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6.3.3 GLOBAL SHUTTER
First, all pixels are globally reset and these reset values are shifted
into so-called diffusion nodes. From there, they are non-destructively
read out into memory as reset dark images. The exposure starts after
transfer of the reset dark image to the diffusion nodes, where they are
stored on the chip. The exposure is stopped by global charge transfer
to the diffusion nodes. Then, the exposure image is read out to the
memory, where the former reset dark image is subtracted to perform
an external correlated double sampling, which reduces the noise.
Since two images have to be read out to receive one resulting image,
the sCMOS image sensor’s Global Shutter mode has only half of the
frame rate of the Rolling Shutter mode.
Reset Exposure Readout
Timing
The exposure and delay time can be adjusted in steps of one line
time (see 1.2).
Camera (Global Shutter) Exposure time Delay time
0 µs … 1 s
pco.edge 5.5 Camera Link HS
FPS based (only edge 5.5 Camera Link)
The camera will optimize the image recording to achieve the selected
frame rate with chosen exposure time as close as possible.
Only for Auto Sequence trigger mode and only available with
Camera Link Interface.
First the frame rate is set. If the time required for readout of the image
is longer than 1 / frame rate, then the frame rate will be reduced to
1 / t
readout
. Minimum frame rate is 1 / max. exposure time.
The frame rate can be adjusted in steps of 1 mHz (Global Shutter).
If the selected exposure time would require a lower frame rate, the
exposure time is cut to the maximum possible time at that frame rate.
Camera Frame rate (FPS Based) Exposure time
pco.edge 5.5 Camera Link
10 … 50 fps @ 286 MHz 10 µs … 100 ms
Global Shutter is not
available for pco.edge
4.2 (all interfaces).
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