Controlling a Particle Image Velocimetry (PIV) System with DAQmx

Issue Details

• I am currently making a Particle Image Velocimetry (PIV) system. I am using DAQ hardware and NI-DAQmx. My program needs to output several specific pulses after it receives an external trigger.
• I want to control my PIV system using LabVIEW and DAQmx. I need my application to fire a pulsed laser several times per second while my external trigger signal is high.
• We have a PIV system with two lasers. I need to read a signal line and see if there is a trigger. When the trigger happens I want to fire both lasers alternately, each one ten times with 10 Hz. The two lasers shall fire 10 µs apart every time.

Solution

Syncing (dual) lasers and Q-switches to an external trigger as it is often needed in Particle Image Velocimetry (PIV) systems can be easily done with Retriggerable Tasks in NI-DAQmx : Each time your DAQ hardware receives the external trigger it will fire the pulses you defined.

It is both possible to:

• Output a pulse/finite train of pulses every time an external trigger is obtained.
• Send such an output continuously as long as the eternal trigger signal is active through using a Pause Trigger. Pause Triggers are described in section F and G of this article: NI-DAQmx Data Acquisition Triggering Techniques Using LabVIEW .

Additional Information