THORLABS M2MS, Operating Manual

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BP209 Series 6 The Graphics User Interface (GUI)
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21424-D02
6.5.3.3 Miscellaneous
Photodiode Bias
Biasing a photo diode decreases its rise time. Set Bias to On for measurement of small beam
diameters and M² measurement.
Note
Biasing is possible only for BP209-VIS and BP209IR1 models.
Aperture Width
The maximum aperture diameter is 9 mm. The resolution can be improved if using only 10% of
the aperture for beam analysis, particularly in case of small beam diameters or when using the
the
knife edge mode .
Active Slit Pair
The BP209 Series comes with two pairs of slits. The identification of the slit pairs is given by
their location on the perimeter of the drum, and only the active slit pair is used for beam ana-
lysis.
With 5 µm slit pair, beam diameters down to 20 µm can be measured using the standard Slit
Scanning method. If the beam diameter is less than that, the Knife Edge Mode must be used
instead, in combination with the
25 µm slit pair. This is explained in detail in the Knife Edge
Mode section .
Scanning Mode
Select Slit Scanning for beam diameters > 20 µm (with 5 µm active slit pair) and Knife Edge
for beam diameters < 20 µm (with 25 µm active slit pair).
6.5.4 Calculation Parameter
This section in the Beam Settings is used to set parameters for beam profile calculation.
Shown below is the view of the Calculation Parameter section at the first start of the Beam Soft-
ware or after pressing the " Reset Application Settings to Defaults " button in the toolbar:
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