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ISSN1001-3806 CN51-1125/TN Map

2000 Vol. 24, No. 1

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Analysis of two-wave coupling intensity at the intermediate regime with deep modulation
Wang Jinlai, Ji Xuanmang, An Yuying, Liu Jinsong
2000, 24(1): 1-4.
Abstract:
A new theory about two-wave coupling at the intermediate regime with deep modulation is presented.Under the condition,the coupling equation can be numerically resolved.Compared with other theories,this one is more significant.
Review of fast axial flow CO2 laser
Zuo Duluo, Li Shimin
2000, 24(1): 4-8.
Abstract:
Fast axial flow CO2laser is one of the most important industrial lasers.Its developing state and related key technologies such as gas flowing pattern,discharging electrode structure and resonator stability are reviewed in the paper.It is hoped to be helpful for the development of fast axial flow CO2laser in the country.
Study of marking to enamelware with excimer laser
Wen Xiaoming, Shi Mingxia, Yang Xueling
2000, 24(1): 9-11.
Abstract:
The experiments of marking to enamelware with 308nm excimer laser are finished. A fine and visible pattern can be acquired when the enamelware sample is irradiated by one or several 308nm excimer laser pulses if their fluences are over the marking threshold. The marking fluence threshold is far lower than that based on the vaporizing and etching principle. The marking mechanism is studied in this paper and the conditions of marking are optimized in experiments.
Combined effect of shock waves induced by laser pulse and discharge pulse
Yao Bing, Wang Su, Cao Yan, Liu Xun, Zeng Chuanxiang
2000, 24(1): 12-14.
Abstract:
Combined effect of shock waves induced by laser pulse and discharge pulse is analyzed.Experiments show that this new technique is more advantageous than that to induce shock waves just with laser pulse.
Applications of holographic interferometry in surface mount technology
Wang Weining, Liang Jingming, Zhang Cunlin, Ai Lun, Dai Fulong
2000, 24(1): 15-20.
Abstract:
In this paper, the applications of holographic interferometry (HI) in surface mount technology are presented. Out of plane deformations of a PLCC-PCB assembly induced by power dissipation are given by using Double exposure HI. To solve the problem of the fringes discontinue between two bodies of surface mount device and PCB, and to further determine the deformations of the SMD leads and solder joint, a "bright" technique is used in Double exposure HI measurements. Real time HI is used to test the whole hard-disk board deformation during power cycling. A-over heat device is found in the defective board. The results show that the HI is a quite effective tool for the studies of thermal mechanical behavior and quality control of SMT products.
The application of organic materials in optical limiting
Luo Ting
2000, 24(1): 20-23.
Abstract:
We simply review the nonlinear optical process in organic materials which can be utilized in passive limiting devices.The mechanism of optical limiting for a self-defocusing processis examined.We experimentally investigate the nonlinear optical refraction and optical limiting characteristics of organic material,and the results are discussed.The analysis is useful in optimizing optical limiting behavior of devices based on self-action.
Studies on the microstructure of the textured point on laser textured huge rolls
Zhu Daqing, Zuo Duluo, Li Shimin, Zhou Xinjun, Liu Jiangong
2000, 24(1): 24-26.
Abstract:
This paper studied the microstructure of laser texture rolls by SEM.Aftel laser caved,the four regions named melt region,phase change region,thermal effective region and substrate region,are formed near the surface.Du to the very large supper cooling rate brought by rapid solidification,the melt region consists of very fine microlitic dendritical or cytostate organization,which is well-distributed and fine and compact.So the hardness and anti-etching performance of the melt region are greatly improved.Furthermore,the scanning speed has an important influence on the size of phase change region and thermally affected region.
A fresnel rhomb type phase retarder insensitive to the incident angle
Wang Xia, Wu Fuquan, Shao Weidong
2000, 24(1): 27-30.
Abstract:
This paper presents a fresnel rhomb-type phase retarders that is much highly insensitive to the incident angle.It is based on the properly choosed optical material and internal reflection angle.It shows that the device is stable within 0.3° of 90° fori ±2.5°,which is nearly one sixth of the ordinary fresnel rhomb phase retarders variation.
Investigation on diffraction efficiency of BOE for beam shaping
Li Qi, Gao Huide, Dong Yunhua, Shen Zuochun, Wang Qi
2000, 24(1): 30-33.
Abstract:
A binary optical element which is designed to convert a single-mode He-Ne laser beam into a ring-shaped intensity distribution is investigated experimentally. The measured diffraction efficiency are compared with numerical calculation when the distance between BOE and the output plane is changed.
Polarization of optical modes in ring lasers
Zuo Chao, Yuan Xiaodong, Zeng Chun
2000, 24(1): 34-37.
