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Proceedings Paper

Figure of merit and fundamental range limitations in surface sensing direct-detection mid-infrared random-modulation continuous-wave lidar
Author(s): Adam Rybaltowski; Allen Taflove
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Paper Abstract

We perform maximum range calculations for surface sensing direct-detection mid-infrared Random-Modulation Continuous- Wave (RM-CW) lidar, and propose a system's figure of merit. In this type of lidar, noise can be additive and determined by detector's noise given by its specific detectivity D, area, and integration time. Fundamental limits of the sensing range are then imposed by diffraction, provided that the Background-Limited Infrared Photodetection (BLIP) limit (controlled by the field-of-view) is not exceeded. There is no dependence on a specific pseudorandom code (PRC) used since noise spectral density is assumed to be independent of frequency. Under most favorable conditions, including no losses due to optics or atmospheric attenuation, an object of angularly uniform unity reflectance and size not less than the laser beam can be detected within 1s with a 20-cm diameter telescope and a signal-to-noise ratio of one from a distance of about 200 km if a cooled detector and a laser emitting 500 mW cw at 5 micrometers are used. For an integration time of 0.1 ms (which is well below a typical atmospheric correlation time), or a room-temperature detector, the maximum range reduces to about 20 km. As the technology of Quantum-Cascade lasers (QCLs) advances, the maximum range of several tens of kilometers can be expected in this type of lidar with all-thermoelectrically-cooled semiconductor components, and, perhaps after some modifications in the technique, about 1 km with all-room-temperature components.

Paper Details

Date Published: 23 January 2002
PDF: 5 pages
Proc. SPIE 4546, Laser Radar: Ranging and Atmospheric Lidar Techniques III, (23 January 2002); doi: 10.1117/12.453997
Show Author Affiliations
Adam Rybaltowski, Northwestern Univ. (United States)
Allen Taflove, Northwestern Univ. (United States)

Published in SPIE Proceedings Vol. 4546:
Laser Radar: Ranging and Atmospheric Lidar Techniques III
Ulrich Schreiber; Christian Werner; Gary W. Kamerman; Upendra N. Singh, Editor(s)

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