JPS593698B2 - Kiyoumenhanshiyaritsusokuteisouchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION x The present invention relates to a specular reflectance measuring device that can easily and accurately measure the reflectance of an object having a smooth plane.

There are various methods of measuring the plane reflectance of an object that have been proposed in the past, examples of which are shown in FIGS. 1, 2, and 3. 30 In Fig. 1, a very common method is shown in which a light beam from a light source Q is guided by a reflecting prism P to a standard sample R having a known reflectance, or to a sample to be measured s, and the reflected light is made incident on a photodetector PM. This is a great method.

To explain the specific measurement method, first, the standard sample, ■
5R is set at the position shown in the figure, but generally it is set so that the incident light flux Li to the prism matches the output light flux Lo. What is the output ER of the photodetector PM at this time? ?
It is expressed as Tn9rhChang.

Here, K is a constant, Ii is the intensity of the incident light beam Li, P1 is the reflectance of the prism P, ? is the reflectance of standard sample R. Next, the sample S to be measured is replaced at the same position as the standard sample R. The output Es of the photodetecting element PM at this time is expressed as in equation (2). L) Story Todoroki 1I1r floor 1,.
Here, S is the reflectance of the sample S to be measured.

From (1) and (2) ~ Therefore, S, = [! /ER)...R,tonashi~Es゜ER
Since is a measured value and Rr is known, the reflectance Srl of the sample S to be measured is determined.

Although this method has a simple structure, it requires a stable and highly accurate standard sample because it calculates the relative value to the reflectance of the standard sample, and there is also a large difference in reflectance between the standard sample and the measured sample. If there is a problem, the error will be magnified, making accurate measurement difficult, and the angle of incidence will also be fixed. In FIG. 2, the plane reflecting mirror M is movable from the position shown by a solid line to the position shown by a broken line so as to be symmetrical with respect to the surface of the sample to be measured. During measurement, first place the flat reflecting mirror M at the position shown by the solid line and perform 100% alignment, then move the flat reflecting mirror M to the position shown by the broken line, set the sample to be measured S'', and adjust the light from both. By taking the ratio of the outputs of the detection elements, the square of the reflectance of the offshore sample can be determined.With this method, it is possible to measure the absolute reflectance rather than comparing it with the standard sample R as shown in Figure 1. However, the structure of the device is complicated)
Further, there are drawbacks such as the angle of incidence is fixed and the area of the sample to be measured cannot be made small. In Figure 3, Q' is the light source and P
M5 is a photodetection element, x is a light source Q″ and a photodetection element P
This is an arbitrary point on the optical axis connecting M5. When measuring,
First, place the light source Q' and the photodetector PM' in two straight lines,
Perform 96 matches. Next, the sample to be measured Sll is set so that the reflective surface is at the position of point X, and the photodetector element PM''
is rotated around point x and moved to the position indicated by the dotted line to obtain photoelectric output. By taking the ratio of the outputs of both photodetecting elements, the reflectance of the sample to be measured can be determined. This method improves the disadvantages of the above examples (Figures 1 and 2), such as the angle of incidence being fixed and the sample to be measured not being able to be made small, but the structure is complicated as the photodetecting element must be rotated. Therefore, it is difficult to apply it to other equipment such as the currently most popular, highly accurate, and reliable double beam spectrophotometer, which will be described later. The present invention aims to solve the above-mentioned drawbacks of conventional reflectance measuring devices, and to provide a highly accurate specular reflectance measuring device that is simple in operation and structure, and easy to apply to other devices. This will be explained in detail below with reference to the drawings.

In FIG. 4, 1 is a light source, 2 is a semi-transparent mirror, 3 is a flat reflecting mirror 4 is a photodetecting element, 5 is a sample to be measured, and 3 is a flat reflecting mirror having the same characteristics as 3.

FIG. 3A shows the case of 100% alignment without inserting the sample to be measured 5. The light beam from the light source 1 is reflected by the semi-transparent mirror 2,
The light enters the plane reflecting mirror 3 perpendicularly, and the reflected light passes through the semi-transparent mirror 2 and enters the photodetecting element 4. Letting the photoelectric output at this time be IO, it is expressed by the equation IO (3), and for ease of explanation, it is assumed that the photoelectric output of the photodetecting element 4 and the amount of light are proportional. 10ゞ且ν5V1↓VZ▲1
where h is a constant, L is the luminous flux emitted from the light source, R1 is the reflectance of the semi-transparent mirror 2, T1 is the transmittance of the semi-transparent mirror 2, and R2 is the reflectance of the plane reflecting mirror 3.

