Optical Path

General Overview:

The NIST Fourier transform spectrometer consists of a folded Michelson interferometer with the two mirrors replaced by cat's-eye retroreflectors. Each cat's-eye runs on a rail consisting of an oil bearing and linear motor. The cat's-eyes move in opposite directions along the rails, with the zero path difference being when both cat's-eyes are in the center. Each rail is 1 m long, giving a maximum possible path difference of 2 m, which in turn gives a maximum possible resolution of 0.0025 cm^-1.

The wavelength range of the instrument is 200 nm to 5.5 µm, with various detectors and beamsplitters.

Photograph of spectrometer with vacuum chamber lifted away.

Atomic Spectroscopy Group   |   Atomic Physics Division   |   Division Technical Highlights

Online: July 2002