Teledyne ProEM Series, System Manual

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84 ProEM System Manual Issue 3
Example 2: Frame Transfer Mode when Exposure Time > Readout Time
If the exposure time is set to 50 ms with the readout time remaining at 30 ms, the time
taken to acquire 3 frames will be 180 ms (3 x 50 ms + 30 ms), which is equivalent to a
frame rate of 16.67 fps.
See
Figure 5-21 .
Figure 5-21: Timing Diagram for Frame Transfer Mode when
In Frame Transfer mode when exposure time > readout time, the total time (TN) taken
to capture N frames is expressed as:
T
N
= (t
exp
x N) + t
R
where:
• T
N
= Total time taken to capture a sequence of N frames;
• t
exp
= exposure time;
• N = total number of frames in a sequence;
• t
R
= readout time for one frame.
From the timing diagram, you can see that because the exposure time is greater than
the readout time, all frames are precisely exposed for the duration entered into the
software and have similar intensities.
Exposure Time > Readout Time. Timing information shown is for illustration purpose
only. Specific readout times vary depending on the model.
EXPOSE
(Effective)
EXPOSE
(Program’d)
READ OUT
SHUTTER
IMAGE SHIFT
EXPOSE (Effective) = High during the time when the CCD is collecting light.
EXPOSE (Program’d) = High during programmed exposure (as entered in the software).
SHUTTER = High during “Shutter open comp + Exposure”. Follows Disabled Opened or Disabled Closed.
READ OUT = High during “Vertical Tr Digitization.”
IMAGE SHIFT = High while the image is being shifted under the mask. When low, the CCD is light-sensitive.
Open
Comp.
Exp #1
50 ms
Readout #1
30 ms
Exp #2
50 ms
Exp #3
50 ms
Readout #2
30 ms
Readout #3
30 ms
Logic Out Signal Descriptions:
T = 180 ms
N
4
4
11
-01
26
_
004
2