Application of a Wave-Length Modulation Device to Problems concerning Spectrometer Misalignment

The use of wave-length modulation as a tool for minimizing spectrometer spectral misalignment is examined. A vibrating quartz plate is employed to repetitively scan a small wave-length interval at the exit slit of a spectrometer. Increased latitude is thereby provided for any slit or wave-length misalignment of the spectrometer, as long as the correct signal detection system is employed. Investigation of the effects of wave-length modulation on a typical line spectrum has revealed signal averaging as the optimum detection system for this approach. From this, additional approaches are suggested for manual and automatic routine correction of spectrometer wave-length drift using existing optical systems. Also, a new technique is suggested for automatic feedback correction of the spectrometer using an on-line digital computer. Methods of implementation of all these procedures are considered and discussed.