DIAL with heterodyne detection including speckle noise: Aircraft/shuttle measurements of O3, H2O, and NH3 with pulsed tunable CO2lasers
Abstract
A parametric analysis of DIAL sensitivity with heterodyne detection is presented and comparisons with direct detection are discussed. Examples are given for monitoring vertical distributions of O3, H2O, and NH3 using a ground-, aircraft-, or shuttle-based pulsed tunable CO2 laser DIAL system. Results indicate that maximum sensitivity at minimum laser energy per measurement requires multiple pulse operation with the energy per pulse selected so that the measured photon rate is approximately equal to the detector IF bandwidth. Measurement sensitivities can be maximized and interference effects minimized by fine adjustment of measurement frequencies using the tunability of high pressure lasers. The use of rare isotope lasers minimizes loss due to CO2 atmospheric absorption.
- Publication:
-
Heterodyne Systems and Technolology
- Pub Date:
- August 1980
- Bibcode:
- 1980hst..rept..557B
- Keywords:
-
- Atmospheric Composition;
- Heterodyning;
- Optical Radar;
- Tunable Lasers;
- Airborne Equipment;
- Carbon Dioxide Lasers;
- Electromagnetic Absorption;
- Pulsed Lasers;
- Random Errors;
- Signal Detectors;
- Signal To Noise Ratios;
- Speckle Patterns;
- Lasers and Masers