JP3236643B2 - How to determine the direction of the quartz plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a quartz plate having a predetermined crystal lattice plane inclined with respect to a cut plane (for example,
(AT cut plate).

[0002]

2. Description of the Related Art A quartz AT cut plate is defined so that a predetermined crystal lattice plane is inclined at a predetermined angle with respect to the cut plane. It is known that X-ray diffraction measurement is used to accurately inspect the inclination angle and measure a deviation from a specified angle. By the way, in order to measure the inclination angle, it is necessary to set a square AT-cut plate on a sample stage for X-ray diffraction, for example, after directing it in a correct direction. If the AT cut plate is oriented in the wrong direction, diffraction X-rays cannot be detected.

Conventionally, several methods are known for aligning an AT cut plate in a predetermined direction. The most accurate method is to use an X-ray diffractometer for direction discrimination and set an X-ray optical system so that diffracted X-rays are detected only when the AT cut plate is oriented in the correct direction. is there.

There is also a method of marking a direction on an AT cut plate. In this method, for example, a chamfer is formed at two adjacent vertices among four vertices of a square. This allows the operator to determine the direction with the naked eye. Further, in order to automatically determine the direction of the AT cut plate, the chamfer may be optically detected.

[0005]

The direction discrimination by X-ray diffraction measurement requires an X-ray source and an X-ray detector for the direction discrimination, and is very expensive. Further, the method of chamfering the AT cut plate and optically detecting the chamfer has a limitation that the AT cut plate must be chamfered, and furthermore, a discrimination error occurs due to lack of a vertex of the AT cut plate. Is easy to occur. An object of the present invention is to provide a method for accurately determining the direction of a crystal plate using a relatively simple device.

[0006]

According to the method of the present invention, when a quartz plate is arranged between two polarizing elements, the intensity of light passing through the optical system depends on the direction of the quartz plate. Utilize the phenomenon. That is, the present invention provides a method for determining the direction of a quartz plate in which a predetermined crystal lattice plane is inclined with respect to a cut plane, wherein the first polarizing element and the first polarizing element are disposed in the optical path from the light source to the light receiving element. Disposing two polarizing elements, disposing a quartz plate between the two polarizing elements, and detecting light passing through the first polarizing element, the quartz plate, and the second polarizing element with the light receiving element. And a step of rotating the quartz plate around an axis perpendicular to the cut surface and determining a direction of the quartz plate based on the detected light intensity. In this case, even if the light that has passed through the first polarizing element reaches the second polarizing element after passing through the quartz plate, or reaches the second polarizing element after being reflected by the quartz plate, It can be used to determine the direction of the quartz plate.

As a more specific method, a rectangular quartz plate is rotated by 90 ° between the two polarizing elements, and when the intensity of the transmitted light is larger or smaller than a predetermined threshold value. , It can be determined that the crystal plate is oriented in a predetermined direction.

[0008]

When the two polarizing elements are arranged in parallel with each other rotated by 90 °, the intensity of the light passing through the two polarizing elements becomes almost zero. When a quartz plate is arranged between these two polarizing elements, the intensity of light passing through this optical system does not always become zero. In addition, the intensity of the passing light changes by rotating the quartz plate in the plane. Therefore, if the relationship between the detected light intensity and the rotation angle of the quartz plate is determined in advance, the direction of the quartz plate can be determined.

[0009]

FIG. 1 is a perspective view showing an embodiment of the present invention. The first polarizing plate 2 and the second polarizing plate 4 are set at 90 ° to each other.
Arrange them in parallel while rotating. Light from the light source 6 passes through the first polarizing plate 2 and the second polarizing plate 4, passes through the condensing lens 8, and is detected by the light receiving device 10. The light from the light source 6 becomes linearly polarized light by the first polarizing plate 2, and in a state where the AT cut plate 12 made of quartz does not exist, the linearly polarized light is cut off by the second polarizing plate 4, and the transmitted light becomes almost zero. Become.

