Investigation of temporal contrast effects in femtosecond pulse laser micromachining of metals.

Campbell, Benjamin (Pennsylvania State University, Freeport, PA) ; Palmer, Jeremy Andrew

Sandia National Laboratories

关键词: Machining.;    Morphology Lasers-Experiments.;    Lasers-Experiments.;    36 Materials Science;    Ceramic Materials-Machining.;   

DOI  :  10.2172/887259
RP-ID  :  SAND2006-2664
RP-ID  :  AC04-94AL85000
RP-ID  :  887259

美国|英语

来源: UNT Digital Library

【 摘 要 】

Femtosecond pulse laser drilling has evolved to become a preferred process for selective (maskless) micromachining in a variety of materials, including metals, polymers, semiconductors, ceramics, and living tissue. Manufacturers of state-of-the-art femtosecond laser systems advertise the inherent advantage of micromachining with ultra short pulses: the absence of a heat affected zone. In the ideal case, this leads to micro and nano scale features without distortion due to melt or recast. However, recent studies have shown that this is limited to the low fluence regime in many cases. High dynamic range autocorrelation studies were performed on two commercial Ti:sapphire femtosecond laser systems to investigate the possible presence of a nanosecond pedestal in the femtosecond pulse produced by chirped pulse amplification. If confirmed, nanosecond temporal phenomena may explain many of the thermal effects witnessed in high fluence micromachining. The material removal rate was measured in addition to feature morphology observations for percussion micro drilling of metal substrates in vacuum and ambient environments. Trials were repeated with proposed corrective optics installed, including a variable aperture and a nonlinear frequency doubling crystal. Results were compared. Although the investigation of nanosecond temporal phenomena is ongoing, early results have confirmed published accounts of higher removal rates in a vacuum environment.