SU894350A2 - Interferential method for measuring linear and angular displacement value - Google Patents

Description

(54) INTERFERENCE METHOD OF MEASUREMENT

VALUES OF LINEAR AND ANGULAR DISPLACEMENTS

one

The invention relates to the control of measuring technique and can be used to measure the magnitude of the linear and angular movements of the moving parts of precision metal-cutting machine tools, measuring instruments and machines, systems and devices for automatic control, as well as for the study of transparent inhomogeneities , optics of the atmosphere.

Basically, auth. 399722 known interference method of measuring the magnitude of linear and angular displacements, namely, that monochromatic radiation is divided into two streams, these streams act on two ultrasonic light modulators excited at different frequencies, and re: diffuse the first and second light moduli tori 1.

The disadvantage of this method is that the sensitivity to movement is not high enough.

The purpose of the invention is to increase the sensitivity.

In order to achieve the goal, one IU of the streams is directed to the object before acting on the ultrasonic light-guided module.

The drawing shows a diagram of a device implementing the method.

The device contains a laser 1 and a beam-splitting element 2 along the light flux, forming parallel streams, a mirror element 3 consisting of two

10 rigidly connected prisms and intended for alignment of optical flow paths, an angular reflector 4, the movement of which is controlled, ultrasonic light-modulators 5 and b,

15 mirror 7, photodetectors 8 and 9 and phase meter 10, the inputs of which are connected to the outputs of the photodetectors.

Ultrasonic waves propagate in ultrasonic light guides in one direction. The frequency of the ultrasound fed to the ultrasonic light modulator 5 is equal to Q.4, and to the ultrasonic light modulator 6 0.4. Photodetector 8 is installed so

25 that spatially-coupled streams diffracted in one order (for definiteness, let's say, in (4–4) order) arrive from both ultrasonic light modulators. Photodetector 9 is installed so

that spatially combined streams diffracted upon repeated passage of the light modulators in (-1) order come from both ultrasonic light modulators to it.

The method is carried out as follows.

The light flux from the laser 1 is divided by the beam-splitting element 2 into two separate streams, one of which is directed to the corner reflector 4 by means of the mirror element 3. Then the light modulators are applied by streams, for which each of the streams is passed first in one and then the opposite direction through the corresponding ultrasonic light modulator 5, b. In the light modules 5 and b, ultrasonic waves traveling in the same direction with frequencies Si and Sl excite

The photodetector 8 records the result of the interference of the first and second streams in (in + 1) order of diffraction.

The variable signal U at the output of the photo-receiver 8 will look like

and, and „cos (a, -I,) t +4,

where Ug, is the amplitude of the signal, f is the phase difference of both beams, due to the position of the object under study. The photodetector 9 records the result of the interference of the first and second streams in (-1) diffraction order.

The variable signal Uj, at the output of the second photodetector will be

2 ° cos (Q.-ft2) t -f phase meter 10 determines the phase difference of the signals U, Uj arriving at it which is equal to 2f, which is twice the value recorded by the basic method.

Thus, due to the fact that one of the streams is directed to the object before the impact on the ultrasonic light modulator, a doubling of the sensitivity to movement is achieved.

Claims (1)

1. USSR author's certificate 399722, cl. G 01 9/02, 1973 (prototype).