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Title: Real-time imaging using a 4.3-THz quantum cascade laser and a 240320 microbolometer focal-plane array.

Abstract

No abstract prepared.

Authors:
 [1];  [2];  [3]; ;  [2]
  1. (Massachusetts Institute of Technology, Cambridge, MA)
  2. (Massachusetts Institute of Technology, Cambridge, MA)
  3. (Massachusetts Institute of Technology, Cambridge, MA)
Publication Date:
Research Org.:
Sandia National Laboratories
Sponsoring Org.:
USDOE
OSTI Identifier:
901402
Report Number(s):
SAND2006-0245J
TRN: US200714%%6
DOE Contract Number:
AC04-94AL85000
Resource Type:
Journal Article
Resource Relation:
Journal Name: Proposed for publication in Optics Letters.
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; LASERS; PERFORMANCE; OPTICAL PUMPING; REAL TIME SYSTEMS; IMAGES

Citation Formats

Kumar, Sushil, Lee, Alan W. M., Williams, Benjamin S., Reno, John Louis, and Hu, Qing. Real-time imaging using a 4.3-THz quantum cascade laser and a 240320 microbolometer focal-plane array.. United States: N. p., 2006. Web.
Kumar, Sushil, Lee, Alan W. M., Williams, Benjamin S., Reno, John Louis, & Hu, Qing. Real-time imaging using a 4.3-THz quantum cascade laser and a 240320 microbolometer focal-plane array.. United States.
Kumar, Sushil, Lee, Alan W. M., Williams, Benjamin S., Reno, John Louis, and Hu, Qing. Sun . "Real-time imaging using a 4.3-THz quantum cascade laser and a 240320 microbolometer focal-plane array.". United States. doi:.
@article{osti_901402,
title = {Real-time imaging using a 4.3-THz quantum cascade laser and a 240320 microbolometer focal-plane array.},
author = {Kumar, Sushil and Lee, Alan W. M. and Williams, Benjamin S. and Reno, John Louis and Hu, Qing},
abstractNote = {No abstract prepared.},
doi = {},
journal = {Proposed for publication in Optics Letters.},
number = ,
volume = ,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}
  • A versatile mid-infrared hyperspectral imaging system is demonstrated by combining a broadly tunable external cavity quantum cascade laser and a microbolometer focal plane array. The tunable mid-infrared laser provided high brightness illumination over a tuning range from 985 cm-1 to 1075 cm-1 (9.30-10.15 μm). Hypercubes containing images at 300 wavelengths separated by 0.3 cm 1 were obtained in 12 s. High spectral resolution chemical imaging of methanol vapor was demonstrated for both static and dynamic systems. The system was also used to image and characterize multiple component liquid and solid samples.
  • An uncooled microbolometer focal plane array (FPA) has been developed and used for imaging of objects illuminated by monochromatic coherent radiation of a free electron laser tunable in the range of 1.25-2.5 THz. A sensitivity threshold of 1.3x10{sup -3} W/cm{sup 2} was obtained for the FPA with a homemade absolute interferometric power meter. Videos up to 90 frames/s were recorded in both transmission and reflection/scattering modes. When objects were illuminated by laser radiation scattered by a rough metal surface, speckled images were observed. Good quality terahertz images were achieved through the fast rotation of the scatterer.
  • We report on a fast self-mixing approach for real-time, coherent terahertz imaging based on a quantum-cascade laser and a scanning mirror. Due to a fast deflection of the terahertz beam, images with frame rates up to several Hz are obtained, eventually limited by the mechanical inertia of the employed scanning mirror. A phase modulation technique allows for the separation of the amplitude and phase information without the necessity of parameter fitting routines. We further demonstrate the potential for transmission imaging.
  • We present an 8-beam local oscillator (LO) for the astronomically significant [OI] line at 4.7 THz. The beams are generated using a quantum cascade laser (QCL) in combination with a Fourier phase grating. The grating is fully characterized using a third order distributed feedback (DFB) QCL with a single mode emission at 4.7 THz as the input. The measured diffraction efficiency of 74.3% is in an excellent agreement with the calculated result of 75.4% using a 3D simulation. We show that the power distribution among the diffracted beams is uniform enough for pumping an array receiver. To validate the gratingmore » bandwidth, we apply a far-infrared (FIR) gas laser emission at 5.3 THz as the input and find a very similar performance in terms of efficiency, power distribution, and spatial configuration of the diffracted beams. Both results represent the highest operating frequencies of THz phase gratings reported in the literature. By injecting one of the eight diffracted 4.7 THz beams into a superconducting hot electron bolometer (HEB) mixer, we find that the coupled power, taking the optical loss into account, is in consistency with the QCL power value.« less