We report the main parameters of a nine-electrode bimorph piezoelectric adaptive mirror designed to correct low-order aberrations. We describe measurements of the control coefficients for defocus, astigmatism, pure coma, and spherical aberration of this mirror and the temperature stability of its profile. The performance of a simple adaptive optical system for imaging through laboratory-generated turbulence is investigated. This low-order device is suitable for small (<1-m-diameter) telescopes and for nonastronomical applications of adaptive optics.
We propose an optical method that uses phase data of a laser beam obtained from a Shack-Hartmann sensor to estimate both the inner and outer scales of turbulence. The method is based on the sequential analysis of normalized correlation functions of Zernike coefficients. It allows the exclusion C(n)(2) from the analysis and reduces the solution of a two-parameter problem to a sequential solution of two single-parameter problems. The method has been applied to estimate the outer and inner scales of turbulence induced in the water cell.
Compact Doppler lidar with monostatic receiving geometry has been developed and tested. Laser source of the lidar is continuous wave fiber laser ELD-1000 with 1.5 µm wavelength and 1 W output. For distances up to 100 m the range of measurable wind velocities is 1.5 -20 m/s. Results obtained show that performance conditions for the lidar corresponds to the visibility range up to 1 km. Sonic vibrations with small amplitudes (∼ 10 nm) of remote targets with diffuse reflection has been registered by this device at distances up to 60 m.
The general expression for the entropy production in cosmologies with variable effective cosmological 'constant' (A) is presented. By assuming that A decays as A = aR'"+@(R/R)', where R(f) is the scale factor of the FRW models, the second law of thermodynamics and the Landau-Lifshitz theory for non-equilibrium Buctuations are used to establish constraints on the parameters a, @ and m.
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