Wednesday, 13 October 2004 - 4:45 PM

This presentation is part of : Micro- and Nano-scale Materials Characterization II

Effect of Optical Delivery System on Beam Profile in Laser Micro Materials Processing

Benxin Wu, Department of Mechanical Engineering, Purdue University, West Lafayette, IN 47907 and Hai-Lung Tsai, Department of Mechanical and Aerospace Engineering and Engineering Mechanics, University of Missouri-Rolla, Rolla, MO 65409.

In micro materials processing using ultra-short laser pulses, the laser beam passes through an optical delivery system, which may consist of lenses, masks and other devices, before it reaches the target material. The final laser beam profile, which will determine the quality of the processed material, is strongly influenced by the parameters of the optical system, such as the focal lengths of the lenses, the size of the mask, and so on. So far, most numerical models assume a final laser beam distribution (e.g., Gaussian distribution) directly. Therefore a numerical model which can predict the final laser beam profile will be very desirable in designing and optimizing process parameters for a micro materials processing system. In this paper, a numerical model considering diffraction effects has been developed based on Fourier optics theories to predict the final beam profile. Parametric studies were conducted to identify key parameters influencing the final beam distribution. The predicted beam distribution is then used to calculate three-dimensional temperature fields of the metal heated by ultra-short laser pulses based on the two-step heat conduction model. The results are very useful in designing and optimizing process parameters for a laser micro materials processing system.

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