METHOD AND DEVICE FOR PHOTOTHERMAL EXAMINATION OF MICROINHOMOGENEITIES

摘要

The invention relates to optical microscopy, in particular to methods for photothermal examination of absorbent microinhomogeneities using laser radiation sources and can be widely used in laser engineering, industry and biomedicine for examining relatively transparent objects containing submicron impurities, including the detection of local inclusions and defects in ultrapure optical and semiconductor materials and the non-destructive diagnosis of biological samples on a cellular and subcellular level. The aim of the invention is to increase the sensitivity, spatial resolution and informativity of examination of local absorbent microinhomogeinities in transparent objects and to measure said microinhomogeinities even when they are less than the used emission wavelength. The inventive method consists in radiating a sample with a pumping laser beam. The duration of the radiation is equal to or less than a representative time for cooling the examined microinhomogeinity. The relatively large surface of the sample is radiated, the shape thereof being greater than the wavelength of the used pumping laser. Thermal variations of the refractive index occurring in the sample as a result of absorption produced with the aid of the pumping beam are recorded by measuring parameters of a test laser beam. The diameter of the test beam is chosen in such a way that it is equal to or greater than the diameter of the pumping beam. A diffraction-limited phase distribution along the cross-section of the testing laser beam is transformed into an amplitude image, the microinhomogeinity properties being determined by measuring said amplitude image.