An AT cut plate 1 is provided between two polarizing plates 2 and 4.
When 2 is inserted, the intensity of light passing through the second polarizing plate 4 does not always become zero. When the AT cut plate 12 was rotated around an axis perpendicular to the cut surface, a phenomenon was confirmed in which the intensity of the transmitted light changed according to the rotation angle. FIG.
Indicates a state in which the traveling direction of light and the cut surface (surface) of the AT cut plate are at a right angle. It is confirmed that the same phenomenon occurs even when the light is inclined at any angle other than the right angle. Was done. FIG. 2 shows that the light traveling direction is the AT cut plate 12.
It is a front view showing the state where it inclined by 40 degrees to the cut surface of.

FIG. 3 is a graph showing the relationship between the in-plane rotation angle of the AT cut plate and the intensity of the passing light, which was measured by the optical system shown in FIG. The horizontal axis indicates the rotation angle about the axis 14 perpendicular to the cut surface of the AT cut plate. The rotation angle at the position where the intensity of the passing light becomes zero is set to 0 °. The vertical axis is a detection voltage when the output of the light receiving device is converted into an electric signal, which is proportional to the intensity of the passing light.
The following can be seen from this graph. (1) The intensity of the transmitted light greatly changes depending on the rotation angle of the AT cut plate. (2) There are four rotation angles at which the intensity of the passing light has a maximum value,
The angles are 40 °, 110 °, 208 °, 328 °. The distance between the four angles is offset from 90 ° or a multiple thereof. (3) There are four rotation angles at which the intensity of the passing light takes a minimum value,
The angles are 0 °, 80 °, 148 °, 285 °.
The distance between the four angles is again offset from 90 ° or a multiple thereof.

Next, a procedure for aligning the AT cut plate in a predetermined direction will be described. The shape of the used AT-cut plate is a square, and two of the four vertices are chamfered at adjacent vertices. First, two polarizing plates 2 and 4 are arranged in parallel at 90 ° from each other,
The intensity of the transmitted light is set to zero. Next, the AT cut plate 12 is inserted between the polarizing plates 2 and 4 with the posture shown in FIG. Then, the two polarizing plates 2 and 4 are rotated by the same angle in the same direction in the plane so that the intensity of the transmitted light is minimized. This completes the adjustment of the polarizing plate. Further, a threshold value indicated by a broken line 18 in FIG. 3 is set for the detection output voltage of the passing light. When the output voltage is smaller than the threshold value 18, a high-level signal is output from the determination circuit. When the output voltage is larger than the threshold value 18, a low-level signal is output. Preparation is completed above.

Next, the AT cut plate 12 whose direction is to be determined
Is inserted between the two polarizing plates 2 and 4 in the direction of arrow 16. At this time, the AT cut plate is conveyed in a state where any one side of the square is parallel to the direction of arrow 16. That is, the AT cut plate 12 faces any one of the four types of directions shifted by 90 ° from each other. In this state, the intensity of the passing light is detected. If the AT cut plate 12 is in the posture shown in FIG. 1, the detection intensity of the transmitted light is in the state of the rotation angle of 0 ° in FIG. That is, the detection output falls below the threshold value 18, and a high-level signal is output from the determination circuit. As a result, it is determined that the AT cut plate 12 is oriented in a predetermined correct direction, and the AT cut plate 12 is carried out in the direction of the arrow 17 as it is.

If the AT cut plate 12 faces any of the other three directions other than those shown in FIG.
The detection output is in one of the rotation angles of 90 °, 180 °, and 270 ° in FIG. 3, and in this case, the detection output exceeds the threshold value 18 in any state. Therefore, a low level signal is output from the determination circuit. When the low level signal is output from the determination circuit, the AT cut plate 12 is rotated by 90 ° in the plane by a rotating device, and the transmitted light is similarly detected. The same operation is repeated until a high level is output from the determination circuit. If the determination is made at most four times, a high-level signal can always be obtained, and at that time, the AT cut plate 12 is oriented in the direction shown in FIG. And the AT cut plate 1 facing the right direction
2 is transported in the direction of arrow 17.

As described above, if the AT cut plates are inserted between the polarizing plates one after another, the AT cut plates 12 that exit in the direction of arrow 17 are always aligned in a fixed direction.

In the above-described embodiment, the AT cut plate 12 has a size of 9 × 9 mm and a thickness of 0.2 mm.
As the light source 6, a semiconductor laser having a wavelength of 670 nm was used, and as the light receiving device 10, a phototransistor was used. In the embodiment, in order to confirm the effect of discrimination with the naked eye, an AT cut plate with a chamfer is used, but even if an AT cut plate without a chamfer is used, it can be accurately aligned in a specific direction. .

