JPH07159284A - Spectral characteristics inspection apparatus for optical mirror - Google Patents

Abstract

PURPOSE:To provide a spectral characteristic inspection apparatus for optical mirror in which the spectral characteristics can be measured continuously in a short time regardless of the wavelength region to be measured, the measurements can be processed easily and a decision of pass/fail can be made instantaneously. CONSTITUTION:A sample holder 3 sets an optical mirror 4 on the optical path of diffused white light. The diffused light passed through the optical mirror 4 is condensed by a condenser lens 14 and converted at a light receiving section 6 into an electric signal which is further converted into three stimulus values X, Y, Z of color. A data processing section 16 converts the three stimulus values X, Y, Z into a color difference which is then compared with a threshold value, thus deciding pass/fail of the optical mirror 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical mirror spectral characteristic inspection device for measuring the spectral characteristic of an optical mirror, for example.

[0002]

2. Description of the Related Art Conventionally, a reflecting mirror used for an incandescent light source such as a halogen lamp reflects only light having a wavelength component in the visible region among light emitted from the halogen lamp, and particularly has a wavelength component in other regions. It is desired to have a property of absorbing heat rays of infrared wavelengths and transmitting / radiating to the side opposite to the halogen lamp.

That is, the reflecting mirror as the irradiated body of the halogen lamp as the light source transmits the heat rays of the infrared wavelength, which may be thermally damaged, to the back side, while always reflecting the light of the visible wavelength. Therefore, effective irradiation of the halogen lamp is required.

Therefore, a multi-layered film that constitutes a reflecting mirror, for example, a multi-layered reflective film formed by laminating a high-refractive-index vapor deposition film and a low-refractive-index vapor deposition film, can be used to determine what kind of spectrum for light of each wavelength. It is important to have transmittance and spectral reflectance. Generally, a reflecting mirror having a characteristic of reflecting only light of a specific wavelength of this kind is called an optical mirror, but the spectral characteristics such as spectral transmittance and spectral reflectance for light of each wavelength are The superiority or inferiority will be determined. Therefore,
In developing, manufacturing, and commercializing such an optical mirror, the spectral characteristics such as spectral transmittance and spectral reflectance are measured,
It is necessary to inspect the optical mirror based on the measured value.

Conventionally, the measurement of the spectral characteristics of this type of optical mirror is generally performed by the following means using a spectrophotometer.

First, the optical mirror to be inspected is mounted on a predetermined jig. Next, the light that enters the optical mirror
The spectrum is measured by a spectrophotometer from the transmitted light or reflected light of the optical mirror by scanning within a predetermined wavelength range. After that, the spectral characteristic of the optical mirror in a predetermined wavelength range is obtained based on the spectral spectrum measured by the spectrophotometer.

However, the method of measuring and evaluating the spectral characteristics of the optical mirror using the above-mentioned spectrophotometer has the following problems.

(1) Since a set wavelength range having a certain width is scanned, a relatively long time is required for measurement.

(2) When changing the set wavelength range, it takes a relatively long time to initialize the measurement system.

(3) Since the measurement result obtained by the spectrophotometer is a spectrum, the post-processing for digitizing the spectral characteristics becomes complicated.

(4) When measuring and evaluating a large number of optical mirrors, it is necessary to mount the optical mirrors one by one on the jig, which requires a lot of time.

[0012]

As described above, the conventional optical mirror spectral characteristic inspection device has a problem that the time required for measurement is relatively long. Further, when changing the set wavelength range, there is a problem that a relatively long time is required for initialization of the measurement system. In addition, there is a problem in that post-processing for digitizing the spectral characteristics becomes complicated. In addition, when measuring and evaluating a large number of optical mirrors, it takes a lot of time to mount the optical mirrors.

The present invention has been made in order to solve such a problem, and it is possible to continuously measure the spectral characteristics in a short time regardless of the wavelength range to be measured, and to process the measurement result. It is an object of the present invention to provide an optical mirror spectral characteristic inspection device that is simple and can instantly determine pass / fail.

