RMS
of samples of the output
voltage for one pixel.
Signal
to Noise ratio (S/N,
SNR)
1
Output
signal voltage range
/ output signal noise
in the dark.
Differential
S/N (dS/dN)
1
Output
signal saturation voltage
/ output signal noise
at the same signal
level.
Noise
equivalent contrast ratio
%
Noise
measured at a certain
signal level / that
signal level. Is the
ability to discriminate
between nearby levels
of intensity (1/(dS/dN)).
Dynamic
range (DR)
1
Saturation
intensity / noise equivalent
intensity. In a linear system
this is equivalent
to the S/N.
Linear
dynamic range (LDR)
1
DR,
but using the highest
intensity for which the
opto-electrical transfer
is still linear (within
bounds).
FillFactory's
dynamic range
1
Ratio
between the largest and
smallest radiation intensity
for which dS/dN is > 1.
We introduced this definition
as in some systems (film,
multipliers), the noise
in the dark is zero.
Fixed
pattern noise (FPN) or
spatial noise
mV
p/p
Static
spread of voltages of
all pixels of the array,
in the dark.
Charge
conversion factor (C
eff )
fF
The
ratio between the photo
charge at a pixel and
its output voltage. Effective
photo junction capacity.
Noise
charge (Q noise ) or
Number of noise
electrons (#e-)
C
electrons, e-
N
x C eff
N x C eff / q
Number
of noise photons (#h
n )
photons,
p
#e-/(QExFF)
Noise
equivalent power (NEP)
W
Light
power equivalent to
RMS noise in one pixel
over time: NEP = NxC
eff /t int /SR.
Specific
noise equivalent power
(NEP*)
W/sqrt(Hz)
NEP
normalized to 1 Hz
framerate: NEP* = NEP
/ sqrt(framerate),
but only in the specific
case of white noise.
Specific
detectivity (D*)
cm
sqrt(Hz)/W
NEP*
normalized to pixel
area A: D* = sqrt(A)
x sqrt(framerate) /
NEP.
Dark
current (I dark )
A
or A/cm 2
(Apparent)
photodiode current
in the dark per pixel,
or normalized per unit
area.
Dark
signal (V dark )
V
or V/s
(Apparent)
signal voltage in the
dark, due to dark current.
Autosaturation
time t auto
s
Integration
time where the dark
signal saturates the
pixel.
Sensitivity
in lux
lx
Lowest
environmental light
level for "good" sensor
operation.
1 W/m 2 is about
70 lux (visible light
only).
1 W/m 2 is about
180 lux (over the
full Silicon diode
band).
Spectral
response (SR)
A/W
Ratio
between photo current
and light power for
a given wavelength.
Quantum
efficiency (QE)
%
Ratio
between the number
of impinging photons
and the electrons generated.
QE = SR x h n /
q
Fill
Factor (FF)
%
Ratio
between a pixel's light
sensitive area and
its total area.
Sensitivity
Vm
2 /Ws
V/lx s
Output
[V/s] versus input
[W/m 2 ].
Output [V/s] versus
input [lx].
Instead of the analogue-domain
output the number
of post-conversion
ADC bits versus input
flux can also be
used, e.g "bits /
lx s".
ASA
/ ISO
-
Empirical
procedure to obtain
equivalent film speed.
(ISO12232)
ADC
bits
1
Number
of (useful) bits in
the digital output
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