Graded Interference Filter Spectrometer

The release of volatile organic compounds (VOCs) from industrial processes can have negative impacts on the environment while also posing significant health and safety concerns. In the environment, many of these chemicals are considered precursors to ground-level ozone, which is the primary component of smog. In addition, many VOCs are cancer-causing in humans while others pose dangerous explosion hazards. These chemicals are used or produced in a variety of industries, including the chemical, automotive, and semiconductor industries. Although chemical recovery and waste treatment strategies are employed to reduce the emissions of VOCs, there is a strong need for a low-cost, compact sensor that can quickly and reliably identify leaks in the facility process line. Infrared spectroscopy is an excellent method for the analysis of VOCs; however, infrared spectrometers are complex instruments that are too expensive and physically bulky for leak detection applications where low cost, portability, and maneuverability are critical. Advanced Fuel Research, Inc. proposes to develop a low-cost, very compact infrared spectrometer based on a novel graded interference filter, in combination with an infrared microbolometer focal plane array detector. Phase I will fabricate the graded interference filter. A prototype spectrometer then will be assembled with the filter coupled to a microbolometer focal plane array. Gas-phase measurements will demonstrate the spectral accuracy and resolution of the instrument. Phase II will result in a complete infrared spectral sensor covering the mid- and long-wavelength infrared regions, including the analysis algorithms and light-gathering optics for remote chemical sensing. In addition to applications as a remote VOC leak detector, the technology developed in this program will have applications for gas sensing in process monitoring and control, and in continuous emissions monitoring.