JPH05240779A - Sample holder for birefringence measuring device - Google Patents

Abstract

PURPOSE:To provide a simple structural sample holder by which a sample can be set simply and the sample can be held stably so that a measurement point does not change even if the sample is rotated. CONSTITUTION:A sample holder for a birefringence measuring device is adhered/ fixed while sandwiching a spacer 5 between the edge parts of two plates formed of a resilient material, and a hole 2B is arranged so that the respective centers can coincide with each other on the opposite side of the edge parts where the two plates are adhered/fixed to each other. A presser plate 3 is rotatably installed in the hole 2B, and a sample is sandwiched between these upper/lower presser plates.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sample holder in an apparatus for measuring the polarization property of a sheet-shaped material exhibiting optical anisotropy.

[0002]

2. Description of the Related Art Stretched plastic sheets exhibit birefringence. The degree of stretching of the plastic sheet can be checked by the degree of the birefringence, or conversely, the thickness of the plastic sheet having a constant degree of stretching can be checked. In this case, the measurement operation can be simplified if the direction of the optical axis of the sample is known. In some cases, it may be said that it is sufficient to determine the presence or absence of birefringence of the sample sheet and the direction of the optical principal axis. However, there is also a case where the sample is tilted with respect to the incident light flux and the retardation of the sample transmitted polarized light at that time is desired to be measured. Therefore, it is necessary to rotate the sample while tilted.

The determination of the optical principal axis in birefringence is usually performed by rotating the sample between a polarizer and an analyzer whose polarization planes are parallel to each other and measuring the intensity change of the transmitted light to maximize the transmitted light intensity. When the optical axis of the sample becomes parallel to the azimuths of the polarizer and the analyzer, the direction of the optical axis with respect to the sample is determined. Therefore, the sample holder that holds the sample must have a function of securely fixing the sample, a function of rotating the sample even when the sample table is tilted, and a function of easily exchanging the sample. ,
It is also necessary to have a property that the measurement point of the sample does not change when the sample is rotated, but there are few such sample holders.

[0004]

SUMMARY OF THE INVENTION The present invention provides a sample holder in which a sample can be easily set and can be stably held so that the measurement point does not change even when the sample is rotated, and which has a simple structure. The purpose is to do.

[0005]

In a sample holder of a birefringence measuring device, two plates made of a material having elasticity are adhesively fixed by sandwiching a spacer at an end, and the two plates are adhered. A hole was provided on the opposite side of the fixed end so that the centers of the two were coincident with each other, and a holding plate was rotatably mounted in the hole, and the sample was sandwiched between these upper and lower holding plates.

[0006]

The sample holder of the present invention is intended to hold a sample by sandwiching the sample between two elastic plastic plates (sample holder bodies). Each plate has a circular hole. Is provided, and a holding plate (grip) having a hole in the center is rotatably fitted in the hole.

[0007]

