An Adaptive Focal Plane Array (AFPA) device that enables a "chip scale" imaging spectrometer is being developed. The AFPA device consists of an array of MEMS tunable filters that is intimately coupled to a dual band IR FPA. The MEMS filters provide narrowband tuning in the LWIR and simultaneous broadband imaging in the MWIR. Each filter element can be independently tuned. In the current design, each filter tunes the wavelength of pixel subarrays. Ultimately, filter size will be reduced to achieve independent wavelength tunability for each pixel element.
This unique architecture of an AFPA device enables adaptive spectral analysis of the scene. Rather than collecting the complete hyperspectral cube, methods being developed 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. The analyzed LWIR spectral information may then be overlaid with a pixel registered high resolution MWIR image.
The investigation of the InAs/Ga1-xInxSb strained layer superlattice (SLS) has been largely motivated by the promise of overcoming limitations of current mature high-performance IR detectors, such as those using HgCdTe and extrinsic silicon. It also offers fundamentally superior performance over other newly emerging III-V bandgap- engineered materials such as QWIPs. The inherent properties of the InAs/GaInSb SLS have identified it as an attractive alternative for niche VLWIR applications requiring high performance under low backgrounds at operating temperatures > 40K. If this material system proves to meet the stringent demands of VLWIR applications, it will most certainly play a significant role as an alternative materials for photovoltaic focal pane arrays operating in the LWIR and MWIR regimes as well. This paper is an overview of SLS technology development, and focuses on critical development needs as seen from the perspective of the IR detector industry.
Conference Committee Involvement (1)
Infrared Technology and Applications XXXII
17 April 2006 | Orlando (Kissimmee), Florida, United States