Solar-B SOT/FPP 1 SOT April 2006Ted Tarbell FPP CCD Camera Performance Ted Tarbell 17-Apr-2006
Solar-B SOT/FPP 2 SOT April 2006Ted Tarbell FPP CCD Detectors 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 FG CCD CT CCD SP CCD
Solar-B SOT/FPP 3 SOT April 2006Ted Tarbell 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)
Solar-B SOT/FPP 4 SOT April 2006Ted Tarbell 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
Solar-B SOT/FPP 5 SOT April 2006Ted Tarbell FG Gains & Read Noise Levels GainElectrons/DNRead Noise (DN) Read Noise (e) Prime Prime Prime Prime Red Red Red Red Results from FPP Thermal/Vacuum Test, 27 Mar 2004 FG CCD –32 C SP CEB +5 C Darks
Solar-B SOT/FPP 6 SOT April 2006Ted Tarbell SP Gains & Read Noise Levels GainElectrons/DNRead Noise (DN) Read Noise (e) Prime Prime Prime Prime Red Red Red Red Results from FPP Thermal/Vacuum Test, 8 April 2004 SP CCD –38 C SP CEB 0 C Darks
Solar-B SOT/FPP 7 SOT April 2006Ted Tarbell CT Gains & Read Noise Levels GainElectrons/DNRead Noise (DN) Read Noise (e) Prime Prime Prime Prime Red Red Red Red Results from CT CEB Checkout, 26 Nov 2003 Room Temperature Light Transfer Curves
Solar-B SOT/FPP 8 SOT April 2006Ted Tarbell FG & SP have Additional “ADC” Noise Before Repair After Repair
Solar-B SOT/FPP 9 SOT April 2006Ted Tarbell 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
Solar-B SOT/FPP 10 SOT April 2006Ted Tarbell Orbital Temperature Variation
Solar-B SOT/FPP 11 SOT April 2006Ted Tarbell 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: < arcsecond rms error per axis in image displacement The FG and SP cameras will be cold enough that dark current will be negligible