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9 July 2008 Daisy chain expandable readout system for infrared arrays
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Abstract
We have developed a control system for infrared array detectors with 16, 32 or more outputs. Our system consists of five boards (clock pattern generator, clock driver, A/D converter, parallel-in, and isolation), and is operated with a Linux (kernel 2.4 or 2.6) PC. It is capable of supplying 24 DC bias voltages and 16 clock voltages, adjustable between -7.5V and +7.5V and the shortest clock width of 156 ns. One A/D board converts 16 analog array outputs to digital data simultaneously using 16 A/D converters. The rms of A/D conversions for fixed voltages is 2-3 ADU (or 150-200 μV) at a sampling rate of 250 kSPS. The parallel-in board has 32 optically isolated input channels, and can receive data from 2 A/D boards simultaneously. The maximum data rate to main memory of PC is 40 MB/sec, corresponding to 20 frames/sec of a 1024×1024 array. Our system is now utilized for Aladdin 2 (InSb, 1024×1024, 32 outputs) of Wide Field Cryogenic Telescope 2 and SB-774 (Si:As, 320×240, 16 outputs) of 17μm Fabry-Perot spectrometer. The A/D boards have daisy-chain capability for next generation arrays with more than 32 outputs. In the daisy-chain mode, all A/D converters are triggered simultaneously, but the A/D boards make time-delayed data transfer. The parallel-in board receives data sequentially by every 32 A/D converters. When we apply our system for 2048×2048 detectors with 64 outputs, the frame rate will be 5 frames/sec.
© (2008) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Takahiro Nagayama and Kentaro Haraguchi "Daisy chain expandable readout system for infrared arrays", Proc. SPIE 7014, Ground-based and Airborne Instrumentation for Astronomy II, 70146R (9 July 2008); https://doi.org/10.1117/12.789194
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