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TOOLS & INSTRUMENTS

Robotic Optical Scattering Instrument (ROSI)

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 Reference Integrating Sphere for Spectral Reflectance.

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.

Video

'ROSI' the Robot — Lots of companies care about how lighting affects the color and "look" of their product, whether it's a car, a magazine ad, a pantsuit, or a paint sample. NIST's Robotic Optical Scattering Instrument -- called “ROSI” for short -- is a new system that industry customers can use to measure precisely how light reflects and scatters off of materials to produce these different colors and appearances. To use ROSI, scientists first mount a sample to the end of the robotic arm. ROSI's articulated wrist, shoulder, and elbow allow the machine to move the sample in almost any direction with respect to a beam of light. Meanwhile, a receiver can be positioned to collect the light reflecting off of the material from different angles. Credit: Jennifer Lauren Lee/NIST

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 %

Optical / photometry / laser metrology and Optical physics and communications

Created May 9, 2018, Updated January 10, 2025