Real-time grey-tone mask technique to fabricate the microstructures is presented in this paper. It combines the advantages of programmable digital LCD system and projection photolithography system, utilizing the LCD panel to display a serial of patterns which transfer light intensity distribution with representative of height information of 3D-profile into exposure time distribution. As a result, this continuous grey image on the recording plate is obtained. This technique principle is explained. Then based on partial coherent imaging theory, the process to fabricate the microlens has been simulated. As an experiment, the microlens array has been fabricated on panchromatic silver-halide sensitized gelatin with enzyme etching. The radius of microlens and etching depths are 59.33 μm and 1.638 μm, respectively.

Optical limiting behaviors of a methyl-red doped liquid crystal mixture-E7 are studied using a Q-switched frequency-doubled Nd∶YAG laser at 532 nm with a few ns pulse-width. Far-field optical irradiance distributions beyond a sample cell and their variations with increasing the energy incident upon the cell are also observed. The experimental results show that, for the 46 μm thick methyl-red doped liquid crystal mixture E7 film with a weight-to-volume ratio of 6 mg/0 5 ml, the clamped output values of the first three tests are 0.70, 1.00 and 1.52 μJ, respectively, and the input limiting thresholds are between 23 and 28 μJ. The unusually low clamped output property of the film is very significant to the optical limiting for eye and sensor protection.

A photonic crystal fiber was fabricated by drawing milled silica rods. It consisted of a pure silica core with a diameter of 30μm, which was surrounded by two rings of air holes with a hexagonal symmetry, the hole diameter and the spacing between holes were 4 μm and 17 μm, respectively. Simulation and experiments showed that this fiber was single mode for wavelength beyond 632 8 nm.

The 532 nm light of YAG laser is used as recording light and the monochromatic-light is used as the readout light. At the different wavelength, the changed tendency of the image contrast based on the BR D96N thin film is observed. Using the method of the gray integration of the image, the contrast curve of the recorded image is achieved. All the results show that a maximum image contrast of ～1.63∶1 is obtained in the peak absorption region of the B-state (～570 nm) and the reverse images are obtained in the absorption region of the M-state (390～450 nm).

In this paper, the signal pre-processing and real-time imaging techniques were studied. By partitioned access method the real-time laser radar imaging was realized. The data processing was reduced using range strobing grating and the system information processing ability was improved by using ADSP21060 processor chip.

The experiments of laser cladding of Ni-base composite alloy powder doped with TiO 2 were carried out. Various laser processing parameters and different TiO 2 content were chosen to obtain a perfect clad layer. The microstructure observation and microhardness test of the cross-section of the laser cladding zone were performed. X-ray diffraction analysis and tribotesting of the surface of the laser coatings were also accomplished. A good finish and crack- and porosity-free surface clad layer was obtained with the TiO 2 content of 3 wt.-%～4 wt.-% at the beam scanning velocity of 2～4 mm/s. An excelled interface between the coatings and the substrate was formed. It is shown that the addition of TiO 2 can enhance the toughness of coatings, refine the microstructure of clad layer, and reduce the cracking susceptibility obviously. The improvement of properties of the laser-clad layer is due to the effect of TiO 2 on it, in which TiO 2 with a proper content can uniformly refine the structural grains, entirely suppress the formations of big nubbly hard-phases, greatly reduce the size of dendritic phases and increase the tenacity of coatings.

A technique using pulsed UV laser to process or correct the circuit boards was studied. The influences of the laser wavelengthes, pulse energy and lens focus length on the circuit ablation were investigated, and the optimal parameters were got.

PET film surface was irradiated and grafted with hydrophilic monomer by XeCl excimer laser to improve surface hydrophilicity. The influences of laser fluence and pulse numbers on surface hydrophilicity changes of ablated and grafted PET films were studied, and the differences of surface property between ablated films and grafted films were discussed. Based on the analysis of factors influencing the weights of ablated films and grafted films, a new formula reckoning graft degree was presented.

High power red laser by intracavity-doubling of Nd∶YAlO 3/LiB 3O 5 1 3414 μm laser was reported The parameters of the folded laser resonator are calculated. Based on the theory analysis, the suitable cavity parameters are determined and the 670 7 nm laser of 3 26 W was got at the average electrical pumping power of 1783 W.

The eigen states of LD-pumped Nd∶YVO 4/KTP intracavity-doubled green laser were analyzed through spatially generalized Jones matrix formalism and the polarization states and eigen-frequency were obtained. The experimental phenomena observed by inserting a Brewster plate into the cavity to obtain the stability of green laser was explained.

This paper reported a CW Nd∶YAG laser with the wavelength of 1319 nm. The radiation energy level of 1319 nm wave was analyzed. Restraint of 1064 nm wave resonance and improvement of 1319 nm output was discussed. Coating of mirror and cavity structure was studied and a maximum cw output of 43 W at 1319 nm was realized in the experiment.

