Abstract

Wavelength accuracy is a key characteristic of FTS, and impressive results are available with relative ease. Assuming adequate signal-to-noise ratio, wavelength uncertainty arises from two primary phenomena — the effect of using a finite size aperture (and photon detector), and from cosine errors arising from imperfect alignment of the sample and reference beams. These effects are typically small enough to ensure uncalibrated accuracy of about 1 part in 10⁵. Significant improvement can be attained through a single point, multiplicative calibration approach, which has been reported to reduce uncertainties to several parts in 10⁸. In fact, relative line positions for strong lines within a given spectrum can be determined with a precision of several parts in 10⁹. [1]

© 1995 Optical Society of America