Final Report: A Noncryogenic Tunable Diode Laser Monitor for On-Road Vehicle Emissions

EPA Contract Number: 68D99030
Title: A Noncryogenic Tunable Diode Laser Monitor for On-Road Vehicle Emissions
Investigators: Nelson, David D.
Small Business: Aerodyne Research Inc.
EPA Contact:
Phase: I
Project Period: September 1, 1999 through March 1, 2000
Project Amount: $70,000
RFA: Small Business Innovation Research (SBIR) - Phase I (1999) RFA Text |  Recipients Lists
Research Category: Ecological Indicators/Assessment/Restoration , SBIR - Monitoring , Small Business Innovation Research (SBIR)


Remote sensing of on-road vehicle pollutant emissions has proven to be a powerful technique for learning about real world automotive and truck emissions. Thousands of vehicles can be inspected by a single instrument during a single day. We have demonstrated a laser spectrometer which remotely senses vehicle emissions with exquisite sensitivity and selectivity. This existing instrument uses continuous wave lead salt diode lasers which are operated at cryogenic temperatures using a liquid nitrogen dewar. This use of cryogenic lasers significantly increases the construction cost of the instrument as well as its operating cost. An instrument that was free of cryogenic fluids could be significantly more compact and could be deployed more easily and less expensively. We proposed to accomplish this by using lead salt lasers operated in a pulsed current mode rather than with continuous operation.

Summary/Accomplishments (Outputs/Outcomes):

During Phase I we have proven that this approach works using quantum cascade (QC) lasers, which have only recently become available, rather than the lead salt lasers which we had originally proposed. Phase I accomplishments include: 1) the acquisition of a single mode QC laser operating near 965 cm-1, 2) the demonstration of pulsed operation of this laser with pulse widths between 10 and 100 ns and repetition rates up to 200 kHz, 3) the integration of this pulsed laser with Aerodyne's proprietary tunable diode laser data acquisition system, 4) the acquisition of laboratory spectra of ethylene and ammonia using this system, 5) the discovery of operating conditions which produced light with a narrow spectral linewidth (0.012 cm-1), 6) the integration of the QC laser with an open path optical system capable of making remote sensing measurements and 7) remote sensing measurements of ammonia emissions from several automobiles driven through the sensor.


These accomplishments significantly exceed our original Phase I objectives. In particular, we did not expect to make automotive measurements or to employ QC lasers until Phase II of this project. Our Phase I accomplishments virtually assure the successful development of a Phase II prototype instrument. The resulting instrument could approach the sensitivity of the existing instrument at a fraction of the cost and without using cryogens.

The market for such an instrument is large. For example, infrared tunable diode laser methodology will be widely implemented in state and federal emissions monitoring programs when the current research type instrument is redesigned into a less expensive, more easily operated commercial version. We have received repeated inquiries from several states encouraging us to offer a portable, compact, non-cryogenic and inexpensive version of our highly successful (and recently patented) cryogenic remote sensing instrument. We are also involved in active negotiations with companies which conduct state inspection and maintenance (I&M) programs. These companies understand the automotive I&M market and are likely commercial partners for launching this business initiative.

Supplemental Keywords:

remote sensing, automotive emissions, inspection and maintenance, quantum cascade laser., Economic, Social, & Behavioral Science Research Program, Air, Ecosystem Protection/Environmental Exposure & Risk, Sustainable Industry/Business, Technology for Sustainable Environment, Monitoring/Modeling, mobile sources, Engineering, Chemistry, & Physics, Economics & Decision Making, remote sensing, cars, monitoring, cost reduction, vehicle emissions, noncryogenic diode laser, detect, air pollution, automotive exhaust, optical sensor, spectroscopy, automobiles, electro-optic sensing, electrochemical sensor cell, trucks, diode laser, vehicular exhaust, diode laser based monitoring, measurement, electrochemical, emission sensors, sensor, sensor technology

SBIR Phase II:

A Noncryogenic Tunable Diode Laser Monitor for On-Road Vehicle Emissions  | Final Report