User manual

Rolera Thunder User Manual 12
Overlap Mode
(Simultaneous
Exposure-Readout)
Overlap mode is extremely useful in applications requiring continuous imaging (100% duty cycle).
Once a frame is exposed and transferred into the frame transfer area, the next exposure
immediately starts and continues until the previous frame is read out or until the exposure time
is finished, whichever is longer (so the minimum effective exposure time in this mode is the
readout time). This mode of operation allows you to continuously image a specimen to obtain
better kinetic information about a process.
Figure 10 shows required Rolera Thunder settings for overlap mode. Note that the clearing mode
is set to "Pre-sequence" (as opposed to "Pre-exposure" in Non-Overlap mode).
Figure 10. Required Settings for Overlap Mode Operation
Note: In Overlap mode, the minimum effective exposure time is the readout time.
The simultaneous exposure-readout mechanism is illustrated with two examples.
Example 1: Overlap Mode when Exposure Time < Readout Time
Consider a situation where full frame readout is 34.8 ms, the exposure time is 10 ms, and three
frames are taken in overlap mode. The first frame is exposed precisely for the length of time
entered into the software (10 ms) and all subsequent frames are exposed for the readout time.
The total time to acquire 3 frames is then 114.4 ms (3 × 34.8 ms + 10 ms), equivalent to a frame
rate of 26.2 fps (3 frames ÷ 0.114 seconds).
Note: Because the first frame is exposed for 10 ms and the others for 34.8 ms, the first frame may look less
bright compared to all other frames.
Select these parameters to
operate your Rolera
Thunder camera in
Overlap mode.