Given are the results of experimental study on the quasi real time holographic correction for the lens distortions in the passive observational telescope in the visible range of spectrum, using the liquid crystal optically addressed spatial light modulator.

Large numerical aperture telescope with nonlinear optical correction for distortions, designed for the remote self- luminous object imaging, was realized in experiment and investigated. Dynamic hologram, recorded in optically addressed liquid crystal spatial light modulator, was used as the corrector. Nearly diffraction limited performance of the system was demonstrated.

A novel approach to the liquid crystal modulators design is suggested under which the liquid crystal is treated as a distribution capacitor. To control the capacitor, we introduced a distribution high resistance control electrode. We devised methods of control and investigated modal liquid crystal modulators that can be used as adaptive cylindrical and spherical lenses. Analytical derivations, computer and experimental results are presented and discussed.

We used a combined approach, investigating capacitance, resistance, and electrooptic reply of nematic liquid crystals within the same experimental framework, which enabled us to plot the phase delay as a function of electric parameters. Phase delay vs. capacitance curves are almost linear, but the slope is frequency dependent for the liquid crystal with the low-frequency dispersion of the dielectric anisotropy. To interpret the results, equivalent electric parameters definition, consistent with the AC current measurement techniques, is presented and phenomenological theory of the RC-parameters is developed. When completed by the Ericksen-Leslie equation for the liquid crystal molecules realignment in the external electric field, the theory is in good agreement with the experiment.

A novel algorithm of compensation for repetitively-pulsed laser beam wandering at propagation paths, caused by the atmospheric turbulence and mirror vibrations has been proposed and verified in experiments with a TE-CO₂ laser. The algorithm is based on the precise temporal control of triggering each of the TE-laser pulses at the moments when the auxiliary probe cw-laser beam modified by a modal-type adaptive optics system and having exactly the same wavefront profile, as the pulsed radiation, hits the remote object (retroreflector in the pre-set point at the path exit) by its brightest speckle.

Proposed is the novel method of dynamic nonlinear-optical correction for distortions in wide spectral band. The method is based on combining of the negative optical feedback correction and dynamic holography correction in the system, using optically addressed phase modulators. State-of-the-art of key technologies is evaluated.

Novel technique of object's vibration monitoring is proposed. It is based on self-diffraction of the speckle pattern on adaptive correlation filter recorded in photorefractive crystal owing to the fanning effect. The technique provides linear response on the displacement amplitude and high sensitivity. Both sensitivity and dynamic range of measurements can be adjusted varying the average speckle size on the input face of crystal.

Q-switched regimes of the nanosecond pulse-periodic Nd:YAG laser with dynamic cavity formed with participation of dynamics holographic gratings in laser elements have been investigated. A Sagnac interferometer was applied as a laser cavity mirror for angular selection of initial radiation. As a passive Q-switch, we used saturable absorber crystal LiF:F₂^-, which increased total intracavity diffraction efficiency of dynamic gratings completing the cavity. Self-pumped phase conjugation in Nd:YAG amplifier and LiF:F₂^- absorber provided adaptive properties of the cavity. The peak power of generated beam with diffraction quality exceeded 17.5 MW and the average power achieved 50 W.

We present a spatial mode analysis of a self-adaptive holographic laser oscillator formed by a non-linear medium in a self-intersecting loop geometry incorporating additional intracavity elements and a feedback mirror acting as output coupler. We use an ABCD transfer matrix approach for cavity elements as well as the four-wave mixing in the nonlinear medium and demonstrate transient evolution as well as self-consistent steady-state solutions for the fundamental mode configuration. We find the transient case evolves to the self-consistent solution if one exists. We show the effects of intracavity lens focal length and position in cavity, as well as the finite transverse dimensions of the nonlinear medium, on the size of the self- consistent mode to find regimes for large mode size, good phase conjugate quality and low loss operation.

The role of a small-scale diffraction in resonator with holographic mirror for providing the effective selection of wave conjugated to operating speckled wave has been investigated theoretically and experimentally. Possibility of high fidelity reconstruction of complicated amplitude- phase information on spatial structure of signal radiation in the zero mode of the `holographic' resonator have been studied in the parametric space singularity satisfying the geometric-optical approximation. The reasons for some disagreement between the model conclusions and experimental data obtained in the YAG:Nd-laser with hologram of gain saturation have been discussed.

