The specific features of scattering of the Gaussian wave packet by the simplest of all reflectionless potentials, the Sech-squared well, are considered. The results of numerical computation show that a wave packet that has passed through this potential overtakes a free wave packet and is both higher and narrower than a free wave packet; in other words, the scattered wave packet accelerates inside the well and preserves its shape better. Comparisons with scattering by the square well and by a series of reflectionless potentials are also presented. Possible applications of the Sech-squared as well as other reflectionless potentials are discussed.

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The application of laser speckle and speckle-interferometric methods to cardiovibrations measurements is presented. The homodyne and heterodyne measuring techniques that use the Michelson mterferometer are compared. As shown, the space-time projections of the mterferometer output signal can be useftil for analysis of biovibrations. New diffraction methods based on speckles dynamics with a small number of scatterers are suggested that allow pulse waves to be sensed and recorded without distortion.

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The paper presents an analysis of the optical technique for low frequency biovibrations sensing. The suggested method makes use of dynamics of speckles induced by focused coherent fields diffiacon from vibrang surface.Computer simulation of strongly focused coherent beams scattering from a vibrating skin surface has been carried out for cases ofin-plane and angular vibrations. The dependence of output characteristics of the developed speckle-using vibration sensor on vibration type and relations between the amplitude of surface oscillations, illuminating beam waist size and the scale of the surface inhomogeneities has been analyzed. Results of biovibration monitoring using proposed technique are presented.