Publications & Presentations

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.

Cost-Effective Manufacturing of Compact TDLAS Sensors for Hazardous Area Applications

Michael B. Frish, Matthew C. Laderer, Clinton J. Smith, Ryan Ehid, and Joseph Dallas
SPIE Photonics West, San Francisco, CA, February 13-18, 2016

Tunable Diode Laser Absorption Spectroscopy (TDLAS) is finding ever increasing utility for industrial process measurement and control. The technique’s sensitivity and selectivity benefit continuous concentration measurements of specific gas components in complex gas mixtures which are often laden with liquids or solid particulates.

Tradeoff options among optical path length, absorption linestrength, linewidth, cross-interferences, and sampling methodology enable sensor designers to optimize detection for specific applications. Emerging applications are demanding increasing numbers of distributed miniaturized sensors at diminishing costs. In these applications, the TDLAS specificity is a key attribute, and its high sensitivity enables novel sampling package designs with short optical pathlengths. This paper describes a miniature hermetically-sealed backscatter TDLAS transceiver package designed for high-volume production at acceptable cost. Occupying a volume less than 1in3 and weighing less than 0.06 lb, the transceiver is a key component of TDLAS sensors intended for in-situ measurements of potentially explosive gas mixtures.