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Description of the data path
MARLIN Technical Manual V2.4.0
67
IBIS5A multiple slope (High Dynamic Range
mode)
The MARLIN F-131 sensor has a high dynamic range of about 60 dB. This can
be extended to almost 100 dB by switching to a special mode.
This mode is called dual (in the case of rolling shutter) or multiple slope
mode (in the case of global shutter).
The following diagram, taken from FillFactory's application notes, explains
the functionality.
The colored lines represent the analogue signal on the photo diode which
decreases as a result of exposure. The slope is determined by the amount of
light at each pixel (the more light, the steeper the slope). When the pixels
reach the saturation level, the analogue signal will no longer change despite
further light exposure. As shown in the diagram, without any dual or multiple
slope pulse, pixels P3' and P4' reach saturation before the sample moment of
the analogue values.
When dual slope is enabled, a second reset pulse will be given (blue line) at
a certain time before the end of the integration time.
Figure 34: Multiple slope (high dynamic range) pixel charge as a function of time