Laser Radiometry

 

Summary: Accurate characterization of photonic equipment is important for optical communications, medical devices, semiconductor lithography, manufacturing and materials processing. Our project focuses on metrology of selected critical laser parameters, especially the calibration of laser and optical-fiber power meters. Our calibration services range in wavelength from the ultraviolet to far infrared and from picowatts to tens of kilowatts. The Project’s staff participate in national and international standards committees for laser safety and optoelectronic devices. We continually undertake research and development to improve our ability to characterize laser sources and detectors, including development of low-noise, spectrally uniform and high-accuracy standards for optical-fiber and laser power measurements. Description: Meeting the needs of the photonics industry and anticipating emerging technologies requires investigation and development of improved measurement methods and instrumentation. With few exceptions, all of the primary measurement standards for establishing traceability to fundamental units for radiometry are based on thermal detectors. We have recently demonstrated thermal detectors with absorber coatings consisting of carbon nanotube arrays. Separately, we have developed high power laser measurement capability based on radiation pressure; a completely different approach that, when realized, will provide traceability to the kilogram. High-power laser systems for manufacturing processes such as cutting and welding are becoming more widely employed in the US and much of the world. Our 10 kW fiber laser system and welding workstation provides us with the capability to undertake laser measurements to support development of new applications and processes of laser-based manufacturing. Figure: Planar Bolometric Radiometer based on Carbon Nanotubes Major Accomplishments: International comparisons with Germany, Great Britain, Japan, Mexico, Switzerland, South Korea and Russia. Demonstrated a small, portable laser power meter based on radiation pressure (photon momentum). Established 10 kW laser power meter calibration facility. Carbon nanotube based bolometers for absolute measurement of laser power at visible and far infrared wavelengths. http://www.nist.gov/pml/div686/sources_detectors/laser.cfm