Alkeria NECTA Series - Hardware Description; Sensors; Monochrome Quantum Efficiency; Color Quantum Efficiency

3. Hardware Description 30
3
Hardware Description
3.1 SENSORS
NECTA line scan cameras employ last-generation linear CMOS sensors manufactured by AMS, featur-
ing an ADC module for each pixel which allows very high-speed acquisition. The tables in Section 2.2.1
help identifying the sensor used in each camera model, indicating the resolution and size of the pixel cell;
sensors whose size is indicated by ”2x...” are made by two sensitive pixel lines, parallel and contiguous.
3.1.1 Monochrome Quantum Efciency
Figure 3.2 shows the quantum efciency of the sensors used by NECTA cameras. The graph refers to
the sensors used in monochrome variants; to derive the quantum efciency of NECTA color cameras it
is necessary to take into account also the transmittance of the Bayer lter, as reported in Section 3.1.2.
3.1.2 Color Quantum Efciency
AMS sensors discriminate colors using the Bayer color lter array shown in Figure 3.1, that makes each
pixel sensitive to only one of the primary colors. To recover the quantum efciency of a color sensor cam-
era, it is sufcient to combine the monochrome quantum efciency with the transmittance of the Bayer
lter array (Figure 3.3) for every wavelength. Solid lines in Figure 3.3 refer to the maximum achievable
transmission, dashed lines to minimum guaranteed transmission index.
0
0
1
1
G
G
R
B
G
G
R
B
G
G
R
B
G
G
R
B
2 3 4 5 n-2 n-1
Figure 3.1: Bayer pattern of color lters