Design and Fabrication of the DOE for flat-top laser beam

• Main Author: 連世璋
• Other Authors: Chao-Chia Cheng
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/00538403720541871779

碩士 === 中華大學 === 電機工程學系碩士班 === 92 === The output intensity profile of a laser beam is decided by the resonator structure, such like the curvatures of mirrors, the length of resonator, and the optical property of gain medium. Different kinds of the intensity profile will fit the different kinds of applications. For example, in the applications of laser drilling or laser cutting, a sharper laser beam profile is needed. But in the applications of laser surface treatments, an uniform intensity profile will be better than the previous one. In this thesis, a concentric binary phase zone plate was used to re-shape the sharp Gaussian filed profile into an 1-D sinc(x) (or 2-D Bessinc(r)) complex field profile approximately, which could achieve excellent flat-top beam shaping effect. Such binary phase plate was designed and manufactured by the same process for the design of the Diffraction Optical Elements (DOE) which was characterized by its thinness, lightness, high optical efficiency, and the potential for mass-production. The design and simulation was achieved by a Matlab program base on the theory in Fourier Optics. The results of design and the analysis of errors had been proposed. The fabrication issues for the laser beam shaping element in semiconductor process had been evaluated.