Dr. Gabriel Laufer Profile

Dr. Gabriel Laufer

Associate Professor at Univ of Virginia

SPIE Involvement:

Author

Publications (12)

Proceedings Article | 4 June 2011 Paper

The ChemSight: an open-path, multichemical detector for security applications

S. Holland, Gabriel Laufer

Proceedings Volume 8018, 80181R (2011) https://doi.org/10.1117/12.883861

KEYWORDS: Sensors, Infrared sensors, Detection and tracking algorithms, Absorption, Hydrogen, Cyanide, Databases, Chemical detection, Signal detection, Infrared radiation

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Proceedings Article | 10 May 2006 Paper

A low-cost chemical sensor for fixed security applications

Stephen Holland, Gregory Lewin, Robert Zehr, Jason Baker, Gabriel Laufer, Roland Krauss

Proceedings Volume 6201, 62010T (2006) https://doi.org/10.1117/12.665712

KEYWORDS: Sensors, Mahalanobis distance, Chemical analysis, Absorption, Infrared sensors, Bandpass filters, Distance measurement, Pyroelectric detectors, Algorithm development, Detection and tracking algorithms

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SPIE Journal Paper | 1 October 2005

Effect of temperature on passive remote sensing of chemicals by differential absorption radiometry

Stephen Holland, Roland Krauss, Gabriel Laufer

OE, Vol. 44, Issue 10, 106201, (October 2005) https://doi.org/10.1117/12.10.1117/1.2080760

KEYWORDS: Sensors, Signal detection, Absorption, Absorbance, Passive remote sensing, Chemical analysis, Calibration, Signal to noise ratio, Bandpass filters, Target detection

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Proceedings Article | 20 May 2005 Paper

Algorithms for chemical detection with a low-cost multi-spectral sensor

Gregory Lewin, Stephen Holland, Gabriel Laufer

Proceedings Volume 5778, (2005) https://doi.org/10.1117/12.606712

KEYWORDS: Chemical analysis, Sensors, Virtual colonoscopy, Channel projecting optics, Error analysis, Data analysis, Absorption, Chemical detection, Signal to noise ratio, Infrared sensors

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SPIE Journal Paper | 1 October 2004

Demonstration of an uncooled LiTaO₃-detector-based differential absorption radiometer for remote sensing of chemical effluents

Stephen Holland, Roland Krauss, Gabriel Laufer

OE, Vol. 43, Issue 10, (October 2004) https://doi.org/10.1117/12.10.1117/1.1782612

KEYWORDS: Sensors, Signal detection, Absorption, Pyroelectric detectors, Temperature metrology, Remote sensing, Bandpass filters, Infrared sensors, Signal to noise ratio, Target detection

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Proceedings Article | 15 September 2004 Paper

Demonstration of multispectral remote chemical sensing and identification using uncooled detectors

Stephen Holland, Roland Krauss, Gabriel Laufer

Proceedings Volume 5403, (2004) https://doi.org/10.1117/12.541200

KEYWORDS: Sensors, Remote sensing, Absorption, Absorbance, Pyroelectric detectors, Bandpass filters, Signal detection, Optical filters, Target detection, Signal to noise ratio

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Proceedings Article | 22 September 2003 Paper

Comparison of HgCdTe- and LiTaO3-detector-based differential absorption radiometers (DARs) for remote chemical effluent detection

Stephen Holland, Roland Krauss, Gabriel Laufer

Proceedings Volume 5071, (2003) https://doi.org/10.1117/12.487155

KEYWORDS: Sensors, Mercury cadmium telluride, Pyroelectric detectors, Signal to noise ratio, Signal detection, Absorption, Bandpass filters, Remote sensing, Temperature metrology, Radiometry

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The need for the development of a low-cost, low-energy, portable remote sensor of hazardous chemicals for first responders and facility protection has been recognized. Differential absorption radiometry (DAR) based on uncooled detectors has been identified as a possible solution. However, uncooled detectors have lower detectivity than cooled detectors and thus require efficient light management. Two prototype DARs, one consisting of two cryogenically cooled HgCdTe detectors and the other consisting of two LiTaO₃ pyroelectric detectors, designed to detect methanol vapor, were built and tested in the laboratory to compare their relative performance by measuring detectivity limits under controlled conditions. With ΔT = 8.3 K between the methanol vapor and a radiation source having an emissivity of ε_s = 0.92, methanol detection limits of 3.14x10^-4 atm-cm and 3.5x10^-3 atm-cm were projected for the HgCdTe and pyroelectric based DARs with similar optics, respectively, assuming that a minimum SNR less than or equal to 5 is required for positive detection and identification. Evaluation of the individual detectors in each DAR demonstrated that the detector limited noise equivalent temperature difference (NETD) for the HgCdTe detector was 381 μK whereas the detector limited NETD for the pyroelectric detector was 110 mK. With a 1 s exposure to the source, temperature fluctuations in the environment increased the NETD of the HgCdTe detector to 31.0 mK whereas the NETD of the pyroelectric detector was 115 mK. These results indicated that the advantage of the HgCdTe based DAR relative to the pyroelectric based DAR is much smaller than the advantage projected by their detector limited characteristics such as D*. Thus for remote sensing applications where cost is critical, the use of pyroelectric detectors can provide acceptable performance characteristics when the signal incident on the detector is increased only by x10 relative to the signal required for similar sensitivity using HgCdTe detectors.

