Product Code: ICA10_P150

Real-Time Control of Polarisation in High-Aspect-Ratio Ultra-Short-Pulse Laser Micro-Machining
Authors:
O. J. Allegre, Laser Group of Engineering, University of Liverpool; Liverpool Great Britain
W. Perrie, Laser Group of Engineering, University of Liverpool; Liverpool Great Britain
K. Bauchert, Boulder Nonlinear Systems, Inc.; Liverpool
G. Dearden, Laser Group of Engineering, University of Liverpool; -
K.G. Watkins, The Laser Group, Department of Engineering; -
Presented at ICALEO 2010

A variety of micro-machining applications benefit from the very precise, melting-free processing of almost all materials using ultra-short pulse lasers. Concrete industrial applications are for example the drilling of holes for fuel injection nozzles and the machining of metallic and organic materials for the production of various medical implants. An even greater control of the laser-material interaction could be gained from real-time modulation of the laser beam polarization. This technique could further improve the processing accuracy achieved with ultra-short pulse lasers.

The use of a fast response transmissive ferroelectric liquid crystal device for controlling laser polarization, and the benefits on various aspects of ultra-short pulse micro-processing, are discussed. Several configurations have been used, including real-time amplitude modulation of femtosecond pulses, averaging of polarization induced distortions in micro-drilling and optical polarization trepanning. Following successful testing of these applications, real-time polarization control has emerged as a flexible toolbox for the laser processing engineer.