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6.4.6. PIV mode.
PIV mode (Particle Image Velocimetry) can be used in applications where 2 images should be
taken with a very short time interval. It can only be used with strobe flash as illumination. The
first accumulation time is fixed at 4 µsec. After a delay >1.5 µsec. the second exposure period
starts. It is as long as the time for a full frame. The accumulation is LVAL a-synchronous. The
first exposure period starts at the trigger leading edge. The first strobe flash should be fired
within the first exposure period, and the second strobe flash during the first frame read out
period. The result will then be 2 frames exposed with the flash interval.
To use this mode:
Set function: Trigger mode “PIV” TR=5
LVAL synchronous accumulation LS=1
Scanning format SC=0 through SC=4
Output select OS=0, OS=1
Polarity and other functions
Input: Ext. trigger to Camera Link or pin 10 on 12-pin connector.
2 strobe flash
Important notes on using this mode.
• The duration of the trigger should be >2LVAL to <3FVAL.
• A new trigger must not be applied before FVAL is low after second frame readout.
• 1LVAL = 47.9 µsec (single). 27.3 µsec (dual).
For horizontal timing refer to 6.2.3. through 6.2.6. (Fig.17. through fig. 20.)
For LVAL a-synchronous accumulation refer to 6.2.8. (fig. 22.)
LVAL
DAT A OUT
SUB
SG
FVAL
EEN
Ex t . Tr i g1
Second Fr ame
4us( 1/ 250, 000s)
Fi rst Exposur e Peri od
1 f r ame read-out peri od
Second Exposure Peri od
Fi r st Fr ame
Readout del ay:
1 to 2L
Min.:2L
Fig. 28. PIV mode
LVAL
FVAL
SUB
SG
104ck
Exposure
Per i od
52ck
40ck(1us)
120ck(3us)
Ext.Trig
Exposure del ay:
156ck(3.9us)
Fi rst exposure ti me:
160ck(4us)
EEN
60ck(1. 5us)
Fig. 28A. PIV mode details