以雷射功率在空間上以及時間上的調變提高雷射加工的品質

Improving quality of laser material processing by spatial and temporal modulation of laser power

楊智翔(Chih-Hsiang Yang)

指導教授 ： 湯華興 ； 林錫禎

國立臺北科技大學/機電學院/機電整合研究所/碩士(2014年)

https://doi.org/10.6841/NTUT.2014.00424

摘要

雷射掃描工件輪廓時，若雷射功率為高斯分佈，在照射區工件材料會造成類似高斯分佈的能量吸收，導致切割邊緣的不鋒利。再者，雷射掃描在加減速區或者轉彎處，速度會變化，導致工件材料被照射的時間不一致，使得低速部分能量過多或高速部分能量過少，因此本研究的目的在以雷射功率在空間上以及時間上的調變提高雷射加工的品質。
空間上調變將使用光束整形器將功率為高斯分佈的雷射形狀改變成平頂分佈的形狀。此光點的功率分佈將非常均勻，照射區內的工件材料吸收的能量將為一致，導致切割邊緣較為鋒利。
時間上調變則是使用配有閉迴路功率穩定系統的CO2雷射機，經一聲光調變器將雷射功率配合工件移動速度做功率大小的調變，工件速度快功率變大，反之變小。如此使得低速部分吸收的能量可與高速部分相等。
最後，以雷射照射於工件上，並且使用顯微鏡去觀察雷射照射區域的能量吸收，用以證明經過空間調變以及時間調變的雷射掃描有提高加工的品質。這樣的技術能應用於雷射鑽孔、切割、焊接及其它雷射加工。

關鍵字

二氧化碳雷射 ； 功率調變 ； 光束整形器 ； 聲光調變器

並列摘要

Scanning along the contour of the workpiece with a Gaussian power distribution CO2 laser will lead to a Gaussian distribution of energy absorption which results in the cutting edge being not sharp. In addition, laser scanning during the accelerating, decelerating or turning around a corner, the various speed leads to the variation of the irradiation time, the absorbed energy in the low-speed portion is too high while the absorbed energy in the high-speed portion is too low. The aim of this study is to improve the quality of laser material processing by spatial and temporal modulation of laser power.
Spatial modulation was that using a beam shaper, which transfers the Gaussian distribution of the laser beam shape to the hat-top shape distribution, and a focusing lens to obtain a smaller light spot in the imaging point. The power distribution of the light spot was uniform. The equal energy absorbed in the irradiation area led to a sharp cutting edge.

Temporal modulation was that using a CO2 laser with a power feedback control system, and an acousto-optic modulator for adjusting the laser power in accordance with the speed of the workpiece. The faster the workpiece speed is, the higher the laser power is, and vice versa. Consequently, the energy absorbed in the low-speed region and in the high-speed region can be equal.
Finally, a scanning on parts and then a microscopic investigation to verify the quality improvement using above technology were conducted. This technology can be applied to laser drilling, cutting, welding, and other laser material processing.

並列關鍵字

CO2 Laser ； power modulation ； beam shaper ； acousto-optic modulator

參考文獻

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