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Robotic Optical Scattering Instrument (ROSI)

ROSI

ROSI (Robotic Optical Scattering Instrument)

ROSI performs specular and bidirectional reflectance measurements of spectrally neutral, non-fluorescent specular and diffuse samples at room temperature. It serves as the national reference instrument for specular and bidirectional reflectance measurements. The national reference instrument for directional-hemispherical reflectance measurements is the Spectral tri-function automated reference reflectometer (STARR).

ROSI uses a quasi-monochromatic system for illumination of the sample and broadband detection for the reflected radiation. Sample angles and positioning are controlled by a robotic-arm-based goniometer. Specular and bidirectional calibrations are collected in-plane, meaning the sample normal, illumination axis, and receiver axis are in the same plane. ROSI can also perform out-of-plane bidirectional reflectance measurements for research and special tests.

Specifications/Capabilities

Conditions for specular and bidirectional reflectance measurements using ROSI

Geometrical

Illumination Angle

0° to 80°

Viewing Angle

0° to 80°

Sample size

25 mm to 300 mm

Illumination beam size

10 mm

Spectral

Wavelength

250 nm to 2400 nm

Bandwidth

14 nm

Polarization

0° to 90° linear

Measurand

Quantity

     Specular

Reflectance

     Bidirectional Diffuse

Reflectance Factor, BRDF

Technique

Absolute

Nominal Uncertainty (k=2)

     Specular

0.2 %

     Bidirectional Diffuse

0.65 %

Created May 9, 2018, Updated November 15, 2019