JPH06281567A - Double refraction measuring apparatus - Google Patents

Abstract

PURPOSE:To simplify the measurement by making a sample holding stage on a holding board rotatable by a motor or the like, and making the holding board inclinable by a motor or the like about a line along the surface of a holding plate as a central shaft, thereby performing measurements while the rotating angle and the inclining angle of a sample are changed. CONSTITUTION:A sample S is set on a sample holding stage, and a motor 5 is started to turn a polarizer 1 and an analyzer 2. A data processing device 11 starts to take in the outputs of an optical sensor 10 when a photoelectric detector 6 detects a reflecting body at a side face of a holding disk of the polarizer 1, with rotating the polarizer 1 and analyzer 2 once. The retardation of the sample S is calculated and stored from the maximal and minimal values of the outputs during this time. After finishing the measurement, the motor is driven to rotate the holding stage, e.g. by 10 deg.. The same measurement is repeatedly carried out. Moreover, the holding stage is inclined, for example, by 5 deg. by a motor 29, and the same measurement is repeated. When the difference between the maximal and minimal values is small, a 1/4 wave plate 15 is inserted into an optical path and the measurement is conducted again. Accordingly, the retardation is obtained from these measurements and the measurement is automated.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a birefringence meter for measuring the triaxial refractive index of a material exhibiting optical anisotropy.

[0002]

2. Description of the Related Art Stretched plastic sheets generally show birefringence, and if the sheets are made of the same material and have a constant thickness, the degree of stretching can be determined by the degree of birefringence.
When the degree of stretching is constant, the thickness can be determined. It may also be necessary to measure the triaxial index of refraction of the material. In addition to this, the birefringence of the sheet-shaped material is measured for various purposes, but the sample is rotated relative to the polarizer and the analyzer arranged in parallel to detect the change in transmitted light intensity, In the case of obtaining the phase difference between the two linearly polarized lights that are transmitted, there is a drawback that the accuracy of the measured value becomes low when the phase difference is in the vicinity of π.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a birefringence meter capable of easily measuring the refractive index of a sample in the three-axis directions and the retardation when the phase difference is in the vicinity of π. And

[0004]

In a birefringence meter, a table holding a sample is rotatably installed on a sample holding substrate, and a means for rotating the sample holding table by a motor or the like is provided on the sample holding substrate. A means for holding the sample holding substrate in the refractometer main body so as to be tiltable about a straight line along the surface of the sample holding base as a central axis and for tilting and driving the sample holding base by a motor or the like is provided.
A control means is provided for performing a measurement operation while rotating the rotation drive means and the tilt drive means by a fixed angle, and a quarter wave plate is provided above the sample holder so that it can be moved in and out on the optical axis of the refractometer. .

[0005]

[Function] Since the sample can be rotated and tilted automatically, the sample is rotated at various tilts while changing the tilt of the sample, and the transmitted light at that time is measured to transmit the sample at various angles. The birefringence of the light can be measured, and the 1/4 wavelength plate can be overlaid on the sample if necessary, so that the accurate retardation can be measured even when the phase difference is near π. Is possible.

[0006]

FIG. 1 shows an embodiment of the present invention. 1, 2 in the figure
Is a polarizer and an analyzer, each of which is mounted on a disc, and each disc is integrally rotated by a pulse motor 5 via belts 3, 3 and pulleys 4, 4. 1 and the analyzer 2 are in a parallel Nicol state. A mark of a reflector is attached to one side surface of the disc on which the polarizer 1 is mounted, and the initial position of rotation of the polarizer and the analyzer is detected by detecting this reflector with a photoelectric detector. To do.
6 is a light source, and the emitted light is a parallel light flux by the lens 7,
After passing through the polarizer 1 and the analyzer 2, it is detected on the light receiving element 8. This photodetection output is amplified by the amplifier circuit 9, and A /
After A / D conversion by the D converter 10, the data processing device 1
Input to 1. The data processing device 11 processes the measurement data, sends a pulse to each motor, and controls the rotation thereof. Reference numeral 12 is a CRT that displays the measurement result. Reference numeral 13 is a wavelength filter, and various wavelength filters 13 are replaced by rotation of the motor 14. Reference numeral 15 is a quarter-wave plate, which is held along the guide 16 so as to be able to move in and out of the measurement optical axis. S is a sample held by the sample holding device A.

