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Spectral tri-function automated reference reflectometer (STARR)


STARR is the national reference instrument for spectral reflectance measurements of spectrally neutral, non-fluorescent samples at room temperature.

The illuminator has two sources, a xenon (Xe) arc lamp and a quartz-tungsten-halogen (QTH) incandescent lamp, order-sorting filters, a shutter, a single-grating monochromator, a parabolic mirror, a chopper, and a polarizer. An in-plane goniometer is used for bi-directional measurements, meaning the sample normal, illumination axis, and receiver axis are all in a horizontal plane. The receiver is attached to the goniometer and has a precision aperture, a lens, and a photodiode detector, either silicon (Si) or extended indium-gallium-arsenic (InGaAs). An integrating sphere is used for directional-hemispherical measurements, and can accommodate Si and extended InGaAs photodiode detectors.

Specifications / Capabilities:


Conditions for reflectance measurements using STARR

  Bi-directional Directional-hemispherical
  Specular Diffuse  
Illumination Angle 0° to +80° 0° to +80° 6° (specular included) 0° (specular excluded)
Viewing Angle 0° to +80° 0° to +80° Hemisphere
Sampling Aperture 17 mm 17 mm 25 mm

Wavelength 250 mm to 2500 nm 250 nm to 1100 nm 250 nm to 2500 nm
Bandwidth 14 mm 14 nm 14 nm
Polarization 0° to 90° 0° to 90° Slight
Sample Size 50 mm to 300 mm 50 mm to 300 mm 50 mm to 300 mm

Quantity Reflectance BRDF, Reflectance factor Reflectance factor
Technique Absolute Absolute Relative to PTFE
Range 0.001 to 1 0.001 to 1 0.001 to 1
Uncertainty (k=2)
0.1% to 0.2% 0.15% to 0.6% 0.15% to 0.6%


Name: Catherine Cooksey
Phone: 301-975-6208
Email: ccooksey@nist.gov
100 Bureau Drive, M/S 8442
Gaithersburg, MD 20899-8442