ALLIED Vision Technologies Bonito CL-400 200 fps - Manual (Page 51)

Parameters and commands
Bonito Technical Manual V2.3.0
51
PIV mode (bit group p)
Particle Image Velocimetry (PIV) is a contact-free method for tracking and visu-
alizing the movement of particles in liquids or gases that travel at high velocity.
At first, the position of identical particles in two subsequent images is deter-
mined. This allows to calculate speed and direction of the particles, in every
part of the acquired images.
If PIV mode is enabled, the camera outputs two images for each trigger event.
That way, it is possible to minimize the time between the exposure of the two
images to the possible minimum. This improves the measuring precision at high
velocities.
The evaluation always and only takes place between images of the same pair.
Figure 26: Exposure timing mode, M=3, flow diagram
Parameter Value
Trigger High Duration
(Sync Pulse) t
L
< t
TH
< F * t
TR
– t
L
Exposure Jitter 0 < t
j
< t
L
Exposure Time t
Exp
= E * t
TR
– t
L
± t
j
Frame Duration F * t
TR
≥ max (t
FDmin
+ t
L
, E * t
TR
+ t
L
)
Table 15: Exposure timing mode, M=3, timing parameters