High spectral resolution Fourier transform imaging spectroscopy in a Michelson interferometer with homodyne laser metrology control

Abstract

High spectral resolution Fourier transform imaging spectroscopy has been demonstrated at the Lockheed Martin Advanced Technology Center. A testbed was built using a Michelson interferometer with a two-stage end-mirror control system. Homodyne laser metrology was used to sense relative tip, tilt and piston in the interferometer, and a 3-degree of freedom fast steering mirror in conjunction with a linear actuator stage provided sub-nanometer actuation control over 20 millimeters of piston range. The range of piston over which signal was present allowed for spectral resolution at the nanometer level in the visible / near infrared (VNIR) band for every pixel in the reconstructed image.

Superimposing interferogram method using a multi-slit array to enhance sensitivity and interference definition of spatial-phase-shift interferometers

“…Fourier spectroscopy uses one of two types of instruments. The first is the temporal phase-shift interferometer [4][5][6][7], which registers optical path differences by moving a mirror, as used in the Fourier-transform infrared spectrometer based on the Michelson interferometer. The second is the spatialphase-shift interferometer [8][9][10][11][12][13][14][15], which registers optical path differences using a Wollaston prism to remove the need for moving parts, as used in the static imaging Fourier transform spectrometer.…”