THORLABS BC207UV, Operating Manual

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BC207 Series Chapter 5: The Graphics User Interface (GUI)
Page 29
MTN026962-D02
Meter Value" control. Click "Apply" and both values will coincide. Click "Close'" to leave the
panel.
The difference between the power measured externally and measured by the Beam Profiler will
be displayed as an offset in [dB].
This offset (in dB) is stored in the Beam Profiler and is read out and activated automatically
each time after connecting this instrument.
Note
The user calibrated power reading is correct only at the actual wavelength and the selected ND
filter and when the external power meter is used in the same conditions (ambient light). If any of
these parameters change, the power correction needs to be repeated.
After executing the Power Correction it is activated automatically, which is indicated by the
check mark.
The activation state is saved in the software. When restarting the software using the same in-
strument, the offset is recognized, read out and the same activation state (active / inactive) as
in the previous software session will be restored.
If the power correction is not active, the attempt to activate it lets the software check the cam-
era for a saved offset. If no saved offset is found, the Power Correction dialog opens and asks
for a power meter value. If an offset is recognized, it will be applied immediately. For this
reason it is recommended to perform a power correction if the environment of the instrument
was changed.
5.5.1.4 Ambient Light Correction
It is highly recommended to shield ambient light from entering the entrance aperture as best
possible, e.g. by using the supplied ND attenuation filters. However, a considerably high ambi-
ent light level may still occur within the camera image that cannot be distinguished from beam
power. Accordingly, an offset level will add to the measured beam profile which leads to inac-
curate beam parameters. Therefore, a correction for the remaining ambient light level is
provided and should be carried out in cases where the ambient light level is measurable. An in-
dication for this is when the far-off wings of the X Y profiles do not go down to zero intensity
level.
Note
It is recommended to proceed with the ambient light correction after a 30 min warm-up time and
repeat it if needed (e.g., ambient light conditions changed).
Click the 'Start' button - the Ambient Light Correction Dialog appears.