© 2011 Thorlabs
122 Thorlabs Beam 4.0
Scan Range
The Scan Range determines the range from where to where sleigh of the translation
stage is driven during a measurement. Start has to be at least 5 mm smaller than
Stop and greater-than-or-equal to 0 mm. Valid values for Stop are
5 mm < Stop < stage length.
Note
It is advisable to set up a larger scan ranges than 40 mm to ensure higher accuracy.
A scan over the entire translation length is often the best choice.
Reset
Restores the default settings for M² settings:
4-Sigma Diameter (ISO-Standard)
150 / 300 mm (depending on the stage length)
Calculation Area
The settings for the Calculation Area can be made in the Application Settings .
During a Beam Quality Measurement (M
2
or Divergence) the Automatic Calculation
Area is enabled by default for effective noise reduction. Reflections and artefacts
from filters, lenses or other optical elements can be suppressed as well using the
automatic Calculation Area which is close to the beam profile.
This setting can be changed to manual, but this may affect the measurement.
By default the Clip Level of the Calculation Area is set to 1%. This is a reasonable
value for most applications and measurements. Lowering the clip level leads to
increased calculation area and noise level, this way increasing the measured the
beam width.
Note
Setting the Clip Level of the Calculation Area for divergence measurements is not as
critical as for M
2
measurements. Increasing the Clip Level will give smaller beam
widths but might cut the beam profile.
Initial settings
Independently from the user-defined settings the following options are set
automatically for every beam quality measurement.
59