FIG. 1 shows an embodiment of the present invention. In FIG. 1, reference numeral 1 is a retaining ring, and an index 1A is stamped on the outer peripheral edge thereof. Two
Is an upper plate made of an elastic material and has a hole 2 in the center.
B is provided, and a scale 2A is engraved on the outer edge thereof. A pressing plate 3 is provided with a circular protrusion 3A at the center, and the pressing plate 3 and the retaining ring 1 are integrally fixed by fitting the outer diameter of the protruding portion 3A with the inner diameter of the retaining ring 1 and the pawl. The inner diameter of the hole 2B of the upper plate 2 is loosely fitted to the outer diameter of the protrusion 3A of the pressing plate so that the pressing plate 3 is rotatable with respect to the upper plate 2. Rotate the holding plate 3 to the upper plate 2 by passing the protruding portion 3A of the holding plate through the through hole 2B of the upper plate 2 and fitting the retaining ring 1 to the portion protruding from the upper plate 2 of the protruding portion 3A. Install as possible. The snap ring 1 is transparent and the lower scale 2A is visible. The rotation angle of the holding plate 3 can be grasped by the index 1A engraved on the retaining ring 1 and the scale 2A engraved on the upper plate 2.
Reference numeral 4 denotes a lower plate (sample holder body), to which the pressing plate 6 is rotatably fitted like the upper plate 2 and the pressing plate 3. 5 is the upper plate 2
The spacer is sandwiched between the lower plate 4 and the lower plate 4 and fixedly adhered to each other. The thickness is such that a pressing force is generated between the pressing plate 3 and the pressing plate 6 by the elastic force of the upper plate 2 and the lower plate 4. S is a sample, and as shown in FIG. 3, the space between the upper plate 2 and the lower plate 4 is widened,
When the sample S is inserted between the pressing plates 3 and 6 and the upper plate 2 and the lower plate 4 are separated from each other, as shown in FIG. 2, the elastic force of the upper plate 2 and the lower plate 4 causes the sample S to be pressed down. It is sandwiched between the plates 3 and 6. By rotating the holding plate 3 and the holding plate 6 integrally, the direction can be changed without applying stress to the sample S. Therefore, it is advisable to adhere a material having a high friction coefficient (for example, a rubber sheet) to the surfaces sandwiching the holding plates 3 and 6 samples. The use of this holder is effective when the retardation is measured mainly by changing the incident angle of light, and it is effective when it is necessary to match the direction of the main refractive index with the incident surface.

FIG. 4 is an overall configuration diagram of the birefringence meter. In FIG. 4, reference numeral 41 is a polarizer, 42 is an analyzer, and they are held in parallel with each other by holding frames which are rotatably attached to the apparatus. The motor 45 through the belts 43 and 44.
It is made to rotate integrally by. Reference numeral 46 is a light source, 47 is a light receiving element, S is a sample to be measured, K is a standard sheet whose optical principal axis direction is known, and holds the optical axis in alignment with an index. The standard sheet only needs to have a known direction of the optical principal axis, and the retardation d itself may be unknown. The sample S to be measured is held on the sample holder A shown in FIG. 1 so that its direction can be changed. The sample holder A is attached to and detached from the device in a fixed direction.
Reference numeral 48 is a control device that performs data processing on the output of the light receiving element 47 and controls the rotation of the polarizer 41 and the analyzer 42, and 49 is a display device of measurement results and the like.

In the above embodiment, the operation for determining the optical principal axis of the sample S to be measured is performed as follows. The sample S is held by the sample holder A in an arbitrary direction. When this sample holder A is set on the sample stand of the device and the measurement operation is started, the control device 48 drives the motor 45 and the polarizer 4
1. The analyzer 42 is rotated by a constant angle, the output data of the light receiving element 47 for each angle is taken in, and the difference Di between the maximum and the minimum output of the light receiving element 47 during one rotation of the polarizer and the analyzer is calculated. Calculate and display. Here, the subscript i of D is 1,
The numerical value of 2, ... Shows the number of measurements, and i = 1 for the first time. When one measurement is completed as described above, the sample S is rotated on the sample holder A at a constant angle, for example, 5 °, and the second measurement is performed in the same manner as above. In this way, 5
The maximum and minimum difference Di of the light receiving element output for each interval is obtained.
Therefore, Di is compared with the previously measured value of Di-1, and Di-
Stop the measurement operation when Di <1>Di> Di + 1 was found. At this time, the direction indicated by the index on the sample holder of the sample corresponding to Di is the direction of the optical principal axis of the sample. In this measurement, since the sample changes its direction by 5 °, there is an error of ± 2.5 ° in the direction of the optical principal axis. Find Di while turning 5 ° each, and when the maximum Di is found,
If the maximum measurement D is obtained by performing the same measurement operation as above at an interval of 1 ° between the side that gives the larger value of Di-1 and Di + 1 and Di, the direction is accurate to ± 0.5 °. Desired. The rotation angle range of the sample may be 90 ° at the maximum.

