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10 Thorlabs Beam 4.0
The nominal filter loss and also the appropriate wavelength range (UV / VIS) is
engraved to the filter housing. Note that the filter loss is wavelength dependent and
may diverge largely from its nominal value, especially for operating wavelengths at
the border of the Beam Profiler wavelength range. See chapter Wavelength
Response for details.
Which attenuation to choose?
To adapt a light source with unknown power level to the Camera Beam Profiler it is
highly recommended to use the automatic exposure control (see chapter Device
Settings ) of the camera. In addition, it is advisable to start with the highest loss
attenuation filter (40 dB) in order to prevent damage to the camera.
In case the Beam Profiler software displays an error "Power too high, camera
saturated!" the light intensity exceeds the maximum detectable power of the BC106
Beam Profiler. In this case additional means for external beam attenuation are
required.
In case the Beam Profiler software doesn't show a "Power too high" error you can
work with this setting and the measurement results are reliable. But, in order to
minimize beam distortions by the ND filters you should work with the lowest possible
attenuation.
Rotate the filter wheel a quarter revolution to bring the nearest lower attenuation filter
in front of the camera aperture. Whether now a "Power too high" error appears,
rotate the filter wheel back to the previous filter which was optimal. If no error
appears, rotate the wheel further until the lowest attenuation filter is in use.
If the optical beam power is low enough you can operate the Beam Profiler camera
also without any attenuation filter in front of it. For this, unscrew a filter holder out of
the filter wheel.
Attention
Be very carefully when operating the Beam Profiler without a protective filter
in front of it! Since the CCD camera sensor is freed from its protective
window it is extremely vulnerable! It is absolutely required to prevent dust
and other contaminations from entering the Beam Profiler aperture. See
Cleaning chapter for details.
When using a high loss attenuation filter in conjunction with a low power light source
the software will display a "Power too low" warning. This means the source is
attenuated too much so that the camera's gain and exposure regulation is not able to
achieve an evaluable signal level. In this case reduce the optical attenuation down to
the lowest available filter loss (10 dB) or remove one filter completely.
Attention
You need to enter the actually chosen ND filter loss in dB into the Beam
Profiler software as a precondition for proper power measurement results!
See Device Settings chapter.
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