Knowledge Bank

Knowledge of the laser wavelength is essential in tunable IR laser spectroscopy. The scanning Michelson interferometer has the potential to compare the IR laser wavelength to a single, well-known calibration wavelength (e.g., HeNe laser) over a wide IR spectral range. In contrast to other recent work with scanning Michelson interferometers, we have added a phase-lock multiplier and counters to a $0.1Cm-1$ FTS laboratory interferometer to achieve an accuracy of $10-3cm-1$. This Idealab interferometer incorporated cats-eye mirrors, but its other features are probably representative of typical commercial interferometers. Measurements of a stable $CO2$ laser have indicated a precision and calibratable accuracy of $0.001cm-1$ with $CO2$ use of the HeNe laser monitor supplied with the interferometer. Achievement of the $0.0001cm-1$ precision and accuracy expected with the phase-lock multiplier is still under study as is the application of the wavemeter to the calibration of tunable diode lasers.