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FocusMonitor FM+
9.8.3
Measure manual caustics with the single plane measurement mode
In Single Plane measurement mode, further measurements can be performed at any z-positions.
With this procedure, a caustic can be measured manually.
For stigmatic and single astigmatic beams, at least 10 different positions on the z-axis must be measured
according to ISO 11146-1. About half of the measurements must be distributed within one Rayleigh length on
both sides of the beam waist and about half must be distributed beyond two Rayleigh lengths starting from
the beam waist.
An odd number of measurement planes makes it more likely that one of the measurement planes will be at
or close to the focal plane. PRIMES recommends measuring at least 21 planes within ± 3 Rayleigh lengths
around the focus.
For generally astigmatic and unknown beams, ISO 11146-2 requires measurements to be made at a minimum
of 20 uniformly distributed points on the z-axis within a range of at least three times the Rayleigh length both
behind and in front of the beam waist.
PRIMES recommends measuring at least 21 planes within ± 3 Rayleigh lengths around the focus. An odd
number of measurement planes makes it more likely that one of the measurement planes will be at or close
to the focal plane will be measured.
Single measurement with manual input of the z-position:
This procedure is used when the laser system moves to
the position of the next measurement. The z-axis of the
FM+ is deactivated for this purpose.
1.
Click on the Settings tab.
2.
Set the checkmark at Deactivate z-axis.
3.
In the z-position in mm field, enter the desired position
of the next plane to be measured.
4.
Start and stop the measurement according to chap-
ter 9.8.4 „Start measurement" on page 54.
Single measurements using z-increment spacing:
This procedure works with the z-axis of the FM+ enabled
and disabled.
1.
Click on the Settings tab.
2.
Enter the spacing for the further measurements in the
z-Increment in mm field.
3.
Start the measurement according to chapter 9.8.4
„Start measurement" on page 54 and wait until the
measurement is completed.
The measured plane is one z-increment away from
the previously measured plane.
4.
Start a measurement again and wait until the measure-
ment is finished.
The measured plane is one z-increment away from
the previously measured plane.
5.
Repeat the last step as often as you like.
Revision 08 EN - 08/2023
53
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