The peculiarities of thermooptical excitation of elastic waves in nonlinear crystals, which appear due to modulated absorption of the energy from a Bessel light beam at the second harmonic, were theoretically examined. The amplitude-phase characteristics of the photoacoustic signal were found, and the conditions of the most effective thermooptical excitation of the sound were determined. The received results can be used in the design of new optoacoustic scanners for diagnostics of subsurface structures and new quantum electronics and integrated optics devices.
It is developed a method o photodeflection spectroscopy o±' flowing gyrotropic media, having circular dichroism bands. Particular cases o collinear and transversal geometry o excitating and probing beam interaction are discussed. Probe beam deflection angles are deflned, and their magnitudes are analised depending on modulation frequensy Q, interaction time t1 and elipticity o excilating beam, velocity o sample translation movement V, as well a value of reduced coordinate x/a (where a is a Gause beam radius ). it is show, that there is no influence o gyrotropic efiects on the angular dependence magnitude ifl case o interaction collinear geometry. Application o right-and left-cjrcular polarised excitated radiation in case o transversal geometry o interaction leads to appearance o±' two deflection angles 1)÷ o the probe beam. Deflection angles dierance L1) = -() may reach quite measable values (1O3-1Ora) and depends on movement velocity modulation frequency , heatihg time o gyrotropic sample t and on the circular dichro±sm parameter 7"= 1m7. A method o defining o an image part o gyration complex parameter 7" on the basis o the spectroscopy photodeflectlon method. 300
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