In the paper, a solid- state master oscillator amplifier (MOPA) system is built, which consists of a single-longitudinal-mode resource pumped by semiconductor, three amplifiers pumped by xenon lamps which beam light passes double times and the phase conjugating SBS-mirror to compensate the phase distortions. In this laser system, image transfer, thermal depolarization compensation, elimination of self-lasing and other key technologies are employed to improve the quality of the output beam. In addition, the output energies over 450 mJ are attained at 40 Hz, with output energy stability of 3.5% (RMS), the pulse width about 8 ns, and mode quality <1.3DL.

In this paper, a flashlamp pumped Cr∶LiSAF (Cr∶LiSrAlF 6) regenerative amplifier was developed to amplify chirped light pulses which were stretched from 80 fs to 103 ps. The relation between the amplified output energy and the input energy and that between the net gain and the round-trip number of the chirped pulses in the cavity were determined. Using the regenerative amplifier, a net gain of 8×10 5 and the maximum output pulse energy of 0.4 mJ were obtained.

This article describes the design and testing of a laboratory prototype single diode laser system for remote detection of methane gas using harmonic detection. Harmonic signals are contained within radiation backscatter from topographic targets. A function of detected gas concentration depends on these harmonic signals is given by theoretical derivation. Base on it, minimum theoretical detection limit for methane is calculated to be about 87×10 -9 and the minimum measurable path-integrated concentration is estimated to be about 420×10 -9 by experimentation with real situation in laboratory at 2ν 3-band R(6) line of methane.

This paper argues that how to compute the center position of the knife in the image obtained by CCD accurately is a key issue by introducing the principle of laser scanning system. In this paper, a new method based on NURBS curve interpolation is designed. The experiments show that the results computed by this method are stable and the errors are controlled below 0 1 pixel. Thus, the errors in the height direction are less than 0 02 mm.

This paper describes the fundamental and performance of a self-developed phase-shifting digital interferometer. This instrument can be used to test wavefront distortion of laser rods whose aperture is 30 mm with accuracy better than λ/20, the repeatability better than λ/50. The instrument has four characters: magnification changing, focusing , luminous flux controlling, and changeover of adjustment and test. Software based on the platform of windows98 can finish interferogram sampling, processing and wavefront drawing, the operation is easy and convenient. The whole testing only spends 26 seconds. This instrument can also measure the refractive-index homogeneity, the flatness, the angle error, the wedge angle of crystal element. By testing the same samples with Zygo GPI-XP, both results were same.

The technique for the atmospheric wind measurement with a Fizeau interferometer has been proposed. The system uses a Fizeau etalon for spectral analysis, and the comb-like interference patterns are determined by a linear CCD array. The gravity of the pattern is proportional to the Doppler shift of the backscattering signal from wind. The simulation with the Monte-Carlo method shows that the accuracy of Doppler measurement is better than a tenth of the spectral width of a single CCD component in 90% detection probability. The accuracy of the lidar system is about 2 m/s in the vertical up to height of 2 km.

A novel method is proposed to optimize EDFA+ Raman hybrid amplifiers based on genetic algorithm in this paper, and a simple fitness function is achieved according to Giles two-level approximation equations and Raman power-coupled equations. The calculated results show that a flat gain profile from 1542 to 1602 nm, with a maximum gain ripple less than 1 dB can be obtained without any gain flatten filter, by using only three Raman pump diodes with proper power and wavelength. And some useful design principles are discussed.

A novel structure of two-stage EDFA pumped by C-band and 980 nm LD for gain enhancement of L-band signal was investigated via experiments and numerical calculation. C-band light was controlled by erbium-doped fiber laser. The influence of C-band power and wavelength on gain of L-band was analyzed principally. In the experiment, with an injection of 5 mW at 1525 nm, the gain enhancement of 7.7 dB for -20 dBm signal power at 1580 nm was achieved.

This paper investigates the near-far effect stemming from different signal power of users in OCDMA system. Based on the assumption that user′s signal power is Gauss-distributed, the impacts of near-far effect on system performance are presented. Results show that near-far effect significantly degrades the probability for the error and outage probability for the power-less users. Furthermore, increase of user′s signal power variance degrades both probability of error and outage probability for all users in the system. A method of coping with near-far effect, i.e. using an optical hard-limiter in the ODN, is proposed. Additively, the optical hard-limiter alleviates the multiple access interference.

In this paper, based on the rate equations in a steady state of the Tm 3+ ions, an analytical solution of the gain for thulium doped fiber amplifiers (TDFAs) is obtained after some reasonable simplicities. The gains of the three TDFAs with different parameters are calculated which show good agreement with the experimental data.