High power lasers capable of continuous output powers ranging from hundreds of watts to tens-of-thousands of watts present exciting opportunities for rapid, directed delivery of energy – particularly in the area of materials processing and laser machining. These same high power lasers also present difficult challenges for the accurate measurement of their delivered power. The Laser Applications Project exists to enhance NIST's ability to measure high power laser output parameters with the necessary accuracy and ease of use. This is done by developing, testing, and implementing unique technologies such as a thermal flowing-water-based approach and a force-based technique using optical radiation pressure. The Laser Applications Project also makes use of NIST's high power laser facilities to develop technologies and measurement tools associated with laser machining and materials processing. Our10 kW fiber laser and integrated laser welding booth provide opportunity for the development of supporting metrology for materials processing related to such applications as photovoltaic manufacturing and laser welding.
Lasers are a well-suited tool to rapidly transform materials on small length scales when both high temperature and high precision are required. Large research efforts are underway worldwide to further develop laser processing techniques across multiple sectors of advanced manufacturing. Some techniques implemented at production scale include laser processing of silicon for multi-crystalline silicon displays, pulsed laser scribing for thin film solar cells, and precision laser welding. Temperature determines key physical phenomena like dopant diffusion, particle sintering, and crystallographic phase changes. However, the control of these complex and often non-linear laser-matter interactions in dynamic high temperature processes continues to rely solely on empirical measurements, which do not transfer well to different materials or different instrumentation. New in situ traceable measurements are needed to enable real-time process control and optimization based on a predictive understanding of light-matter interactions under extreme conditions.