measurement surface Sa, or in the modification [2]. In this case, the measurement surface Sa is irradiated through the reflecting mirror 201). Note that the light beam 124a reflected by the extension 110x of the toroidal mirror 110 is irradiated on the diffusion plate 251 (see FIG. 17) as a reference light beam 260r.

  [4] When manufacturing the toroidal mirror 110 as in the modified embodiments [1] to [3], adopting a method of manufacturing the entire toroidal mirror 110 by integral molding provides a uniform and high reflectivity over the entire inner surface of the curved surface. It is difficult to secure. Therefore, the toroidal mirror 110 may be configured by a plurality of divided parts, and the toroidal mirror 110 may be configured by connecting (combining) these parts. However, in this case, due to a manufacturing error, a concave portion or a convex portion is formed on the surface of the joint portion of each component as indicated by an arrow W in FIG. 19, and the curved surface continuity of the reflecting surface of the toroidal mirror 110 is impaired. In such a joint portion, as shown in FIG. 20, the reflection of light is disturbed and a loss occurs in the reflectance of light. When the joint portion is located on the optical path from the measurement surface Sa of the object S to be received by the light receiving sensor 23, depending on the rotation angle of the plane mirror 131 when scanning is performed by the light receiving sensor 23. The loss amount changes, and the change in the loss amount appears as an error. Therefore, if the parts are designed so that the joint portion is located in an area used for illumination, that is, on the optical path from the light source 121 to the measurement surface Sa of the object S to be measured, the plane mirror 131 is rotated. Even if the angle changes, the amount of loss becomes substantially constant, so the above error hardly occurs (this error can be canceled if calibrated in advance).

  As described above, according to the optical characteristic measuring apparatus (multi-angle colorimeter 1, 100, 200) according to the present embodiment, the measurement object (measurement object S) is illuminated by the illumination unit (illumination unit 10, 120). Then, the reflected light reflected by the object to be measured under the illumination state by the illuminating unit is received by the light receiving unit (the light receiving units 20 and 130). Then, the light receiving control unit (control unit 30) at a plurality of light receiving angles (angle pitch positions) within a predetermined angle range (near the set light receiving angle) including a preset set light receiving angle (standard measurement position). The reflected light is received by the light receiving unit, and the photometric value (original sensitivity, original light receiving angle distribution characteristic) at each light receiving angle obtained by the light receiving unit is calculated by the calculation unit (control unit 30, calculation processing unit 33). A predetermined weighting calculation is performed and a predetermined addition / subtraction calculation is performed.

  Further, according to the optical characteristic measuring method in the present embodiment, the object to be measured is illuminated, and the reflected light is reflected by the object to be measured under the illumination state, and includes a predetermined light receiving angle that is set in advance. Reflected light at a plurality of light reception angles within the angle range (near the set light reception angle) is received, and a predetermined weighting calculation is performed and predetermined addition / subtraction is performed on the photometric values at each light reception angle obtained by the light reception. An operation is performed.

  As described above, reflected light at a plurality of light receiving angles within a predetermined angle range including a preset set light receiving angle is received by the light receiving unit, and for each photometric value obtained by this light reception, a predetermined value is obtained. Since a weighting operation and a predetermined addition / subtraction operation are performed, a desired (target) photometric value can be obtained from each photometric value, that is, a certain light receiving opening angle (light receiving angle range; angle) in the light receiving unit. Range (photometric value) (original sensitivity, original light reception angle distribution characteristic), any (other) photometric value, that is, another light reception opening angle (combined light reception angle distribution characteristic, light reception angle distribution characteristic H, I, composite sensitivity) H, I) can be obtained, that is, the light receiving opening angle can be made variable. Therefore, it is possible to measure at an arbitrary light receiving opening angle. Further, since it becomes possible to obtain an arbitrary photometric value based on the certain photometric value, compatibility with a measured value by another device or a previous measured value by the same device is maintained (the compatibility of the device is reduced). Can be maintained). In addition, even when the photometric value (light-receiving angle distribution characteristic) has wavelength dependency, it is possible to obtain an arbitrary photometric value from a certain photometric value by weighting for each wavelength. Can be maintained.

