Laser material processing
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.
Application examples
Multi-point laser material processing
Hamamatsu Photonics KK with Kyoto University and New Glass Forum
Using an LCOS-SLM achieves high speed by multi-point processing inside transparent material by controlling light distribution in 3-dimensional space including the depth.
* Joint research between Hamamatsu Photonics KK with Kyoto University and New Glass Forum in NEDO project: "High efficiency processing technology for three-dimensional optical devices".
Laser parallel processing
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.
Videos
Advantages SLM can offer and why
The benefits that Spatial Light Modulators offer in the field of Laser Material Processing are:
- Individual Laser Beams can be independently manipulated and controlled allowing precise micro-structuring processes to be undertaken
- Using multiple parallel beams directly increases the throughput and efficiency of laser processing thereby reducing overall operating costs
Hamamatsu’s range of LCOS-SLM models with dielectric coatings, have extremely high power handling capabilities due to the following reasons:
| Large Active Area (16 x 12 mm) | Higher laser powers can be accepted leading to higher damage tresholds |
|
|---|---|---|
| Dielectric Mirror Coating | High reflectivity up to 95% enables higher damage threshold. This compares to inferior metallic coatings which have lower reflectivities and consequently lower damage thresholds. | |
| Ceramic Packaging | High stability allows excellent temperature controllability by connection to Peltier systems | |
| DVI Refresh Rate of 60 Hz | Fast Dynamic Optical Element can create a highly parallel array of laser beams for processing | |
| High laser powers can be irradiated onto the SLM chip | Adaptive optics within Laser Material processing (e.g. marking inside high refractive index materials such as glass and diamond) |
