Theory And Technique Research On Photosensitive Glass Micro-machining Using UV Nanosecond Pulse Laser

With the rapid development of MEMS (Micro-Electro-Mechanical Systems) and microfluidic chip technologies, photosensitive glass has been widely used in micro machining field for its own advantages. Based on the increasing requirement in photosensitive glass shape-control fabrication, in this dissertation a UV nanosecond pulse laser micro-machining system is designed and successfully performs the micro-structure machining on the FOTURAN photosensitive glass.The main work in this paper is as follows:1. Based on energy transfer through electron to lattice, the interaction between the nanosecond pulse laser and the solid material is analyzed. Then the two-temperature diffusion model is discussed and simplified in the scale of nanosecond pulse width. A heat exchange function has been extracted. And the existence of heat effect is testified theoretically.2. The FOTURAN photosensitive glass is sample in this work. With the doping of Ag+ and Ce3+, the photosensitive glass shows not only the normal property but also some characteristics of metal. The reaction of FOTURAN photosensitive glass in UV exposure is explored on the research of the interaction process of laser with transparent materials and metal.With the combination of following process, the mechanism of manufacture procedure has been researched.3. Based on optical properties of FORTURAN and laser machining mechanism, a nanosecond pulse laser micro-machining system, including laser, optical system, mechanical system, host computer software and control system, is designed. The micro-machining system consists of a laser source with 355nm wavelength and a bridge style mechanical structure. The host computer software can be programmed in graphic style, and resolve the graphics by line segment based on the rule of shortest path seeking from inside to outside. Taking the great advantage of digital signal processor (DSP) and field programmable gate array (FPGA), the two axis linked movement is achieved. The system is capable of FOTURAN photosensitive glass micro-machining. 4. The atom force microscope (AFM) is used to evaluate the surface roughness of the FOTURAN photosensitive glass during every single micro-machining step. The roughness information is used to improve the procedure of the FOTURAN photosensitive glass micro-machining. A new four-step method is proposed:UV exposure - heat treatment– etching - heat treatment. After 10 minutes ultrasonic vibration in deionized water, the tested samples show satisfied results.5. Shallow holes, deep holes, and microchannels are machined on the surface of the FOTURAN. The hydrofluoric acid effect, pulse energy and stage movement velocity are investigated in detail.6. According to the relation between pulse energy and results, concentric circle has been chosen to mold the graphics. Flat bottom holes, curved bottom holes and some simple 3D structures have been successfully fabricated under various laser parameters and different machining speed. Shape-control machining has been done on FOTURAN glass surface.Based on the above theoretical analysis and experiments, the micro-machining capacity on the FOTURAN photosensitive glass of nanosecond pulse laser is successfully illustrated. Different system parameters have been tested to achieve shape-control fabrication and some satisfied microstructures are achieved finally.