Laser Beam Shaping Using Aspheric Optical System

In many fields of laser-based applications,the level of the applications depends on the quality of laser beam.The propagation path of laser beam is hyperbola and the energy profile is a Gaussian function profile,while the fields of surface heat treatment,laser materials processing,nonlinear optics,holography,lithography and so on require the laser beam to transmit in a straght line and have an uniformity of energy distribution. So,in order to improve the application level of laser technology and meet the demands of different occasions,it is necessary to shape the laser beam.The transformation from a Gaussian into a flat-top beam usually recur to the adscititious shaping system or element. Compared with other shaping systems,the asphere optical system is very simple,convenience,and its reliability and practicability are much better.It has a wide prospect of applicaion in the aspect of laser beam shaping.After summarizing the experience of the former researchers shaping the laser beam by aspheric lens,a single aspheric laser beam shaping system applied to TEA CO2 laser beam is designed,which can realize the smooth process.The main works contained in this dissertation are as follows:The sort and history of laser beam shaping system are introduced,and various methods including the aspheric laser beam shaping system are also mentioned. Then,the principle of physical optics and geometrical optics to carry out the laser beam shaping are mentioned respectivly.Through the using of conservation of energy and constant optical path length condition,the ray tracing based on geometrical optics has been used in order to obtain the differential equations expressing between the sag and radius of the shaper of Galilean,Keplerian,single-lens Galilean and Single-lens Keplerian.And then the fittest method of integral and curve fitting for the experiment are discussed.By the Romberg numerical integrating algorithm and the method of the nonlinear least square,the sag's analytical equations of aspheric surfaces are obtained.The system's performance is optimized and the result of the experiment is validated by using the optical design software of Zemax.It is testified a valid approach for design and manufacture and provides a feasible solution for laser beam shaping.