[0014]

An optical mirror spectral characteristic inspection apparatus according to the present invention comprises a white light source, a diffusing means for diffusing white light emitted from the white light source, and a white light diffused by the diffusing means. Holding means for holding the optical mirror at a predetermined position on the optical path of, the light collecting means for collecting white light reflected or transmitted from the optical mirror held by the holding means at a predetermined position, and the light collecting means. Is arranged at the position where the white light condensed by the light is received by the conversion means for receiving the white light and converting the white light into tristimulus values of the color, and the optical means based on the tristimulus values converted by the conversion means. And an evaluation unit for evaluating the spectral characteristic of the mirror.

[0015]

In the present invention, it is not necessary to scan the light incident on the optical mirror within the set wavelength range, and the spectral characteristics of the optical mirror can be measured by making only diffused white light incident on the optical mirror. Shortened. In addition, the white light source includes light in the entire wavelength range necessary for measuring the spectral characteristic of the optical mirror. Therefore, it is not necessary to change the set wavelength range for scanning as in the conventional case, and the time required for the initialization of the apparatus can be omitted. Moreover, since the spectral characteristics of the optical mirror are converted into tristimulus values that are easy to compare, post-processing of measurement results can be easily performed in a short time. Moreover, since the optical mirror can be easily removed by using the holding means of the optical mirror, the total measurement time is greatly reduced when a large number of optical mirrors are measured.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a view showing the arrangement of an optical mirror spectral characteristic inspection apparatus according to an embodiment of the present invention.

In the figure, reference numeral 1 is a light source section for emitting white light having good diffusivity in a predetermined direction. The light source unit 1 is composed of a white light source 11 and a white light diffuse transmission plate 12 placed on the optical path of the white light source. Light source 1
The first light guide path 2 is connected to the. The first light guide path 2 transmits the diffused white light emitted from the light source unit 1 to the first light guide path 2.
To the sample holder 3 connected to. The sample holder 3 holds the optical mirror 4 to be inspected on the optical path, and diffuses white light emitted from the first light guide path 2 into the optical mirror 4.
It has been processed to project only on. The sample holder 3 is held on the optical path by the sample supply / discharge unit 13. The second light guide path 5 is connected to the sample holder 3. A condenser lens 14 is installed on the optical path in the second light guide path 5. The light transmitted through the condenser lens 14 is
Is guided to the light receiving section 6 connected to the light guide path 5. The first light guide path 2 and the second light guide path 5 described above play a role of preventing disturbance light other than white light from entering the optical mirror, and usually the inner surface is mirror-finished or non-treated. A light-shielding tube that has been subjected to reflection processing is used.

The light receiving portion 6 is arranged at a position where the transmitted light from the condenser lens 14 is condensed, and converts the received light into an electric signal, for example, a light receiving element 1 made of a silicon photodiode.
5 for converting an electrical signal into a tristimulus value. A data processing unit 16 such as a personal computer that performs data processing of the obtained tristimulus values is connected to the light receiving unit 6.
The data processing unit 16 includes a portion that compares the obtained tristimulus value with a reference value to obtain a color difference, and a portion that compares the color difference with a threshold value.

Next, the inspection operation of the thus constructed apparatus will be described.

The white light emitted from the white light source 11 is diffused by the white light diffusing and transmitting plate 12 and enters the first light guide path 2. The diffused white light that has passed through the first light guide path 2 is incident on the sample holder 3 that is connected thereto. This incident light passes through the optical mirror 4 mounted on the sample holder 3 and enters the second light guide path 5. Then, the light is condensed by the condenser lens 14 arranged on the optical path inside the second light guide path 5,
The light is incident on the light receiving unit 6. The incident light is converted into an electric signal by the light receiving unit 6, and further converted into a tristimulus value. The output of the light receiving unit 6 is input to the data processing unit 16.

Here, FIG. 2 is a flowchart showing the determination operation of the data processing unit 16.

