應用於雷射加工系統之繞射式雷射光束整形及分光元件

Diffractive Beam Shaper and Splitter for Laser Processing System

陳信安(Sin-An Chen)

指導教授 ： 陳政寰

國立清華大學/工學院/動力機械工程學系/碩士(2011年)

摘要

自從雷射問世以來，其相關的產業就一直不斷的蓬勃發展，不論是在消費性電子產品、顯示技術開發抑或是工業製程用途，均可看到雷射所帶來的革命性突破，例如在光碟讀取、雷射投影機、立體顯示、雷射加工及太陽能或面板製程上，雷射的應用可說是無所不在。
雷射加工隨著科技的進步，其應用的層面也越來越廣泛。現今雷射除了可以用來進行精密製造加工外，在太陽能或面板製程上雷射也時常被用來作退火再結晶的製程。在雷射的應用裡，最常見的雷射光調變為光束整形以及分光兩種功能，而雷射自共振腔激發出來一般皆為高斯雷射光束，其中心能量較高而邊緣較低的特性使其在加工上並不適合直接拿來應用，而必須將高斯雷射整形成為均勻能量分佈之雷射光束。另一方面，面臨日益增大的加工面積以及為了增加加工的速度和效率，將單一道加工用之雷射光束進行複製使其成為多道具圖案化之加工用雷射可滿足大面積之加工範圍以及大幅度提升加工效率。
光束整形以及分光可以藉由折射、反射或繞射原理來達成，而本研究所提出的為設計繞射式整形以及分光元件。整形元件在設計上連續相位調變可以將入射光束完美的整形成平頂化圓形或方形光斑，但是在製造方面上因無法製作出連續的曲面結構，因此必須將連續曲面以階梯化結構近似進行實作，本研究將以四階之繞射整形元件進行實驗驗證，而繞射分光元件則為二元已階梯化之光柵結構，因此不需再近似可直接進入製程步驟，在此所使用的製程為先利用半導體製程將相位微結構蝕刻在矽晶圓，再利用翻模的方式轉印到透光材料上，接著將以繞射整形和分光元件整合作為未來開發複合式雷射加工模組系統的基礎。

關鍵字

繞射光學 ； 繞射光柵 ； 光束整形

並列摘要

Since the advent of lasers in 1960s, more and more fields of applications have been investigated and developed greatly. Nowadays, various applications of lasers including consumer electronics, display technology or material processing have affected the development of technology and launch a breakthrough in modern optoelectronics.
Laser plays an important role in high-precision material processing. It can be used in cutting, laser annealing or laser ablation, etc. In laser applications, it is usually required to modulate laser for beam shaping and beam splitting. However, most lasers possess Gaussian distribution, which is not adequate for uniform processing. Therefore, it is often required to transform laser into top-hat energy distribution with least energy loss as possible. On the other hand, in order to meet the demands for large area processing and high manufacturing efficiency, it is desired to replicate the single top-hat beam into multiple top-hat beams.
Beam shaping and beam splitting can be achieved by refraction, reflection or diffraction. The purpose of the thesis is to design diffractive optical elements (DOE) to modulate laser to fulfill above-mentioned concepts. With regards to the fabrication of DOEs, continuous phase modulation is quantized into four-level surface relief pattern. The DOEs are fabricated by using semi-conductor manufacturing technology and UV curing. Then, the DOEs are integrated together and analyzed to realize the multiple top-hat spots for the laser application module.

並列關鍵字

Diffractive optics ； Diffraction grating ； Beam shaping

參考文獻

[2]M. R. Taghizadeh, P. Blair, K. Balluder, A.J. Waddie, P. Rudman, N. Ross, ‘‘Design and fabrication of diffractive elements for laser material processing applications’’ Optics and Lasers in Engineering 34 (2000) 289-307

[3]Fred M. Dickey, Scott C. Holswade, David L. Shealy, Laser Beam Shaping Applications (Taylor & Francis, 2006), Chap. 8

[4]Richard M. Foster, Edmond Turcu, Jose M. Sasian, Harry Rieger, James M. Morris, Shaped Source of Soft X-Ray, ‘‘Extreme Ultraviolet and Ultraviolet Radiation’’ US patent 6307913 B1

[6]Nandor Bokor, Nir Davidson, “Anamorphic, adiabatic beam shaping of diffuse light using a tapered reflective tube” Optics Communications 201 (2002) 243-249

[9]Toshimitsu TAKAOKA, Naoki KAWANO, Yasuhiro AWATSUJI, Toshihiro KUBOTA, “Design of a Reflective Aspherical Surface of a Compact Beam-Shaping Device” Optical Review Vol. 13 No. 2 (2006) 77-86