Mirror Velocity Sampling Errors in a Michelson Interferometer

Mirror velocity variations in a continuous mirror drive Michelson interferometer result in erroneous interferogram sampling. The effects of both systematic and random mirror fluctuations are evaluated. Four methods of evaluation provide a means to quantify the importance of mirror velocity errors in the Fourier spectrometer's performance as a spectroradiometer. The four methods are time interval signal analysis, sine wave test, optical chopper modulation, and examination of consecutive interferograms. Examination of consecutive interferograms includes the monitoring of a constant blackbody infrared radiation source as well as an interposed ammonia sample cell for wavenumber axis registration. Each method furnishes a known input to the interferometer modulation equation (i.e. 2uv=f) and permits an internal validation of the interferometer mirror velocity evaluation results.