A laser diode interferometer with a feedback control system for micro vibration measurement is proposed. The interferometer can be used to measure micro vibration of an object with high accuracy in real time. The interference signal is processed with a simple signal processing system and the amplitude and frequency of the vibration are obtained. The measurement errors are decreased with a feedback system. The theoretical analysis and experimental results are given.

The aluminum flyers with 5.5 μm thickness and 0.5～0.8 mm diameter have been driven successfully by mini size YAG laser in the energy range of 100～300 mJ. The average velocities of flyer were up to 6.6 km/s, and the relationship between flyer velocities and energy density has been obtained in experiments. The analysis to the recovery samples showed that the flyers have good figure during the process of flying. The whole process can be simutate by using Gurney theory and Lawrence model and the academic results are in good accord with the experimental results.

In this paper, the principle of weighted directional coupler and its application in apodization of integrated acousto optic tunable filter (IAOTF) have been analyzed and discussed. According to the theoretical analysis, the acoustic waveguide has been designed and the TE/TM mode conversion characteristics of AOTF have been analyzed. Based on the results, practical filter has been fabricated on the substrate of X cut, Y propagate  LiNbO 3. Experimental measurement shows that sidelobes are suppressed to -14 dB and -3 dB bandwidth is 2.0 nm.

The research results of all polarization maintaining fiber hydrophone array have been reported in this paper. On the basis of detail introduction of structure and operating principle of all polarization maintaining fiber hydrophone element, the structure and performances of four element array have been described. The measurement results of element frequency responses of relative receiving sensitivity and array directional responses have been given.

By expanding the rect function into a finite sum of complex Gaussian functions, the propagation of flattened Gaussian beams through an apertured optical ABCD system is studied in the rectangular coordinate system, and approximate analytical propagation formulas of flattened Gaussian beams are derived. The validity of our formulas is illustrated with numerical examples.

Through numerical simulation, it is demonstrated that, at zero averaged path dispersion managed optical fiber links, after both second order dispersion and third order dispersion are full compensated, nonlinear effect can make optical pulse narrower. So, optical pulse's peak power has to be kept very small. However, when polarization mode dispersion is considered, the nonlinear effect can be balanced. As a result, the system can be operated in higher power, so that signal to noise ratio of system will be improved.

The dual layer dielectric reflection film of GeO 2/Al is deposited on inner wall of the quartz capillary by CVD. The inner surface reflectivity is increased, and transmission losses are decreased. The transmitting energy hollow fiber can transmit more than 80 W power of CW carbon dioxide laser.

Considering the heterogeneous thermal properties of living tissues, a multilayer heat transfer model for laser tissue thermal interaction is presented in this paper. A closed form analytical solution to the temperature transients within two tissue layers is obtained using the Laplace integral transform method. Heat transfer behaviors inside the tissues before evaporation were investigated. The critical time required to vaporize the surface tissue and the thermal damage depth are numerically predicted. Study shows that there is evident difference in temperature predictions between the uniform model and the heterogeneous one.

By studying an imaginary table top in line X ray holography experiment, the article explained the causation of 0 and +1 rank diffraction stripes on reconstructed plane and presents solutions for both problems. Some common principles of reconstruction and some other methods for improving the resolution are also discussed.

This paper analyses the mechanism of the laser induced plasma current and establishes a mathematical model for laser welding. The model satisfyingly interprets the regularity of the plasma charge signal decreasing monotonously with the increase of the nozzle workpiece distance, which coincides well with the experimental results.

Detailed laser surface remelting experiments of three kinds of Cu Mn alloys were carried out to study the effects of technology parameters (scanning velocity, laser output power) on the growth direction of microstructure in the molten pool. The experimental results show that growth direction of microstructure are strongly affected by laser technology parameters and alloy composition. Ultra high temperature gradient directional solidification can be realized on the surface of samples by laser surface remelting, whose temperature gradient can reach 10 6 K/m and growth velocity can reach 24 mm/s, and the solidification microstructure grows along the laser beam scanning direction. In order to obtain ultra high temperature gradient and rapid directional solidification with laser surface remelting, the key problems are: 1) to ensure temperature gradient in the molten pool parallel to laser beam scanning direction; 2) to select adequate technology parameters to ensure cellular growth.

