Compact and Low-Power Diode Laser Hygrometer for Weather Balloons

Abstract

A vertical cavity laser hygrometer has been developed for balloon-borne measurements. This hygrometer meets many of the specifications that are required for common weather balloon instrumentation, including weight, size, time response, and sensitivity. In addition, the system cost has been dramatically lowered relative to prior diode laser instruments. Sensitivity of 2 and 0.9 ?bar at low- and high-altitude conditions, respectively, has been obtained in a 1-s measurement period, with the strong possibility of improved performance in the near future. The engineering advances that are demonstrated by this system make balloon-borne diode laser hygrometry a practical technique for more frequent use.