Publications & Presentations

Advanced LWIR hyperspectral sensor for on-the-move proximal detection of liquid/solid contaminants on surfaces

Jay P. Giblin, John Dixon, Julia R. Dupuis, Bogdan R. Cosofret, William J. Marinelli
SPIE Defense and Commercial Sensing
Anaheim, CA, 9 - 13 April 2017
(SPIE Paper No. 10183-4)

Sensor technologies capable of detecting low vapor pressure liquid surface contaminants, as well as solids, in a noncontact fashion while on-the-move continues to be an important need for the U.S. Army.

In this paper, we discuss the development of a long-wave infrared (LWIR, 8-10.5 μm) spatial heterodyne spectrometer coupled with an LWIR illuminator and an automated detection algorithm for detection of surface contaminants from a moving vehicle. The system is designed to detect surface contaminants by repetitively collecting LWIR reflectance spectra of the ground. Detection and identification of surface contaminants is based on spectral correlation of the measured LWIR ground reflectance spectra with high fidelity library spectra and the system’s cumulative binary detection response from the sampled ground. We present the concepts of the detection algorithm through a discussion of the system signal model. In addition, we present reflectance spectra of surfaces contaminated with a liquid CWA simulant, triethyl phosphate (TEP), and a solid simulant, acetaminophen acquired while the sensor was stationary and on-the-move. Surfaces included CARC painted steel, asphalt, concrete, and sand. The data collected was analyzed to determine the probability of detecting 800 μm diameter contaminant particles at a 0.5 g/m2 areal density with the SHSCAD traversing a surface

Scanning, standoff TDLAS leak imaging and quantification

Richard T. Wainner, Nicholas F. Aubut, Matthew C. Laderer, Michael B. Frish
SPIE Commercial & Scientific Sensing and Imaging Conference
Next Generation Spectroscopic Technologies X
Anaheim, California
9 - 13 April 2017
SPIE Paper No. 10210-5

This paper reports a novel quantitative gas plume imaging tool, based on active near-infrared Backscatter Tunable Diode Laser Absorption Spectroscopy (b-TDLAS) technology, designed for upstream natural gas leak applications.

The new tool integrates low-cost laser sensors with video cameras to create a highly sensitive gas plume imager that also quantifies emission rate, all in a lightweight handheld ergonomic package. It is intended to serve as a lower-cost, higherperformance, enhanced functionality replacement for traditional passive non-quantitative mid-infrared Optical Gas Imagers (OGI) which are utilized by industry to comply with natural gas infrastructure Leak Detection and Repair (LDAR) requirements. It addresses the need for reliable, robust, low-cost sensors to detect and image methane leaks, and to quantify leak emission rates, focusing on inspections of upstream oil and gas operations, such as well pads, compressors, and gas plants. It provides: 1) Colorized quantified images of path-integrated methane concentration. The images depict methane plumes (otherwise invisible to the eye) actively interrogated by the laser beam overlaid on a visible camera image of the background. The detection sensitivity exceeds passive OGI, thus simplifying the manual task of leak detection and location; and 2) Data and algorithms for using the quantitative information gathered by the active detection technique to deduce plume flux (i.e. methane emission rate). This key capability will enable operators to prioritize leak repairs and thereby minimize the value of lost product, as well as to quantify and minimize greenhouse gas emissions, using a tool that meets EPA LDAR imaging equipment requirements.

Emerging Mobile and Airborne TDLAS Sensors for Natural Gas Leak Quantification

Mickey B. Frish
Presented at:

Miniaturized and Mobile Spectroscopy and Optical Sensor Applications

SPIE Defense and Commercial Sensing Conference
Anaheim, CA, 12 April 2017

Natural Gas is 90% Methane, A Potent Greenhouse Gas. Maintaining system security and integrity is a continual process of searching for, locating, and repairing leaks. PSI's Portable Standoff near-IR TDLAS
for Leak Survey.

Methane Leak Surveying with Small Unmanned Aerial Systems

Mickey Frish
The Woodlands, TX, 7 October 2015

RMLD™ Sentry combines state-of-the art technologies to achieve MONITOR flux measurement goals
- Backscatter TDLAS based on PSI/Heath Remote Laser Leak Detector (RMLD™) and RMLD™ Pipeline Monitor
- Miniature Autonomous Quadrotor Unmanned Aerial Vehicle: PSI’s InstantEye®
- Leak detection, localization, and mass flux quantification algorithms

OCT-based whole eye biometry system

Mujat, Mircea; Patel, Ankit; Maguluri, Gopi; Iftimia, Nicusor V.; Akula, James D.; Fulton, Anne B.; Ferguson, R D.
ARVO 2016 - Advancement in OCT, May 1-5, 2016, Seattle, WA

Purpose: To demonstrate a new dual-conjugate, dual-band approach to whole eye optical biometry. The flexibility and utility of such a system for wide-field measurements and diagnostics far exceeding axial lengths and thicknesses, and IOL power calculations is anticipated to make it commercially viable in many research and clinical applications.

Methods: That system was based upon an ellipsoidal optical scanning/imaging design that produces near-normal incidence scans over large patches of the eye’s surface for efficient profiling and corneal/scleral surface stitching. This method permits simultaneous imaging of pairs of ocular surfaces with respect to the scan pivot point (the system pupil), by integration of dual-conjugate optics. Coordinated dual-reference arms enable ranging to these two focal surfaces at precisely known locations with respect to the scan pivot, and to each other, on a single SDOCT spectrometer without imposing extreme requirements on the axial imaging range. Direct imaging of the eye through the reflective scan optics allows the system pupil/pivot location to be precisely positioned by the operator, while the eye’s position and orientation are monitored by a camera and controlled by a fixation display.
Results: The method has been initially demonstrated with a single imaging system by changing the beam focus and the scanning pivoting point and measuring various eye surfaces sequentially. Typical results for large area scans of cornea, iris and top of lens, and retina are shown in Fig. 1.
Conclusions: Our preliminary corneal/scleral, lenticular and retinal imaging demonstrations (performed at safe light levels for retinal imaging under NEIRB human subjects protocols) have shown coordinated optical delays and focal conjugate zoom control produce high quality SDOCT images ranging throughout the whole eye. Simultaneous measurement of anterior and posterior ocular anatomic structures and surfaces, and their precise spatial relationship to each other over wide angles, is feasible with a two-channel, dual-conjugate non-contact optical ocular biometry system in the optically accessible regions of the eye.