增加飛秒激光光束焦深的折衍混合元件的設(shè)計制作
發(fā)布時間：2018-08-19 15:43
【摘要】：相比于長脈沖激光,飛秒激光具有的閾值效應(yīng)明顯、熱影響區(qū)極小、重鑄層極小、可控性高等特性,使其在微細加工中占有極其重要的地位。而其出射光束的焦深與焦斑則會直接影響到加工精度。在傳統(tǒng)光學(xué)中,焦深和焦斑相互制約,無法在增加焦深的同時實現(xiàn)焦斑的不擴散。本論文選取折衍混合元件來增加飛秒激光光束的焦深,并從理論分析、計算仿真模擬、加工制作、測試四個方面具體介紹了該折衍混合元件的設(shè)計制作測試過程,主要研究內(nèi)容如下:首先,通過理論分析和計算模擬得到折衍混合元件的面型參數(shù)。折衍混合元件的設(shè)計思路遵循改進的能量守恒法。根據(jù)Legend Elite飛秒激光器出射光束的參數(shù)特點和設(shè)計目標(biāo),確定折衍混合元件的基本參數(shù);結(jié)合菲涅爾衍射理論,用MATLAB#174;編寫折衍混合元件衍射面初始相位的計算程序并得到該元件衍射面型的初始相位矩陣,然后通過數(shù)據(jù)擬合得到衍射面歸一化徑向孔徑坐標(biāo)的系數(shù)值;在Zemax#174;中優(yōu)化該元件衍射面型結(jié)構(gòu)和折射面型結(jié)構(gòu),從而得到折衍混合元件的最終結(jié)構(gòu)參數(shù):選取BK7玻璃作為透鏡材料;元件整體直徑為20.000mm;衍射面直徑為11.611mm;中心厚度為2.004mm;凸面曲率為66.542mm;有效焦距為95.257mm。二元面歸一化徑向孔徑坐標(biāo)的偶次冪系數(shù)值分別為:-377.347、335.116、-1174.462、544.835、-130.274。同時模擬分析了該折衍混合元件增加焦深效果,理論上可以使飛秒激光光束的焦深增加至1.5mm左右,焦斑直徑大小為45.722μm左右。其次,對折衍混合元件進行制作。選用傳統(tǒng)的套刻方法制作折衍混合元件的衍射微結(jié)構(gòu)面。根據(jù)二元光學(xué)理論,計算元件各項加工數(shù)據(jù),使用L-edit#174;軟件繪制掩模版,經(jīng)過光刻實驗、等離子體刻蝕實驗,制作完成折衍混合元件的衍射微結(jié)構(gòu)面。在衍射微結(jié)構(gòu)面制作完成后,對元件的另一面進行曲面加工,得到最終的折衍混合元件。最后,測試折衍混合元件的效果。使用顯微鏡、三維形貌儀觀察元件形貌。在PMMA材料上測試元件增加焦深水平、出射焦斑大小。測試得到設(shè)計制作的折衍混合元件可以將飛秒激光光束的焦深增加到1.5mm左右,在PMMA材料上微孔的直徑在100μm左右,符合飛秒激光微加工的要求。
[Abstract]:Compared with the long pulse laser, femtosecond laser has obvious threshold effect, the heat affected zone is very small, the recast layer is very small, and has a high controllability, which makes it play an extremely important role in micro fabrication. The focal depth and focal spot of the outgoing beam will directly affect the machining accuracy. In traditional optics, the focal depth and the focal spot restrict each other, so that the focal spot can not be diffused while increasing the focal depth. In this paper, the refractive-diffractive mixing element is selected to increase the focal depth of femtosecond laser beam, and the design and test process of the hybrid element is introduced from four aspects: theoretical analysis, simulation, fabrication and testing. The main contents are as follows: firstly, the surface parameters of the hybrid element are obtained by theoretical analysis and simulation. The design of the hybrid element follows the improved energy conservation method. According to the characteristic of Legend Elite femtosecond laser output beam and the design goal, the basic parameters of refractive-diffractive mixing element are determined, and the Fresnel diffraction theory is combined with Fresnel diffraction theory. MATLAB #174 was used to calculate the initial phase of diffractive surface of hybrid element and the initial phase matrix of diffraction surface was obtained. Then the coefficient value of the normalized radial aperture coordinate of diffraction surface was obtained by fitting the data. The diffraction and refraction surface structures of the element are optimized in Zemax #174.The final structural parameters of the hybrid element are obtained: the BK7 glass is selected as the lens material; The whole diameter of the element is 20.000mm, the diffractive plane diameter is 11.611mm, the center thickness is 2.004mm, the curvature of the convex surface is 66.542mm, the effective focal length is 95.257mm. The even power coefficients of the binary plane normalized radial aperture coordinates are respectively: -377.347335.116- 1174.462544.835- 130.274. At the same time, the effect of the refractive diffractive mixing element on increasing focal depth is simulated and analyzed. Theoretically, the focal depth of femtosecond laser beam can be increased to about 1.5mm, and the focal spot diameter is about 45.722 渭 m. Secondly, the hybrid element is made. The diffractive microstructures of the hybrid elements are fabricated by using the traditional intersecting method. According to the binary optics theory, the processing data of the components are calculated using L-edit#174.The mask plate is drawn by software, and the diffraction microstructure surface of the hybrid element is fabricated by photolithography experiment and plasma etching experiment. After the fabrication of the diffractive microstructure surface, the surface of the other side of the element is machined and the final hybrid element is obtained. Finally, the effect of the hybrid element is tested. The morphologies of the components were observed by using a microscope and a three-dimensional profilometer. Test elements on PMMA material increase focal depth level and exit focal spot size. The designed hybrid element can increase the focal depth of femtosecond laser beam to about 1.5mm, and the diameter of micropore on PMMA material is about 100 渭 m, which meets the requirement of femtosecond laser micromachining.
