A photoconductor switch and an oscillograph were used to measure the signal to noise ratio (SNR) up to ￣10 6. For laser fusion it needs some times to convert the fundamental laser to its frequency doubling. What is the relation of the SNR of the fundamental and its frequency doubled laser and how to measure the SNR of the frequency doubled laser are discussed.

In this paper we discuss the realization of an optical wavelet transform. While choosing the Mexican hat wavelet to extract an optical signal by computer simulation, we find the defect of this wavelet in signal extraction. Base on this finding, we put forward a new wavelet and its merits have been testified by computer simulations.

The P-N junctions were produced by continuous wave (CW) CO 2 induced diffusion of Zn into a GaAs substrate using a solid state diffusion source. After the samples were exposed to the laser radiation, the features of the exposed region were studied by scaning electron microscopy (SEM), and the dopant profiles were examined using a secondary ion mass spectrometry (SIMS). The performance parameters of the P-N junctions such as xj and C(x,t,T) are presented as functions of the diffusion time t and temperature T. The experimental results show that the junction depth xj reaches submicron and the dopant concentration is of the order of 20 20 cm -3.

The effect of a domestically manufactured excimer laser performed operation together with adujunctive balloon angioplasty in achieving revascularization and reduction of residual stenosis was assessed. 20 femoral arteries with thrombosis and occlusion from 10 dogs were subjected to angiography. At first an excimer laser angioplasty was done followed by the balloon angioplasty. The diameters and residual stenosis of revascularized vessels were measured. The result showed that 17 out of 20 vessels (85%) were revascularized. The typical diameter of the revascularized vessels after excimer laser treatment was 1.20±0.14 mm, while residual stenoses were 54%±5%. After an adjunctive balloon angioplasty the diameter and residual stenoses were 2.04±0.16 mm and 20%±7% respectively (P<0.05 and P<0.01). Complication in a form of vasoperforation occurred in 3/20 vessels (15%). It is concluded that China-manufactured excimer laser angioplasty is effective when used for revascularization. The reduction of narrowing and residual stenoses was enhanced after adjunction of the balloon angioplasty. It would be expected that this method can be employed in treating peripheral occlusive disease effectively and safely.

A new method with a one wavelength laser for making 3D diffusion objects true color rainbow hologram on the photoresist plate is presented. In this method, we have utilized the synthesized slit technology to record the true color rainbow hologram. It results in higher energy utilization and good color reproduction of the reconstructing image. So, it is valuable in fabricting 3D diffusion objects true color embossed rainbow hologram. A satisfactory experimental result is obtained and the analysis is given.

A new type of diffractive optical code (DOC) using binary computer-generated hologram (BCGH) is presented. We introduce a new method of amplitude-compensated CGH to guarantee the DOC correctly decoded and to obtain higher signal-boise ratio. Compared with the phase-shaping method for diffractive optical bar code (DOBC), this DOC can yield substantially lower reconstruction error and higher efficiency. Computer simulation and optical experiment are reported.

In this paper, Fourier transform evaluation of fringe phase is proposed for moire deflectometry. Using this method, high precision and automatic measurement for the axisymmetric gas temperture field has been accomplished.

Ti 6Al 4V titanium alloy was laser surface alloyed with Al+ Nb. Using proper processing parameters, alloyed layers consisting of TiAl 3+TiAl+minor Al were obtained on the substrates. Results of oxidation test carried out at 900℃ in air showed that a dense and continuous α Al 2O 3 oxide scale, which effectively prevented the substrates from oxidation, could be formed on the surface of the alloyed layer.

The characteristic of a LD pumped highly efficient Nd:S VAP laser using a plano plano resonator is presented. The output power at 1.065 μm is 233 mW for an incident pump power of 577 mW, yielding an optical efficiency of 42.4%.

It is reported that laser transversal and longitudinal mode structure as well as other factors such as pumping rate disturbance, causes instability of the output of a cw Nd:YAG laser passively Q-switched with Cr4+:YAG. Effectual methods of improving stability are given and a stability better than 5% is gotten. It is suggested that the thermal effect of Cr4+:YAG and damage to optical coating should be taken into account when increasing the output power of the Q-switched cw laser.

The basic issues of impedance matching in a radio frequency discharge excited CO 2 laser are theoretically discussed in detail. A general and very applicable formula for selecting the parameters of the equivalent matching network is obtained. The results are also used to calculate the matching network parameters for other high frequency discharge excited CO2 lasers.

An analytical expression and a perturbation formula for the cavity resonant frequency dependence upon plasma are derived for the cylindrical TM 010 microwave plasma cavity. A comparison between the exact and the approximate solutions showed that the perturbation theory can be used accurately to analyze the perturbating effect on the cavity resonant frequency caused by microwave plasma in low pressure microwave excited gas lasers. A new method is proposed to prevent the detuning of the cavity from the perturbation of the plasma and the glass tube, so that a uniform and steady-state microwave plasma is successfully formed and the stable laser output is also obtained. The electron density and microwave dielectric constant of the tube material can be measured by the perturbation approach.

In this paper, parasitic oscillation of a multiple pass resonator with a multipath cell of coaxial gas lasers is discussed. Conditions under which the parasitic oscillation takes place, its influence on the output of the resonator and the measures to avoid it are analysed.

A compressible scaling method (CSM) is used to simulate the nozzle flow field and optical flow field of the 3 slot CW HF chemical laser. The effects of gas components′ mass flow rate on the laser′s properties are studied. The mean cavity pressure, the radiation intensity distribution along the flow and the corresponding variations of the coupling output power and chemical efficiency are also given.

With single electron model, harmonic generation is observed from relativistic effets, especially the transformation from the rest frame of the paticle to the observer′s frame. Angular distribution and the dependence on laser intensity are given. It′s found that the harmonic intensities have periodic variation against the angle and the harmonic order. Methods discussed in this paper may be used to explain the expriment carried by P. A. Norreys et al..

In this paper, we solve numerically the Schrdinger equation in which the Hamiltonian is time dependent. We calculate the quantum ionization probability of an atom subjected to a delayed two pulse optical field. The result shows the effect of controlling photoionization by adjusting the delay between the two optical pulses. In addition, the influence on the generation of higher order harmonics by the delay has also been observed.

C60 films fabricated by high vacuum deposition technique are studied by time-resolved photoluminescence spectrscopy from 127 K to room temperature. At 127 K, the peak of the C60 PL emission is at 730 nm and its decay behaviour shows single-exponential character. With the increase of the temperature, the PL peak has a red-shift and its decay obviously deviates from the single-exponential character. Adapting a four-energy-level model, we have got double-exponential decay solution for PL emission and then used this solution to fit the experimental data. The results demonstrate that the intersystem crossing rate of the singlet excited states increases rapidly with the increase of the temperature.

This paper investigates the effect of laser pre irradiation on strengthening of fused silica surfaces. Fused silica surfaces heated evenly with CW CO 2 laser radiation under go in changes including residual compress stress occurred, peak to volley and microcracks decreased, which are observed by polarized microscopy and atom force microscopy. Damage thresholds of fused silica surfaces measured with a Q switched Nd:YAG laser increase by a factor of 1.53 after pre irradiation.

High power pulsed laser induced shock wave pressures in aluminum targets are measured with the use of PVDF gauges made by ourselves. The pressure decay of laser induced shock in aluminum is obtained by measuring the pressure on the rear faces of different thickness targets. The shock peak pressures as a function of laser intensity of about GW/cm 2 are reported.