Accurate measurements of the optical properties of materials in the infrared spectral range play an increasingly important role in the aerospace and defense industries, optical engineering, condensed matter physics, remote sensing, radiative heat transfer measurements and related areas. Our facilities have been developed for high accuracy infrared reflectance, transmittance and emittance measurement over the wavelength range of 1 µm to 20 µm and beyond.
The Fourier Transform Infrared Spectrophotometry laboratory contains several systems that are used to measure the infrared reflectance and transmittance capabilities for wavelengths between 1 µm and 20 µm. Near normal absolute spectral reflectance and transmittance of both specular and diffuse samples can be measured from near ambient to 200 °C using a custom integrating sphere and a Fourier transform infrared (FTIR) spectrometer. Additional capabilities for specular samples include transmittance down to 10 K using an optical cryostat, as well as variable angle transmittance and reflectance using a custom goniometer and polarizers.
Special test measurements are performed for both NIST and external customers in government and industry on a wide variety of materials including mirrors, filters, windows, coatings and cavity structures. Emittance and absorptance are obtained indirectly through combining the reflectance and transmittance under identical conditions. Also, a facility is available for the measurement of directional spectral emittance for sample temperature up to 1000 °C, accomplished through comparison of radiance with reference blackbody sources.
Our overall approach can be summarized in the following 5 key elements:
Lead Organizational Unit:pml
Related Programs and Projects:
For information about special services, see Special tests for measuring the infrared optical properties of materials.
Infrared optical properties of materials:
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