This paper describes the common nature of the three conceptions-Moire phenominon, interferometry and holography, and several examples are given. The principles of holography and its imaging relations in terms of Moire phenomenon are explained.

The holographic information capacity of film is analysed in terms of 3-dimensionsl reconstructed image. Information capacity I is defined by two factors M and K, being I=M log K in simple case, where M is the number of image elements and K the number of gray levels. In the case of holography the image elements are 3-diinensional. The number M of 3-d. image elements is deduced from diffraction, and it merely depends upon the film size. But the number K of gray levels depends upon the fluctuation of grain density in the film. The value of K is deduced with a model of "simplified film", using twice the "random walk" method. Then I is given as a function of a (the radius of film) and r (radius of grains in the film). The ourve of J vs a and of I vs r are given. It is discussed about how to chose the size and density of the grains under certain conditions.

According to the beat concept of de Broglie wave, if two electron beams with slight diffrence in momentum merge into one, an electron beam with high spatial frequency with sinusoidal density distribution will be obtained. Dividing the beam into two, let them collide each other from opposite directions, it will form a standing wave. The standing wave oscillation of electric charge will exhibit to be a radiation source of light wave or even high frequency electromagnetic wave.

The problem about the sensitivity of resonators was analyzed in the canonical theory of resonators, and some theoretical results on the sensitivity were obtained. They show that the sensitivity can be lowered by choosing some appropriate parameters of resonators.

Phase conjugation of backward-arid forward-wave produced by degenerate four-wave mixing using a nearly resonantly enhanced nonlinearity in four-level organic dye solutions was investigated. The conversion efficiency of 22% has been obtained in a 2.5 X 10~5-molar solution of chlorophyll A in methylaleohol with a 5mm interaction length and a pumping energy of—8 mj from SH of a ^-switched Nd:YAG. Degenerate four-wave mixing by two-photon resonant-enhancement in the solution of rhodamine 6G in alcohol was investigated. Measurements were performed which described the dependance of nonlinear reflectivities on the molar concentrations of the media and the intensities of the pumping and object waves. Phase con jugation characteristics of forward-wave in four-wave mixing process were theoretically analysed. Experiments have confirmed the theoretical prediction. The method of quartet degenerate four-wave mixing has been extended to the doublet degenerate eass. Using this method, image conversion from 1.06 mm to 5320 A has been realized with a conversion efficiency of 25% in a 5 mm long saturable absorber made of organic dye 9740 solution in dichloroethane. Theoretical analysis shows that using a medium, which is a near resonant absorber for the infrared object wave but transparent for the visible reconstruction wave, the conversion efficiency may be well in excess of unity.

A new class of bistable optical devices is reported which does not require nonlinear medium. Optical bistability was demonstrated by using a scanning Fabry-Perot interferometer and a monomode laser. The principle, characteristics and experimental results of this device are described.

In this paper the formal analogue between deflections of light due to the optically inhomogeneous medium and due to gravitational field is disscussed. It has been shown that there exists a "relation of equivalence" about these two kinds of deflection. In the last part of this paper, an attempt was made to modify the equation of the light ray geodesies in the gravitational field with the consideration of the effect due to the optically inhomogeneous medium. Essentially this modification is to transform the gravitational space-time metric tensor gaB to a new metric tensor gas which can apply both for the gravitational field and for the optically inhomogeneous medium.

The obvious transient absorption at the laser wavelength in Nd:YAG laser crystals is attributed to the production of transient colour centres, induced by UV light irradia-tion. The filtering characteristics of the materials are investigated by means of this phenomenon. The filtering materials suitable to lasers are selected effectively using the combined Nd: YAG cw laser system. In addition, we obtained the relation between pumping powers of different rods at the threshold in the combined laser. As compared with Mori's, our formula is a quantitative expression containing a variety of coefficients.

The target resolution of line scanners is analyzed quantitatively. It is concluded that its resolution greatly exceeds the limit of instantaneous field of view (IFOV). When the scale of the target or its internal radiance distribution is smaller than the IFOV, we can abtain a distorted, i.e., expanded and boundary blurred response. But if the contrast of target radiance distribution is large enough, this distribution can be imaged and distingushed. Particularly, for linear or spot targets, as long as the contrast or radiance increases by a factor of Sl/St, it can certainly meet the condition of any equations constructed for the distinguishable targets, here SL and ST expresses respectively the areua of the IFOV and the target. If we further make use of the difference of spectral characteristics between the target and background, we can improve the target resolution obviously.

A optical resonant cavity with square coupling output hole suitable for TEA CO2 laser is designed. The intensity profile of this cavity is rather uniform and the beam divergence is four times better than concave-plane cavity.

Recent development of the technique of contact screens and its applications to printing and optical image processing are discussed. The basic principle of the use of the contact screens is analyzed with some experimental results illustrating applications of the technique to non-linear image processing. In addition, the paper also describes how the newly invented contact screens can be applied to improve and simplify the picture printing process. We also describe our research plans on the employment of specitically designed contact screens to systematically simplify optical image communication and television broadcasting.