  Further, in the above configuration, the light reception control unit can detect a plurality of light reception angles at a predetermined angle pitch position (for example, every 0.4 ° pitch) within a predetermined angle range (for example, ± 1 °) including the set light reception angle. Since the reflected light is received by the light receiving unit, a desired (desired) arbitrary photometric value (second light receiving angle distribution) from a plurality of photometric values (first light receiving angle distribution characteristics) at the predetermined angular pitch position. Characteristics) can be easily obtained. In addition, it becomes possible to obtain | require arbitrary target photometry value more accurately and more accurately by making this angle pitch smaller and increasing a light-receiving position (photometry value).

  In the above configuration, the light receiving unit is orthogonal to the geometry plane including the optical axis of the incident light incident on the object to be measured and the optical axis of the reflected light from the object to be measured, and the optical axis of the incident light and the reflected light. Reflected light at a plurality of light receiving angles within a predetermined angle range including a set light receiving angle when the light receiving unit is rotated by the light receiving control unit by rotating around the axis passing through the intersection with the optical axis. Is received by the light receiving unit, the configuration in which the reflected light at the plurality of light receiving angles is received by the light receiving unit can be realized with a simple configuration.

  Further, in the above configuration, the light receiving unit rotates about a toroidal mirror (toroidal mirror 110) having a reflection surface rotationally symmetric with respect to the center axis in contact with the measurement surface of the object to be measured, and a rotation axis coinciding with the center axis. Among the reflected lights reflected by the reflecting surface of the toroidal mirror, the rotating optical system (plane mirror 131) that reflects the reflected light corresponding to the rotation angle, and the light reception that receives the light guided by the rotating optical system. The sensor (light receiving sensor 23) is provided, and reflected light at a plurality of light receiving angles within a predetermined angle range including a set light receiving angle is received by rotating the rotating optical system by the light receiving control unit. Therefore, the configuration in which the reflected light at the plurality of light receiving angles is received by the light receiving unit can be realized with a compact configuration (the device can be downsized).

  In the above configuration, the weight value (weight, Wt) in the weighting calculation is a known first light receiving angle distribution characteristic, which is a characteristic of a photometric value at the light receiving opening angle of the light receiving unit, and the first light receiving angle distribution characteristic. Is a value obtained from the relationship with the known second light receiving angle distribution characteristic in the optical characteristic measuring apparatus or another optical characteristic measuring apparatus different from the optical characteristic measuring apparatus. Using the weight value, a desired (target) photometric value (second light-receiving angle distribution) can be accurately and easily obtained from a photometric value (first light-receiving angle distribution characteristic) at each light-receiving angle obtained by the light receiving unit. Characteristic).

Further, in the above configuration, the relationship between the first light receiving angle distribution characteristic and the second light receiving angle distribution characteristic is the following expression (1) when the angle range and the angle pitch are fixed. The weight value can be easily obtained by using a simple expression such as). In other words, a desired photometric value (second light receiving angle distribution characteristic) can be easily obtained from the photometric value (first light receiving angle distribution characteristic) at each light receiving angle obtained by the light receiving unit using the weight value. Can do.
Σ (first acceptance angle distribution characteristic × weight value) = second acceptance angle distribution characteristic (1)
However, the symbol “Σ” indicates that a sum is obtained for each first light receiving angle distribution characteristic obtained by photometry at the predetermined angular pitch position, and the symbol “×” indicates multiplication. However, the equation (1) indicates the equation of Σ (light reception angle distribution characteristic st1 × Wt) = light reception angle distribution characteristic st2.

