Speckle patterns due to a series of diffusers is treated basing on the model of approximation developed by the author. The formula of signal-to-noise ratio in the tinal receiving plane of cascaded diffusers is given.

A new type of laser beam scanner using computer-generated hologram is proposed. This method (authors call ordinatal scanning) is able to scan any function curves, while the laser beam is deflected in a direction perpendicular to the motion of the CGH.

Deblurring images is a very attractive subject in optical information processing. The content of this paper is making an arbitrary blurring of alphabets "H" by a convolution with a random array in the space domain, and then use a filter in a frequency plane to eliminate the blur by division operation. The complex space filters produced by the computer-generated hologram method can construct many new and fascinating coding and decoding systems for dilute objects. Since the application of the technique of computer-generated hologram these systems become not only more flexible and ambiguous in coding but also more effective in tJie process of decoding. In this paper several computer-generated filters inverse filter, Wiener filter and Wiener filter of exponential type have been described. The capability of all these filters for cryptology has been tested and compared experimentally.

Experimental results of interaction between photon electron as \vell as photon and atom have been studied in this paper. Interaction between photon and tenuous gas has been" observed. The electron pulse and negative ion pulses have been measured.

By the time-domain method this article deals with the interaction between a three-level quantum system (vibrational energy level of the molecule of a dilute gas) and the infrared electric field of CO2 laser. The semiclassical Bloch-Maxwell s equations have been changed into the equivalent differential equations of real function using the rotating wave approximation. This article studies their solutions of the rate-equations approach under the condition of long pulse and short pulse. The area theorem of ooherent short pulses which is propagating through, a three-level system of equal spacing is obtained. The article contains the derivations of the formula of separate coefficient，the coixditions of the selective optical excitation and the excited rate for isotope separation as ail actual application.

Eight new laser lines of the chlorine ions in the visible region are reported in this paper and their wavelengths are 441.48, 459.62, 460.18, 477.11, 477.89, 509.93, 517.59 and 535.61 nm respectively. The experimental results show that when an appropriote quantity of argon gas is mixed into the lasing medium of hydrogen chloride, the intensities of laser lines increase properly and more new lines can be observed. Some phenomena in our experiments are qualitatively explained as well.

We have studied the two-photon resonant excitation and enhancement effect of a high excitation state 15d in Rb atom by using a synchronously pumped tunable mode-locked dye laser and obtained the frequency up-conversion at 1.065μm→4210 A. The relationship between self-phase matching and output of UV coherent radiation output is given. This paper emphasizes the study of the transient coherent effect and dephasing process of this state. It has been shown experimentally that the maximun polarized time by two-photon resonant excitation is 120 ps and UV coherent radiation could be induced tinder the action of probing signal until 350 ps. However up to now no report has been declared about the study of trasient coherent dephasing in higher excitation states oi atom systems.

A rigorous formula for the calculation of the nonlinear absorption coefficient from the laser energy transmissivity was derived. Particular attention was paid to the role of the probe pulse shape playing in the calculation. A sample of glass rod with 1.2wt% Nd2O3 doping concentration was measured with a high power Nd:phosphate glass laser system. The nonlinear absorption coefficient γ= 1.2 cm TW was obtained. Furthermore, the variation of gain and laser pulse shape in the amplifier system, caused by the nonlinear absorption, was studied. The numerical calculation shows that the effect of nonlinear absorption is important. Namely, for a large laser system capable of TW order output, the total gain in case of γ=1.2 and 2.0 cm TW Arill be 18.7% and 27% less than in case of γ=0； also the output pulse duration will increase 14% and 23% more correspondingly.

In this paper we describe the eigen-function expansion for the boundary value problems of electromagnetic theory of cylindrical grating. It is easy to solve them by means of the interaction computing method.

This paper reports some experimental results on vacuum spatial filter in improving laser beam quality and increasing laser beam brighteness.

A new speckle photography method-sandwich speckle photography is proposed. The paper describes the simple principle of this method and it s advantages. Similar to tne sandwich holograhy, it makes up of two pieces of single exposure specklegram. We made each single exposure photograph at various situations, then put two of them together and precisely replaced them. The quality of fringe obtained by sandwich specklegram is quite the same as that obtained by common double exposure speckle. gram. If we make n pieces of single exposure specklegram n(n—1)/2 pairs of double exposure specklegram will be obtained. It is well-known that the double exposure specklegram is very difficult to make at temporal processes and dynamical deformation. High speed photography combined with sandwich speckle photography can overcome this difficulty. Finally an experimental evidence is identical with the result of double exposure. Doubtlessly, the sandwich speckle photography will pavo the way for the application of speckle intexferometry.

From the basic concept that an interferogram is a contour map in intensity, we present a new simpler method, for measuring the shifts of interference fringes. In this method, as long as a intensity profile is taken on any straight line parallel to the equidistant parallel fringes in the interferogram (or in the interferogram film), the shift of the interference fringe at all points to this straight line can be found and the variance of the physical quantity of interest is calculated thereafter. It allows the meastLring equipments and the automatic analysis to be simplified, and data can be taken at any pomt in tlie interferogram disregarding the position of fringes. Our experiments show that the repeatability error is less than 1.5%. Satisfactory results have been obtained when this method is applied to the measurement of refractive-index profiles of optical fibers with the nondestractive traverse interferometry. As compared with the results from reflection method, the error of the maximum relative refractive-index difference is about 1% and the whole profile curves accord well with eath other.

A Cr-doped semi-insulating GaAs cube was used as the optoelectronic switching element. Using the ultrashort pulses at 1.06μm or 0.53/μm to control this switching element, its output characteristics was observed and the dependence of the switching efficiency on the laser energy was obtainded. The behaviour of the photoconductivity at high pumping level was analysed.

A new method-realization of image amplitude substraction is described based on Talbot effect of grating with illumination of coherent convergent light. The theoretical analyses are made to explain the principles of the method, and the experimental results, which are in accordance with the theory are presented.

By means of the configuration interaction the energies and the wave functions for the excited C3?u and B3?g states of the nitrogen molecule are calculated with the electronic computers TQ-16 and CROMEMCO. The set of criteria for selecting configuration function are presented. The effects of other multiplicate states on the excited C3?u and B3Πg states are excluded by using the projection operator. In the dipolar approximation the calculated value of the oscillator strength for the second positive band system of the nitrogen molecule is 0.09739，being in good agreement with experimental value. The presented method in the paper can be applied to all diatomio moleculea.

The calculated formula of equivalent refractive index N* of non-symmetrical three-layer period (a b c) has been derived in this papsr. The formula has been used for the design of anti-reflection coatings in infrared. The calculated and experimental results are given in the paper. The average transmisson of the coatings is 98 in the response wave region of InSb (3~5μm) detector and HgCdTe (8~12μm) detector. The average transmission of the coatings is greater than or equal to 94% in 2~13 μm, 3~14μm and 3.5~15 μm. Especially in 11 μm wavelength region (3.8~14.8 μm), the minimum transmission of the coatings is greater than or equal to 90%.