The opening in Figure 4 shows the measurement state, where the light beam from the light source 1 is reflected by the semi-transparent mirror 2 and enters the sample to be measured 5, and the reflected light is perpendicularly incident on the plane reflecting mirror 3 that has been moved from the position shown in Figure 4. Then, the reflected light enters the sample to be measured 5 again, and the reflected light passes through the semi-transparent mirror 2 and enters the photodetector element 4. Letting the photoelectric output at this time be I, I is expressed as in equation (4), and (
From equations (3) and (4), the reflectance Rx of the sample to be measured 5 is Rx
Required as VCVI/IO. − − −1
-9,. ．． -1 -1A1 Here, Rx is the reflectance of the sample 5 to be measured.

FIG. 4C shows the flat reflecting mirror 3 without moving.
This shows a case in which a flat reflecting mirror 3' having the same reflectance characteristics as 1 and 2 is used, and since no moving parts are required, the device can have a simple structure. As mentioned above, multiple reflectors with the same reflectance characteristics can be easily obtained by simultaneous vapor deposition, and in the following explanations, multiple reflectors with the same reflectance will often be used, but there is no need for this device. This does not impede the implementation of the above. Plane reflector 3 or 3 so that the reflected light from the sample is incident perpendicularly.
If this is set, the angle of incidence on the sample to be measured can be set arbitrarily, and if it is set as shown in Figure 4, it is also possible to easily measure the transmittance of a Benz prism 5' used in single-lens reflex cameras. It is. Furthermore, if the light source 1 is composed of a white light source and a spectrometer, it is of course possible to measure the spectral reflectance.
Next, a case where the present invention is applied as a spectral reflectance annotation for a double beam spectrophotometer will be explained with reference to FIG.

FIG. 5A shows the optical system of a known double beam spectrophotometer. 6 is a sample chamber, 7 is a spectrometer, 8 is a photodetector element, 9a
, 9b are fixed reflecting mirrors, and 10a, 10b are rotating sector reflecting mirrors, which alternately enter and leave the optical path.

With such a structure, the monochromatic light emitted from the spectroscope 7 is divided into a reference side light beam 11a shown by a solid line and a sample side light beam 11b shown by a dotted line.
The light then passes through the sample chamber 6 and enters the photodetector element 8 . A spectrophotometer with such a configuration normally measures the transmittance, and if a sample is placed in the optical path of the sample side light beam 11b, the transmittance can be measured based on the ratio with the reference side light beam. Figure 5 shows a side view of the spectral reflectance measurement attachment, and Figure 5 shows a view from above, both showing the state set in the sample chamber 6. In Figure 5, 12, 13, 14, 15, 16 are plane reflecting mirrors, 17 is a semi-transparent mirror, 1 various reference side light beams 11
The portion a and the portion through which the sample-side light beam 11b is reflected or transmitted have the same characteristics. However, the plane reflecting mirror 16 only needs to be on the optical path of the light beam on the sample side, and its characteristics are similar to that of the plane reflecting mirror 1.
It has the same characteristics as No. 5. The reference side light beam and the sample side light beam are incident on the attachment as 111 and 11 from the spectrometer 7, and the emitted light is incident on the photodetecting element 8 as 11d' and 111/'. 18 is the sample to be measured 45
The setting of the reflector 16 is adjusted so that the reflected light from the sample 17 to be measured is incident perpendicularly.

To explain the measurement method below, first, we performed preliminary operations such as zero point alignment and 100% alignment when measuring transmittance using a general double beam spectrophotometer without placing the sample to be measured. After that, if you set the sample 18 to be measured as shown in Figure 5 and perform the measurement in the same manner as in normal transmittance measurement, the square root of this measurement result will be the reflectance, as explained in Figure 4. It's Tou.

Also, if you set the spectrophotometer in advance so that the square root of the calculation output appears, the reflectance can be determined by direct reading, making measurement easier.In general, the light flux from the light source is not parallel light;
Because of the spread D, for example, when measuring the transmittance of the Penshio prism 19, the optical path length is different when 100% alignment is performed and when the sample to be measured is placed in the optical path. Since the areas of the two are different from each other, when using a photodetecting element such as a photomultiplier tube whose light-receiving surface has an extreme value, errors will occur if the input is not always incident on the same area in the same place.