Abstract:
Degree of polarization of the optical modes in ring lasers are calculated and discussed. Polarization of the optical modes is expressed by Jones matrix under circular coordinate.Degree of polarization of the optical modes,which is decided by the optical property of the thin film and the crystal, depends on the optical modes' positions in ring cavity.
Viewing angle and it’s passageway of reconstructing holographic image
Zhong Liyun, Zhang Wenbi, Yang Qimin, Li Chuan
2000, 24(1): 38-41.
Abstract:
Viewing angle and it's passageway or viewing channel play an important roll in holography, but researches have not pay enough attention to these concepts for long time.First,this paper gives the definition of viewing angle and viewing passageway for holography,and points out that the various holograms can be taken for different viewing angle passageway,such as double passageway,left right passageway,color passageway,synthetic hologram et al.In addition,using of the concept of viewing angle passageway, a lot of holographic original phenomena can be explained.
Control system simulation of CO2 laser semi automatic seeker
Wang Huiqun, Luo Yuang
2000, 24(1): 42-46.
Abstract:
It is described in detail that continuous system simulation program package is applicable for CO2laser semi automatic seeker control system.It is used in single valuable control system.It may be used to equation oriented or block diagram oriented.Module pattern is adopted by program structure.
Design of supersonic nozzles for laser cutting
Liu Jianhua, Chen Yijian, Duan Jun, Hu Xiyuan
2000, 24(1): 46-50.
Abstract:
This paper analyses the reasons of the shock producing when the conventional nozzle is working at the high pressure in laser cutting, and the harmful effects of the shock in laser cutting. In order to solve this problem, a new method for the design of a supersonic nozzle is presented. This supersonic nozzle consists of four sections:stable,convergent,throat and divergent. Each of these sections is designed strictly based on gas dynamic theories. The exit jet from this type of nozzle with high momentum, good uniform and a tidy boundary can be obtained. Laser cutting speed and quality can be efficiently improved by using this type of nozzle.
The effects of curvature radius and cutting speed on the top kerf width of laser cutting of thin pipe with a small diameter
Huang Kaijin, Zeng Dawen, Xie Changsheng
2000, 24(1): 51-54.
Abstract:
The effects of curvature radius and cutting speed on the top kerf width of circumferential laser cutting of thin seamless steel pipes with a small diameter (outer diameter of pipe D<80mm and wall thickness t=2.5mm) were investigated experimentally.Experiments showed three main conclusions:(1)as the cutting curve length increases,the top kerf width of laser cutting also increases,(2)the average top kerf width of laser cutting increases with decreasing curvature radius,and increasing quite dramatically as D is less than 25mm,(3)as the cutting speeds increase,the average top kerf width of laser cutting decreases.The main reasons are curvature effects and different laser interacting on times.At last, the authors regard that variable parameters are necessary for people to adopt in order to obtain a uniform kerf width for thin seamless steel pipe with a small diameter.
Analysis of feasibility of a FEL operation by radiation from relativistic electrons channeled tal in a crystal slab
Feng Jianhui, Zhu Jiaqing, Liu Shengguang, Jiang Mengrui
2000, 24(1): 55-58.
Abstract:
In this paper, we study the single-particel trajectories and stable condition of relativistic electrons in a crystal slab, using the continum model proposed by Gemmell D.S. The angular spectrum of spontaneous emission from relativistic electrons in a crystal is derived, and the result shows that the coherent radiation from relativistic electrons channeled in a crystal is possible.
Research on fibre phase-conjugating mirrors
Hou Yunfei, Liu Yaolan, Wang Ying, Qiu Junlin, Eichler H J, Liu B
2000, 24(1): 59-63.
Abstract:
As a means of phase conjugation, SBS(stimulated Brillouin scattering) can increase the power of solid lasers with high beam quality. The paper focus on the theories of fibre phase conjugation and development of the region. The key technology such as the control on depolarization of fiber and design of single frequency laser is also studied.
Study on the formation features of solidification microstructure for laser cladding layer
Wang Zhongke, Zheng Qiguang, Wang Tao, Gu Jianhui, Tao Xingzhi, Pan Qingyue, Shi Shihong
2000, 24(1): 64-66.
Abstract:
The investigation on the solidification features and formation law of microstructure for laser cladding layer has been carried out.It is shown that there are different solidification parameters for different position in cladding layer.The microstructure at the cladding layer bottom was the typical extension growth on plane basis,the dendrite crystal is coarser.The microstructure at the top and middle was the regular pine-tree eutectic crystal and small cell and column crystal,respectively.The crystalline anisotropy was a main factor to influence the crystal growth form.The grain nucleation has obvious feature of heterogeneous nucleation in microstructure cladding.The results also show that the components in microzone of the cladding layer are not uniform.The different elements segregate along crystalline axis or interdendritic result in the non-uniform microstructure.