The problem of adaptive laser beam projection onto an extended object (target) having a randomly rough surface in an optically inhomogeneous medium (atmosphere) is analyzed. Outgoing beam precompensation is considered through conjugation of either the target-return wave phase or the complex field. It is shown that in the presence of "frozen" turbulence, both phase-conjugate (PC) and field-conjugate (FC) precompensation can result in a superfocusing effect, which suggests the possibility of achieving a brighter target hit spot in volume turbulence than in vacuum. This superfocusing effect is significantly more distinct for FC precompensation. In the quasi-stationary case (slowly moving turbulence or target), PC and FC beam control lead to enhanced intensity fluctuations at the target surface associated with intermittent formation and disintegration of bright target hit spots that sporadically attach to the extended target surface. This intensity fluctuation level exceeds intensity fluctuations in the absence of beam control and is higher for FC precompensation. In the nonstationary case, both PC and FC lead to an increase of beam width and centroid wander at the extended target surface compared with conventional projection of a collimated or focused beam.

Presents a method for the determination of the path-averaged value of the inner scale of atmospheric turbulence, l0, using an optical scintillometric method. The proposed method involves the measurement of the bichromatic correlation of two laser beams of different wavelengths propagating in overlapping paths. Results obtained using this technique are compared with the ratio of the log-amplitude variances of the two laser beams and with l0 values derived from vertical wind velocity fluctuation measurements. The results of the correlation method agree well with theory based upon Hill's refractive index spectrum. Results obtained by the ratio of variances match those obtained by the correlation technique after correction for the refractive index dispersion due to humidity fluctuations. These two methods can be used jointly for the simultaneous determination of l0, CT2 and CQ2.

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The vertical structure of the atmospheric aerosols was investigated during cable car ascents along a steep mountain slope in the German Alps. Aerosol size distributions were measured by operating two particle spectrometer probes with diameter ranges of 0. 15 -3 im and 1 -95 rim. Aerosol and hydrometeorits were sampled under the meteorological conditions of clear atmosphere, haze and thick clouds. For each atmospheric layer the phase function P(O) and the extinction coefficient next were calculated for the visual (X = 0.55 rim), the near JR with Nd:YAG laser radiation (X = 1 .064 rim) and iodine laser radiation (= 1.3 15 Mm) and the middle JR with CO2 laser radiation (? = 10.59 rim) using the computer code AGAUS of the EOSAEL program library of the US Army Research Lab. Jn the visual and the near JR the aerosol extinction coefficient is not sensitive to variations of the complex refractive index. However for the CO2 laser radiation, the uncertainty in the values of optical constants causes large deviations in calculated aerosol extinction coefficients.