SU1000745A1 - Interferometer for checking concave cylindrical surfaces - Google Patents

Description

The invention relates to a measurement technique and can be used, in particular, to control concave cylindrical surfaces on optical and optical enterprises. instrument industry npOMUutnosti.

A Twyman-type interferometer is known in which a synthesized hologram is placed in the working branch to form a cylindrical wave, made in the form of two identical groups of parallel strokes, the width and the distance between which from the middle to the edge decrease according to a parabolic law 13.

The disadvantages of such an interferometer are the complexity of the optical system and the direct dependence of the accuracy of control on the quality of the main optical components of the instrument.

The closest to the proposed interferometer for controlling concave cylindrical surfaces contains an illumination system, including sequentially located, a laser light source, a telescopic tube and a cylindrical lens, an interference and observation system.

The interference system consists of a cube with a beam-splitting face, two slots, one of which is located in the working and the second in the supporting branch, a cylindrical lens and a flat mirror. The observing system consists of a cylindrical lens and a C23 objective.

A disadvantage of the known interferometer is the low accuracy of the r: ontrol, since the interferometer has a low luminosity due to large losses of light on the beam-splitting surface and on the slit.

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The accuracy of the Instrument is also significantly affected by the quality of all surfaces of the cube, as well as the heterogeneity of its glass. In addition, the interferometer is sensitive to vibration, so KckK is built according to a scheme with separated branches.

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

This goal is achieved by

Claims (1)

25 that the interferometer for controlling concave cylindrical surfaces, containing an illumination system, including a sequential laser light source, a telescopic tube and a cylindrical lens, an interference and observation system, is provided with successively spaced between a cylindrical lens and an interference system a plane-parallel plate with a mirror stripe and an additional 1 (; a cylindrical lens adapted to move along its optical axis, and the interference The ion system is made in the form of a phase plate with two identical, symmetrically arranged groups of parallel lines, the distance between which varies arbitrarily Fig. 1 is a schematic diagram of an interferometer for controlling concave cylindrical surfaces in Fig. 2 — the interference systems of the proposed interferometer. concave cylindrical surfaces contain lighting, interference and observational systems. The lighting system includes successively located laser light source 1, a telescopic tube 2, a stationary cylindrical lens 3, a plane-parallel plate 4 and an additional cylindrical lens 5 configured to move along its optical axis (indicated by an arrow in Fig. 1}. Interference system b represents There is a glass phase plate, on the output surface of which there are two identical, symmetrically arranged groups of narrow parallel lines (Fig. 2). Groups can be divided All strokes have approximately the same width, and the distance between them changes arbitrarily - randomly. The minimum distance can be less, equal to or greater than the width of an individual stroke, the number of strokes can reach one hundred or more. The observational system consists of a cylindrical lens 7 and a lens. The interferometer operates in the following manner: An extended telescopic tube 2 beam from a laser light source 1 hits a cylindrical lens 3 and collects it in a line on a narrow mirror strip deposited on the first surface of the plane-parallel plate 4. After reflection from the mirror strip, the beam enters the additional cylindrical lens 5, which turns the interference system 6 in the direction of the monitored part 9. In preparation for for checking, part 9 is set so that the geometrical location of the centers of curvature of the tested cylindrical surface is aligned with the line of symmetry of the interference system. In addition, by axial movement of the additional cylindrical lens 5, the beam emerging from it is focused in the middle of the surface of the part 9. In the following, this beam is called reference. When the reference beam passes through the interference system, a plurality of cylindrical diffraction working beams are formed on its strokes. One of them, going through slot A, is shown in FIG. 1. It is directed to the surface to be tested, it fills the aperture, is reflected from it, and falls on the same stroke A of the symmetric group of strokes. Here comes the rays of the reference beam after reflecting them from the center of the surface being tested. They form a diffraction comparison beam, which superimposes on the working beam and interferes with it. Since the working beam carries traces of surface defects, the interference pattern contains precise information about the quality of the surface. In this manner, the beams that have passed through all the other strokes of the interference system are superimposed on each other and interfere with each other. The result of interference is observed with the help of an observational system consisting of lens 7 and objective 8. Tilted part 9 or a small movement of the interferometer can be used to adjust the interference pattern to the desired width and direction of the fringes. The described interferometer circuit does not contain any beam-splitting surfaces and is large in action the number of strokes of the interference system. This provides an increase in the aperture ratio of the device by 3 times. The accuracy of the interferometer is increased by 1.5-2 times and practically does not depend on the quality of the optical elements included in it, since the working and branches are formed using systems of diffraction width bars, and the formation is carried out at the output of the interferometer. The increased vibraust of the interferometer is ensured by the fact that it is based on a circuit with aligned branches, and both beams, working and supporting, are reflected from the surface being tested. Due to these properties, disadvantages such as vibration sensitivity, low luminosity and the accuracy of the device on the quality of the surface of the cube and the heterogeneity of its glass, which did not allow for the creation of a high-precision device for interference control of concave cylindrical surfaces, are eliminated. The practical application of the interferometer will allow improving the process of shaping cylindrical surfaces, as well as significantly improving the quality of cylindrical axial pairs, anamorphic optical systems and other products with cylindrical surfaces. Claims of the invention: An interferometer for controlling concave cylindrical surfaces, containing an illumination system comprising a successively arranged laser light source, a telescopic tube and a cylindrical lens, an interference and a nab. With a view to improving the accuracy of control, it is equipped with a plane-allelic plate with a mirror stripe between an cylindrical lens and an interference system and an additional cylindrical lens capable of moving along its optical axis. and the interference system is made in the form of a phase plate with two identical, symmetrically located groups of parallel lines, the distance between which varies arbitrarily. Sources of information taken into account during the examination 1.Lukin AV, Mustafin KS, Rafikov R.A. Control of the profile of aspherical surfaces using one-dimensional artificial holograms. OMP, 1973, 6, p. 67. 2, USSR Copyright Certificate 355489, c. 01 В 9/02, 1970 (prototype). cuni empua