The present invention is not limited to the above-described embodiment, but can be modified as follows. (1) In the above embodiment, the optical system is such that light transmitted through the quartz plate reaches the second polarizing element. However, light reflected by the quartz plate reaches the second polarizing element. Similar direction discrimination is possible even with a simple optical system.

(2) In addition to a semiconductor laser as a light source, an experiment was performed using a He-Ne laser and white light, and a graph similar to FIG. 3 was obtained.

(3) In the above-described embodiment, the direction of the AT cut plate is rotated so that the detection output of the transmitted light becomes the minimum value. However, the detection output of the transmitted light is reversed. The direction can also be aligned by rotating the AT cut plate so as to reach the maximum value. In this case, the polarizing plate may be reset so that the position of the rotation angle of 208 ° in FIG. 1 becomes 0 ° of the rotation angle, and the threshold value may be set at a position slightly lower than the maximum peak voltage. . Then, when the detection output is larger than the threshold value, it may be determined that the AT cut plate is oriented in a predetermined direction. However, care must be taken because the detection output may fluctuate due to fluctuations in the intensity of the light source. In order to avoid this, it is necessary to devise to keep the intensity of the light source constant.

(4) A graph similar to that of FIG. 3 was obtained even when the angle of incidence of light on the AT cut plate was other than 40 °. This is the same even when it is vertical as shown in FIG. However, it seems that the inclination is more advantageous because the angle interval between the minimum values or the maximum values deviates from 90 ° or a multiple thereof.

(5) In addition to the above-mentioned AT cut plate, BT cut plate, FC cut plate,
There are IT cut plate, LC cut plate, SC cut plate, RT cut plate and the like.

(6) In the above-described embodiment, the rectangular quartz plate is rotated by 90 °. However, for example, when the direction of a circular quartz plate is determined, the quartz plate is continuously rotated in the plane. Then, a predetermined direction may be found.

[0023]

According to the present invention, the direction of the quartz plate is determined by arranging a quartz plate between the two polarizing elements and detecting the intensity of light passing through the optical system. Compared to X-ray diffraction direction determination, it has the advantage of requiring a relatively simple apparatus.Compared to the method of determining the direction by optically determining the shape, no mark such as chamfering is applied to the quartz plate. There is an advantage that it may be.

[Brief description of the drawings]

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

FIG. 2 is a front view showing a state in which a light incident direction on a quartz plate is inclined.

FIG. 3 is a graph showing a relationship between an in-plane rotation angle of a quartz plate and a detection intensity of transmitted light.

[Explanation of symbols]

 2 First polarizing plate 4 Second polarizing plate 6 Light source 10 Light receiving device 12 Quartz AT cut plate

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields investigated (Int.Cl. ⁷ , DB name) G01N 21/00-21/01 G01N 21/17-21/61 G01B 11/26 Practical file (PATOLIS) Patent file (PATOLIS)

Claims (4)

(57) [Claims] In a method for determining the direction of a quartz plate in which a predetermined crystal lattice plane is inclined with respect to a cut plane, a first polarizing element and a second polarizing element are provided in an optical path from a light source to a light receiving element. Arranging a polarizing plate, and arranging a quartz plate between the two polarizing devices; and detecting light passing through the first polarizing element, the quartz plate, and the second polarizing element with the light receiving element. Rotating the quartz plate around an axis perpendicular to its cut plane,
Determining the direction of the quartz plate based on the intensity of the detected light, and rotating the rectangular quartz plate by 90 ° between the two polarizing elements.
The intensity of the detected light exceeds a predetermined threshold.
When the crystal plate is in the specified direction when it is large or small
Orientation of the quartz plate, which is determined to be facing
Judgment method. 2. The method according to claim 1, wherein the light transmitted through the quartz plate reaches the second polarizing element. 3. The direction discriminating method according to claim 1, wherein light reflected by said quartz plate reaches said second polarizing element. 4. The method according to claim 1, wherein said quartz plate is an AT cut plate.
2. The method according to claim 1, wherein the direction is determined.