Linear Photodiode Array
Imagers
Description (cont.)
Figure 2a: Spectral Sensitivity Curve
100
90
80
70
60
50
40
30
20
10
0
250
350
450
550
650
750
850
950
1050
100
90
Right Scale
80
70
60
50
40
QE (%)
Responsivity (V/ J/cm
2
)
P-series imagers combine high-perfor-
mance photodiodes with high-speed
CCD readout registers and a high-
sensitivity readout amplifier. Refer
to Figure 1 for construction details.
Left Scale
30
20
10
0
Light Detection Area
The light detection area in P-series
imagers is a linear array of contiguous
pinned photodiodes on 14 µm centers.
These photodiodes are constructed
using PerkinElmer’s advanced photo-
diode design that extends short-wave-
length sensitivity into the deep UV
below 250 nm, while preserving 100%
fill factor and delivering extremely
low image lag. This unique design
also avoids polysilicon layers in the
light detection area that reduces the
quantum efficiency of most CCD
imagers. The P-series imagers are sup-
plied with glass windows for general
visible use, and fused silica windows
for use in the ultraviolet below 350 nm.
See Figure 2 for the sensitivity and
window transmission curves.
For lowest lag, all P-series imagers
feature pinned photodiodes. Pinning,
which requires a special semiconduc-
tor process step, provides a uniform
internal voltage reference for the
charge stored in every photodiode.
This stable reference assures that
every photodiode is fully discharged
after every scan.
Wavelength (nm)
Figure 2b: Window Transmission Curve
100
90
80
Fused Silica
Transmission (%)
70
60
50
40
30
20
10
0
150
250
350
450
550
650
750
850
950
1050
Glass
Wavelength (nm)
Photodiodes covered with light
shields included at one or both ends
of the imager provide a dark current
reference for clamping. These are
separated from the active photodi-
odes by two unshielded transition
pixels that assure uniform response
out to the last active photodiode.
Due to the potential for light leak-
age, the two dark pixels nearest
the transition pixels should not
be used as a dark reference.
Figure 1: Imager Functional Diagram
N = 512 for the RL0512P
N = 1024 for the RL1024P
N = 2048 for the RL2048P
3
10
2
N
2
10
Isolation stages
Dark pixels (D1 ... D10)
Transition pixels (T1, T2)
(Light shield ends between D10 and T1)
Active pixels (1...N)
Transition pixels (T3, T4)
(Light shield ends between T4 and D11)
Dark pixels (D11...D20) (Not used in RL0512P)
Antiblooming/Exposure Control Gate
D1 . . . . . . . . . . . . . . . . . . . .D10
T1 T2 1 2 3
. . . . . . . . .
N-1
N T3 T4 D11 . . . . . . . . . . . . . . . . . . . .D20
Transfer Gate
Output
2-Phase Buried Channel CCD Shift Register
{
3 CCD Isolation Stages
Amp
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DSP-101 01H - 7/2002W Page 2
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