Adaptive focal plane array: an example of MEMS, photonics, and electronics integration

Abstract

The effectiveness of infrared imaging sensors for target detection and identification can be greatly enhanced by adding spectral analysis capability. Unfortunately, this usually comes with the penalties of increased size, weight, and significantly increased computational requirements, which limit the rate at which information can be made available to the user. By integrating MEMS, photonics and electronics technologies, a new type of staring spectral imager can be realized. An Adaptive Focal Plane Array (AFPA) device is being developed under DARPA sponsorship that consists of an array of MEMS tunable Fabry-Perot filters, hybridized with a dual band IR focal plane array. The MEMS filters will provide narrowband tuning in the LWIR (8.0-10.7 mm) and simultaneous broadband imaging in the MWIR (3-5 mm). Individual filter elements will be on the size scale of a small number of detector pixels. Each filter will be independently electrically addressable, enabling tailored spectral analysis of different regions in the scene. Rather than collecting the complete hyperspectral cube, work is focusing on methods that will enable selection of spatially optimized spectral band sets for a variety of targets and materials that are selected on-the-fly to maximize the contrast between the local background and the target or material to be identified. This paper discusses the structure and status of the AFPA device and highlights some unique challenges inherent in the integration of MEMS, photonics and electronics technologies.