SU1323926A1 - Device for measuring phase media refractive index - Google Patents

Abstract

The invention relates to the field of optical instrumentation and can be used in experimental hydro and gas dynamics, thermal physics, plasma physics, etc. The aim of the invention is to increase the sensitivity and selectivity of the interference measurements and the quality of the interferograms. The device contains a laser 1 and a dye laser formed by a cuvette 2 with a dye, a deaf mirror 3 and a translucent mirror 4 applied to the input beam-splitting cube 5 of the interferometer 6. Between laser 1 and cube 5 a beam splitter is installed (L with tN3 CO with C5 7 /

Description

A wedge plate 7, oriented at an angle of 45 ° to the laser beam 1j, a swiveling mirror 8, is installed parallel to the plate 7, and a half-wave plate 9, oriented perpendicular to the laser beam 1. Recorders 10, 11 are installed at the output of the interferometer 6 The analyzers 12, 13 are placed. A part of the laser radiation 1, reflected from elements 7 and 8, pumps the laser on the crystal. FromI

The invention relates to optical instrumentation and can be used in experimental hzdro- and gas dynamics, thermal physics, plasma physics, etc.

The aim of the invention is to increase the sensitivity and selectivity of interference measurements and quality, interferograms of rapidly changing phase objects with strong irregularities (high slew rates}: path differences), such as plasma arising from focusing high-power laser radiation in gases or on the surface, solid targets, as well as the removal of restrictions in the choice of the optical scheme of the interferometer and the simplification of the design and methods of working with a device for the refraction of phase media containing m coherent light source, the interferometer including an input and. output beam splitting cubes and mirrors, and two recorders.

The drawing shows the optical layout of the device.

The device consists of a laser 1, used as a coherent light source, tunable: a laser based on an organic dye solution, the optical axis of which is an angle of 90 ° with the optical axis of laser 1, used as the second coherent light source and formed by a cuvette 2 with an organic solution dye, and two mirrors hl :: rx; im 3 and semi-transparent 4, applied on reversed 323926

The emission of both lasers is synchronized in time and has the same polarization. The part of the laser radiation 1 transmitted through the plates 7 and 9 rotates its plane of polarization by 90 and hits the cube 5. After the cube, the radiation of both lasers passes through the interferometer and is divided into two channels, each of which passes through analyzers 12 and 13, crossed with each other at an angle of 90 °. 1 il.

the edge of the input light-splitting cube 5 of the interferometer 6, which is observed in cell 2, and the laser radiation 1 coincides with the maximum of the dye absorption band. Between the laser 1 and the input beam-splitting cube 5, a wedge-shaped plate 7 is oriented at an angle of 45 to the laser beam 1, a rotating mirror 8 mounted parallel to the beam-splitting wedge plate 7 and a half-wave plate 9 oriented perpendicular to the laser beam 1. At the interferro-5 meter 6 meters, recorders are installed

10 and 11, in front of which the analyzers 12 and 13 of polarization are placed.

The device works as follows.

The PI3 portion of the radiation from the pulsed laser 1, reflected from the beam-splitting wedge plate 7 and the rotary mirror 8, pumps the dye laser consisting of a ditch 2 with an organic dye solution, a dummy mirror and a semi-transparent mirror 4 applied onto the face facing the dye cavity. the input beam-splitting cube 5 of the interferometer 6. In this case, the radiation of both lasers is synchronized in time and has the same polarization. The part of the radiation from the pulsed laser 1, passing through the beam-splitting wedge plate 7 and through the half-wave plate 9, rotates its plane. the bone is polarized by 90 ° and hits

at the input beam splitting cube 5 of the interferometer 6. After the input beam splitting cube 5, the radiation of both lasers, having mutually perpendicular polarization, passes through the optical circuit of the interferometer 6 and is divided by the output light of the interferometer into two channels.

In each channel, the radiation np travels through analyzers 12 and 13, which are polarizers crossed at 90 angle with each other, with the optical axis of one and the polarizers coinciding with the plane of polarization of one of the probe radiations. Thus, the analyzers 12 and 13 carry out the selection of the probing laser radiation by polarization and the recorders 10 and 11, located behind the analyzers, emit only one of the probing light sources. Each of the recorders 10 and 11 records the interference pattern of the object under study only in the light of one of the probing radiation.