The details of the sample holder A are shown in FIG. Figure 2
In the above, reference numeral 21 denotes a sample holder, which has a through hole 21A in the center thereof, a back surface which is hollowed out in a circular shape, and two holding plates 21B provided on the upper surface. Reference numeral 22 denotes a rotary table which fits the concave portion of the back surface of the sample holder 21 with the circular protrusion 22A to rotatably hold the sample holder 21 on a vertical axis of the sample surface. A belt 23 is attached to the side surface of the sample holder 21 and the pulley 24, and the motor 25 rotationally drives the sample holder 21. Reference numeral 30 is a substrate on which the motor 25 and the turntable 22 are mounted.
The mounting surfaces of the motor 25 and the rotary table 22 are configured so that the pulley 24 and the sample holder 21 are arranged on one plane, and the shafts 31 are provided on both side surfaces and the surface of the sample holder 21 serves as the central axis. And support this shaft in the main body of the birefringence meter,
A pulley 26 is attached to the coaxial shaft 31, and is driven to rotate by a belt 27 and a motor 29 on the main body of the birefringence meter via a pulley 28.

The birefringence of the sample is measured by the above-mentioned apparatus as follows. The sample is attached to the sample holder 21, the motor 5 is started, and the polarizer 1 and the analyzer 2 are rotated. The data processing device 11 takes in the output of the optical sensor 10 from the time when the reflector on the side surface of the holding disk of the polarizer 1 is detected by the photoelectric detector 6 and rotates the polarizer, analyzers 1 and 2 once. This result is shown in polar coordinates as shown in FIG. 3, and the retardation δ of the sample can be obtained from the maximum value I _max and the minimum value I _min in this figure by the following equation. cos δ = 2I _min / I _max −1 In this way, the data processing device 11 calculates and stores the retardation. After one measurement, the motor 2
5 is driven, the sample holder 21 is rotated by a fixed angle, for example, 10 °, and the apparatus is made to perform the same operation as above again. In this way, the retardation is obtained while changing the orientation of the sample, and the motor 29 is driven to further perform the above measurement operation to incline the sample holder 21 by a constant angle, for example, 5 °, thereby changing the inclination angle of the sample. Ask for retardation. In the above measurement operation, when the difference between the maximum and minimum of the optical sensor output is small and it is determined that the retardation cannot be accurately obtained, the ¼ wavelength plate 15 is advanced to the optical axis and the same measurement is performed again. . The rotation angle of the sample holder 21 is set to the motor 2
5 is read by the drive pulse, and the inclination angle of the sample holder 21 is read by the drive pulse of the motor 29.

[0009]

According to the present invention, the birefringence of a sheet-shaped sample is measured while automatically adjusting the tilt angle and rotation angle of the sample and automatically moving the quarter-wave plate in and out. It has become possible to perform automatic measurement.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an embodiment of the present invention.

FIG. 2 is a detailed perspective view of a sample holder in the above embodiment A sample holder S sample 1 polarizer 2 analyzer 3 belt 4 pulley 5 pulse motor 6 light source 7 lens 8 light receiving element 9 amplification circuit 10 A / D converter 11 Data Processing Device 12 CRT 13 Wavelength Filter 14 Motor 15 Quarter Wave Plate 16 Guide 26 Pulley 27 Belt 28 Pulley 29 Motor

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[Procedure amendment]

[Submission date] March 5, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an embodiment of the present invention.

FIG. 2 is a detailed perspective view of a sample holder in the above embodiment.

FIG. 3 is a polar coordinate display diagram of measurement results in the above-mentioned embodiment.

[Explanation of Codes] A sample holding device S sample 1 polarizer 2 analyzer 3 belt 4 pulley 5 pulse motor 6 light source 7 lens 8 light receiving element 9 amplification circuit 10 A / D converter 11 data processing device 12 CRT 13 wavelength filter 14 Motor 15 Quarter wave plate 16 Guide 26 Pulley 27 Belt 28 Pulley 29 Motor

Claims (2)

[Claims] 1. A sample holding substrate is rotatably installed on a sample holding substrate, and means for rotating the sample holding table by a motor or the like is provided on the sample holding substrate. The sample holding substrate is the surface of the sample holding table. A means for tiltably holding the refractometer main body around a straight line along the axis as a central axis and for tilting and driving the sample holder by a motor or the like is provided, and measuring operation is performed while rotating the rotation driving means and the tilting driving means at fixed angles. A birefringence measuring apparatus comprising a control means for performing 2. The birefringence measuring apparatus according to claim 1, wherein a quarter wave plate is provided above the sample holder so as to be able to move in and out on the optical axis of the refractometer.