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Fremont, CA, United States

Mukherjee A.,Pranalytica | Mukherjee A.,Infrasign LLC | Von Der Porten S.,Pranalytica | Patel C.K.N.,Pranalytica | Patel C.K.N.,University of California at Los Angeles
Applied Optics | Year: 2010

We report detection and identification of trace quantities of explosives at standoff distances up to 150 m with high sensitivity (signal-to-noise ratio of ∼70) and high selectivity. The technique involves illuminating the target object with laser radiation at a wavelength that is strongly absorbed by the target. The resulting temperature rise is observed by remotely monitoring the increased blackbody radiation from the sample. An unambiguous determination of the target, TNT, in soil samples collected from an explosives test site in China Lake Naval Air Weapons Station is achieved through the use of a tunable CO 2 laser that scans over the absorption fingerprint of the target explosives. The theoretical analysis supports the observation and indicates that, with optimized detectors and data processing algorithms, the measurement capability can be improved significantly, permitting rapid standoff detection of explosives at distances approaching 1km. The detection sensitivity varies as R-2 and, thus, with the availability of high power, room-temperature, tunable mid-wave infrared and long-wave infrared quantum cascade lasers, this technology may play an important role in screening personnel and their belongings at short distances, such as in airports, for detecting and identifying explosives material residue on persons. © 2010 Optical Society of America. Source

Mukherjee N.,University of California at Los Angeles | Mukherjee N.,Infrasign LLC
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2010

A comprehensive theoretical analysis is developed for the vectorial phase conjugation using resonant four-wave mixing (FWM) in a highly degenerate rotational vibrational molecular system. The dynamic Stark shifts, saturation, and Doppler broadening are included for a realistic analysis. It is shown that the electromagnetically induced multilevel coherence controls the nonlinear wave mixing yielding interesting results for the phase conjugate (PC) reflectivity. It turns out that the efficiency of the PC reflectivity is decided by the relative phase of the Zeeman coherence and the population grating. When these two contributions are aligned in phase by a small detuning of the pump frequency, a large PC reflectivity (~20%) is obtained with moderate pump intensity (~500 mW/cm2). © 2010 The American Physical Society. Source

Mukherjee A.,Infrasign LLC | Bylund Q.,Infrasign LLC | Prasanna M.,Infrasign LLC | Margalit Y.,Infrasign LLC | And 2 more authors.
Journal of Biomedical Optics | Year: 2013

First measurements of biomedical imaging using quantum cascade lasers (QCL) are presented. We report spectroscopic imaging of serum proteins using QCLs as an example for monitoring surface biocontamination. We found that dry smears of human serum can be spectroscopically imaged, identified, and quantified with high sensitivity and specificity. The core parts of the imaging platform consist of optically multiplexing three QCLs and an uncooled microbolometer camera. We show imaging of human serum proteins at 6.1, 9.25, and 9.5 μm QCLs with high sensitivity and specificity. The sensitivity limit of 3 μg/cm2 of the human serum spot was measured at an S/N = 3.The specificity of human serum detection was measured at 99% probability at a threshold of 77 μg/cm 2. We anticipate our imaging technique to be a starting point for more sophisticated biomolecular diagnostic applications. © 2013 Society of Photo-Optical Instrumentation Engineers. Source

Optically multiplexed mid-infrared laser systems and the use of such systems for detection and measurement of target materials using multispectral image analysis are disclosed. The systems and methods disclosed herein are useful for detecting and measuring materials in applications such as trace detection, medical diagnostics, medical monitoring, quality control, and high-throughput molecular recognition.

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