The polarization of the laser-pumped dye laser is identical to the polarization of the exciting laser radiation. The passage through the half-wave plate, the polarization plane of the radiation of the first laser is rotated 90 °. Thus, two intersecting polarization probes are transmitted through the optical scheme of the interferometer.

Selection of radiation with simultaneous recording of interferograms in the light of both probe radiations is carried out by polarization analyzers of radiation, crossed with each other at an angle of 90 °. Selection of the polarization of the probing radiation ensures reliable recording of interferograms: at each of the wavelengths with a smooth tuning over a wide range of wavelengths, one of the probe radiations.

In addition, the use of lasers as sources of probe radiation significantly increases both the spatial and temporal coherence of probe radiation, which significantly degrades the functionality of the proposed

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device when choosing a specific optical scheme of the interferometer.

The duration of the measurement of the dye laser is determined by the duration of the pumping radiation and is 10-30 HC. A decrease in the duration of the probing radiation increases the contrast of the interference fringes when registering fast-moving or rapidly changing objects, i.e. enhances the quality of the recorded holograms and expands the circle of the objects under study. The wavelength tuning of the dye laser radiation is smooth, since the loss factor of a laser cavity with a dispersion -1 elements is an analytical function of the wavelength. A smooth tuning of the wavelength of the probing radiation makes it possible to approach arbitrarily close to the resonance line of one of the atomic or ionic components of the inhomogeneity under study. At a wavelength of 5 close to the absorption line, the refraction of the component under study can significantly exceed the refraction of the other components of the heterogeneity under study. This allows one to study the spatial distribution of this component without the distorting influence of the others. Thus, the smooth tuning of the probe radiation wavelength increases the sensitivity and selectivity of the interference method for determining the spatial distribution of the concentration of heavy particles in a particular atomic state in the heterogeneity under study (shock wave, flame, gas flow, hot plasma, etc. .).

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Pumping a dye laser with a part of the second laser radiation automatically ensures synchronization of both probing radiation, which simplifies the design of the proposed device, and automatic simultaneous recording of interferograms in the light of both sources of probing radiation increases the accuracy of the interference measurements, especially when studying fast-moving and rapidly changing objects.

The output mirror of the dye laser deposited on one of the faces

the input beam splitting cube, facilitates the alignment of the interferometer and simplifies the design of the device.

The selection of probe radiations using photographic materials of various spectral sensitivity and light filters while simultaneously recording interferograms is extremely difficult with a smooth rearrangement of the length of one of the probe radiations. Selection of probe radiation by polarization using a half-wave plate and polarization analyzers crossed with each other at an angle of 90 is insensitive to a smooth adjustment of the wavelength of one of the probe radiation and allows to get high quality f 4Y over the entire tuning area.

Claims (1)

Invention Formula A device for measuring the refractive indices of phase media, containing a coherent light source, an interferometer, including an input and output beam-splitting cubes and two mirrors, and recorders, so that, in order to increase the sensitivity and selectivity of the interference, Dimension Editor A. Lezhnin Compiled by S.Golubev Tehred A. Kravchuk Order 2957/47 Tyrals 776Subscribe VNSHSHI USSR State Committee on affairs of inventions and otkrr, 1 113035, Moscow, / 1 (-35, Raushsk nab., d. 4/5 Production and printing company, Uzhgorod, st. Project, 4 rhenium by improving the quality of iferferograms, an additional mirror was additionally introduced into the device, a beam splitting wedge plate, a half wave plate, two analyzers, and a dye laser containing a dye solution with an organic dye installed symmetrically to the coherent light source relative to the input beam splitting cube, while the laser mirror is applied to the opposite dye cell with the dye face of the inlet beam splitter, the wedge beam splitter and the floor The plates are installed between the coherent light source and the input beam splitting cube of the interferometer successively along the light of the coherent source, an additional mirror is installed along the light reflected from the beam splitting wedge plate and optically connected to the dye laser cell, the analyzers are installed with a mutually orthogonal direction optical axes between the output beam-splitting cube and the recorders, the optical axis of one of the analyzers coinciding with the plane polarization of the radiation of a coherent light source or laser. Proofreader S. Shekmar