Project Title:

Wide Dynamic Range Airborne Water Vapor Sensor (7114-120)

Physical Sciences Inc.
20 New England Business Center
Andover, MA 01810-1077

93-1-08     06   0003

Wide Dynamic Range Airborne Water Vapor Sensor (7114-120)

Abstract:

Physical Sciences Inc. proposes to demonstrate a flight
qualifiable, wide dynamic range sensor for water vapor
concentration measurements in the troposphere. The sensor is
based on absorption measurements using a room temperature,
tunable InGaAsP diode laser and a unique noise canceling detector
system. The noise canceling detector permits near shot-noise
limited absorption measurements without frequency modulation
techniques, resulting in a simpler, less expensive, lighter
weight, and easier to use instrument compared to frequency
modulation (FM) techniques. Signal dynamic range in excess of 10
will be achieved using selected pairs of absorption transitions.
The Phase I portion of the program will demonstrate quantitative 
absorption measurements of H20 vapor over the temperature range
190 K to 313 K in a pressure-controlled cryogenic environment
chamber.

The proposed instrument has wide commercial application beyond
atmospheric monitoring. PSI anticipates incorporating it into a
product line of diode laser-based, continuous monitoring devices
under development for emissions monitoring in the utility boiler
industry. Other applications include propulsion system monitoring
and general environmental monitoring.

H2O, Diode Laser Absorption, Low-Noise Absorption, Flight
Instrumentation