Investigation of the ground layer of the atmosphere and clouds using laser location

Apparatus for measuring certain parameters of the atmosphere and clouds by laser location is described. The results of measurements of the radiation attenuation factor in the ground layer of the atmosphere, in clouds, and in fog are presented.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 125–128, May, 1972.The authors thank V. S. Shamanaev for his help with the measurements.     

Evaluation of times and arrival angles of surface prereverberation in the ocean

Acoustic prereverberation caused by sound scattering from the rough sea surface is considered. For the case of low-frequency scattering described by the first approximation of the small perturbation method, the arrival times and angles of prereverberation signals in the subsurface sound channel are calculated as functions of the wind speed, sound frequency, and distance.     

Fluctuations of intensity and arrival angles for light waves in spatially-limited collimated beams in a turbulent atmosphere

This paper presents results of an experimental investigation of fluctuations of intensity and arrival angle as a function of the parameter = ka²/L (where k = 2 /,a is the beam radius, and L is the length of the track) for tracks of different lengths. It is shown that, depending on the value of ₀ ² = 1.23 C _n ² k^7/6 L^11/6, the intensity fluctuations can both increase, and also decrease with increase of . The fluctuations of arrival angle have a maximum for beams for which the parameter 5.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, Vol. 16, No. 9, pp. 108–112, September, 1973.     

Molecular absorption of infrared laser radiation in the natural atmosphere

This paper discusses the information available concerning atmospheric molecular absorption of radiation in the 1 to 25m range. Particular attention is given to the high spectral resolution requirements for predicting laser transmittance. The following subjects are reviewed: the content and variability of the atmosphere, calculations of transmittance and the data on which they are based, and laser measurements of molecular absorption.     

Interferometric study of phase fluctuations of laser radiation

An interferometric method is proposed for studying the phase fluctuations of laser radiation during propagation in media with random inhomogeneities. It differs from other methods in that the beam is split into two by the first mirror of a Jamin interferometer before the beam enters the medium. The visibility of the intereference pattern is related functionally to the correlation coefficient of the amplitude fluctuations and the structure function of the phase fluctuations. Results found in an experimental study of phase fluctuations by this method are reported.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii Fizika, No. 11, pp. 103–108, November, 1970.