Laser clad Ni -based alloy coating with 20vol% B4CP(NiB4C) on 16Mn steel substrate has been obtained by 5kW CO2 continuous wave laser. Microstructure and phase constitutes of the NiB4C coating have been studied, and micro - hardness and the performance of sliding wear of the NiB4C coating have been discussed in contrast to laser clad Ni - based alloy coating (Ni60). The result shows that the microstructure of NiB4C coating is consisted of cellular structures in bottom of the NiB4C coating and dendritic ysolid solution plus the eutectic structure between the dendrites in the middle and top of the NiB4C coating. Constituent phases of the NiB4C coating mainly have y - Ni,y - (Ni, Fe) , (Cr,Fe)7C3, CrB, Ni3B, Fe2B and Fe23(C, B)6. B4C Ceramics Particles exist between the dendrites and not totally melted. Micro - hardness and sliding wear resistance of NiB4C coating are higher than that of the Ni60 coating. The strengthen mechanism of the NiB4C coatings is analyzed.

Strengthening the important aerial aluminum alloy material, 7050T7451, 7050T7452 under different conditions by Laser Shock Processing ( LSP) technique with the device which is developed by ourselves and testing the residual compressive stress of LSP area. The comparing test results shows test piece will has very high residual compressive stress after LSP, the residual compressive stress can exceed -200MPa; After twice sequential repeated processing, the residual compressive stress will be increased over one - time than single processing; After twice sequential repeated processing on one side, the residual compressive stress of front side (the side was processed first) is equivalent to twice sequential repeated processing on both sides, and at the same time, after twice sequential repeated processing on both sides, the residual compressive stress of back side (the side was processed latter) is far less than front side. All above results are discovered through experiments first time, and have guide meaning to the practical engineering applications of LSP technique.At last,the corresponding analysis of surface strcture and testing of fatigue life were given.

The techniques of laser quenching and laser honing are introduced briefly in this article. And then we compare the two techniques from the following four factors, including mechanisms of abrasion, the main technique factors, processing methods and the application effects and properties. The above studies indicate laser quenching and laser honing are different surface processing methods.

The experiment that 12CrNi3A steels were treated by carburizing and laser transformation hardening was carried out. The microstructure and abrasion performance of the treated steel were studied in detail by SEM and abrasion tester. The results show that the microstructure obviously varies with the change of depth in laser hardened zone. With the scanning speed going up, the hardness and the wear - resisting property are improved.

Laser welding of 5083 aluminum alloys with high power CO2 laser is experimental studied in this paper. The influence of laser power, welding speed and the focus position to the laser welding process as well as the assist gas to the instability of the welding process are analyzed. The experiment result shows that, under the precondition of the enough power density to striking, the reducing of the heat input and the using of the mix assist gas will achieve the stable and fine welding effect.

Laser beam welding can reduce the size of grain of high strength steel joints due to its rapid cooling resulting from its higher energy density and lower heat input. But there are some important problems in joint, such as solidification cracks, HAZ cracks and soften etc. In this paper, characteristics are described about laser beam welded high strength steel, Measures to avoid cracks and softening are introduced according to the latest researches in the world.

The characteristic of pulsed laser welding process of small - size stainless steel sheets is studied and how welding parameters affect the penetration status and the width of welding line is specially analyzed. Experimental results show that the penetration threshold of laser power density decreases and the one of laser average power increases with the increment of pulse time, but laser power density cannot be always reduced, it must maintain above a certain limit to ensure the penetration. The parameters , which significantly affect the width of welding line, are laser power density, pulse time and frequency. This paper not only offers some useful experience for precise laser welding of small - size workpieces whose condition of heat transferring is limited, but also establishes experimental foundation for numerical simulation analysis of the welding process using Finite Element Method.

Digital Particle Image Velocimetry (DPIV) is a new technology of fluid velocity measurement developed recently , and it has gain more and more attention. This paper expounds the basic principles of DPIV, and develops a set of DPIV measurement system, which is used to study the fuel spray. The system contains a transparent glass vessel, a flexible high powered light guide, a precise X - Y reference frame and a synchronous signal control device which can accurately control the action of the nozzle, the laser system and the CCD camera. Using this system, the whole fuel spray field can be observed from beginning to end. The results of diesel spray experiment show the entrainment phenomenon between surrounding gas and diesel spray, and the vortexes appear in parts of the atomizing area.

A piece - wise function in the dependence of burning rate on the radiant flux and its break point are important characteristics of burning of double base propellants under external irradiation. Using Fourier equation can analyze the burning characteristics, including characteristics near the break point. Considering the shielding effects of carbonous layer forming on the burning surface on the transmission of external irradiation, the burning characteristics of 1040, 1041, N -5 and N propellants were analyzed. One of main reason induced a piece - wise function and the break point is the loss of radiant energy before the radiant energy reaches the surface of condensed phase.

The optical character of IR system is introduced. The back reflectedlaser got when laser irradiated IR system is tested on the base of theory and experiment. Through experiment, the reflect efficiency of back - reflect laser from optical element in IR system, the laser spot and the identification ofback - reflected laser are measured. The research issuers have really signifi-cancefor the use of back - reflected laser, the illuminating tracking and identificationto IR system.

