| 摘要 |
雷射加工隨著科技的演進已逐漸成為業界的主流加工方式之一，惟應用於微製造上，傳統奈秒級雷射（如 CO2 雷射、Nd:YAG
雷射等）經由熱熔融、蒸發去除的過程進行加工，常見微裂縫、不規則毛邊、顯著的熱影響區之問題，且加工材料及尺寸都受限制。準分子雷射因其短波長特性而足以對部分非金屬材料作加工，但因需要製作光罩配合過程繁複，且其波長範圍恰落入許多透明材料吸收區，只能限於應用表面的加工模式。然而，飛秒（fs
= 10-15 s）雷射加工因其脈衝寬度極短，瞬間功率密度可輕易達到 1014 W/cm2
以上，當脈衝作用在材料上時，會瞬間激發電子進而經過一連串非線性的機制使得材料被移除，因此飛秒雷射加工具有熱影響區小、毛邊少，適用於多種材料等優點，且能夠進行小於光波長尺度的精密加工，以適合光學上的應用，這是許多現有的技術難以望其項背的。國內目前並沒有定量探討其加工精密度的研究出現。為更深入瞭解飛秒雷射加工特性，本研究利用飛秒雷射加工於常用的工程材料（SUS
304不銹鋼及PMMA）上進行多脈衝數（50~3000
個）對加工精密度之影響做定量的探討，並進一步將其加工參數（脈衝個數、脈衝能量、焦點位置），與其加工後所得的微細結構之間的關係作完整的討論。本研究同時針對飛秒雷射加工原理及材料移除機制作簡要闡述，並以原理和實驗結果配合證實其加工特性與優點，期有助於各精密產業利用飛秒雷射加工技術的開發及應用。
關鍵字：飛秒雷射加工、不鏽鋼、PMMA、加工精密度、多脈衝數
Laser machining has always been
one of the mainstream manufacturing techniques with the
advantages of noncontact process and high machining precision.
By shortening the time duration, the degree of precision in
laser machining could be higher than ever before. Femtosecond
laser machining（fs = 10-15 s）,which is getting more attention in
removing materials by photolysis process, excels other
techniques for its high machining precision, minimal burrs,
negligible heat-affected-zone, and the feasibility for machining
on any engineering materials. Femtosecond laser machining is
also promising for its ability to nanomachining the size which
is smaller than the light wavelength for the potential optical
applications. However, femtosecond laser is still not widely
adopted in industry as its system cost is high and its machining
characteristics have not been fully studied. The main theme of
this thesis is to quantify machining precision of femtosecond
laser machining by multi-pulse (50~3000) laser irradiation of
the common industrial materials SUS 304 stainless steel and
polymethylmethacrylate (PMMA). Often major focuses include a
qualitative discussion of the relation between machining
parameters and its microstructures. Meanwhile, a machining
principle and material removing mechanism is resulted in this
study, and its machining characteristics and advantages were
clearly demonstrated. It is found to be useful and beneficial
for the precision manufacturers as a result of development and
application of femtosecond laser machining.
Keywords：Femtosecond laser
machining, stainless steel, PMMA, precision machining,
multi-pulse laser irradiation
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