version 2.0 rev 18 Feb 2021
27
2.5.2 Pixel Readout Rate
The Pixel Readout Rate defines the rate at which pixels are read from the sensor. The faster the readout rate
the higher the frame rate that can be achieved. The ability to change the pixel readout rate is important to
achieve the maximum flexibility of camera operation.
Slower readout typically allows lower read noise but at the expense of slower frame rates. The following
readout rates are available on the Zyla (
below shows the typical read noise at each readout rate):
•
Zyla 5.5
: 200 MHz (100 MHz x 2 halves) and 560 MHz (280 MHz x 2 halves)
•
Zyla 4.2
: 216 MHz (108 MHz x 2 halves) and 540 MHz (270 MHz x 2 halves)
Table 7: Typical Read Noise for Rolling and Global Shutter modes
Model
Rate
Read noise (e
-
) Rolling Shutter (typical)
Read noise (e
-
) Global Shutter (typical)
Zyla 5.5
200 MHz
1.2
2.6
560 MHz
1.45
2.6
Zyla 4.2
216 MHz
0.9
N/A
540 MHz
1.1
N/A
Please refer to
Section 2.3
for more information on read noise and the camera performance sheet for read
noise values at the various readout speeds.
2.5.3 ROI Sub-Image Settings
ROI Sub Image
allows for readout of a particular sub-area of the sensor. When a sub image has been defined,
only data from the selected rows will be digitized.
Selecting a sub image increases the frame readout rate and reduces image storage requirements. Examples of
sub-image selection and spooling rates are shown in
Table 7
.
It should be noted that for small ROIs (e.g. < 512 x 512 pixels), the achievable frame rate for 3-tap and 10-tap
becomes identical. This is due to the fact that the amount of data transmitted across the Camera Link interface
for these ROIs is relatively small and the limiting factor becomes the rate at which data can be read off the
sensor.
It should also be noted that while ROIs can also be set up for any area of the sensor, those which are vertically
centred on the sensor mid line will result in the maximum frame rates.
Summary of Contents for Zyla sCMOS 4.2 PLUS
Page 76: ...version 2 0 rev 18 Feb 2021 76...