Now, let the overall retardation when the sample S and the standard sheet K are superposed be Δ, and let the angle between the apparent optical principal axis of this superposed one and the polarization direction of the incident polarized light be θ, and go to S + K The incident light intensity of Io, S + at this time
Letting the transmitted light intensity of K be I, I = I _O [cos ⁴ θ + sin ² θ + (1/2) sin ^{2 2} θ · cos Δ] When θ = 0 and π / 2, I = Io is maximum, θ = π / 4
If I = I ₀ [1/2 + (1/2) cos Δ] and Δ = 0, then I = Io, and if Δ is not 0, then I = Io
<In Io, I has the minimum value when θ = π / 4. There I
Where D is the difference between the maximum and the minimum of, the smaller the value of cos Δ = 1−2D / I ₀ cos Δ, the larger the value of Δ, that is, the larger D is, the larger Δ is. If the sample S is rotated to find a place where D becomes maximum, then Δ is maximum,
The maximum of Δ is when the optical principal axes of the sample S and the standard sheet K are parallel. When the above-described measurement is performed by inclining the sample, the sample stage on which the sample holder is set is inclined.
The axis of tilt of the sample stage intersects with the center line of the measurement light beam, and the center of rotation of the sample on the sample holder is aligned with the center line of the measurement light beam on the tilt axis of the sample stage. This alignment may be performed by contacting the two orthogonal sides of the outer periphery of the sample holder with the contact on the sample table.

[0011]

According to the present invention, the sample can be set only by sandwiching the sample between the two plastic plates, and the outer shape of the sample holder is constant. Therefore, the position of the sample holder with respect to the sample table is determined. As a result, the position of the sample with respect to the measurement light flux is naturally determined, which facilitates sample setting. Further, since the pressing plate is rotatably attached to the two plastic plates, the sample is clamped by the pressing plate, and the sample is rotated in the clamped state, the sample is stably held without displacement or stress. I was able to change direction. In particular, the use of this holder is effective mainly when changing the incident angle of light to measure the retardation and when it is necessary to match the direction of the main refractive index to the incident surface. That is, when light is vertically incident without tilting the sample, it is sufficient to simply rotate the sample together with the sample holder around the vertical axis, and there is little need to hold the sample rotatably with respect to the sample holder. However, when the retardation is measured by changing the incident angle of light on the sample, it is usual that the sample is tilted with respect to the incident optical axis without changing the incident optical axis. In this case, while the sample is tilted at an arbitrary angle, the sample is held in a state in which rotation within the plane perpendicular to the incident optical axis (rotation around the optical axis) and rotation within the sample surface are possible. There is a need. Since the sample is rotatably held in the sample holder, it is possible to easily rotate the sample in the sample plane. Therefore, for example, when the main refractive index direction of the sample is rotated in an arbitrary direction, etc. It is very effective. (Applicable to various cases such as main refractive index direction determination, order determination, three-dimensional measurement, etc.) In addition, in order to change the light incident angle, it is possible to tilt the incident optical axis itself. It is necessary to make the entire photometric system such as the polarizer, analyzer, and light receiver movable, which complicates the mechanism and increases the size.

[Brief description of drawings]

FIG. 1 is a perspective view of an embodiment of the present invention.

FIG. 2 is an overall side view of the sample holder in the sandwiched state in the above embodiment.

FIG. 3 is an overall side view of the sample holder in the open state in the above embodiment.

[FIG. 4] Overall configuration diagram in the above embodiment 1 Retaining ring 1A Index 2 Upper plate 2A Scale 2B Hole 3 Holding plate 3A Projection 4 Lower plate 5 Spacer 6 Holding plate S Measured sample

[Procedure amendment]

[Submission date] July 16, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

Claims (3)

[Claims] 1. A sample holder for a birefringence measuring apparatus, comprising a sample holder main body and a sample grip analysis rotatable with respect to the main body. 2. The sample holder of the birefringence measuring device according to claim 1, wherein the sample gripping analysis is configured to sandwich the sample from above and below. 3. Two plates made of a material having elasticity are adhered and fixed by sandwiching a spacer between the ends, and the centers of the two plates are coincident with each other on the opposite sides of the ends where the two plates are adhered and fixed. A sample holder for a birefringence measuring device, characterized in that a hole is provided as described above, a holding plate is rotatably mounted in the hole, and the sample is sandwiched between the upper and lower holding plates.