Proceedings Article | 1 April 2003 Paper

Wide-field-of-view solar occultation gas filter correlation radiometer for stratospheric methane measurements from a sounding rocket

William Nunnally, Stephen Holland, Gabriel Laufer

Proceedings Volume 5073, (2003) https://doi.org/10.1117/12.486309

KEYWORDS: Rockets, Sun, Absorbance, Methane, Signal processing, Sensors, Image filtering, Radiometry, Atmospheric modeling, Optical filters

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Proceedings Article | 1 April 2003 Paper

University of Virginia suborbital remote sensor array

Keith Moored, Christina Haden, William Nunnally, Gabriel Laufer

Proceedings Volume 5073, (2003) https://doi.org/10.1117/12.487349

KEYWORDS: Sensors, Cameras, Rockets, Bandpass filters, Photodiodes, Calibration, Absorbance, Remote sensing, Atmospheric sensing, Atmospheric modeling

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An Orion sounding rocket will be launched from Wallops Flight Facility and will carry a University of Virginia payload to an altitude of 65.7 km to measure the distribution of methane in the Earth’s upper atmosphere and record images and quantitative measurements of the distribution of chlorophyll in the Metompkin Inlet, Virginia. This new payload launch will be UVa’s second launch as a result of a five-year undergraduate design project by a multi-disciplinary student group. As part of a new multi-year design course, undergraduate students designed, built, tested, and will participate in the launch of a suborbital platform from which atmospheric remote sensors and other scientific experiments can operate. The first launch included a simplified atmospheric measurement system intended to demonstrate full system operation and remote sensing capabilities during suborbital flight. The second and upcoming launch includes a methane GFCR system intended for upper atmospheric measurements, a photodiode/camera system intended for the remote sensing of chlorophyll distribution and concentration in the Metompkin Inlet due to confined animal runoff pollution. Two thermoelectrically cooled HgCdTe infrared detectors, with peak sensitivity at 3 mm, were designed to measure the methane distribution in the upper atmosphere, by having infrared radiation filtered through a methane cell and a nitrogen reference cell. A small camera with a green band-pass filter will be aligned with five photodiodes, each covered by a narrow bandpass filter that matches the filters in the SeaWiFS system, to provide cross-referencing for the remote sensing of the chlorophyll in the Metompkin Inlet and to enhance the chlorophyll distribution. This payload will serve as a platform for future atmospheric sensing experiments. Currently, the GFCR has been tested and calibrated, the chlorophyll measurement system is being calibrated, and the components and mounts are being gathered, calibrated, tested and fabricated. In the next few months, the payload will be integrated and the data reduction models will be constructed.

Proceedings Article | 15 March 2002 Paper

University of Virginia suborbital infrared sensing experiment

Stephen Holland, Clayton Nunnally, Sarah Armstrong, Gabriel Laufer

Proceedings Volume 4710, (2002) https://doi.org/10.1117/12.459616

KEYWORDS: Infrared radiation, Photodiodes, Sensors, Video, Cameras, Infrared imaging, Imaging systems, Infrared detectors, Optical filters, Temperature metrology

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Proceedings Article | 22 August 2001 Paper

Differential absorption radiometry for stand-off chemical detection

Gabriel Laufer

Proceedings Volume 4378, (2001) https://doi.org/10.1117/12.438186

KEYWORDS: Sensors, Absorption, Signal detection, Optical filters, Infrared sensors, Bandpass filters, Atmospheric sensing, Absorption filters, Target detection

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Proceedings Article | 23 March 2001 Paper

University of Virginia infrared sensor experiment (UVIRSE)

Jeffrey Dawson, Meredith Bell, Michael Powers, Gabriel Laufer

Proceedings Volume 4360, (2001) https://doi.org/10.1117/12.421052

KEYWORDS: Sensors, Infrared sensors, Rockets, Remote sensing, Absorption, Cameras, Atmospheric sensing, Methane, Photodiodes, Thermography

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Showing 5 of 12 publications

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