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A new null ellipsometer has been recently proposed that uses photoelastic modulator (PEM). The phase modulation adds a good signal-to-noise ratio, high sensitivity, and linearity near null positions to the traditional high-precision nulling system. The ellipsometric angles Delta and psi are obtained by azimuth measurement of the analyzer and the polarizer--PEM system, for which the first and second harmonics of modulator frequency cross the zeros. In this paper we discuss influence of component imperfection on precision of null measurement. Particular interest is devoted to azimuth angle error of compensator and modulator. Effect of residual birefringence of PEM is discussed. We show that the null system is insensitive to ellipsometer misadjustment and component imperfections and modulator calibration is not needed.

Light diffracted on magnetic domain structure changeable by external magnetic field can be used for fiber - optic switches. Quantitative and comfortable received information about the changeable diffracted light distribution as a function of both polar and azimuthal angles σ, γ is important for this device. Two fully automated spatial filter stations S1 and S2 were constructed for σ and γ angle light distribution analysis, respectively. The S2 station gives new opportunities for analysis of domain structures preference induced e.g. by external magnetic fields. Samples with different σ quality parameter from (Y,Sm,Bi)3 (Ge,FE)5 O12 series grown on (111) GGG substrates were investigated. The obtained results were discussed in comparison with results earlier published.

A stripe domain grating (SDG) has been theoretically analysed to combine some magnetic field changeable grating parameters with a magnetic sample material parameters. The alterable grating properties were discussed for different types of fiber-optic switch device. The quality and prefered directions of SDG have been quantitatively investigated using unconventional set-up based on the light diffraction effect. The gratings have been induced by the magnetic field with different orientations and values. SDG quality was significantly improved applying nontypically oriented magnetic field. We focused our attention on SDG static properties.

TE-TM mode conversion caused by Faraday rotation has been studied in (Y,Ca)3 (Fe,Ge)5O12 garnet films. This conversion was investigated as a function of magnetic field perpendicular to the sample plane H⊥ and in the plane H//. Magnetic domain structure (MDS) influence on the TE-TM mode conversion ratio R was found in the histeresis of R(H//). The character of dependence is connected with behaviour of domain structure. The measured for saturated sample R(H⊥, H//) dependence could be qualitatively explained by theoretical model developed for monodomain structure.