SU1645809A1 - Method of inspecting quality of lenses and objectives - Google Patents

Abstract

The invention relates to a measuring and control technique and can be used to control the quality of lenses and lenses in manufacturing, their manufacture. The purpose of the invention is to increase the sensitivity of monitoring by increasing the contrast of interference fringes. On the same axis set diffuse diffuser. controlled object and recording medium. The object is illuminated through a diffuse diffuser by a convergent spherical wave of coherent radiation and the transmitted radiation is recorded on a hologram. After that, the scatterer and the object are displaced in the same direction in their planes and the transmitted radiation is again recorded on the hologram. By means of spatial filtering, an interference pattern is formed using a lens, according to which quality control is carried out. 1 il.

Description

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WITH

The invention relates to a measuring and control technique and can be used, in particular, to control the quality of lenses and lenses in production, which is occupied by their manufacture.

The aim of the invention is to increase the sensitivity of the control by increasing the contrast of the interference fringes.

The drawing shows one of the possible schemes of the device that implements the proposed method.

The device includes a coherent light source 1, a beam splitter 2, a mirror 3, a collimating system of lenses 4, 5, lenses 6, 7, frosted glass 8 with a shear mechanism 9, a mounting unit 10 for a controlled object with a shear mechanism 11, a recording medium (photographic plate) 12,

aperture diaphragm 13 of lens 14 and interferogram recorder 15.

The method is implemented as follows.

The coherent radiation from source 1 using a splitter 2 is divided into two channels: a reference beam forming channel and an object channel. In the channel of formation of the reference beam, the radiation reflected from the mirror 3, expanded by the lensing system 4. 5, is directed to the photographic plate 12. In the channel of formation of the object wave using lenses 6, 7, the front of a converging spherical wave with a radius of curvature in the plane of frosted glass is formed 8, equal to the distance H from it to the main plane of the object to be inspected, placed in the attachment point 10. The distance h is chosen from the condition, and the distance 2 from the main plane of the contour

4 SL 00 O

h

the rotated object to the photographic plate 12

 "- f | i choose from the condition I .- t,

rflef-focal distance of the controlled object.

Record the hologram during the first exposure. Before the second exposure, the frosted glass 8 is shifted by means of its shift mechanism 9 and the attachment object 10 for the object being monitored by means of mechanism 11 is shifted in one direction perpendicular to the optical axis by quantities satisfying the relation

I, a b, where a is the amount of shift matt

glass 8; B is the magnitude of the shift of the assembly 10 of the monitored object. After the photoplate 12 is developed and fixed, the hologram is restored and, using a lens 14 with an aperture diaphragm 13 installed at a distance, fH

i

- 2 from the hologram, build an image of the pupil of the controlled object in the recorder plane of the interferogram 15 and record the shift interferogram when conducting spatial Filtration using the aperture diaphragm 13, according to which the quality control of the object under study is carried out.

Compared with the prototype, the proposed method allows to increase the sensitivity of the control. Since the sensitivity of the control is proportional to the magnitude of the shift of the object being monitored, in the proposed method the fulfillment of condition 2f contributes to an increase in the magnitude of the shift. This is due to the fact that in the prototype method, the required shift in the matte screen increases with increasing magnitude of the displacement of the object being monitored, therefore, the magnitude of the shift between the fronts of the wave of its illumination increases the frequency of interference fringes localized in the plane of spatial filtering . This circumstance in turn leads to the need to reduce the diameter of the aperture diaphragm in the spatial filtering plane, and therefore, to increase the size of the speckle in the interferogram recording plane corresponding to the object being monitored. Increasing the size of the speckle caused i to decrease the contrast of the interference pattern. In the proposed method prc zoom interference

the pattern localized in the plane of the spatial filtration, the required diameter of the aperture diaphragm increases, therefore, the size of the speckle in the plane decreases

registration, which allows an increase in the magnitude of the shift of the object being monitored, by the most increasing the sensitivity of the control.

Claims (1)

Invention Formula The method of controlling the quality of lenses and lenses, which means that a diffuse diffuser on a single axis, a controlled object and a recording medium, illuminate the controlled object through a diffuse diffusor with a spherical converging spherical wave of its front in the diffusor plane equal to the distance from scattered to the main plane of the monitored object, recorded on the recording medium the hologram of radiation transmitted through the monitored object, displaced the diffuser and the monitored object in their planes in the same direction, recorded the hologram of the transmitted radiation on the same recording medium and recorded with the help of a lens when restoring the two-exposure holograms, the interference pattern, according to which the quality of the controlled object is judged by the fact that, in order to increase the control, when set, the split h from the diffuser to the main plane of the object being monitored and the distance 2 from the main plane of the object being monitored to the recording medium are chosen from the ratios 2f. li / (li - f), where f is the focal distance of the object being monitored, and when registering an interference pattern, spatial filtering is performed using the aperture diaphragm of the lens at a distance from the hologram that satisfies the ratio , f | i i I --- - n 1 h-f l2 O; with IP 5