Photon Focus D-2048 CameraLink Series, Руководство пользователя

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5 Functionality
e x t e r n a l t r i g g e r p u l s e i n p u t
t r i g g e r a f t e r i s o l a t o r
t r i g g e r p u l s e i n t e r n a l c a m e r a c o n t r o l
d e l a y e d t r i g g e r f o r s h u t t e r c o n t r o l
i n t e r n a l s h u t t e r c o n t r o l
d e l a y e d t r i g g e r f o r s t r o b e c o n t r o l
i n t e r n a l s t r o b e c o n t r o l
e x t e r n a l s t r o b e p u l s e o u t p u t
t
d - i s o - i n p u t
t
j i t t e r
t
t r i g g e r - d e l a y
t
e x p o s u r e
t
s t r o b e - d e l a y
t
d - i s o - o u t p u t
t
s t r o b e - d u r a t i o n
t
t r i g g e r - o f f s e t
t
s t r o b e - o f f s e t
Figure 5.18: Timing diagram for the camera controlled exposure time
isolated from the camera electronic which leads to an additional delay of t
d − iso − output
Table 5.8
and Table 5.9 gives an overview over the minimum and maximum values of the parameters.
External Trigger with Pulsewidth controlled Exposure Time
In the external trigger mode with Pulsewidth controlled exposure time the rising edge of the
trigger pulse starts the camera states machine, which controls the sensor. The falling edge of
the trigger pulse stops the image acquisition. Additionally the optional external strobe output
is controlled by the rising edge of the trigger pulse. Timing diagram Fig. 5.19 shows the
detailed timing for the external trigger mode with pulse width controlled exposure time.
The timing of the rising edge of the trigger pulse until to the start of exposure and strobe is
equal to the timing of the camera controlled exposure time (see Section 5.2.3). In this mode
however the end of the exposure is controlled by the falling edge of the trigger Pulsewidth:
The falling edge of the trigger pulse is delayed by the time t
d − iso − input
which results from the
signal isolator. This signal is clocked into the FPGA which leads to a jitter of t
jitter
. The pulse is
then delayed by t
trigger − delay
by the user defined value which can be configured via camera
software. After the trigger offset time t
trigger
−
offset
the exposure is stopped.
In the trigger pulse width controlled exposure mode the image sensor operates
in sequential read out mode (see Section 5.1.6). The maximal frame rate is there-
fore lower than normal as the exposure start is only allowed after the read out
of the previous frame.
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