Matched Filter Enhanced Fiber-based Lidar for Earth, Weather and Exploration

Among the science investigations that are of interest in the NASA Space Science, Earth Science and Planetary Science disciplines are data for surface elevation information, atmosphere chemical composition, atmosphere dynamics and meteorology. A laser sensor architecture has been developed at ITT using both internal and IIP funds which is capable of addressing these science data needs. This architecture also simultaneously transmits online and offline wavelengths. This reduces noise from the atmosphere, target and sensor into a common-mode term which is readily removed. An end-toend simulation of a multi-channel laser absorption spectroscopy system using amplitude modulated laser beams has been constructed and verified by experimental data from a near IR system tuned to a CO2 absorption line using telecom laser components (DFB, Modulator, EDFA) and a cooled HgCdTe detector. The verification has been accomplished using multipath absorption cells in the laboratory, horizontal column measurements in the field and vertical column measurements from an aircraft platform. This architecture is also viable in the MWIR wavelength region using readily available sources. In addition, a single channel end-to-end system simulation using pseudo-noise (PN) codes has been developed for ranging applications. Here the information is extracted from the received signal using correlation techniques. This waveform has the promise of being more sensitive than the sinusoidal waveform because digital detection approaches can be used. With sufficient backscatter cross section or laser power this PN waveform can be used to address the need for the distribution of winds in the atmosphere.