FPP CCD Camera Performance

1
FPP CCD Camera Performance

• Ted Tarbell
• 17-Apr-2006

2
FPP CCD Detectors
FG CCD
CT CCD
SP 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

3
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)

4
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

5
FG Gains Read Noise Levels
Results from FPP Thermal/Vacuum Test, 27 Mar 2004
FG CCD 32 C SP CEB 5 C Darks
6
SP Gains Read Noise Levels
Results from FPP Thermal/Vacuum Test, 8 April
2004 SP CCD 38 C SP CEB 0 C Darks
7
CT Gains Read Noise Levels
Results from CT CEB Checkout, 26 Nov 2003
Room Temperature Light Transfer Curves
8
FG SP have Additional ADC Noise
Before Repair
After Repair
9
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

10
Orbital Temperature Variation
11
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 10001 polarimetric SNR in normal mode
• FG 2001 SNR in single images, 5001 pol. SNR
  in normal mode
• CT lt 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