Ulf Griesmann (Fed)

Ulf Griesmann is a physicist in the Surface and Interface Metrology group of the Sensor Science Division specializing in the application of optical interferometry to precision measurements of size, shape, and surface properties of objects. Ulf Griesmann has worked on optical phase measuring interferometry for the characterization of precision flats, spheres, and aspheric surfaces, and on interferometry with infrared light for optical thickness measurements of silicon wafers. He has contributed to the adoption of optical methods, based on coherence scanning interferometry, for NIST calibrations of step height and surface texture parameters.

Ulf Griesmann is responsible for NIST’s Aperture Area Measurement Facility, which provides precision measurements of the areas of radiometric apertures. Apertures with precisely known area are used in radiometry and photometry to define the optical phase space into which radiant flux is emitted or received. For example, apertures with known area are needed for the realization of the Candela. Another common application is the measurement of irradiance, the radiant flux received at a surface per unit area (or its photometric analog illuminance), which requires an aperture with known area to be placed in front of an optical radiation sensor.