Power Meters FAQ's

BeamTrack Power/Position/Size Sensors


The Vega, Nova II, StarLite. StarBright and Juno support the BeamTrack (PPS) sensors. All other instruments can display power and single-shot energy of a BeamTrack sensor, but do not display beam position and size.


Yes StarLab can log beam position. The BeamTrack sensors are thermal sensors. The power measurements for all Ophir power sensors are logged at 15 times a second. When a BeamTrack sensor is connected to StarLab via a Juno, the position / size measurements are also logged 15 times a second. When a BeamTrack sensor is connected to StarLab via a Vega/ Nova II, the position / size measurements are logged once a second. This is because in the Vega / Nova II we sample these parameters slower.


The Ophir BeamTrack series of Power/Position/Size meters may be just the thing. In addition to all the things an ordinary power/energy meter does, the BeamTrack will measure the beam position and size as well to a precision of ~0.1mm. For a gaussian beam it will give you the actual beam waist diameter and for other beams it will give a relative number that changes with beam size. See http://www.youtube.com/watch?v=U2oliO-Cz8M for a demo of the BeamTrack.


The specified response time is only for the power and not for the size or position; response time is intentionally given in the Power section of the spec.
We haven't defined a position and size measurement response time because it depends on too many different parameters. For example:

  • Small changes in size or position will respond quickly, large changes are much slower.
  • Going from a large spot size to a smaller one is faster than going the other way.
  • Position and size can change at the same time.
  • If the power also changes it is even more complicated.

So the response time for size and position cannot be meaningfully specified by a single number. Having said all that, however: 
In general, unlike the power reading which is accelerated by the predictive “speedup” function, the size and position measurements can't use the speedup so they are a bit slower.

The rise time for Position and Size is typically 5x – 10x the specified power response time.

Fall times for a decrease in power density (i.e. increase in size relative to power, as above) can be longer.