Abstract

The Los Alamos Fourier transform spectrometer is a folded Michelson interferometer using cat's-eye reflectors for the moving mirrors. The maximum path difference is 5 m which gives a resolution of 0.001 cm⁻¹. The interferometer is capable of obtaining spectra from 200 to 20,000 nm with the appropriate optics and detectors. Acquisition time for one scan is 2-6 min depending on resolution and spectral region. The servo control of the interferometer uses a Zeeman split He-Ne laser in a phase lock loop operating at 1.5 MHz. The servo is capable of position accuracies of 0.3 nm and can acquire an interferogram with any reasonable free spectral range that is desired. The A/D converter is an effective 22-bit floating point converter connected to an array processor. The A/D converter control has self-calibration to ensure linearity over the full range. The array processor corrects for any errors in the A/D converter as determined by the calibration and then digitally filters the data to remove noise outside the bandpass of interest. The servo control and the A/D converter are operated by separate 68,000 microprocessors.

© 1985 Optical Society of America