THORLABS M2MS, Operating Manual

Page: 107 / 167

BP209 Series 7 Operation Instructions
Rev: 8.1, 14-Feb-2022 © 2022 Thorlabs Page 105
7.2.7.5 Running the M² Measurement
Prior to starting a measurement, make sure that the following conditions are fulfilled:
· The beam is aligned properly - it should ideally remain centered with respect to the sensor
center over the entire scan range. Section
Beam Alignment describes in detail how to
achieve this.
· The beam diameter should be in accordance with the Requirements to Beam Diameter
.
·
The exact wavelength of the laser under test is well known, as the wavelength value influ-
ences the M² results.
·
Reflections and interferences are avoided as far as possible.
·
The laser system is warmed up - depending on the source this might take up to 1 hour.
·
The laser output is spatially and temporally stable.
Start the measurement by clicking the Start button .
You will be prompted to confirm the laser wavelength:
Verify the wavelength and click OK .
While running the measurement most of the buttons and options are disabled, e.g. the M² Mea-
surement Settings and the Toolbar. This is intentional and prevents any settings changes dur-
ing the measurement.
The measurement can be interrupted at any time by clicking the Stop button .
After starting the measurement the X axis of the graph is adapted to the user-defined scan
range, for example from 50 to 125 mm. The Y axis scales automatically to the recorded beam
width.
If the Normal Scan is applied the scale on the graph zooms in when the fine scanning adds ad-
ditional data points. After this step (at the end of the measurement) the full scan range is shown
again.
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