The classification concepts and operational conditions for metastable resonators are given by using geometric-optics theory. The mode discrimination and restriction characteristics of the principal two-element metastable resonators (such as parallel-plane, imaginary concentric, real concentric and various zero g cavities)are analysed. Some problems concerning practical applications of metastable resonators are discussed in conclusion.

This paper describes the design and experiments of three types of aerodynamicwindows——expansion window, compression window and vortex window. Three windows have anaperture of 3 cm and were designed to operate at a cavity pressure of 0.1 atm. While the beam passes through the window, the minimum beam degradation is 1.5 times as large as the diffraction limit of the aperture. The minimum mass flow required for the operation of the window is 0.012 kg/sec.cm2.

It is believed that interference effect of Ge-window is an important factor affecting CO2 laser output staibilty. The two parallel surfaces of a Ge-window constitute a Fabry-Parot interferometer, so for an incident laser beam, the transmissivity depends sensitively on thickness as a result of interference. And the thickness of Ge-window varies with laser intensity and ambient temperature. Therefore it is suggested that this may constitute a important cause of instability of the power output, frequency and transverse mode.

The average electron temperature has been measured by using a double probe. The influence of the addition of N2, He, Xe, and that of dissharge current, gas pressure on the electron temperature were studied.

According to our experience in solving the problems of adjusting and designing laser monoehroineter, the paper present some points which should be taken into account in applying etalon in the cavity: selection of parameters, some possible phenomena and their solutions. Data and photoes used in this paper were obtained in adjusting model WDJ-1 laser monochrorneter.

Influence of defects, such as residual stress, facet and scattering particles in Nd:YAG crystals on the optical properties of crystal and CW laser performances were investigated experimentally.

Some problems on coupling of GaAs heterojuuction laser into multimode optical fibers are discussed, and coupling efficiency has been calculated for optical fibers with microlens.

A new method for detection of the difference between two images is presented. In this method, the authors regard a white light speckle pattern as a random carrier for optical processing. The experiment demonstrated that it can be used to code information of images in an efficient way yielding a high degree of redundancy. The result obtained is similar to that by Frangon’s modulated coherent light speckle patterns. But this method is simpler than Francon’s.

The interferometer introduced in this paper has such properties as simple optical arrangment for holographic recording, automatic insurence of the optical path quality and reproducibility of receded wavefronts in different reference background. It can be applied to interferometry with high temporal and spatial resolution requirements.

A single shearing interferogram is not sufficient to describe a wavefront. Two interferograms sheared in orthogonal directions must be used to reconstruct the wavefront of any arbitrary shape. Two types of two dimensional lateral shearing interferometers have been studied: orthogonal shearing prism and crossed grating. A method is described that uses data obtained from the interferograms to reconstruct the wavefront. It was used in processing the interferograms obtained in our experiment.

In this paper, holographic interference inspection of striae and bubbles in optical glasses is described. Compared with the conventional methods, this one has the characteristics of higher accuracy and easier automation in inspection.

The conditions for discharge stability in gas laser tubes electrically connected in parallel are discussed, and the coefficient of discharge stability is given. These may provide tlleoretieal basis for designing power supplies of stable folded gas lasers, as well as a reference in designing power supplies for other discharge tubes electrically connected in parallel.

Lassr induced harms on parsons in Shanghai Institute of Optics and Fine Mechnics during more than the past ten years are reported. Some typical cases are selected and the causes for accidents analysod. It is pointed oat that the reflected light from the laser irradiated spot is a serious hazard to human eyes, and some problems on laser safety are discussed.