  Further, in the above configuration, since the weight value is a value calculated as a weight value satisfying the expression (1) for each wavelength of light received by the light receiving unit, the photometric value has wavelength dependency. In addition, a desired photometric value (second light receiving angle distribution characteristic) can be obtained from the photometric value (first light receiving angle distribution characteristic). As a result, between devices (between photometric values, light receiving angle distribution characteristics). Compatibility) can be maintained.

  Further, in the above configuration, the calculation unit further performs a calculation using the predetermined value for calculating the reflection characteristic for the calculated photometric value obtained by performing the predetermined weighting calculation and the predetermined addition / subtraction calculation on the photometric value. Thus, since the reflection characteristic value of the object to be measured is calculated, the reflection characteristic value can be easily calculated (the reflection characteristic is obtained) based on the photometric value at each light receiving angle obtained by the light receiving unit.

It is a figure which shows the example of an external appearance of the multi-angle colorimeter which is an example of the optical characteristic measuring apparatus which concerns on one Embodiment of this invention. It is sectional drawing which shows the structure of measurement aperture vicinity. It is a figure which shows an example (1st Embodiment) of the internal structure of the said multi-angle colorimeter. It is a block diagram which shows the control system of the said multi-angle colorimeter. It is a block diagram which shows an example of the spectroscopy part of the said multi-angle colorimeter. (A) is the figure which showed typically an example of the light reception angle distribution characteristic of a certain optical characteristic measuring apparatus (multi-angle colorimeter). (B) is the figure which showed typically an example of the light reception angle distribution characteristic of the optical characteristic measuring apparatus (multi-angle colorimeter) used as the target which is going to make compatibility with the optical characteristic measuring apparatus of (a). is there. It is a schematic diagram for demonstrating that a measured value (photometric value) changes with the difference in a light reception angle distribution characteristic, (a) is a case where the light reception angle distribution characteristic of the said FIG. FIG. 6B is a diagram corresponding to the case where the light reception angle distribution characteristic of FIG. (A) is a figure which shows an example in case the peak position of a light reception angle distribution characteristic changes according to the difference in a wavelength. (B) is a figure which shows an example in case the way of acceptance angle distribution characteristic changes according to the difference in wavelength. (A), (b) is a further calculation after applying a predetermined calculation to the acceptance angle distribution characteristic obtained by measuring with a measuring instrument, specifically, applying a predetermined weight (weight). It is a schematic diagram illustrating that it is possible to obtain a photometric value of a target light reception angle distribution characteristic (referred to as a target light reception angle distribution characteristic) by performing calculation. It is a flowchart which shows a series of processes by a control part. It is sectional drawing which shows the other example of the internal structure of a multi-angle colorimeter. It is a sectional side view in the normal line G of FIG. It is a sectional side view in the position of the light source shown in FIG. It is the perspective view which showed the internal structure of the multi-angle colorimeter three-dimensionally. It is a figure for demonstrating the function of a plane mirror. It is a front view which shows the other structure of a multi-angle colorimeter. FIG. 17 is a side sectional view of FIG. 16. It is a figure which shows the deformation | transformation form of an illumination part. It is a figure which shows the case where a toroidal mirror is comprised with several components. It is a figure for demonstrating reflection of the light in a joint part.

Explanation of symbols

1, 100, 200 Multi-angle colorimeter 3 Measuring aperture 10, 120 Illumination unit 11, 121 Light source 20, 130 Light receiving unit 23 Light receiving sensor 25 Motor 26 Arm 30 Control unit 31 Illumination control unit 32 Light reception control unit 33 Calculation processing unit 34 Drive control unit 110 Toroidal mirror 131 Flat mirror 131x Rotating shaft 201 Reflecting mirror 253 Motor unit 253a Rotating shaft A Aperture center F Focal point G Normal line H, I Light receiving angle distribution characteristics, composite sensitivity J Light receiving angle K, K 'Light receiving opening angle M Reflection Intensity R Measurement plane, geometry plane Sa Measurement plane X Aperture plane Z Center axis S Object Sf Bright material

