Lumenera Lt-C1610, User Manual

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54 • Model Specifications Teledyne Lumenera Lt Series
3.20.1 Overview of Electronic Rolling Shutter (ERS)
Exposures
Referring to the following graphic:
•
Each sensor line is exposed for the programmed time integration period.
•
Exposures start with Line 1. The sensor design uses a shared line readout circuit. Due to this
simplified circuitry, only a single line of pixel data can be readout at any given time. Therefore,
the line 2 exposure (integration period) is delayed by the required readout time of line 1.
•
This delayed line exposure is repeated from the sensor’s first line to its last sensor line.
• This sequence allows the common readout circuit to read the data from each row. This results
in an exposure start time delay between the first to last row – thus the name rolling shutter.
• To avoid motion artifacts the user needs to freeze motion using flash lighting of suitable length
in a dark environment. The flash is triggered at the start of the last line’s exposure and stops at
the end of the first line’s exposure. The flash must maintain a constant light output during this
period.
• To control the flash device, use the Lt output signal with these feature selections:
outputLineSource=PulseOnStartofExposure, outputLinePulseDelay=flashZoneDelay (delay to
the start of the last line exposure), outputLinePulseDuration=flashZoneDuration (optimal
flash zone time as shown in the graphic below).
•
The two new features mentioned, flashZoneDelay and flashZoneDuration, automatically
provide the optimal flash zone time values no matter the exposure duration and any vertical
cropping/offset settings. The user is free to use any delay or duration as required. See
Strobe and Flash Zone (Lt-3840, Lt-5500) for settings.
•
The dark environment illumination ensures minimal exposure (and thus minimal motion
artifacts) during the sensor lines integration time occurring before and after the flash period.