SU378758A1 - DEVICE FOR MEASURING THE DIFFERENCE OF PHASES BETWEEN MUTUALLY PERPENDICULAR VECTOR COMPONENTS - Google Patents

Description

one

Photoelectronic devices are known for measuring the phase difference between the mutually perpendicular components of the reflected wave vector, which occurs, for example, with full internal reflection of plane-polarized light from the interface surface of the reference and test environments. In these devices, the measurement is carried out with the help of phase difference compensators, the use of which significantly reduces the accuracy of measurements due to the additional errors associated with their manufacture, adjustment and installation in the optical path of the device.

At present, devices for measuring the phase difference of the mutually perpendicular components of the reflected wave vector in the study of thin films, nanowires, optical metal constants, refractive indices of transparent and opaque media, etc. are of great importance. Therefore, the elimination of complex compensators of phase difference from the optical circuit of the device is excluded. It is of great practical importance.

In the proposed device for measuring the phase difference, the photoelectric tracer is coupled with feedback to the analyzer and the reading device, which eliminates the compensator from the measuring circuit of the device and improves the measurement accuracy.

The drawing shows the principal

scheme of the proposed device in relation to the measurement of the refractive index of the medium.

The device consists of a source / light, a polarizer 2, a modulator 3 of the light according to the oscillations of its polarization plane, a prism 4 of total internal reflection washed by the test medium, an analyzer 5 with a reading device, a photodetector 6, an electronic amplifier 7 and a phase motor 8.

A monochromatic light flux from a source / light, passed through a polarizer 2 and a modulator 3 of light, is directed at an angle to the measuring surface of the prism 4. It is known that plane-polarized light falling from a transparent isotropic medium 9 at an angle φ to the boundary with the medium 10, with full internal reflection, it appears elliptically polarized; in this case, between the mutually perpendicular components of the reflected wave vector, phase shift b is detected, depending on the angle of incidence φ and the refractive indices of medium 9 and 10, defined by the equation:

/

N slnji - (-

Costp

(one)

Reflected elliptically polarized light enters analyzer 5. Next, the intensity modulated luminous flux is converted by photoelectric device 6, 7 into alternating voltage, which is supplied to one of the two stator windings of the reversing electric motor 8. The second motor winding is supplied with voltage from a common source with modulator. Engine S is kinematically associated with the analyzer. The intensity of light at the output of the analyzer in such a system (in the absence of light modulation according to the oscillations of its polarization plane) is expressed by the relationship: g /, GaO3 (P - a) - sin 2a Sln2p Sln - 1 where / o is the intensity of the polarized beam rays missed by the polarizer; air is the angles between the directions of oscillations transmitted by the polarizer and the analyzer, respectively, and the direction of oscillations of one of the components of the electric vector of the reflected wave. When the analyzer is rotated, i.e., when the angle p varies, extreme values of intensity correspond to angle p rextr- associated with the phase difference b dependence: tg2p «eTp. tg2aCOs8. (This dependence arises from the condition that the partial derivative is equal to zero. When introduced into a light modulation system according to the oscillations of its polarization plane, the variable component of the modulated light intensity after the analyzer consists in general of the components varying with frequency equal to the modulus frequency because of their smallness can be neglected. At the Racktr. angle, corresponding to the extreme values of the intensity, the component that changes in the intensity component a c is the modulation frequency. This indicates that the tracking system of the lobby with the analyzer in the feedback circuit will automatically monitor the change in the phase difference, and therefore, according to dependence (1), the change in the refractive index of the medium being measured. dependencies (1) and (2) gives for Rackstr: -. (- Y.tgN tg2p UJ where K slncp (- 1). Object of the Invention A device for measuring the phase density of phases between mutually perpendicular components of the reflected wave vector, containing the source monochromatic light, polarizer A light modulator, an analyzer and a photoelectron tracking system, characterized in that, in order to improve the measurement accuracy, the photoelectron tracking system is connected to the analyzer with a reading device.