U
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ANUAL
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34
The Full Exposure Control
In 4S Sensor Mode, the Sensor is working as a double TDI (Time Integration Delay) : The two Top
Pixels and the two bottom Pixels are working together in TDI with a delay between their exposure
and outputting by the same Memory node and ADC. The summation of the pixels is done in the
“charge domain” before the Digital Conversion.
In TDI, control of the exposure is not possible: Only the full Exposure during the Line Period is
possible. In order to allow the User to control the exposure in this 4S Sensor mode (Synchronization
Modes 1 and 3, described in the Acquisition control chapter), The Camera implement a “Full
Exposure Control Mode” :
When the User selects a synchronization mode which requires the control of the exposure, the
camera enters a specific mode:
The Line Period (measured) is
Tper
, its minimum value is
TPer
mini
(10µs on this camera) and the
exposure time set by the User is
Prog_Tint.
If Tper < Prog_Tint
Not relevant.
Prog_Tint
has to be smaller than
Tper.
The sensor is in full exposure and the gain applied on the output is
fixed b
y the User =
G
stb
(max. x4)
If Tper < 4 x Max (TPer
mini
, Prog_Tint) + 10µs
The Sensor works in Full Exposure during the whole Line Period (LP) and the gain applied on the
output is variable (max x 4), set by User =
G
stb
The Output is multiplied by the following Gain =
G
stb
x Prog_Tint / Tper
If Tper >= 4 x Max (TPer
mini
, Prog_Tint) + 10µs
The Sensor Switches in a specific 2S mode (equivalent)
The exposure is now controlled as the sensor doesn’t work in “TDI” mode.
The Exposure applied is =
4 x
Pro 1.9µs
A fixed Gain of
x2
is applied on the output to ensure the continuity with the output before the switch
Switch Point