Tunable Fabry-Perot etalon-based long-wavelength infrared imaging spectroradiometer

Area of Science:

• Remote sensing
• Spectroscopy
• Chemical detection

Background:

• Imaging spectrometry offers passive, stand-off analysis of chemical composition.
• Existing methods require extensive data processing for species identification.

Purpose of the Study:

• To develop and demonstrate a tunable Fabry-Perot etalon-based imaging system.
• To enable selective, efficient multispectral detection of chemical vapor plumes.

Main Methods:

• Utilized a long-wavelength infrared imaging spectroradiometer with a tunable Fabry-Perot etalon and HgCdTe detector array.
• Covered the 9.5-14 micrometer spectral region with 7-9 cm(-1) resolution.
• Performed stand-off detection and quantification of chemical vapor plumes against near-ambient-temperature backgrounds.

Main Results:

• Achieved detection limits of 22 ppmv x m for dimethyl methyphosphonate and 0.6 ppmv x m for SF6 at a 6 K temperature difference.
• System noise-equivalent spectral radiance measured at approximately 2 μW cm⁻² sr⁻¹ μm⁻¹.
• Presented model calculations comparing sensor sensitivity to anticipated signal levels for chemical release scenarios.

Conclusions:

• The etalon-based imaging system allows for targeted wavelength imaging, minimizing data volume for selective species detection.
• Demonstrated the system's capability for sensitive stand-off detection and quantification of chemical vapors.
• Initial results show promising performance for environmental monitoring and threat detection applications.