Performance and application of a very high-speed 2-12 μm ultraspectral FTIR imager

Abstract

As an offshoot of hyperspectral imaging, which typically acquires tens to slightly more than 100 spectral bands, ultraspectral imaging, with typically more than 1000 bands, provides the ability to use molecular or atomic lines to identify surface or airborne contaminants. Surface Optics Corporation has developed a very high-speed Fourier Transform Infrared (FTIR) imaging system. This system operates from 2 μm to 12 μm, collecting 128 ×128 images at up to 10,000 frames-per-second. The high-speed infrared imager is able to synchronize to almost any FTIR that provides at least mirror direction and laser clock signals. FTIRs rarely produce a constant scan speed, due to the need to physically move a mirror or other optical device to introduce an optical path difference between two beams. The imager is able to track scan speed jitter, as well as changes in position of the zero path difference (ZPD) position, and perform real-time averaging if desired. Total acquisition time is dependent on the return stroke speed of the FTIR, but 16 cm -1 (1024 point) spectral imagery can be generated in less than 1/5 second , with 2 cm -1 (8192 point) spectral imagery taking proportionately longer. The imager is currently configured with X-Y position stages to investigate surface chemistry of varied objects. Details of the optical design, focal plane array, and electronics that allow this high-speed FTIR imager to function are presented. Results of using the imager for several applications are also presented.