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Summary
NIST maintains the national scales for reflectance and transmittance in the ultraviolet, visible, and near-infrared spectral regions (250 nm to 2500 nm). Our primary objective is the dissemination of those scales and the advancement of SI-traceable reflectance and transmittance metrology.
Description
NIST serves as the nation's primary source for spectral reflectance and transmittance measurements from 250 nm to 2500 nm. Our reflectance and transmittance measurements support the measurement infrastructure of communities involved in optics, photonics, color technology, instrument manufacturing, pharmaceutical, healthcare, coatings manufacturing, and remote sensing. NIST also supports the measurement services of our nation's military standards laboratories and interacts with its peers at nation metrology institutes through international intercomparisons.
Calibrations
NIST offers world-class calibrations of spectral reflectance and transmittance through NIST Calibration Services at the NIST Storefront. The catalog of available calibrations includes Green filter transmittance, Spectral tests of spectral reflectance, and Special tests of spectral transmittance. For some services, the measurement parameters are customizable, within the limits of our capabilities. Pricing is based on actual costs, labor and time, and various measurement parameters. Each calibration results in a calibration report is issued, which includes the calibration values and uncertainties for the customer-supplied test item(s).
Wavelength Standards
NIST previously offered calibration of holmium oxide glass under the Service IDs 38050C and 38051C. However, based on NIST's extensive experience with holmium oxide glass and its long-term stability, NIST no longer sells or recertifies this standard. These standards have shown insignificant spectral variation from batch to batch and from one manufacturer to another. More information can be found in the paper, Holmium Oxide Glass Wavelength Standards. Transmittance and absorbance data from this paper can be download as an Excel file (404 kB).
Major Accomplishments
NIST continually strives to improve its capabilities for providing these measurements and add to the general knowledge by performing research on related topics.
- Published NIST Measurement Services: Ultraviolet to Short-Wave Infrared Spectral Reflectance, a comprehensive, up-to-date, publicly accessible technical guide to NIST reflectance calibrations.
- Conducted UVC reflectance measurements to support the development of methods to disinfect occupied spaces.
- Commissioned the Reference Integrating Sphere for Spectral Reflectance, the new national reference instrument for directional-hemispherical reflectance calibrations and research. The new sphere is collocated with the Robotic Optical Scattering Instrument (ROSI) facility for specular and bidirectional reflectance.
- Conducted UV exposure studies of various reflectance materials. Exposure study on UV-induced degradation of PTFE and ceramic optical diffusers
- Participated in the Optical Interference Coatings conference's 8th Manufacturing Problem Contest.
- Participated in bilateral comparison of 0/45 reflectance factor scales from 330 nm to 1100 nm. Bidirectional reflectance scale comparison between NIST and PTB.