Claims (9)

An illumination unit for illuminating the object to be measured;
A light receiving unit that receives reflected light reflected by the object under measurement by the lighting unit;
A light receiving control unit that causes the light receiving unit to receive the reflected light at a plurality of light receiving angles within a predetermined angle range including a preset light receiving angle set in advance;
An optical characteristic measurement apparatus comprising: a calculation unit that performs a predetermined weighting calculation and a predetermined addition / subtraction calculation on a photometric value at each light receiving angle obtained by the light receiving unit. The light reception controller is
The optical characteristic measurement apparatus according to claim 1, wherein reflected light at the plurality of light receiving angles at predetermined angular pitch positions within the angle range is received by the light receiving unit. The light receiving unit is
The intersection of the optical axis of the incident light and the optical axis of the reflected light is perpendicular to the geometric plane including the optical axis of the incident light incident on the object to be measured and the optical axis of the reflected light from the object to be measured. It is configured to be rotatable with the passing axis as the rotation axis,
The light reception controller is
The optical characteristic according to claim 1, wherein the light receiving unit receives reflected light at a plurality of light receiving angles within a predetermined angle range including the set light receiving angle by rotating the light receiving unit. measuring device. The light receiving unit is
A toroidal mirror having a reflection surface rotationally symmetric with respect to a central axis in contact with the measurement surface of the object to be measured;
A rotating optical system that is configured to be rotatable about a rotation axis that coincides with the central axis, and that reflects reflected light corresponding to a rotation angle among reflected light reflected by a reflecting surface of the toroidal mirror,
A light receiving sensor for receiving light guided by the rotating optical system,
The light reception controller is
3. The optical according to claim 1, wherein the light receiving unit receives reflected light at a plurality of light receiving angles within a predetermined angle range including the set light receiving angle by rotating the rotating optical system. Characteristic measuring device. The weight value in the weighting operation is
A known first light-receiving angle distribution characteristic that is a characteristic of the photometric value at a light-receiving opening angle of the light-receiving unit, and a light-receiving angle distribution characteristic that is calculated based on the first light-receiving angle distribution characteristic, the optical characteristics 5. The optical characteristic according to claim 2, wherein the optical characteristic is a value obtained from a relationship with a known second light receiving angle distribution characteristic in a measuring apparatus or another optical characteristic measuring apparatus different from the apparatus. measuring device. The relationship between the first light receiving angle distribution characteristic and the second light receiving angle distribution characteristic is:
The optical characteristic measuring apparatus according to claim 5, wherein the following expression (1) is obtained when the angular range and the angular pitch are fixed.
Σ (first acceptance angle distribution characteristic × weight value) = second acceptance angle distribution characteristic (1)
However, the symbol “Σ” indicates that a sum is obtained for each first light receiving angle distribution characteristic obtained by photometry at the predetermined angular pitch position, and the symbol “×” indicates multiplication. The weight value is
The optical characteristic measuring apparatus according to claim 6, wherein the optical characteristic measuring apparatus is a value calculated as a weight value satisfying the expression (1) for each wavelength of light received by the light receiving unit. The computing unit is
A reflection characteristic value of the object to be measured is calculated by performing a calculation using a predetermined value for calculating reflection characteristics on a calculation photometric value obtained by performing a predetermined weighting calculation and a predetermined addition / subtraction calculation on the photometric value. The optical property measuring device according to claim 1, wherein the optical property measuring device is calculated. Illuminates the object to be measured,
Receiving reflected light at a plurality of light receiving angles within a predetermined angle range including a preset light receiving angle that is reflected by the object under measurement in the illumination state;
A method for measuring optical characteristics, comprising performing a predetermined weighting operation and a predetermined addition / subtraction operation on the photometric values at the respective light receiving angles obtained by the light reception.

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