Parameters of CCD and CMOS cameras
by Christian Buil
This page gives the optoelectronic parameters measured by the author of some models of popular cameras used for astronomical observation.
For measurement of quantum efficiency (QE = quantum efficiency) I used as a reference the adapted value of the efficiency given by the manufacturer at the peak of sensitivity for the sensor KAF-3200ME (Kodak). With this exception, all profiles are derived from data measured by the author using spectrographs (Lhires III, Alpy 600) and stable light sources.
Note that I always give the « apparent » quantum efficiency (taking into account the windows of the camera and the protection window of the detector itself). The absolute quantum yields displayed are therefore not strictly that of the detector alone, but the gap is quite small (slight under-evaluation of a few percent).
The electronic gain (in electrons/ADU (e-/ADU) is given by the formulae:
where B is the mean value signal (in ADU) for a given area of a bias image, F is the mean value of the signal of the same area for a flat-field image (in ADU), σ(B1-B2) is the standard deviation of the pixels signal in the area of the difference of two bias images, σ(F1-F2) is the standard deviation of the pixels signal in the area of the différence of two flat field images.
The external camera (include detector) readout noise (RON) in electrons is given by:
The dark signal rate, in electrons/s/pixel, is given by:
where σADU is the standard deviation observed in the difference of two dark frame exposed each T seconds.
KAF-3200ME (test camera : QSI 532)
Origin : Kodak
Type : CCD
Shutter type : global shutter
Number of pixel : 2184 x 1742
Pixel size : 6.80 microns
Electronic gain (G) : 1.413 e-/ADU
Read Out Noise (RON) : 12.6 e-
Dark signal at 0°C : 0.080 e-/s/pixel
Quantum Efficiency at 6563 A : 79%
Digital coding : 16 bits
Apparent charge capacity : 70000 e-
ICX694AGL (test camera : ATIK 460EX)
Origin : Sony
Type : CCD
Shutter type : global shutter
Number of pixel : 2749 x 2199
Pixel size : 4.54 microns
Electronic gain (G) : 0.276 e-/ADU
Read Out Noise (RON) : 5.8 e-
Dark signal at 0°C : 0.0065 e-/s/pixel
Dark signal at -20°C : 0.0014 e-/s/pixel
Quantum Efficiency at 6563 A : 58%
Digital coding : 16 bits
Apparent charge capacity : 18000 e-
MN34230PL (test camera : ASI1600MM)
Origin : Panasonic
Type : CMOS
Shutter type : rolling shutter
Number of pixel : 4656 x 3520
Pixel size : 3.80 microns
Electronic gain (G) : 0.477 e-/ADU (g = 20 dB)
Read Out Noise (RON) : 1.4 e- (g = 20 dB)
Dark signal at 0°C : 0.042 e-/s/pixel
Dark signal at -20°C : 0.010 e-/s/pixel
Quantum Efficiency at 6563 A : 39%
Digital coding : 12 bits
Apparent charge capacity : 1950e-
MN34230PL (test camera : ASI1600MC)
Origin : Panasonic
Type : CMOS (CFA version)
Shutter type : rolling shutter
Number of pixel : 4656 x 3520
Pixel size : 3.80 microns
Electronic gain ( g = 20 dB) :
- Red channel : 0.460 e-/ADU
- Green channel : 0.460 e-/ADU
- Bleu channel : 0.255 e-/ADU
Read Out Noise (RON) : 1.4 e- (g = 20 dB)
Quantum Efficiency at 6563 A : 34%
Digital coding : 12 bits
Apparent charge capacity : 1950e-
IMX290 (test camera : ASI290MM)
Origin : Sony
Type : CMOS (back illuminated)
Shutter type : rolling shutter
Number of pixel : 1936 x 1096
Pixel size : 2.90 microns
Electronic gain ( g = 20 dB) : 0.373 e-/ADU
Electronic gain (g = 40 dB) : 0.037 e-/ADU
Read Out Noise (RON) : 1.26 e- (g = 20 dB)
Read Out Noise (RON) : 0.99 e- (g = 40 dB)
Quantum Efficiency at 6563 A : 67%
Digital coding : 12 bits
