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6CCVD Research

Control of quantum cascade laser sources in stand-off detection of trace explosives

At a Glance

Section titled ā€œAt a Glanceā€
MetadataDetails
Publication Date2019-05-13
AuthorsYohan Yoon, Christopher J. Breshike, Christopher A. Kendziora, Robert Furstenberg, Andrew R. McGill
InstitutionsUnited States Naval Research Laboratory, American Society For Engineering Education
Citations2

Abstract

Section titled ā€œAbstractā€

We pursue the development of an eye-safe stand-off technique suitable for the detection of trace explosives. As the active illumination sources, tunable quantum cascade lasers (QCLs) are employed in Mid-LWIR (long-wave infrared) in the range of 6 to 11 Ī¼m, which contains many spectral features from analytes of interest. Any fluctuation of the laser beam direction and/or beam profile is amplified at the sample position, which would lead to diminished performance of the detection technique, both in sensitivity and selectivity. Several beam stabilization approaches were conducted to overcome this challenge: 1) Using a KBr/diamond pellet as a diffuser in combination with a multimode fiber 2) Feedback stabilization of quantum cascade laser beam steering. The purpose of the first method is to make a temporally and spatially incoherent laser beam source through the multimode fiber and KBr/diamond pellet. The second approach is to stabilize the beam position by using an active feedback loop. We have demonstrated that beam wander and speckle noise were successfully suppressed by these approaches. Independently, we have developed a custom-built broadband laser source in the Mid-LWIR range consisting of several high power Fabry Perot (FP)-QCLs. The FP-QCLs were operated in both CW and pulsed modes at different diode temperatures, and the emission spectra were collected by a FTIR. For our future work, the output beams will be collimated to spectrally combine multi-QCLs and aligned toward the same target. Also, a spatial heterodyne spectrometer (SHS) will be applied to discriminate spectral and spatial information from a single snapshot.

Tech Support

Section titled ā€œTech Supportā€

Original Source

Section titled ā€œOriginal Sourceā€

References

Section titled ā€œReferencesā€
  1. 2012 - Chemical imaging using infrared photothermal microspectroscopy

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