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FPP CCD Camera Performance. Ted Tarbell 17-Apr-2006. FPP CCD Detectors. FG CCD. FG: 4096 x 2048 pixels, thinned, back-illuminated SP: two 24 x 1024 on the same chip, front-illuminated CT: 50 x 50, front-illuminated All have 12 micron square pixels. CT CCD. SP CCD. FPP CCD Cameras.
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FPP CCD Camera Performance Ted Tarbell 17-Apr-2006
FPP CCD Detectors FG CCD • FG: 4096 x 2048 pixels, thinned, back-illuminated • SP: two 24 x 1024 on the same chip, front-illuminated • CT: 50 x 50, front-illuminated • All have 12 micron square pixels CT CCD SP CCD
FPP CCD Cameras • All cameras: • Low power, radiation resistant, cooled electronics boxes • 2.5 Mega-pixels/sec readout rate, with 12-bit A-D conversion • SP & FG detectors are cooled, CT at room temperature • FG Camera • On-chip summing of 1x1, 2x2 or 4x4 pixels • Full frame readout in 3.75 sec (1x1) or 1.9 sec (2x2) • Full frame exposure with shutter or partial frame continuous exposure in shutterless frame transfer mode • SP Camera • Continuous exposure, shutterless frame transfer mode • 112 spectral x 1024 spatial pixels on each of 2 detectors • On-chip summing of 1x2 pixels possible (spatial summing)
Linearity & Noise from Light Transfer Linearity Plot • Average intensity vs. exposure time for a constant source • There is an electronic offset at exposure time = 0 Noise Plot • Noise-squared vs. average intensity • Straight line for an ideal camera • Slope is square-root-of-N noise • Value at electronic offset = read noise
FG Gains & Read Noise Levels Results from FPP Thermal/Vacuum Test, 27 Mar 2004 FG CCD –32 C SP CEB +5 C Darks
SP Gains & Read Noise Levels Results from FPP Thermal/Vacuum Test, 8 April 2004 SP CCD –38 C SP CEB 0 C Darks
CT Gains & Read Noise Levels Results from CT CEB Checkout, 26 Nov 2003 Room Temperature Light Transfer Curves
FG & SP have Additional “ADC” Noise Before Repair After Repair
Dark Current in FG Camera • Dark Current is not measurable below about -30 deg C and is negligible below about 0 deg C • Read noise does not depend on temperature
Conclusions • Developing these cameras to meet the requirements of high readout rate, low noise, excellent linearity, low power, and radiation tolerance was a significant challenge • FG and SP have ADC noise, and SP has more readout noise than desired • Nevertheless, they meet their fundamental noise requirements • SP: 1000:1 polarimetric SNR in normal mode • FG: 200:1 SNR in single images, 500:1 pol. SNR in normal mode • CT: < 0.005 arcsecond rms error per axis in image displacement • The FG and SP cameras will be cold enough that dark current will be negligible