© 2016 Thorlabs Scientific Imaging
2 Camera Basics
33
2.3.5 Shutter Methods
Global shutter
Rolling shutter
Rolling shutter with global start
Note
Note on the schematic diagrams: These illustrations show a schematic view of the image capture
sequence. The sensor exposure and readout times and the transmission times depend on the
camera model and settings.
For more information on flash timing see the Digital In-/Output (Trigger/Flash) chapter.
General
The image is recorded in the sensor in four phases:
Reset pixels of the rows to be exposed
Exposure of pixel rows
Charge transfer to sensor
Data readout
The sensor cells must not be exposed during the readout process. The sensors of the DCx
Cameras have no mechanical shutters, but work with electronic shutter methods instead.
Depending on the sensor type, either the rolling shutter method or the global shutter method is
used.
Global shutter
On a global shutter sensor, all pixel rows are reset and then exposed simultaneously. At the end of
the exposure, all rows are simultaneously moved to a darkened area of the sensor. The pixels are
then read out row by row.
Exposing all pixels simultaneously has the advantage that fast-moving objects can be captured
without geometric distortions. Sensors that use the global shutter system are more complex in
design than rolling shutter sensors.
All CCD sensors as well as some CMOS sensors use the global shutter method.
Global shutter sensor in live mode
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