A high-energy phase-conjugate mirror (PCM)/Nonlinear Isolator (NLI) based on pressurized methane was tested to the 5 J level, using 200 ns, 300 MHz bandwidth pulses from a phase conjugated multiple Nd:glass amplifier. Performance was good when a 50 cm focal length lens was employed. With a 25 cm lens, PCM performance was good except when gas breakdown occurred. In the presence of gas breakdown, reflectivity and return beam quality dropped. NLI isolation was aided by breakdown. A model was developed that shows that if breakdown occurs for a short focal length lens, then increasing the focal length raises the breakdown threshold but does not eliminate the problem at all input energies. This is a consequence of the fact that as input energy increases, the amount of energy leaking into the focal region increases faster than the breakdown threshold increase due to temporal broadening of the leaked pulse. High reflectivity (> 80%) single-cell tight-focus PCMs are feasible for use at the 10 J level, but as an NLI appears limited compared to glass based Faraday rotators.

An investigation is reported of the characteristic features of a four-wave mixing of a chirped signal with bandwidth- limited pump waves in a resonant medium modeled by a two- level scheme. Analytic estimates are obtained and a numerical analysis is made of the combined influence of various mechanisms (spatial phase matching, a finite nonlinear response time, and phase cross-modulation) on the spectral composition and on the temporal behavior of the fourth pulse. Conditions are found for achieving, with practically undetectable distortions, phase conjugation of a chirped signal accompanied by shortening of the pulse envelope and narrowing of the spectrum of the phase- conjugate wave.

The behavior of the fundamental, Stokes, and anti-Stokes waves in a single-mode birefringent fiber is investigated. Analysis of the nonlinear dynamics of the four-wave mixing are developed using Hamiltonian representation of equations describing the process. Significant mathematical progress has been made in solving problem of the four-wave mixing, in particular, analytical solutions in the terms of Jacobian elliptic and hyperbolic functions and graphic solutions on the phase plane are obtained. The main problems addressed concern optical switching among the waves.

Conversion of light beams by the dynamic volume holograms in resonant media revealing the fifth- and higher-order nonlinearities has been analyzed. The experimental results on the energy and angular characteristics of laser radiation diffracted from a dynamic transmission grating in the solution of Rhodamine 6J dye and polymethine dye 3274U are considered. A theoretical model that allows for the calculation of the energy efficiency of light-beam conversion at different propagation directions of a reconstructing wave has been proposed.

The results are presented on experimental investigations of action onto an optical glass BK-7 and some other materials of a CO₂ laser radiation with the pulse duration of 20 - 70 microsecond(s) and the energy density of 0.1 - 3 J/cm². The dynamics of a thermal response, temperature of heating and emissivity of irradiated glass samples are under consideration. The results obtained can be used in imaging techniques for objects selection.

There are discovered physical aspects of one-pulse laser forming of 2D periodical surface microstructures with the characteristic sizes about 30 times less than the used laser radiation wavelength. It is experimentally shown that by means of TEA carbon dioxide laser treatment of the 800 A^o-aluminum film, evaporated on the K8-glass substrate, the periodical system of microhollows with the diameter about 0.5 micron can be formed. The proposed method may be useful for surface microstructures producing in microelectronics or precise filters fabrication.

Adaptive phasing system for large-sized composite telescope mirrors intended for transportation of high-power CO₂- lasers radiation by long distances are presented. The phasing system consists of a wave-front censor and a unit for controlling drives. A heterodyne side-shift interferometer with a rotated radial diffraction grating was used as the wavefront censor. The grating can operate both in visible and IR spectral ranges. The phasing system allows to monitor and control automatically the correct form of the composite mirror in conditions of mechanical vibrations and thermal effects with the error not greater than (lambda) /40. At external perturbing factors, whose phase variations may reach 100 degree(s) to 120 degree(s)C, the (Strehl) phasing efficiency is 0.977. The phasing system can be also applied in astronomical telescopes and other systems for observation of remote objects.

It is extraordinary useful to conserve the advantages of the heterodyne interferometry with high sensitivity of straight phase measurements in oblique incidence interferometer. In our case the directions of test and referent beams are made by the diffraction gratings. The special-property phase plate is located in collimated beam path between the diffraction gratings and test mirror, and incidence test and referent beams pass through this plate twice. The particularity of the phase plate is that one creates the path difference (lambda) /4 at reference beam direction, and (lambda) /2 at test beam direction. Initial polarization vector of reference beam is rotated on 90 degree(s) and polarization vector of test beam on 180 degree(s). Such two beams with different frequency interfere at the exit. It has been found optimum decision of polarization frequency component dividing and combining.