SU1565205A1 - Holographic interferometer - Google Patents

Description

 ABOUT

(46) 08/15/91. Bksh. No. 30

(21) 4490246/25

(22) 10/06/88

(71) Frunze Polytechnic Institute

(72) A.Naripov and P.A.Turganbaep

(53) 772.99 (088.8)

(56) A.H.Lohmann, D.E.Silva. An Interferometer based on Talbot effect opt. Corramms, 1971, v. 2, 9, 413-415.

Smirnov A.P. On the laser-free optical Fourier transform using a perforated mask and a method for analyzing j interferograms based on it in a modified Talbot interferometer. Optics and spectroscopy, J987, t.62, vol. 3, p. 636-637.

(54) HOLOGRAPHIC INTERFEROMETER TALBOTA

(57) The invention relates to holography. The aim of the invention is to expand the capabilities of the device. The interferometer contains a periodic grating, a bleached hologram, a subject and controversial beams of light. The object under study is inserted between the lattice

and a hologram. With simultaneous illumination of such a system with source object and reference beams beyond the holomer, images on four screens located on the paths of four beams come to war: one of them restores self-reproduction of the lattice states, the other two - topographic, ordinary moire stripes that characterize the spatial heterogeneity and changes in the state of the object under study. The frequency of the guar strips is performed by rotating the lattice with respect to ifTjibno spatial coordinate axes. Clear contrasting images are obtained by positioning the screen in the plane of lattice self-reproduction, reconstructed from holograms. At the same time, four output information channels have different sensitivities: for the second and third channels, it coincides with the sensitivity of the topographic interferometer 8 and the fourth channel - with the usual Talbot interferometer, 3 sludge.

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This invention relates to holography and can be used to study optical components and dynamic phase objects (shock waves, gas flows, plasma jets, etc.) in real time.

- The purpose of the invention is to expand the functionality of the device.

The drawing shows the scheme of the proposed interferometer.

The interferometer contains a periodic grating J, a bleached hologram 2, an object 3, object beams 4 and a reference 5, the object under study 3 is inserted between screen 1 and hologram 2, screens 6-9, output information channels 10-33.

The interferometer works as follows.

Initially, an off-axis scheme using beams 4 and 5 records the hologram 2 of the lattice I. The distance between the lattice 1 and the hologram 2 is arbitrary. The hologram is developed, fixed, bleached and dried in place. The object under study 3 is introduced into the space between the grid 1 and the hologram 2, the device is ready for operation. Such a system is illuminated by the initial beams 4 and 5. On the screen 6, self-reproduction of the initial state of the lattice I is restored, on screens 7 and 8 there are holographic moire bands in opposite phases (negative and positive), on screen 9 - moire picture obtained in a conventional Talbot interferometer. The required frequency of moire stripes on screens is set by rotating the lattice 1 around the spatial axes X0, Y0, 20. reconstructed from hologram 2, the sensitivity of the device in channels I, 12 coincides with the sensitivity of the holographic interferometer (high), and in channel 13 corresponds to the sensitivity of a conventional Talbot interferometer (low. The sensitivity of the proposed interferometer will increase. and 13, since the conjugate waves interfere, corresponding to +1 and -1 diffraction rates.

In this interferometer, the problems of localization and removal of information are removed, since moire patterns arise in the self-reproduction planes of the lattice from holograms (in the real image space area).

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photosensitive plates located in place of screens 6-9 without

JQ -} $ - 20 - 25 ™). Jq

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optics application. In this case, the moire patterns do not have glass, since the object is illuminated through the grid. The requirement of lattice identity is fulfilled automatically, since in this device the second lattice is a hologram of the first lattice. In the study of transparent media, it is often necessary to change the sensitivity of the interferometer. Various methods are used for this. This interferometer is no longer necessary, since the interferometer is both high and low. sensitivity.

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Thus, the device has four output information channels with different sensitivity, combines the properties of a Talbot interferometer and a holographic interferometer, eliminates the drawbacks of the latter.

The presence of four information channels in the device allows us to simultaneously investigate areas with large and weak gradients of optical difference within the object under study. This is especially important in the study of dynamic processes in real time, simplifies the acquisition and processing of information by highlighting the corresponding diffraction orders in each channel.

Claims (1)

Invention Formula A Talbot holographic interferometer containing a radiation source and two parallel spaced periodic gratings, characterized in that, in order to extend the functionality, the second diffraction grating is made in the form of a bleached hologram of the first diffraction grating, formed by an off-axis scheme, moreover, screens are installed in the image restoration plane. Kvvvvvvv