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Bidirectional reflectance capabilities of the NIST Robotic Optical Scattering Instrument (ROSI)



Heather Patrick, Catherine Cooksey, Thomas A. Germer, Maria E. Nadal, Clarence Zarobila


The NIST Robotic Optical Scattering Instrument (ROSI) serves as the national reference instrument for specular and diffuse bidirectional reflectance measurements in the ultraviolet (UV) to short-wave infrared (SWIR) wavelength regions. This paper gives a comprehensive overview of the design, operation, and capabilities of ROSI. We describe measurement methods for diffuse and specular reflectance, identify and quantify the elements of the uncertainty budget, and validate the reflectance scale through comparison with NIST's previous reference instrument, the Spectral Tri-function Automated Reference Reflectometer (STARR). Examples of the range of ROSI's capabilities, including the limits for low-reflectance measurements and a research application using out-of-plane measurements of bidirectional reflectance for remote sensing reference reflectors, are also covered.
Applied Optics


bidirectional reflectance distribution function, reflectance, spectrophotometry, goniometer, goniospectrophotometry


Patrick, H. , Cooksey, C. , Germer, T. , Nadal, M. and Zarobila, C. (2021), Bidirectional reflectance capabilities of the NIST Robotic Optical Scattering Instrument (ROSI), Applied Optics, [online],, (Accessed June 19, 2024)


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Created October 1, 2021, Updated November 29, 2022