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100 ST-133 Controller Manual Version 3.B
ESABI (Electronic Shutter Active Between Images)
The last timing mode, ESABI, allows separation time between the two images. This
mode gives the user the ability to capture two images and use the interline chip’s
electronic shutter feature between images so that no signal is integrated in the time
between. The exposure time for both images is the same but they can be separated in
time. Each time the camera is ready to receive a trigger,
goes low. Thus
goes low twice during each ESABI cycle and the controller can be triggered
once by a sync pulse applied to Ext Sync each time. Thus two sync pulses are required,
one for each image, during each double capture. The programmed Exposure Time, as set
on the Experiment Setup Main tab page, sets the first image time and the time after the
start of the second image time when the shutter begins to close. Figure 59 illustrates
ESABI mode timing.
Note that charge produced by light impinging on the photosensors during the interval
between the two images is discarded and does not affect the second image. The time
between the first and second image can be as long as required according to the
experimental requirements. This can be particularly useful in fluorescence measurements.
By doing captures with different intervals between the two images, the fluorescence
decay characteristics can be easily measured.
Image 1
EXT. SYNC. (A)
Images
t
trig
Mechanical
Shutter
8 ms
8 ms
NOTSCAN
t
trig
Image 2
No Signal
Integration
t
exp
t
exp
200 ns200 ns
READY
Figure 59. ESABI Timing Example; Image Exposure Time = t
exp
set in Software
Note: To prevent the second image from occurring immediately after the first one, the
input trigger pulse, t
trig
, must be shorter than the exposure time t
exp
.
Summary of ESABI Timing mode
• The exposure time selected in Experiment Setup sets the exposure time of both the
first and second image.
• Requires that the switch, if present on the back of the camera, be set to INACTIVE.
•
An externally derived trigger edge applied to Ext Sync is required to begin each
image exposure period.
•
goes low when the system is ready to capture each image.