|Smoke and Mirrors: Ultra-Rapid-Scan FT-IR
After filtering, the laser frequency profile is clean enough to see small
vibrations. The drive for these vibrations is probably a combination of bearing noise and
aerodynamic forces. These velocity fluctuations are too small to have any significant
effect on spectra. Indeed, if these small fluctuations were a problem, the overall
sinusoidal variation would be a serious problem.