Development of a Miniature Snapshot Multispectral Imager

Report No. ARL-TR-5320
Authors: Neelam Gupta, Philip R. Asheb, and Songsheng Tan
Date/Pages: September 2010; 34 pages
Abstract: We present a miniature snapshot multispectral imager that operates in the short wavelength infrared (SWIR) region and has a number of applications. The system is low weight and portable with a miniature platform, and requires low power. The imager uses a 4¿4 Fabry-Perot filter array operating from 1487 to 1769 nm with a spectral bandpass ~10 nm. The design of the filters is based on using a microelectromechanical system (MEMS) shadow mask technique to fabricate a Fabry-Perot etalon with multilayer dielectric mirrors. The filter array subsystem is installed in a commercial handheld indium gallium arsenide (InGaAs) camera, replacing the imaging lens with a custom designed 4¿4 microlens array with telecentric imaging performance in each of the 16 sub imaging channels. We imaged several indoor and outdoor scenes. The microlens optics and filter design is quite flexible and can be tailored for any wavelength region from ultraviolet (UV) to longwave infrared (LWIR) and the spectral bandpass can also be customized to meet requirements. In this report, we discuss the design and characterization of the filter array, microlens optical package, and imager and present the imaging results. A main motivation behind development of such a compact imager is to be able to detect chemicals used in improvised explosive devices (IEDs).
Distribution: Approved for public release
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Last Update / Reviewed: September 1, 2010