In order to look for a cheap compact laser source for a micro pulse lidar to remotely sense aerosol and cloud in the troposphere, the studies of diode pumped, Cr4+:YAG passively Q switched Nd:YAG lasers were present. Using different laser cavities with different initial transmissions of Cr 4+:YAG, the output properties of laser were demonstrated. The output energy of 20 μJ per pulse and the repetitive frequency of 2.8 kHz were generated by a LD with 1.1 W and a Cr4+:YAG crystal with an initial transmission of 82%, which it can match the requirement of micro pulse lidar. The measured CW output power and pulse repetitive frequency were consistent with the results of theoretic calculation well.

The LD pumped Nd:YVO 4/KTP laser is modulated by AOM of light intensity. The modulating frequency achieved is above 15 MHz, and the diffraction efficiency attained is up to 40%～60%, which can meet the needs of laser accurate measure and new type laser color television.

Based on the nozzle flow field equations on the assumption of quasi one dimension, steady, non balance flow and vibration relaxation equations build by 3 vibration and 3 temperature model, the small signal gain and some influence parameters are calculated and analyzed. The results of calculation and measurement are compared.

An experiment of mini waveguide CO 2 laser including master oscillator and local oscillator, excited by radio frequency (RF) for active imaging lidar is reported in this paper. The following main experimental results have been gotten: 150 ns pulse width (FWHM), 360 W peak power at 41.67 kHz pulse repetition frequency by electrooptical Q switch for master oscillator. 3 05 W CW output for local oscillator. EH 11 mode, long time stable P20 line output with 1 76×10 -8 stability (short time) for this laser.

The UV, visible and IR absorption spectra of annealed and as grown Yb:YAG grown by Czochralski technique were measured, and some changes of absorption bands and shifts of absorption peaks are observed and discussed. With the disappearance of broad absorption bands of color center at 370 nm and 625 nm, the new absorption band at 254 nm of annealed Yb:YAG is probably the result of change of color center. The little shifts of absorption peaks at 220 nm and 940 nm are regarded as the result of crystal lattice deformation, which was proved by X ray diffraction. In laser experiment of Yb:YAG crystals, the influence of doping level on laser performance has been observed.

In this paper, Nd:KGW multi wavelength laser crystal has been grown by mean of the top seeded solution method (TSSG). The structure of crystal was analyzed using X ray diffraction. XFA shows the existence of element of W, K, Gd, and Nd. The spectra of IR, Raman and absorption were measured, the absorption cross sections of Nd 3+ were calculated.

Preliminary results on characterisation of optical waveguides fabricated in Er doped phosphate glasses by ion exchange are presented. Planar waveguides with low losses are easy to be fabricated in Er doped phosphate glasses containing a suitable percentage of sodium oxide, and the ion exchange process did not affect the spectroscopic properties of the glasses.

The principle and measurement system of Sagnac interferometer and fixed analyzer are introduced. The polarization mode dispersion of optical fiber by a Sagnac interferometer is measured. Comparing with fixed analyzer, Sagnac interferometer is simpler and spectrum is more readable.

A simple method based on total internal reflection is presented for accurately measuring the refractive index of biological tissue. The refractive indices of water and a few kinds of porcine tissues have been determined at 0 488 μm, 0 6328 μm, 1 0795 μm and 1 3414 μm laser wavelength respectively, and their dispersion equations have been calculated. It proves that the method has great reliability and accuracy.

The differential equation ,discribing the small scale self focusing effects caused by nonlinear growth of perturbation when laser beams are propagating in nonlinear media with gain(or loss), have been deduced from nonlinear propagational equation. Some characteristics of small scale self focusing of laser beams propagating in nonlinear media with gain have been analysed. Variations of cutoff spatial frequency, the fastest growing frequency, integral exponential gain of perturbation with different parameters have been specified.

Atomic potassium is ionized by three channels when it is excited by a pulse dye laser. They are energy pooling induced ionization, 4S→6S and 4S→4D two photon resonant three photon ionization. The ionization current intensity at various vapor temperature and laser intensity were investigated for the former two ionization channels. The atomic radiation trapping and nonlinear ionization were found in ionization current spectra. The qualitative explanations for above phenomena are given.

A series of super RENS thin films were fabricated using magnetron sputtering technique. The dependence of relative transmission intensity and microstructure of AgO x (magic layer) on temperature was measured. The interrelation between the optical switching property and microstructure of AgO x film was analysed.