First, the data processing section 16 first receives the tristimulus values X, Y and Z from the light receiving section 6 and the already measured tristimulus values X ₀ , Y ₀ and Z _{0 of} diffused white light (step 211).
Is converted into three coordinates L ^* , a ^* , b ^*, etc. in the L ^* a ^* b ^* uniform color space (step 201).
Subsequently, the three coordinates L ^* , a ^* , and b ^{* of} this uniform color space that represent the color of the transmitted light of the optical mirror 4 and the color of the transmitted light of the reference optical mirror that has already been measured by the same method are represented. Three coordinates of uniform color space L ₀ ^* , a ₀ ^* , b ₀ ^* (Step 2
21) and the color difference ΔE ^* _ab, that is, [(ΔL ^* ) ² + (Δa ^* ) ² + (Δb ^* ) ² ] ^1/2.
Etc. (step 202). Next, this color difference Δ
The quality of the optical mirror is judged by comparing E ^* _ab with a preset threshold value (step 2).
03).

As described above, according to the spectral characteristic inspection apparatus of this embodiment, the white light source 1 covering the entire wavelength range is used as the light source.
Therefore, the measurement time is reduced as compared with the conventional spectral characteristic inspection device that scans while changing the wavelength within the set wavelength range. In addition, even when changing the set wavelength range, it is not necessary to initialize the device, which requires a lot of time, so that the total measurement time is significantly reduced. Furthermore, since the spectral characteristics of the optical mirror 4 can be converted into tristimulus values and further converted into color differences for comparison, post-processing becomes simpler than that of a conventional spectral characteristic inspection device that processed spectral spectra. Furthermore, since the optical mirror 4 can be easily removed by using the sample supply / discharge unit 13, it is possible to omit the time required for mounting the sample as in the conventional spectral characteristic inspection device.

In this embodiment, the spectral characteristics of the optical mirror are measured by using the transmitted light of the diffused white light incident on the optical mirror, but the reflected light of the diffused white light incident on the optical mirror is measured. May be used. Further, although the diffuse transmission plate is used as the diffusing means, a diffuse reflection plate may be used. Further, in this embodiment, the silicon photodiode is used as the light receiving element, but other light receiving elements may be used.

The criteria for judging the quality of the optical mirror are:
It is not always necessary to use the color difference of the three coordinates L ^* , a ^* , b ^* coordinate system. If the numerical values of the colors obtained from the tristimulus values X, Y, and Z are used, the quality of the optical mirror may be determined by using another display system. In addition, the tristimulus values X, Y, and Z are | X-
Y | + | Y−Z | + | Z−X |, | L ^* −a ^* | + | a
^{* -B * | + | b *} -L * |, [X 2 + Y 2 + Z 2]
^The pass / fail judgment may be performed by digitizing into ^1/2 or the like.

Further, for example, a conveyor may be used as the sample supplying / discharging unit 13 so that the sample holder 3 is continuously conveyed on the optical path. This is particularly effective when a large number of optical mirrors are continuously measured.

[0028]

As described above, according to the spectral characteristic inspection device for an optical mirror of the present invention, the measurement time can be shortened and the time required for the initialization of the device can be omitted. Further, the processing of the measurement result can be easily performed in a short time, and when the optical mirror is continuously measured, the total measurement time including the setup is greatly reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a spectral characteristic inspection device for an optical mirror according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a determination operation of a data processing unit 16 shown in FIG.

[Explanation of symbols]

3 ... Sample holder, 4 ... Optical mirror, 6 ... Light receiving part,
11 ... White light source, 12 ... White light diffusion / transmission plate, 13 ...
Sample supplying / discharging section, 14 ... Condensing lens, 15 ... Light receiving element, 16 ... Data processing section.

Claims (1)

[Claims] 1. A white light source, a diffusing means for diffusing white light emitted from the white light source, and a holding means for holding an optical mirror at a predetermined position on the optical path of the white light diffused by the diffusing means, The condensing means for condensing the white light reflected or transmitted from the optical mirror held by the holding means at a predetermined position, and the condensing position of the white light condensed by the condensing means are arranged. A conversion means for receiving white light and converting it into tristimulus values of color; and an evaluation means for evaluating the spectral characteristic of the optical mirror based on the tristimulus values converted by the conversion means. Optical spectroscopic characteristic inspection device for.