ALOHA - Adaptive Large-capacity Optical-infrared High-dynamic-range Array

The proposed effort addresses a need expressed in Topic S11.04 Sensor and Detector Technologies for Visible, Infrared (IR), Far-IR, and Submillimeter, for photodiode arrays with in-pixel DROIC for high-dynamic-range IR imaging focal plane arrays to circumvent the limitations in charge capacity, by using in-pixel digital counters that can provide orders of magnitude larger effective well depth, thereby affording longer integration times needed for Earth-science applications in the infrared (IR) and far-IR regimes. The effort focusses on developing a high charge capacity ROIC optimized for sensing in the MWIR and LWIR bands, suitable for all typical detector types used for these bands, such as (but not limited to) quantum well IR photodetectors (QWIP), HgCdTe (MCT), III-V quaternary bulk detectors and strained-layer superlattice (SLS) detectors. Traditional analog pixel ROICs, although power-efficient, have charge capacity limitations due to the limit on the size of the capacitor that can be fit in a pixel. Digital pixel ROICs (DROIC) have an analog to digital converter (ADC) in the pixel to overcome the charge capacity limit, but at the expense of very high power. There are no known ROICs capable of achieving the high dynamic range requirements in NASA’s advanced earth observing missions while fitting within power budget restrictions. The proposed SAAZ ROIC will feature several innovations to address the challenge by creating an adaptive high dynamic range (HDR) digital pixel based ROIC. The SAAZ team, with extensive space mission experience, is leveraging a close working relationship with NASA to develop an optimal ROIC solution for the high flux thermal band. The proposed adaptive high dynamic range ROIC will provide the desired high well capacity, a high frame rate, a large format, space qualifiable design, while simultaneously keeping the cold space power very low, making it suitable for space missions.