Basler Vision Technologies Sprint Series, User Manual

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Line Acquisition Modes
Basler sprint Mono Cameras 61
3.9 Recommendations for Using Time
Delayed Line Summing or Time Delayed
Line Averaging
3.9.1 Camera Operating Recommendations
To achieve the best results when using time delayed line summing or time delayed line averaging,
certain operating requirements should be met.
„
Exposure start should be triggered by an ExSync signal (see Chapter 4 on page 67 ).
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Use of the programmable exposure mode is recommended to ensure uniform exposure.
„
The edge controlled or level controlled exposure modes can be used, but only if the conveyor
speed is 100% stable. If the conveyor speed is not stable, unacceptable variations in exposure
time will result.
3.9.2 System Design Recommendations
When you are using time delayed line summing or
time delayed line averaging, for a given point on the
object to be captured correctly, its image must fall
precisely on line A in the sensor and then precisely
on line B in the sensor. If delayed line summing or
averaging is being done correctly, the captured
images will be sharp and clear as shown in the right
side of Figure 26. If there are variations in the
positioning of the image when it is captured by line A
and by line B, the captured images will include gray
“halos” as shown in the left side of Figure 26.
A list of system design requirements is given below.
When these design requirements are met, the image
will not have halos.
Position Encoder
You should use a position encoder to monitor the movement of the system’s conveyor. You should
also use the encoder output to trigger line acquisition so that a given area of an object on the
conveyor is acquired when its image falls precisely on line A and precisely on line B.
If you do not use a position encoder, haloing in the transport direction can result and the halos will
vary in size.
Fig. 26: The Halo Effect