The total world market for Laser Material Processing systems is now a multi billion euro industry. However, existing laser surface micro-structuring technology is limited by the need to attenuate the laser output (to the uJ level) and this resulting slow speed leads to a significant loss of both throughputs and efficiencies.

These problems can be overcome by integrating a LCOS-SLM with a high power handling capability into such systems. This has allowed parallel processing using diffractive multiple beams generated by the LCOS-SLM to increase the throughput by over an order of magnitude. The incoming laser beam (using short laser pulses from nanosecond down to picosecond or even femtosecond pulses) is dynamically split into many lower energy beams to produce a particular light intensity distribution at a given surface. Using the LCOS-SLM, each beam is then simultaneously capable of independent motion control for surface micro-structuring.

This has applications for the manufacture of flat panel displays, solar cells, silicon wafers and plastic electronics.

Furthermore, direct laser marking can be achieved inside glass or aluminum cans instead of using traditional ink-jet printing systems or high speed laser scanning systems. The precise information is contained in the Computer Generated Hologram (CGH) and the laser marking is done in just one shot each time.

Dr Walter Perrie, Lairdside Engineering, University of Liverpool, UK

Images show the Parallel Processing, Laser Ablation of Silicon Dioxide layers on a Silicon substrate. The silicon is heated and the back contacts are created (opened) by a lifting mechanism activated by the melting and evaporation of the Silicon substrate.

A Coherent Talisker picosecond laser is used with pulse energies between 0.2 - 3 microjoule/spot depending on the degree of parallelism and lens focal length. The LCOS-SLM, optimized for 532 nm, is used to generate either 6 or 16 parallel spot patterns. Each contact is around 24 microns in diameter for the 6 spots and around 8 micron diameter for the 16 spots.

The 6 spots are processed at around 0.5 million contacts per second while the 16 spots are processed at around 1.5 million contacts per second. The scanning direction is to the right.