To prevent this, it is sufficient to make the optical path lengths at the time of 100-chip alignment and at the time of measurement the same.
, 3', and 16 plane reflecting mirrors in FIG. 5 may be constructed to be movable in the optical axis direction of the incident light from the sample to be measured, and the optical path lengths may be adjusted to be the same. Adjustment of the optical path length using this structure will be explained with reference to the case shown in FIG. First 10
When adjusting to 0%, a screen such as ground glass is placed at the position of the reflecting surface of the plane reflecting mirror 15, and the area of the light beam is measured. Next, set the sample to be measured, for example, the pentaprism 19, place a screen in the same way at the reflective surface of the flat reflector 16, measure the plane jet of the luminous flux, and set the screen so that the area is equal to the previously measured area. Move in the direction of the optical axis. If the surface reflector 16 is set at the position where the area is equal, 10
The optical path length at the time of 0% adjustment and measurement can be made equal. As described above, according to the configuration of the present invention, it is possible to measure the absolute reflectance, and it is possible to measure a minute area by narrowing down the light beam without using a standard sample, and the incident angle is 0 degrees and 90 degrees. Any angle is possible except for the nearby area, and the structure is simple as there is no need to move the light-receiving part.B It is easy to apply to double-beam spectrophotometers, and it can be used on both the reference side and the sample side. The number and angle of reflection and transmission by the reflecting mirror and semi-transparent mirror can be configured to be equal, and the optical path length can be easily matched, so the optical characteristics of the reference side and sample side and the incident conditions of the photocathode of the photodetector are the same. Therefore, it is possible to measure with high precision, and furthermore, it is possible to easily measure not only the reflectance of a plane mirror but also the total transmittance including the reflectance of a pentaprism, which is highly effective.

[Brief explanation of drawings]

Figures 1, 2, and 3 show conventional specular reflectance measurement equipment. FIG. 4 shows a specular reflectance measuring device of the present invention. FIG. 5 shows a specular reflectance measuring device for a double beam spectrophotometer according to the present invention. Q, Q'': light source, PM, PM': photodetector, S,
S': S'': Sample to be measured, R: Standard sample, M: Reflector, 1: Light source, 2: Semi-transparent mirror, 3, 3/: Reflector, 4: Photodetection element, 5, 5': Subject to be measured Sample, 6: Spectrophotometer sample chamber, 7: Spectrometer, 8: Photodetection element, 9a, 9b: Reflector, 10a, 10b: Rotating sector reflector, 11a, 11
b: Luminous flux, 11a'11b5: Luminous flux, 12, 13, 14
, 15, 16: Reflecting mirror, 17: Semi-transparent mirror, 18, 19: Sample to be measured.

Claims (1)

[Claims] 1. At the time of 100% correction, the light beam from the light source 1 is reflected by the semi-transparent mirror 2 and enters the reflecting mirror 3 perpendicularly, and the reflecting mirror travels backward along the same optical path as the incident light. It constitutes a light record that passes through and enters the photodetecting element 4. During measurement, the light beam from the light source 1 is reflected by the semi-transparent mirror 2 and enters the sample to be measured 5, and the reflected light enters the reflecting mirror 3 at right angles. Then, the reflected light travels the same optical path as the incident light, is reflected by the sample to be measured 5, passes through the semi-transparent mirror 2, and forms an optical path in which it enters the photodetector element 4,
A specular reflectance measuring device characterized in that the reflectance of the sample to be measured 5 is determined by the ratio of the luminous flux incident on the photodetecting element during the 100% correction and the luminous flux incident on the photodetecting element during the measurement. 2 At the time of 100% correction, the light beam from the light source 1 is reflected by the semi-transparent mirror 2 and enters the reflecting mirror 3 perpendicularly, and the reflected light travels the same optical path as the incident light and passes through the semi-transparent mirror 2 to the photodetector element. During measurement, the light beam from the light source 1 is reflected by the semi-transparent mirror 2 and is incident on the sample to be measured 5, and the reflected light is perpendicularly incident on the reflecting mirror 3, and the reflected light is incident. Constructing an optical record that travels in the same optical path as the light, is reflected by the sample to be measured 5, passes through the semi-transparent mirror 2, and enters the photodetector element 4,
In an apparatus for determining the reflectance of the sample to be measured 5 based on the ratio of the luminous flux incident on the photodetecting element during the 100% correction and the luminous flux incident on the photodetecting element during the measurement, the sample of a double beam spectrophotometer is used. A specular reflectance measuring device characterized in that the optical path for the 100% correction is placed on the reference side of the room, and the optical path for the measurement is placed on the sample side. 3 At the time of 100% correction, the luminous flux from the light source 1 is reflected by the semi-transparent mirror 2 and enters the reflected light 3 perpendicularly, and the reflected light travels the same optical path as the incident light, passes through the semi-transparent mirror 2, and reaches the photodetector element. During measurement, the light beam from the light source 1 is reflected by the semi-transparent mirror 2 and is incident on the sample to be measured 5, and the reflected light is perpendicularly incident on the reflecting mirror 3, and the reflected light is incident. Constructing an optical path that travels in the same optical path as the light, is reflected by the sample to be measured 5, passes through the semi-transparent mirror 2, and enters the photodetector element 4,
In the apparatus for determining the reflectance of the sample to be measured 5 based on the ratio of the luminous flux incident on the photodetecting element during the 100% correction and the luminous flux incident on the photodetecting element during the measurement, the reflector 3 is connected to the sample to be measured. It is possible to move in the optical axis direction of the reflected light from 5,
A specular reflectance measuring device characterized in that the optical path length during the 100% correction and the optical path length during the measurement are the same.