1.2 CCD Operations, Performance Parameters, and
CCD
Transfer Curves
Low-light-level CCD performance parameters are grouped into four primary
CCD operations: 1) Charge Generation (e.g. QE), 2) Charge Collection (e.g. MTF), 3) Charge
Transfer (e.g. CTE), and 4) Charge Detection (e.g. Read Noise). Table 1.2 contains the
four principle CCD operations required for low light level imaging, the performance
parameters that comprise each operation, the CCD Transfer Curve(s) used to measure each
parameter, and a list of influencing variables.
Table 1.2. Four Basic CCD Operations and
Associated Performance Parameters and CCD Transfer Curves Used to Measure Performance
1.2-1. Charge Generation Performance Parameters
and CCD Transfer Curve Tests
| Performance Parameter |
Units |
CCD Transfer Curve |
Variables |
| 1. Quantum Efficiency
(QE) |
Interacting Photons/ Incident Photons |
QE Transfer |
Wavelength, Temperature |
| 2. Quantum Efficiency
Hysterisis (QEH) |
% modulation |
Modulation Transfer |
Clock Bias |
| 1.2-2.
Charge Collection Performance Parameters and CCD Transfer Curve Tests |
| Performance
Parameter |
Units |
CCD
Transfer Curve |
Variables |
| 3. Pixel
Non-Uniformity |
% rms.
variation |
Photon
Transfer |
Clock Bias |
| 4. Modulation Transfer
Function (MTF) |
% modulation |
Modulation Transfer |
Clock Bias |
1.2-3. Charge Transfer Performance Parameters
and CCD Transfer Curve Tests
| Performance
Parameter |
Units |
CCD
Transfer Curve |
Variables |
| 5. Global CTE (CTEG) |
Fraction of charge
transferred |
CTE Transfer |
Charge Package Size,
Temperature, Clock Rate and Bias, Clock Overlap |
| 6. Local CTE (CTEL) |
Fraction of charge
transferred |
Bar Target Transfer |
Charge Package Size,
Temperature, Cock Rate and Bias, Clock Overlap |
| 7. Vertical Register
Well Capacity |
Electrons |
Photon Transfer Full Well Transfer |
Clock Bias, Clock Rate |
| 8. Horizontal Register
Well Capacity |
Electrons |
Photon Transfer Full Well Transfer |
Clock Bias, Clock Rate |
1.2-4. Charge Detection Performance Parameters
and CCD Transfer Curve Tests
| Performance
Parameter |
Units |
CCD
Transfer Curve |
Variables |
| 9. Node Sensitivity
(Sv) |
V/e- |
Photon Transfer |
Temperature |
|
Amplifier Time Constant
|
Sec |
Video Transfer |
Output Capacitance |
|
Linearity (g )
|
% |
Linearity Transfer |
On-chip Amp Bias, Signal
Processing Chain |
|
Read Noise
|
Electrons rms. |
Photon Transfer X-ray Transfer |
Signal Processing/Analog
Chain |
|
Dark Current Noise
|
Electrons rms. |
Dark Current Transfer |
Temperature |
|
Spurious Charge
|
Electrons rms. |
Photon Transfer X-ray Transfer |
Clock Bias and Edges |
|
Dark Cosmetics
|
Electrons/sec |
Dark Transfer |
Temperature |
|
Residual Image
|
Electrons |
Dark Transfer |
Temperature, Signal,
Integration and Read Time |
|
