SU838321A1 - Method of holographic checking of three-dimensional phase object with double exposure - Google Patents

Description

The invention relates to a measurement technique, is intended to study three-dimensional phase objects in transmitted light, and can be used to conduct various kinds of scientific research related to the study of plasma, gas flows, shock waves, etc. The known method of holographic control of a phase object with double-exposure without a diffusor, concluded in that they illuminate the photosensitive medium with a flat reference and continuous wave at the first exposure, they change the optical path length of one oh from the waves and placed on the putt of the object wave, the controlled object during the second exposure, chemical-photographic processing of the photosensitive medium is performed, the water is mastered by its supporting water, the interference pattern is recorded in the form of stripes and the controlled parameter O is determined as a disadvantage of the three-dimensional non-axisymmetric phase control object without its rotation, due to the fact that the object being monitored shines through along only one direction, which coincides with the direction stray ground wave. The closest in technical essence and the achieved effect to the invention is a method of holographic control of a three-dimensional phase object with a double exposure, which consists in illuminating the photosensitive medium by the source opsf and. the source of the wave during the first exposure, change the optical length of the path of the reference wave or the subject wave, and place the controlled object between the source of the fine wave and the photosensitive medium at the second exposure, carry out chemical-photographic processing of the photosensitive medium, illuminate it with a reference wave , register the interference pattern and determine the distribution of the indicator of the deflection of the controlled object 23-,

The disadvantage of this method & n low monitoring performance, due to the need to scan the interference pattern while observing it with a small-sized diaphragm. In addition, since the object wave is formed with the help of a scatterer, the resulting interference pattern has a pronounced patchy structure, which also complicates the control process.

The purpose of the invention is to improve the performance of measurements.

H,), c)

A. and 0 are the amplitudes of the spherical reference and subject waves, respectively;

9 are the corners between the normal to the surface of the photosensitive medium and the segments b and E / ii connecting the point of the photosensitive medium and the point sources of the reference and object waves, respectively;

. X - coordinate in the plane

. (, 4 -2e, x & in9j -, (. (. C ... aH it2 in J

where L is the magnitude of the change in the optical path length of the subject wave; F (x) is the distortion of the phase of the wave,

due to the controlled object

The hologram obtained after the chemical-photographic processing of the light-sensitive medium is illuminated by the source of the reference wave. In this +1

,,. ne.sm9., - ;. i.X% M0 (x)

The goal is achieved by the fact that during the first exposure the photosensitive medium is illuminated with point sources of object and reference waves, the distance from which to the photosensitive medium is twice as different, and the interference pattern in the form of Newton rings is recorded in diffraction order.

The method is as follows.

Since the first exposure does not have a controlled object, and the distances from point sources of the object and reference waves to the photosensitive medium are twice as different, the distribution of the light intensity in the plane of the photosensitive medium during the first exposure is described by

photosensitive environment;

1 wave number. Since, during the second exposure, the optical length of the path of one of the waves, for example, the optical path of the path of the subject wave, is placed and the controlled object under the rays between the source of the subject wave and the photosensitive medium, the distribution of the light intensity in the plane of the photosensitive medium during the second exposure is described by expression

In the diffraction order, two waves appear behind it.

First, the plane wave is described by the equation

, .., (,,,

Claims (2)

secondly, a wave with a small angular surface, described by the equation. The result of the interference of these two waves is a holographic interferogram of a controlled phase object nxj tOof. Л, {, Ф (Х, (5) due to axial symmetry of spherical waves, the ratio (5 ) can be rewritten for the case of a two-dimensional photosensitive medium, replacing T with T (k,), H with v U F (x) with F (x,) The first term in the cosine argument in R 5 (5) describes Newton's rings, and the second - the shift of the rings of Newton, due to the presence of a controlled phase object, The drawing shows a schematic diagram of one of the possible variants of devices that implement the proposed method.The device includes a laser 1, a light divider 2, flat mirrors 3 and 4, objectives 5 and 6, a photographic plate 7 and an interference pattern recorder 8. Objectives 5 and 6 are set so that the intersection point of their optical axes (point M) lies in the plane of the emulsion of the photographic plate 7, and the distances from the back foci of the lenses 5 and 6 to the point M are twice as different. The lens 5 is installed with the possibility of small displacements along the optical axis. The method is carried out as follows. The beam of light from laser 1 is divided by a beam splitter 2 into two parts, one of which after reflection from mirrors 3 enters lens 5, and the other after reflection from mirror 4 into lens 6. Objective 5 forms a reference spherical wave, and objective 6 is spherical the wave, the result of interference of which is recorded by the photographic plate 7 at the first exposure. Then, the controlled object 9 is placed in the course of the rays between the lens 6 and the photographic plate 7, and the lens 5 is displaced along the optical axis by a small amount and the result of the interference of the reference and subject waves on the same photographic plate 7 is again recorded at the second exposure .. - photographic processing of a photographic plate (hologram) 7 is illuminated only by a reference spherical wave, and a holographic interferogram in +1 diffraction order is recorded by the recorder 8 of the interference pattern. The use of this invention improves the performance of monitoring a three-dimensional phase object due to the fact that the entire holographic Interfrogram is recorded simultaneously and does not contain optical interference in a visible texture. The invention The method of holographic control of a three-dimensional phase object with a double exposure, which consists in illuminating a photosensitive medium with a source of reference and a source of subject waves during the first exposure, changes the optical path length of the reference or subject wave, and places the controlled object between the source of the subject wave and photosensitive medium during the second exposure, carry out chemical-photographic processing of the photosensitive medium, the light is illuminated by its reference wave, striruyut interference pattern and determining the refractive index distribution of the controlled object, characterized in that, in order povsheni performance measurements, when the light-sensitive first exposure light point source object and the reference wave, the distance from which to the photosensitive medium is characterized twice. and the interference pattern in the form of Newton's rings is recorded in +1 diffraction. Sources of information taken into account in the examination of I.OcTpOBCKiA Yu.I. et al., Holographic Interferometry .M., Science; 1977 p. 153-156, 163-184. t - 2. Ibid, p. 156-162 (prototype).