Double Grating Sagnac Fourier Transform Spectrometer

Case ID: 00470


Researchers in the University of Hawaii's Free-Electron Laser Group have developed a Fourier transform spectrometer based on a modified Sagnac interferometer. The instrument uses two gratings as dispersive elements to greatly improve the spectral resolution, and in-line optics to match the beam size in the interferometer to optimize the efficiency. A CCD or photodiode array is used as the detector and the fast Fourier transform of the fringe pattern is performed by a computer.



  • Practical applications include remote sensing, process monitoring, and basic research.
  • The fast response time of the detector also makes the spectrometer possible to perform real time spectral analysis.



  • The use of two gratings permits unprecedented spectral resolution by over an order of magnitude compared to the present state of the art.
  • Since no mechanically moving part is used, this spectrometer is compact and easy to align.
  • All other benefits of compact spatial Fourier transform spectrometers are retained, including compact size, rugged construction, single-shot recording with no moving parts, and quick response time.
Patent Information:
Eric Szarmes
Huan Ma

For information, contact:
Avery Munoz
Licensing Associate
University of Hawaii

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