SU1272106A1 - Polarimeter - Google Patents

Abstract

This invention relates to the investigation of mechanical stresses in transparent materials with polarization-optical methods. The purpose of the invention is to increase productivity by eliminating the need to reinstall the quarter-wave plate 3 during measurements. For this field, the meter is equipped with a second quarter-wave plate 8, mounted in front of the first plate 3. so that their main axes are deployed in space. The second beam splitter 9 is installed in front of the block 7 for measuring the difference in travel, and the second block 10 for measuring the difference in travel is mounted along the light beam reflected from the second beam splitter 9. The polarimeter has three light channels, the outputs of which register the azimuth of the main directions and the magnitude of the main voltages at the illuminated point of the sample, 2 Il. th VI th O5

Description

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The invention relates to the investigation of mechanical stresses in transparent materials by a polarization-optical method.

The purpose of the invention is to increase productivity by eliminating the need to reinstall a quarter-wave plate during measurements. On . 1 shows a schematic diagram of a polarimeter; FIG. 2, a scheme for determining the azyfa of the main directions and the path difference.

The field meter contains a source of light (1) (Fig. 1), which emits at least an EMF of wavelength / H, and / 1, and a circular achromatic polarizer 2 along the light beam, an achromatic quarter-wave plate 3, a fixture 4 for the polarization plane is rotated, the beam splitter 5, the main directions azimuth measurement unit 6, mounted along the reflected beam from the splitter 5 n; uchka, the path difference measuring unit 7, the second achromatic quarter-wave plate 8 installed by the rotation tool 4 audio the polarization plane of the first plate 3 and the second beamsplitter 9 placed in front of the measurement unit 7 {zaznosti stroke and a second unit 10 measuring the path difference mounted downstream from the reflected second light beam splitter 9,

The main axes of quarter-waves of 1.1x plates 3 and 8 are rotated relative to each other in space. The main directions azimuth measurement unit 6 and the path difference measurement units 7 and 10 can be equally implemented and each comprises a beam splitter 11, two light filters 12 rd different regions of the spectrum, two photodetector devices 13 and a recording unit 14. The sample under study 15 is located between the polarizer 2 and the quarter-wave plate Z. Adaptation 4 for rotation of the polarization plane is rotated

engine 16,

.1. The floor meter works according to its image.

The light beam from the source 1 of the light emitting at least two wavelengths and D becomes circularly polarized after passing through the achromatic circular polarizer 2 and enters

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At the entrance of the test sample 15, it is not the exit of the sample that the light becomes malignant, liptically polarized. The polarization characteristics of the light at the exit of the sample carry information about the parameters of birefringence at the point under study. The divider 5 divides the light beam into two parts, the first of which (A) passes only through the device 4, mine quarter-wave plates 3 and 8,

The tool 4 may be an analyzer or a set of a half-wave achromatic plate and a fixed analyzer rotating with a constant angular speed, which rotates at a constant angular velocity. The rotation is carried out with the help of the engine 16. Part of the light beam (A) from the splitter 5 enters the block 6 measuring the azimuth of the main directions. A beam divider I1, included in the azimuth measurement unit of the main directions, divides the light beam A into two parts, each of which passes through one of the light filters 12, separating the working wavelengths A and 1. After the light filters, the light beams arrive at the photodetectors 13 The outputs of which are connected to the input of the registration unit 14 containing phase meters.

Claims (1)

The registration unit 14 measures the phases of the variable components; the light intensities for the lengths of the sol, L, and L. Part of the light beam B is fed to the measurement unit for carrying the stroke. The splitter 9 divides it into two components, one of which (v) passes successively through the quarter-wave plate 3 and the fixture 4, and the second (B) through the quarter-wave plate 8 and the fixture 4, Each of these components of the light beam is separated by a splitter 11, entering the units of measuring the difference in stroke, into two parts, passing through one of the light filters 12, separating the working wavelengths D and A. After the light filters, the light beams arrive at the photodetector devices 13 whose outputs are connected to the inputs of the blocks 14 registrations containing phase meters. The registration units are made from-i measuring the phases of the variable components of the light intensity for the d-waves D and. After passing through the sample under study 15 (Fig. 1), the light becomes elliptically polarized, with points C, and C ..j (Fig. 2) representing the polarization characteristics of the light on the Poincaré sphere for two working wavelengths, and A, will be located on the same meridian M, the longitude of which is determined by the position in the main axis of the tensor of the dielectric constant. The equator diameter of the Poincare AAU sphere, which displays the main axes in space, is perpendicular to the meridian M. Thus, by measuring the longitude of points C and Cn, one can determine the position in space of the main axes or azimuth of the main directions. The intensity of the variable component of the light beam A, which enters the input of the azimuth measurement unit of the main directions, is equal in the case of a rotating analyzer, l-Bin4sin2 (u) t-ol) l, where 1 is the initial intensity; K - coefficient of proportionality; H - the phase difference created by the sample; 2о1 is the longitude of the point reflecting the polarization characteristics of light on the Poincaré sphere; t "J is the angular frequency of rotation of the analyzer. From the above expression it can be seen that the phase of the variable component of the signals from the outputs of photodetectors contains information about the azimuth of the main directions. The latitudes of points C and C are determined by the path differences, respectively, for wavelengths and A. The light beam B, a part of which has passed through a quarter-wave plate 3, and a part through a quarter-wave plate 8, is fed to the input of the block and the measurement of the path difference. Let the principal axes of the plates 3 and 6 form an angle of 45 between them and their position on the Poincare sphere is displayed by the points D, and DJ. In this case, the point, which represents the spatial position of the analyzer rotating at a constant angular 106 4 speed (adaptive 4, fig. |), Does not move uniformly along the meridians M and f, respectively. The measured phases of the MeHjaix components of the signals in the unit for measuring the difference in stroke determine the position on the sphere of large circle arcs passing through points D and D and perpendicular to the meridians M and Mj, respectively, for each of the lengths wolf A and I, their mutual intersection and the intersection with the meridian M determines the coordinates of points C and C, which reflect the polarization characteristics of the light at the output of the sample. The use of two quarter-wave plates with the main axes deployed in space relative to the friend's FRD allows you to determine the coordinates of points C and C with high accuracy at any value of the azimuth of the main directions that do not require the gate's gate during measurement, which significantly reduces the measurement time . The measurement of the phases of the variable components in all three recording units is carried out simultaneously and, without increasing the measurement time, allows an increase in the measurement accuracy. The use of two wavelengths in the unit for measuring the difference in stroke makes it possible to unambiguously determine a fraction of the difference in the course and an integer number of orders, and in the measuring unit the azimuth of the main directions to determine the azimuth for any value of the difference in stroke. Formula of the image of the Retenie Polimeter, containing a light source of radiation and located along the light beam, a circular Achromatic Polarizer, a quarter-wave plate, a device for rotating the polarization plane, a beam splitter, a unit for measuring the azimuth of main directions, mounted along the beam splitter, and a path difference measurement unit, characterized in that, in order to increase productivity, it is equipped with a second quarter-wave plate, installed between the device scheni plane of polarization and the first plate, the second beam splitter, the development unit before measurements 1272106® The difference mifl, the second blocking along the cholera reflected from the second measurement of the path difference, is installed as the beam splitter of the light beam. , H |