SCATTERING OF ELECTROMAGNETIC WAVES BY ROUGH SURFACES AS A PART OF INTERACTION OF LASER LIGHT WITH BIOTISSUES

摘要

Among different problems in different theories of laser light propagation and scattering in biological tissues there is one (especially for laser illumination), which is now not widely discussed yet in application to biomedical optics - the effect of boundary roughnesses. But this effect can have potentially a strong influence on a total light field into a tissue. So, the development of different theoretical methods and models to calculate a surface scattering is the important problem in biomedical optics. One of such theoretical approach can be based on the electromagnetic wave diffraction theory (EWDT) if the peculiarities of optical waveband will be taken into account. The basis exact EWDT allows to determine the scattering field from the perfectly conducting rough surfaces in relative units or in the terms of radiophysical cross section. For light wavelengths in biomedical optics another conducting boundary conditions are needed and the result must be presented in optical terms and absolute units. The use of EWDT in application to the biomedical optics becomes possible by means of exact comparative analysis of the essential conceptions of the photometry and diffraction theories, which has been made in this work. The physically correct approximation for biomedical optics was obtained with the Leontovich's (well-conducting) boundary conditions (LBC). Using the EWDT and LBC for a randomly rough surface we had studied the possibilities of description of light scattering on a real poor-conducting and rough biological tissues, especially for the transmitted through surface intensity of the light. The analytical equation for scattered and transmitted intensity in case of LBS was obtained in our work. It is theoretically shown that the roughnesses of biological surfaces have not a strong influence on a total reflected light and have a some influence on an internal scattered light field.