An Airborne Wavemeter for an Atmospheric DIAL Experiment

Abstract

A wavemeter is being designed and developed as a subsystem to support the NASA LASE (Laser Atmospheric Sounding Experiment) ER-2 airborne project. The prime objective of this project is to use a DIAL remote sounding system with a pulsed tunable Alexandrite laser to measure vertical profiles of water vapor and aerosols. The technology to make the required wavelength centroid and wavelength profile measurements has been demonstrated by others in laboratory environments. The developmental effort in building this wavemeter is to operate within requirements inside the Q-bay environment of an ER-2 aircraft. In this environment, the temperature can vary from 15 to 40 degrees Celsius and the pressure can vary from 14.7 psi to 3.5 psi. The interferometers in the wavemeter must be isolated from this thermal and pressure variation. A thermally controlled housing and thermal vacuum chambers have been designed and brassboarded to demonstrate the required stability.