We report in this paper a method of measuring the cavity spacing of a Fabry-Perot interferometer with error less than several tenth of wavelength. First the central fractional order was obtained from interference pattern by a OMA system, which consists of a diode array and a microcomputer, for 32 different wavelengths and He-Ne 6328 A line. Then by using the method of excess fractions to process data, the absolute interference order and cavity spacing of F-P interferometer was worked out from the data corresponding at least to 4 different wavelengths. Further more, the relative reflection phase dispersion curve for silver mirror was obtained by using the data fitting method.

A new Nd:YAG ultra-short pulse laser system is reported. The single pulse energy of this sysrtem is more than 100 mJ at 1.06 μm. Output single pulse energy at 0.53μm is more than 50 mJ. This laser system is used for ranging LAGEOS with φ600 mm received telescope in Shanghai observatory. Its ranging distance is 8000 kM. Ranging a couracy is about 5 cm.

In the present paper, the absorption spectra and their temperature-dependence of barium mateborate (β-BaB2O4) crpstals in the wavelength range of UV-VUV(50nm-350 nm)are reported. The characterises of the absorption spectra can be well explained with the theory of the indirect interband transition. The indirect absorption dege of this crystal is E0 = 6.24eV (at room temperature), and the average temperature coefficient of the indirect band gap is -6.5×10-4eV/K(288K-363K). The types and Debye temperatures of the phonons participating in the indirect transition have also been determined.

The theory of tandem SHG and the requirement on the relative orientations of two KDP crystals are discussed in detail. Using two 1.4-cm-thick type-II KDP tandem crystals, an overall energy efficiency higher than 60% was obtained in our experiment with the incident intensity ranging from 0.33GW/cm2 to 0.67GW/cm2. The laser beam had a diameter of 42mm. The experimetal results were in agreement with theoretical calculations. The measured performance of the tandem doubler (L1 = L2 = 1.4cm) was compared with those of simple crystal doublers with thicknesses of 3 cm and 1.4 cm respectively. The tandem doubler was found to have a combined merit of both the thick crystal doubler and the thin crystal doubler.

The formula of arrival angles of spatially partial coherent light beams propagating through turbulent atmosphere is derived from Markovian process approximation, which can be used in both weak and strong intensity fluctuations. We also, have devived the beam wander angle and arrival angle fluctuation variance of the light beam reflected by a mirror when the beam propagating through the turbulent atmosphere. The reflecting "amplification" characteristics of the beam wandersa and arrival angles of light beams propagating along a fold path is discussed, which passes the distance twice between the transmitter—receiver and the mirror relfecter in weak and strong intensity fluctuation.

This paper presents a simple and effective method for fitting and analysis of the kinetic model of double exponential fluorescence decay. According to four typical cases, we give the rules for selection and modification of decay parameters to get the best fit. In this paper, the judgment of correction of the model fitted by our method is also discussed. The calculation program of this method is simple and can be carried out on a microcomputer. It can be easily used in further.

This paper describes a new interferometer-point-diffraction holographic interferometer. In this interferometer, a collimated beam from a He-Ne laser is divided into beams (reference and object beams) by a beam splitter; the lens to be tested is placed in the object beam with a pinhole at its focal point; another lens is placed behind the pinholt to collimate the outgoing beam and a holographic plate is placed at the position where the reference and object beams are over lapped. The pinhole is small compared with the Airy disc of the lens. After the hologram is processed, it is replaced at the original position while pinhole is taken away. The hologram is then illuminated bj both the reference and nnfiltered object beams so tlxat two interferogxams with the same distribution are formed in the object and referenoe beams behind the hologram. It is known by theoritioal analysis that this is an iBdieation of the aberration of the lens under test. The principle of this method is basically the same as thai; of a point-diffractions interferometer. But in the case of a point diffraotien interferometer, adjustment is very difficult beeau5e it uses a glass plate with a highly absorbing layer and a very small hole on it and one can not find its position easily. While if oar method is used ihere is no more adjustment diffiotilty provided that the replacement is correct. In the tranditional intexferometrio testing of a lenft, auch as Twyman-Greeii interferometer, a standard spherical mirror must be used to reflect the beam back. In addition Twyman interferograms are sensitive to vibration and temperuture. Our method, however, does not require a standard spherical mirror and can provide more stable interferograms. In addition，the same hologram can also be used in testing other lenses provided that their fecal points are exactly at the pinhole position. This method can be naed 111 testing of lenses, telescope and microscope objectives during their proceflsing or assembling. It has the merit of simple structure and easy operation.

Using a branch-tuning CW CO2 laser in the range of 9.2μm to 10.8μm we have studied the IR laser photoacoustic spectra of organic molecules adsorbed on the surface of silver. The adsorbed molecular spectra of four layers of arachidic acid and cellulose diaoetate with different surface densities have been studied. No peak shift was ound in the comparision between the IR photoacoustic spectra of four layers of arachidic acid near 944cm-1 and the corresponding IR Fourier spectra of solid ar-achidic acid. For the IR photoacoustic spectra of cellulose diacetate with σ1=1.4×10 15 cm-2 and σ2=5.5×10 15 cm-2 respectively, we compared them with corresponding IR transparent spectra, of solid cellulose diacetate. It has been found that the peak of tlie former near 1054 cm-1 has a red shift about 5 cm-1 and the peak of the later has no obvious shift within the accurancy of the experiment.

A series of IR stimulated and c scade stimulated radiation (ws) were detected when the 7S state of potassium was populsted by two-photon resonance excitation. Nine UV coherent radiation lines (wP) were generated through the two-photon resonant four-wave mixing wP=2wL-ws. By the second four-wave mixing process wc = wP-w s ws", a gereies of UV and violet coherent radiation were formed. The schemes for generating IR stimul ted and UV, violet coherent radiation were discussed in this paper.

Polarized Raman spectra of single crystal KTiOPO4 have been measured in the wavenumber shift range 10-4000 cm-1 at 300K and 210K. The infrared absorption spectrum of KTiOPO4 has also been measured in the 200-4000cm-1 range for powder samples dispersed in the pressed KBr disks. An assignment of the spectra is given hy using the group theory. Some characteri tics in the spectra have been investigated.

This paper reports the generation of the stimulated radiation of UV (350.0-385.0nm) and violet (405.0-460.0nm) diffuse bands by two-photon pumping covering a wide wavelength region (620.0-670.0nm) in Na2. The processes of the excitation and emission are discussed.

By using laser excitation of three different photon energies, we have experimen tally studied the SERS spectra of pyridine molecules adsorbed on the surface of an electroohemically roughened silver electrode. The experiment shows the relation between SEES spectra intensity and the photon energy as well as the applied voltage. We introduce the viewpoint that the applied voltage has influence on the energy levels of adsorbed pyridine molecules and make improvement of the exising charge-transfer excitation theory of SERS spectra. The experimental results are explained in this way.