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Fourier transform infrared spectrophotometry (FTIS) facility

The Fourier transform infrared spectrophotometry (FTIS) facility serves as the measurement facility for characterizing the optical properties of materials in the infrared spectral range of 1 µm to 100 µm, with particular emphasis on the 2 µm to 20 µm region.

The facility is built around several commercial Fourier transform infrared instruments. Custom specialized accessories have been developed to enable transmittance, reflectance, and emittance measurements of a wide variety of sample types and under the variable control of measurement geometry, beam polarization, and sample temperature.

Methodologies and new techniques have been developed for high accuracy measurements. Major sources of error have been thoroughly evaluated and their resulting uncertainties minimized. Techniques have also been implemented for the characterization and derivation of other properties such as refractive index and Mueller matrix elements.

IGRT and IRIS schematics
Detailed top-view layout of the primary system for reflectance and transmittance measurements.

Fourier transform infrared spectrometers

Bruker 70

Bruker Vertex 70 

  • Wavelength range: 0.8 µm to 330 µm
  • Highest resolution: 0.4 cm-1
  • Purge for FT and all instrumentation
  • Gold-coated optics for greater IR flux
  • Multiple source and beam ports
  • Step-scan mode for specialized applications

Digilab FTS-7000

  • Wavelength range: 0.8 µm - 50 µm
  • Highest resolution: 0.25 cm-1
  • Purge for FT and all instrumentation
  • High stability and repeatability
  • External beam to multiple instruments
  • Step-scan mode for specialized applications

Custom accessory equipment


Cryostat for sample temperature control, 10 K to 600 K (for studying temperature dependence of emittance).



Integrating Sphere with Heaters for Indirect Emittance Measurements (20 °C - 200 °C)


Brewster angle high contrast broadband polarizer


Goniometer for variable angle transmittance and reflectance, polarimetry and ellipsometry


Created January 19, 2010, Updated May 2, 2022