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BioMEMS Lab Mechanical and Aerospace Engineering University of Texas Arlington. Femtosecond Laser Micromachining of BioMEMS. Comparison of Micromachining Processes. Laser Micromachining Process. Advantages of Laser Micromachining. Non-contact machining
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BioMEMS Lab Mechanical and Aerospace Engineering University of Texas Arlington Femtosecond Laser Micromachining of BioMEMS
Advantages of Laser Micromachining • Non-contact machining • Very high resolution, repeatability and aspect ratios • Localized heating, minimal redeposition • No pre/post processing of material • Wide range of materials: fragile, ultra-thin and highly reflective surfaces • Process can be fully automated
Characteristics of Femtosecond Laser Micromachining • Very high peak powers in the range 1013W/cm2provide for minimal thermal damage to surroundings • Very clean cuts with high aspect ratios • Sub-micron feature resolution • Minimal redeposition • Possible to machine transparent materials like glass, sapphire etc
Ultrashort Pulses vs. Long Pulse Micromachining Courtesy: Sandia National Labs Ti: sapphire,120fs a) air b) vacuum c) Nd:YAG, 100ns Extremely short pulses provide for minimal thermal damage to surroundings
Femtosecond Laser System at BioMEMS Lab • Spectra PhysicsHurricaneFemtosecond Ti: sapphire Laser • Pulse width: 106fs • Wavelength range: 750nm-850nm • Average energy: 1mJ/pulse • Beam profile: Gaussian • Polarization: linear, horizontal
Femtosecond Laser Micromachining (Preliminary Experimental Testbed)
Additional Equipment for Femtosecond Laser Micromachining • Ultra-high precision 3-axis linear stage assembly by Aerotech Inc . • Ultrafast High Energy Beam Attenuator by Newport Corporation. • Power Meter by Scientech Inc. • 2GHz Oscilloscope by Hewlett Packard Under development • 10-3 Torr, 1m3 Vacuum Chamber with inert gas and electrical and power ports • Fully automated multiple lens changer • LabView based control environment
Preliminary Experimental Results Micromachining in 18μm Thick Aluminum Foil • Array of shots (b) Thru-hole drilled after 33 shots at a pulse energy of 14μJ
Preliminary Experimental Results Single Shots in 18μm Thick Aluminum Foil Focal position Off-focal position
Thru-holes Drilled in 25μm Thick Brass Foil Preliminary Experimental Results 56μJ/pulse 27μJ/pulse
Ablation Rate vs. Energy Density in 18m Thick Aluminum Foil
Femtosecond Laser Bonding of Optically Transparent Materials • Explore femtosecond laser bonding of optically • transparent PMMA or glass to a substrate • Automatic lens changer will be used to study the • effect of variable focal length on the bond strength
Laser Intensity Distribution in PMMA Focal length of 9mm Focal length of 40mm
Through the Thickness Intensity Distribution of Transmitted Laser Beam in PMMA Focal length of 9mm Focal length of 40mm