SU1551989A1 - Method of checking the shape of reflecting surface of mirror reflectors - Google Patents

Abstract

The invention relates to optical instrumentation, specifically to optical measurements based on speckle interferometry. The purpose of the invention is to improve the accuracy of control. The method involves exposing the photographic plate to diffuse radiation produced by passing coherent radiation through a diffuser, and then reflecting it from a specular reflector, whose location from exposure to exposure is changed by displacing the reflector parallel to the photographic plate. An odd number of exposures is carried out, the duration of the first exposure is chosen from the equality of exposure to the inverse photosensitivity of the photoplate, and subsequent exposures are carried out in cycles, including two exposures, after placing the reflector before each exposure in symmetrical positions relative to the initial position from cycle to cycle to a value equal to the initial offset, and the duration of each exposure in the cycle is determined from the mat ny 1 hp f-ly, 1 ill.

Description

The invention relates to optical instrument making, and more specifically to optical measurements based on speckle interferometry.

The purpose of the invention is to improve the accuracy of control.

The drawing shows one of the possible schemes of the device, allowing the proposed method to be implemented.

The device includes a coherent light source 1, a shutter 2, a condenser 3, a diffuse diffuser 4, a beam splitter 5, a controlled mirror reflector 6 with its movement mechanism 7, a photographic plate 8.

The method is carried out as follows.

The coherent radiation from source 1, after passing through the condenser 3, illuminates diffuse diffuser 4 with open shutter 2. Diffuse radiation reflected from the beam splitter 5 and mirror reflector 6 enters the photographic plate 8 and is recorded on it during the first exposure. Before the second exposure, the mirror reflector 6 is displaced in the plane passing through its top and parallel to the plane of the photographic plate 8 by means of the mechanism 7,

ate

co oo co

ml of baseline Before the third expo- sure (the mirror reflector 6 is displaced by a and symmetrically relative to its initial position, and so on, with the displacement value being a multiple of a before each subsequent exposure.

When the recording is restored, the developed photographic plate is illuminated with a flat coherent wave from the source used during recording and in the focal plane of the lens mounted behind the photographic plate, a picture of periodically alternating narrow interference fringes is obtained. Based on the results of measuring the repetition period DF, the radius of curvature of the spherical mirror R 2aDX1 / (flf) is determined, where 1 is the distance from the plane passing through the top of the reflector 6 to the plane of the photographic plate 8; 1 is the wavelength of the light source used; f is the focal length of the lens used.

Violation of equidistance of interference fringes characterizes the deviation of the surface from a spherical shape or wave aberrations of spherical mirrors. The measurement accuracy is determined by the accuracy of determining the center of interference fringes and increases with increasing number of exposures. in symmetrical with respect to the initial positions, while the magnitudes of the displacement of the reflector successively increase t from nickel to cycle to a value equal to the initial contiguity, and the duration of each exposure in the cycle is chosen equal to

N -1

„

 -t j - N-l.

N-LC

WITH

M-1

- the duration of the 1st exposure; - total number of exposures; is the sequence number of the exposure cycle;

- the number of combinations from N-1 to --- - m and from N-1 to ---, respectively.

Claims (2)

1. A method of controlling the shape of the reflecting surface of mirror reflectors, which includes illuminating the reflector with diffusion-scattered radiation, sequential exposure of the photographic plate with radiation reflected from the specular reflector at its different positions, characterized in that, to improve the accuracy of control, a coherent source radiation and exposure, starting from the second, are performed in cycles when the reflector is displaced in a position symmetrical with respect to the initial one and in a plane parallel to the plane photographic plates, while the magnitude of the displacement of the reflector sequentially from cycle to cycle increases. 2. The method according to claim 1, characterized in that the duration of each exposure in the cycle is chosen equal to N- sg-- l NH / SShT V WITH N- N m total number of exposures; the sequence number of the exposure cycle; - V, and WITH N- Where - the number of combinations of N-1 N-1 m. N-1  - m and from N-1 to --22 respectively j C0 - the duration of the first exposure.