THORLABS M2MS, Operating Manual

Page: 102 / 167

BP209 Series 7 Operation Instructions
Page 100
21424-D02
The Normal Scan pursues an ISO compliant measurements. The ISO standard requires that
"... at least 10 measurements shall be taken. Approximately half of the measurements
shall be distributed within one Rayleigh Length on either side of the beam waist, and ap-
proximately half of them shall be distributed beyond two Rayleigh Lengths from the
beam waist
."
The first run of the Normal Scan is executed with respect to the entered number of Data
Points , in other words, like a coarse scan. A preliminary Rayleigh Length is calculated in order
to evaluate if the number of measured data points is sufficient to fulfill the ISO standard require-
ments. If so, a hyperbolic fit is applied. If not, a second run adds additional measurements
within the Rayleigh Length on both sides and/or beyond twice the Rayleigh Length.
For a M
2
measurement, running the Normal Scan is highly advised. The coarse scan is suitable
for a first estimate of the beam waist position or other preliminary measurements.
Reset
Restores the default settings for M² settings:
Parameter Default Setting
Beam Width Beam Width Clip (1/e²)
Wavelength 635 nm
Timeout 15 sec
Start 0 mm
Stop 200 mm
Min. Data Points 10
Scan Method Normal Scan
Device Settings
It is important to set Gain and Base Line Correction of the Beam Profiler to Auto; Bandwidth to
125 kHz (see
Slit Beam Profiler Parameter ).
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