【學(xué)位授予單位】：北京工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TN249
，
本文編號：2192111
[Abstract]:Compared with the long pulse laser, femtosecond laser has obvious threshold effect, the heat affected zone is very small, the recast layer is very small, and has a high controllability, which makes it play an extremely important role in micro fabrication. The focal depth and focal spot of the outgoing beam will directly affect the machining accuracy. In traditional optics, the focal depth and the focal spot restrict each other, so that the focal spot can not be diffused while increasing the focal depth. In this paper, the refractive-diffractive mixing element is selected to increase the focal depth of femtosecond laser beam, and the design and test process of the hybrid element is introduced from four aspects: theoretical analysis, simulation, fabrication and testing. The main contents are as follows: firstly, the surface parameters of the hybrid element are obtained by theoretical analysis and simulation. The design of the hybrid element follows the improved energy conservation method. According to the characteristic of Legend Elite femtosecond laser output beam and the design goal, the basic parameters of refractive-diffractive mixing element are determined, and the Fresnel diffraction theory is combined with Fresnel diffraction theory. MATLAB #174 was used to calculate the initial phase of diffractive surface of hybrid element and the initial phase matrix of diffraction surface was obtained. Then the coefficient value of the normalized radial aperture coordinate of diffraction surface was obtained by fitting the data. The diffraction and refraction surface structures of the element are optimized in Zemax #174.The final structural parameters of the hybrid element are obtained: the BK7 glass is selected as the lens material; The whole diameter of the element is 20.000mm, the diffractive plane diameter is 11.611mm, the center thickness is 2.004mm, the curvature of the convex surface is 66.542mm, the effective focal length is 95.257mm. The even power coefficients of the binary plane normalized radial aperture coordinates are respectively: -377.347335.116- 1174.462544.835- 130.274. At the same time, the effect of the refractive diffractive mixing element on increasing focal depth is simulated and analyzed. Theoretically, the focal depth of femtosecond laser beam can be increased to about 1.5mm, and the focal spot diameter is about 45.722 渭 m. Secondly, the hybrid element is made. The diffractive microstructures of the hybrid elements are fabricated by using the traditional intersecting method. According to the binary optics theory, the processing data of the components are calculated using L-edit#174.The mask plate is drawn by software, and the diffraction microstructure surface of the hybrid element is fabricated by photolithography experiment and plasma etching experiment. After the fabrication of the diffractive microstructure surface, the surface of the other side of the element is machined and the final hybrid element is obtained. Finally, the effect of the hybrid element is tested. The morphologies of the components were observed by using a microscope and a three-dimensional profilometer. Test elements on PMMA material increase focal depth level and exit focal spot size. The designed hybrid element can increase the focal depth of femtosecond laser beam to about 1.5mm, and the diameter of micropore on PMMA material is about 100 渭 m, which meets the requirement of femtosecond laser micromachining.
【學(xué)位授予單位】：北京工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TN249
，
本文編號：2192111
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