Concepts for scalable CDMA-networked M/LWIR semiconductor laser standoff chemical detection system

et al. 2006

SPIE Proceedings

Self Cite

This paper describes an application-centric development of broadly tunable and multi-spectral mid/long-wave IR semiconductor lasers. Examples of various external-cavity lasers capable of broad, continuous wavelength tuning with type-I and type-II quantum cascade lasers are discussed. Laser configurations studied include conventional Littman-Metcalf, Littrow, multi-segment and Bragg-grating-coupled surface-emitting. All were capable of single-mode continuous tuning with high side-mode-suppression ratio. The lasers were evaluated with spectroscopic applications, which include wavelength-modulation spectroscopic imaging and multi-wavelength decomposition of a gas mixture. The results showed that these lasers were capable of maintaining wavelength accuracy and stability over the entire tuning range. Multispectral imaging with discrete wavelengths over a wide spectral range was also studied. The results with a modest 4-wavelength system demonstrated the potential application for target discrimination, detection, and identification. These results suggest potential value for broadly tunable, wide-band M/LWIR laser technology.

Section: Target Of Some Common Materials With Non-distinctive Visiblementioning

confidence: 84%

“…12 [7,8]. The X-Y scanning system is primarily for 2-D imaging, although it also has 3-D capability using a near-IR diode laser.…”

Section: Methodsmentioning

confidence: 99%

Broadly tunable and multi-spectral mid-IR semiconductor lasers and applications

Peng

et al. 2006

SPIE Proceedings

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“…Details and demonstration of this system architecture have been described elsewhere [9][10][11], which is not the topic in this paper; But the approach is essential in this study of multi-spectral imaging. In practice, a system with up to 5 Rx's has been demonstrated.…”

Section: Technical Approach and System Designmentioning

confidence: 99%

“…However, there are challenging issues in both system engineering and basic principles that are intrinsic to the fundamental physics of laser scattering. This paper describes a development of multi-spectral laser imaging with a mid-IR emphasis [8][9][10][11], but also provides a study of the general and basic aspects of the technology irrespective of any spectral range. An objective is to also achieve a better understanding for further application development.…”

Section: Introductionmentioning

confidence: 99%

Multi-spectral imaging with mid-infrared semiconductor lasers

2006

SPIE Proceedings

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Multi-spectral laser imaging can be a useful technology for target discrimination, classification, and identification based on object spectral signatures. The mid-IR region (~3-14 m) is particularly rich of molecular spectroscopic fingerprints, but the technology has been under utilized. Compact, potentially inexpensive semiconductor lasers may allow more cost-effective applications. This paper describes a development of semiconductor-laser-based multi-spectral imaging for both near-IR and mid-IR, and demonstrates the potential of this technology. The near-IR study employed 7 wavelengths from 0.635-1.55 m, and used for system engineering evaluation as well as for studying the fundamental aspects of multi-spectral laser imaging. These include issues of wavelength-dependence scattering as a function of incident and receiving angle and the polarization effects. Stokes vector imaging and degree-of-linear-polarization were shown to reveal significant information to characterize the targets. The mid-IR study employed 4 wavelengths from 3.3-9.6 m, and was applied to diverse targets that consist of natural and man-made materials and household objects. It was shown capable to resolve and distinguish small spectral differences among various targets, thanks to the laser radiometric and spectral accuracy. Colorless objects in the visible were shown with "colorful" signatures in the mid-IR. An essential feature of the study is an advanced system architecture that employs wavelength-division-multiplexed laser beams for high spectral fidelity and resolution. In addition, unlike conventional one-transmitter and one receiver design, the system is based on a scalable CDMA network concept with multiple transmitters and receivers to allow efficient information acquisition. The results suggest that multi-spectral laser imaging in general can be a unique and powerful technology for wide ranging applications.

“…Each wavelength is independently modulated and the Rx can simultaneously decode to receive signals for all wavelengths. More details of the experimental approaches can be found elsewhere [6][7][8].…”

Section: B Experimental Apparatusmentioning

confidence: 99%

Laser Multi-Spectral Polarimetric Diffuse-Scatter Imaging

2009 Symposium on Photonics and Optoelectronics

2009

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Laser multi-spectral polarimetric diffuse-scatter imaging is a technique that maps the spectral, polarimetric, and diffused scattering response functions of an object, rather than the scattered light intensity. Application of the technique to a number of targets, which included controlled objects with known optical properties and unknown objects including drug pills and insect wing, suggests its capability to discriminate and interpret features that are ambiguous or not evident with conventional Fourier optics images. Theoretical study also indicates its potential for large-angle diffuse scatter scanning microscopy that collects image information not available for on-axis scanning.