The gain of high power multi-pass amplifier is studied. The conditions for raising the energy extracting efficiency are discussed. We obtain the general rule to select the optimum parameters. This result has been used to build a disk amplifier, there are three optical paths in the amplifier, and the laser beam of 100mm aperture passes through it six times back and forth. Theoretical calculations are in agreement with the experimental results.

A negative lens effect induced by strong laser field in liquid phase of .liquid crystals is described. The relaxation time of the effect is measured. It is about 100 msec. The related physical mechanism is also discussed.

Theoretical analysis and numerical simulation calculations have been carried out to explain the dependence of ruby laser output on temperature, solvent and impurity of cryptocyanine solution used as the passive-Q-switch. The results show that the absorption of excited state is the main cause of the temperature, solvent and impurity effects, especially the transition of S1-S2 Optical bleaching of cryptocyanine depends mainly on the saturation of S1-S2 transition, and is influenced by the population of the first triplet state as well. Therefore the thermal stability of the cryptocyanine-switched ruby laser is largely controlled by the solvent quenching rate of singlet states.

According to breakdown condition of gas discharge,we have made a preliminary theoretical analysis on some phenomena in the improved-type laser tubes and the old ones. Theoreticol analysis, elucidates well the experimental results with considerably lowered voltage in improved laser tubes.

Based on practical work in 1971~1976, some problems to be considered in designing of rapid expansion nozzles for gas-dynamic lasers were summarized, including the selection of important parameters,, the discussion on methods for contoured nozzles design and the correction for boundary layer grouth etc. Through a large amount of numerical analysis, a simple convenient method for correcting boundary layer grouth under various conditions was also presented.

Quantitative relations between parameters of two dimensional transonic-supersonic nozzle flow of circular throat are expressed through the form of "characteristic curves without reverse pressure gradient". These relations can be regarded as a guide for design of laser nozzles of big throat curvature in rapid expansion without reverse pressure gradient. To Combine with the associated calculation program of transonic-supersonic nozzle contours in which the value of five parameters can be changed, it is possible to select nozzle contours of this type on computer. These characteristic curves can also be used as a reference, forh estimating character of reverse pressure gradient of this type of nozzle obtained by other ways.

Based on the theory by BecnaJlOB[1]with regard to linearity instability of self-focusing, Glass[2] and others introduced as an important parameter the breakup integal(B integal) in the design of high power laser amplifier. Upon these works criterion in choice of the maximum B value for amplifier is given, problems as how to chooss B value for an amplifier is also discussed.

In this article several kinds of spatial filters fabricated by the method of computer hologram are introduced. These spatial filters are used in contrast inversion and differential processing of image. Their characteristics are discussed with additive experimental results.

In this article, anisotropy of the cubic nonlinear polarization P(3) in a cubic crystal is investigated, general expression of anisotropy of nonlinear refractive index is derived, and self-induced polarization change of high intensity light beam in a cubic crystal is discussed.

Discharge delay and voltage increase of cross-exeitation in laser microspectroscopy are presented, which play a very important part in improving analytical sensitivity.

An opto-acoustic spectrometer tuned by a grating and with CO2 laser as light source has been established. The spectrometer was used to measure the absorption spectra of ethylene, butadiene, trichloroethylene, benzene, ammonia, rnethanol and N, TV-dimethyel hydraziue at the tunable CO2 laser emission wavelengths.