TFT-LCD is a very important spatial light modulator in optical information processing. The matrix of TFT -LCD is constructed with a metal mask that covers the inter - pixel spaces, obscuring the thin fihn transistors and preventing light leakage through the unswitched parts of the panel. It result in diffraction. The overlap of adjacent order of diffraction limited the spatial frequency used in optical information processing with TFT - LCD. The analysis shows that the relative amplitude spatial distributings of different diffraction orders are same. This has been checked by the experiment of JTC.

The paper discussed the principles of PRK(Photorefractive Keratectomy) and LASIK( Laser in - situ keratomile-usis), mechanism of action of excimer laser on cornea ,mode of laser delivery to the cornea , relationship between the ablation rate and the energy of the excimer laser and the " flying - spot" scanning technology. The results of this paper have been applied to ophthalmic excimer laser system . During clinic practice , it has achieved satisfied outcomes.

The Paper depicted the harm of CO2 Laser for human and environment. The adopted measurement was discussed.

Aim:To observe cure effect in alveolar fossa post - extraction of teeth by irradiation of He - Ne laser, we have treated 100 cases patients of with or without laser acupuncture. Methods: Post - extraction, fifty cases wereradiated directly by He - Ne laser acupuncture in Low Energy for ten times during 3 weeks as observing group, another 50 cases were treated usually without irradiation as a control group. The recovery of epitherium in surface of alveolar fossa and reconstruction of alveolar bone were compared between two groups. Results; The recovery of epitherium in surface of fossa of extraction of teeth is more rapid in study group, but there is no difference in alveolar bone reconstruction. Conclusion:Our study suggested that the irradiation by He - Ne laser in low energy profit in promotion of repairing the damage post - extraction of teeth.

Object:To study the clinical effect of otorhinolaryngologicai papillomas treated by CO2 laser. Methods:Among 166 cases were 45 cases of nasal papilloma, 39 cases of aural papilloma, and 82 cases of pharyngal papilloma. After local anaesthesia, We cut and vaporize tumor with CO2 laser in 15W of continuous output power. Results: The healing rate is near 100%. Conclusion:The methods have some advantages as follows: (1) With 70 - 90% of water in biologic tissues, laser hardly affect contiguous tissue during vaporizing tumor, and rarely affect healing of wound ; (2) After vaporizing and cutting tumor with laser, it can maximum keep the function of original organs, and not form tissue defection; (3) The laser can block and coagulate the vessel surrounding tumor tissue, so less bleeding during operating; (4) The laser incision is sterile, rarely affect infection of wound; (5) The operation is simple, so less painful for patient.

Objective:To study the effect and availability of epistaxis in nasal septum by pulsed CO2 laser. Methods:The venous and arterial epistaxis patients are coagulated with different handpiece of pulsed CO2 laser(output power 2 ~3 watts and 3 ~ 4 watts). Results:After follow-up 1 ~6 months,40 cases were significantly efficient (69%) ,15 cases were efficient(26%). There was no charge in 3 cases(5% ). Conclusion:CO2 laser is a safety,low cost and efficacious therapeutic methods in epitaxis of nasal septum.

Objective:To observe the repairing effect of recorabinant human epidermal growth factor (rhEGF) to laser burned epidermal tissues. Methods:The experimental rabbits with shallow two degree burn wound in its back made by CO2 laser were divided into two groups. Routine treatment and local rhEGF sprinkling were used in treatment group,no rhEGF usage in control group. Results:The average healing time of treatment group is 2.1 days early than control group. Conclusion:rhEGF can accelerate laser wound healing.

Objective:To study the clinical effect of epidermal pigmented dermatoses treated by the frequency - doubled Q - switched Nd:YAG laser. Methods:361 cases with ephelides, seborrheic keratosis, lentigines, cafe aulait macules, pigmentation - polyposis syndrome were treated by the frequency - doubled Q - switched Nd:YAG laser. Several times of treatment could be done if the pigment was not removed after a single irradiation. The time of interval treatment was 3 months. Results:169 cases with ephelides, 9 cases with lentigines and 1 case with pigmentation - polyposis syndrome were cured after 1 ~ 2 times of treatment. Of the 123 cases with seborrheic keratosis, 103 were cured and 17 had marked effect after 1 ~ 4 times of treatment. Of the 59 cases with cafe au lait macules, 12 were cured and 19 had marked effect after 1 ~6 times of treatment. No scars appeared in all patients. Conclusion:The frequency - doubled Q - switched Nd:YAG laser is secure and efficient in treating epidermal pigmented dermatoses.

Objective:For inquire into the clinical effect of tattoo treated by Q - Switched Nd: YAG Laser. Methods:We treated patients of Various tattoo by Q - Switched Nd:YAG Laser. The Q - Switched Nd:YAG energy density was 5 - 12J/pulse, pulse repetition rate 1,2,5,10Hz, beam spot sizes 2,3,4,6mm. For pigmentary disease involving deep layer tissue need treatment for several times. The time of interval treatment was about 3 months. Results: In all 150 cases of tattoo. Cure rate in the first session was 30%. The frequency of treatment effect was up to 100%. Conclusion:It is a securing method having good cured results with no sear and less pain.

Objective: To treat pigment skin diseases of external causes with VersaPulse laser observing the response of treatment and the effect. Methods:Choosing different wave length(1064/755/532nm) to treat the diseases according to the colours of pathological changes. Results:Of 791 cases, the cure rate is 87% and the total effective rate is 99%. Conclusion:To treat pigment skin diseases of external causes with tunable Q - switched laser has the peculiarity of safety, less wound, good effects, besides operating easily.