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MSM+ HB
9.7
Manual caustic measurement
In the Manual caustic measuring mode, only the z-range and the number of planes have to be specified.
All other required settings are automatically determined and adjusted. In addition, advanced settings can be
applied.
According to ISO 11146-1, at least 10 planes shall be measured. Approximately half of the measurements
shall be distributed within one Rayleigh length on either side of the focus, and approximately half of them
shall be distributed beyond two Rayleigh lengths from the focus.
For two reasons, an odd number of measuring planes makes it more likely that the focal plane will be measu-
red. First, the LaserDiagnosticsSoftware LDS always sets the spacing between the measuring planes equal.
Second, the measuring range along the z-axis is almost always symmetrical around the focus. We recom-
mend measuring at least 21 planes within 6 Rayleigh lengths.
By means of the variable integration time control, not only cw lasers but also pulsed lasers can be measured
in quasi-cw operation. An exception are, for example, laser beams with a very low pulse frequency. Trigger
operation is available for measuring such beams. If this is enabled, the device only measures within defined
time periods. The laser pulse or the corresponding trigger signal marks the beginning of such a period and
the (freely adjustable) integration time marks its end. A measurement can be triggered internally or externally.
Internal signals are triggered by the photodiode integrated in the device. Externally triggered signals enter the
device via a BNC socket. For detailed information on the measurement of pulsed laser beams and the trigger
operation, please refer to chapter 16.3 on page 110.
9.7.1
Configure settings
1.
Click on the Settings tab.
2.
Maintain the options according to the
explanations in in the following table..
Option
Optimized measurement settings
Number of planes *
z-Axis position (z1 / z2) in mm *
Caustic suggestion
Tab. 9.7:
Options in the Device control > Settings tab of the Manual caustic measuring mode
Revision 00 EN - 02/2022
Explanation
If this option is activated, the measurement takes shorter time. Fe-
wer process steps are required, since the initial settings for a pla-
ne measurement are taken from the settings of the previous plane
measurement.
Please note, however, that beam artefacts may not be adequately
detected in the single plane measurements due to the transfer of the
settings.
X Set the check mark to activate the option.
X Enter the number of planes to be measured.
This option enables configuring the z-range in which the measurement is
to be performed.
X Regarding the traversing range in which the measurement is to be
performed, enter the lower limit z1 in the left field and the upper limit
z2 in the right field.
X Alternatively, use the sliders.
When a caustic measurement is completed, a z-range is displayed in
these fields. The limits of the suggested z-range have a distance of
± 3 Rayleigh lengths to the determined beam focus. This z-range is
optimized according to Primes quality criteria.
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