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Proceedings Paper

Optimization of a 3.6-THz quantum cascade laser for real-time imaging with a microbolometer focal plane array
Author(s): Barry N. Behnken; Gamani Karunasiri; Danielle Chamberlin; Peter Robrish; Jérôme Faist
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Paper Abstract

Real-time imaging in the terahertz (THz) spectral range was achieved using a 3.6-THz quantum cascade laser (QCL) and an uncooled, 160×120 pixel microbolometer camera fitted with a picarin lens. Noise equivalent temperature difference of the camera in the 1-5 THz frequency range was calculated to be at least 3 K, confirming the need for external THz illumination when imaging in this frequency regime. After evaluating the effects of various operating parameters on laser performance, the QCL found to perform optimally at 1.9 A in pulsed mode with a 300 kHz repetition rate and 10-20% duty cycle; average output power was approximately 1 mW. Under this scheme, a series of metallic objects were imaged while wrapped in various obscurants. Single-frame and extended video recordings demonstrate strong contrast between metallic materials and those of plastic, cloth, and paper - supporting the viability of this imaging technology in security screening applications. Thermal effects arising from Joule heating of the laser were found to be the dominant issue affecting output power and image quality; these effects were mitigated by limiting laser pulse widths to 670 ns and operating the system under closed-cycle refrigeration at a temperature of 10 K.

Paper Details

Date Published: 14 February 2008
PDF: 9 pages
Proc. SPIE 6893, Terahertz Technology and Applications, 68930L (14 February 2008); doi: 10.1117/12.767671
Show Author Affiliations
Barry N. Behnken, Naval Postgraduate School (United States)
Gamani Karunasiri, Naval Postgraduate School (United States)
Danielle Chamberlin, Agilent Labs. (United States)
Peter Robrish, Agilent Labs. (United States)
Jérôme Faist, Univ. de Neuchâtel (Switzerland)

Published in SPIE Proceedings Vol. 6893:
Terahertz Technology and Applications
Kurt J. Linden; Laurence P. Sadwick, Editor(s)

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