Description: Tunable filters based on electro-optic effect have shown great potential in detecting gas concentration through obtaining its absorption spectrum. In filter-based technologies, the x-y 2D imaging is usually taken at once, while the wavelength dimension is performed by tunable filters that are mounted in front of a monochrome IR camera. Several types of tunable filters are currently available, including mechanically tuned Fabry-Perot etalon (FP filter), liquid-crystal Lyot-Ohman filters and acousto-optic filters. However, these EO tuning technologies have some shortages, such as slow tuning speed, bulky design, limited working band and small aperture. Boston Applied Technologies, Inc. (BATi) proposes a unique remote sensing system which is based on a tunable filter with under millisecond tuning time for high speed detection of gas concentration. The core part, tunable filter, of the proposed system is made of patented OptoCeramic® material. The system features high speed, wide spectral range from visible to MWIR, low cost, light weight, big aperture, and robust.

Benefits: The primary goal of the final product is to provide NASA a mobile/airborne imaging system for remote detection of gas emission source. The core technologies developed in this SBIR project, a high speed tunable filter, can also be applied to combustion research for jet engine diagnosis. By capturing emission spectrum and using multi-wavelength algorithm the 2D temperature measurement of flame can be realized at once. With proper design of multi-chamber enclosure this temperature measurement is applicable in harsh environment up to 4000F. Same approach that is used in this SBIR project for gas detection can also be applied to measurement of specie concentration in flame. In addition, the proposed tunable filter is a great candidate for general airborne hyperspectral imaging.

The proposed system itself can be used for environment monitoring, military surveillance, firefight department and homeland security. The proposed core technology, a high speed tunable filter, will find wide non-NASA applications. Generally, any measurement requires fast acquisition of x-y 2D cube data is a potential application of this filter. For example, it can be used for high temperature measurement, which is a useful means for kilns, the steel and iron industries to monitor temperatures throughout the product making process. 2D spectral data is also desirable in clinical applications such as in vivo skin cancer diagnosis, hemoglobin dynamic monitoring, and pathological analysis.