RU1806343C - Method of controlling stresses in quartz crystals - Google Patents

Abstract

Usage: the invention is intended to control stresses in crystalline quartz and is based on the influence of stresses on the angle of rotation of the plane of polarization of light in quartz. SUBSTANCE: crystalline quartz sample placed between crossed polarizer and analyzer is illuminated along its optical axis by a parallel or converging light beam, and the invention analyzer relates to metrology of optical materials and electronic materials and is intended for voltage control in crystalline quartz. The aim of the invention is to increase the accuracy and sensitivity of stress control in crystalline quartz, reducing the complexity of sorting crystals by the presence of stresses in them. The indicated goal is achieved by that. that in the method of controlling the stresses in the crystals, they rotate relative to the initial position by an angle a at which the transmission of the polarizer-crystal-analyzer system is minimal at a given wavelength of light A. The presence of stresses in the crystal is determined from the conditions a - (I. p „- 180 ° K) J / I 0 for the right quartz when the analyzer rotates counterclockwise along the beam from the light source, or for the left quartz when the analyzer rotates clockwise; (180 ° - a). (I, ppm -180 ° K) / lf 0-dl for the right quartz when the analyzer rotates clockwise in the direction of the beam from the light source, or for left quartz when the analyzer rotates counterclockwise, where I is the thickness of the crystal in place passage of light; R . the natural angle of rotation (constant rotation) of the plane of polarization at the wavelength of light I; K is an integer from the series O,. 1,2, 3, ... are chosen so that (I. rg. - 180 ° - .. K) 180 °. The greater the stress in the crystal, the greater the difference from the zero left sides of the inequalities. quartz, including transillumination by a parallel or convergent beam of light from a crystal placed between crossed polarizer and analyzer, the crystal is translucent along the optical axis, the analyzer is rotated through an angle a. equal: eat with oo o o oo Јv CO co (f-180 ° K) 0) -. for a dextrorotatory quartz when the analyzer rotates counterclockwise or for a levorotatory quartz

Description

when the analyzer rotates clockwise;

or

and 180 ° - (I. -180 ° K)

(2)

- for a dextrorotatory quartz when the analyzer rotates clockwise or for a dextrorotatory quartz when the analyzer rotates counterclockwise; where I is the thickness of the crystal at the point of passage of light;

p is the rotational ability at the wavelength of light A, K is an integer from the series 0, 1, 2, 3 ..., and K is selected from the condition: (I. f - 180 ° K) 180 ° and the change in the angle of rotation is recorded the plane of light polarization by turning the analyzer by an additional angle ft, at which the transmission of the polarizer-cristall-analyzer system is minimal, and the voltage in the crystal is controlled by condition.

The present invention is based on the detected effect of stresses in crystalline quartz on the value of the angle of rotation of the plane of polarization of light. A significant and fundamental difference between the proposed method and the known one is registration of a change in the angle of rotation of the plane of polarization of light, but not registration of a change in birefringence in the known method.

A linearly polarizing wave in an active crystal (quartz) can be represented as a combination of two circularly polarized waves (left and right) with the same periods and amplitude (see, for example). Stresses in quartz crystals have been found to affect the propagation velocity of circularly polarized waves (or, equivalently, the corresponding refractive indices of these waves), as a result of which the angle of rotation of the plane of polarization of light in a strained the quartz crystal differs from the corresponding angle in the unstressed crystal. .

The experimentally obtained accuracy of setting the angle of rotation of the plane of polarization of only 0.5 ° makes the proposed method for controlling stresses in quartz crystals superior in sensitivity and control accuracy to the known methods.

Example 1 A right-quartz crystal in the form of a plate cut perpendicular to the optical axis with a thickness of 40.5 mm was placed between crossed polarizers so that the light passed along the optical axis. A 2-harmonic of solid-state laser radiation with a wavelength of A 0.53 µm was used as a light source. To obtain a convergent beam

In front of the crystal, a positive lens with a focal length was placed. 10cm The rotational ability for quartz at a wavelength of 0.53 microns is 27 deg / mm.

The analyzer was rotated counterclockwise by an angle a, calculated by formula (1) and comprising: a 40.5. 27 ° -1080 ° 13.5 °, while complete extinction of the beam at the exit from the analyzer was not observed.

To completely extinguish the beam, the analyzer was rotated by an additional angle ft 24 °, which indicates the presence of stresses in the crystal.

Indication of light fading conditions

(for a converging beam — dimming its central region) at the exit from the analyzer, it was carried out using a photodetector with an arrow indicator, which made it possible to more accurately establish the moment when the beam went out. After that, the crystal was cut into blanks, some of which cracked during cutting. The remaining workpieces cracked during grinding and were unsuitable for

further use.

Thus, the presence of mechanical stresses in quartz crystals makes them unsuitable for the manufacture of articles. Since the current control

crystalline quartz for the presence of stress is not carried out, and all crystals are processed a little, this leads to a significant number of defective products from quartz and a significant laboriousness of manufacture, since labor is also spent on the processing of unfit products. Therefore, the introduction of stress control in quartz leads to a decrease in the complexity of manufacturing products.

PRI me R 2. Preparation of a crystal of left quartz with a thickness along the optical axis of 17 mm The control was carried out in a parallel beam of a gas laser with a wavelength A of 0.63 µm and there was no lens. Conditions

the measurements were the same as in Example 1. The rotational ability at a given wavelength is 18.8 deg / mm. The analyzer was turned counterclockwise by a angle calculated by formula (2), equal to:

and 180 ° - (17 .18.8 ° -180 °) 40.4

about.

at this angle, the transmission of the polarizer – crystal – analyzer system was minimal, i.e. / 3 0, which means the absence of stresses in this crystal. Products were made from this crystal, the parameters of which fully met the technical requirements.

Claims (1)

SUMMARY OF THE INVENTION A method for controlling stresses in quartz crystals, comprising illuminating a parallel or converging beam of light from a crystal placed between crossed polarizers and analyzers, characterized in that, in order to increase the accuracy and sensitivity of the control, the complexity of sorting crystals by the presence of stresses, they shine through the crystal along the optical axis, turn the analyzer through an angle a equal to а- (I. ръ -180 ° К) for a dextrorotatory quartz when the analyzer rotates counterclockwise or for a dextrorotatory quartz when the analyzer rotates clockwise or a 180 ° - (1 -180 ° K) for a dextrorotatory quartz when the analyzer rotates clockwise or for a dextrorotatory quartz when the analyzer rotates counterclockwise, where I is the thickness of the crystal at the point of passage of light; p - rotational ability at a wavelength of light I; K is an integer from the series 0, 1,2, 3 ..., where K is selected from the condition (I p - 180 ° K) 180 ° and the change in the angle of rotation of the plane of polarization of light is recorded by turning the analyzer by an additional angle /, in which the transmission of the polarizer-crystal-analyzer system is minimal, the stresses in the crystal are controlled by condition / 0.