Monitoring Multiple Volatile Organic Compounds with Cost Effective Optical Remote Sensing Instrumentation

Future air pollution monitors must become widely deployed and have the ability to monitor continuously in real time. To be widely deployed, they must be inexpensive and monitor multiple species with one sensor. Currently, each sensor must be uniquely developed (and uniquely different) for each species being studied. This increases sensor cost, limiting the sensor's availability and utility. One method to dramatically reduce the cost associated with air quality sensors is to develop a sensor technology whereby all sensors share a large degree of commonality in hardware, software, manufacturing, and calibration. The economy of scale provided by largely equivalent sensors will enable these devices to be economically mass produced. The success of the U.S. Environmental Protection Agency's Residual Risk Program (which addresses the serious impacts of hazardous air pollutants) will be based largely on achieving widely distributed (and inexpensive) monitoring technologies. Ophir Corporation proposes to develop a correlation spectrometer based on synthetic spectra gratings to addresses this critical need. Ophir's method utilizes broadband infrared sources, eliminating specific lasers or light-emitting diodes for every different trace gas of interest. The goal of this Phase I research project is to prove the concept of combining Ophir's proven long-path (fenceline), active correlation spectrometer method with synthetic spectra gratings. Synthetic spectra gratings are an important, enabling technology. They enable many gases to be monitored in real time using a single sensor, and they can be economically mass produced. This research will provide the first demonstration of long-path, open atmosphere measurements of trace gas pollutants based on active, synthetic spectra correlation radiometry. This research project includes a laboratory demonstration of the detection of toluene using a synthetic spectrum grating. In addition, Phase I will focus on the design and performance assessment of a prototype sensor for Phase II construction and testing. The prototype sensor design will accommodate the detection of many volatile organic compounds in real time from a single sensor. Cost-effective trace gas sensors (with a high degree of hardware, manufacturing, and calibration commonality) that can be mass produced will find strong market support. The economy of scale provided by highly common sensors will provide low-cost sensors for industrial, chemical, air quality, leak detection, and compliance applications.