Real-time control of polarisation in high-aspect-ratio ultra-short-pulse laser micro-machining

The use of a fast-response, transmissive, ferroelectric liquid-crystal device for real-time control of the polarisation direction of a femtosecond laser beam, and the benefits on various aspects of ultra-short pulse micro-machining, are discussed. Several configurations have been used to drive the polarisation in real-time. Our microscopic investigations of the resulting features revealed significant improvements in process quality. Following successful micro-machining tests, real-time polarisation control has emerged as a flexible tool for the laser processing engineer.