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Functions and Operations
FIGURE 56. Pulse Width Control Trigger
6.4.6Particle Imaging Velocimetry Fixed Exposure Mode
In Particle Imaging Velocimetry (PIV) Fixed Exposure Mode, when an external trigger is applied, the first time exposure starts the same as PWC mode does. It lasts a very short period (8µs). The second time exposure starts during the transferring time of the first image accumulated in the first exposure time. The second time exposure continues until the first image transfers completely. The second image is transferred after the second exposure. There is a short period (500ns) between the first exposure and the second exposure. In order to keep two exposure periods constant, the LDV is reset before the first image is transferred out.
The maximum trigger frequency in this mode is equal to 1/ (transfer time of two frames + 4µs). The minimum active period of the external trigger is 5μs
FIGURE 57. PIV Exposure Timing Table
External |
|
Trigger | pA |
FDV | pB |
| |
Vsub |
|
| pC |
. . .
P
. . .
. . .
P
. . . . . . . . .
TG |
|
Exposure |
|
Strobe | pE |
| |
Digital | pD |
| |
Data |
|
Analog |
|
Video |
|
. . .
. . .
pF. . .
. . .
. . .
.. .. ..
.
. . .
. . .
. . .
. . .
. . .
. . .
. . .
