THORLABS BC207UV, Руководство по эксплуатации

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BC207 Series
Chapter 6: Operation Instructions
Rev: 8.1, 10-Jan-2022
Page 106
© 2022 Thorlabs
6.3.7.3 M² Settings
For a successful and reliable measurement, the appropriate measurement settings are essen-
tial. Click
to enter the M
2
Measurement Settings dialog.
Beam Width
Gaussian Diameter: The beam
profile will be fit using a Gaus-
sian curve prior to the determin-
ation of the beam width. A
Gaussian fit can reduce the im-
pact of noise and/or unstable beam shape on the results.
Beam Width Clip (1/e²): This is the value specified in ISO
standard 11146-3. If a different clip level was used for normal
Beam Profiler operation this will be overwritten by the M² mea-
surement initialization.
Correct Beam Width : This option should be activated by de-
fault. Due to the finite slit width so called convolution errors
(blurred beam shape) appear, particularly at small beam diamet-
ers, that results in an artificial increase of the beam width. Since
this convolution error is systematic it can be calculated and elim-
inated. This feature increases the measurement accuracy, par-
ticularly when measuring narrow beams.
Measurement Parameters
Setting the wavelength is mandat-
ory for a correct M² measurement.
If the lasing wavelength is un-
known, measure the wavelength using a spectrometer.
Attention
Do not use the nominal wavelength of the laser, use the
actual (measured) value! Accuracy of this input significantly
impacts the measurement accuracy.
Measurement Range
The Measurement Range determines the distance between the Start and Stop position, in
other words, the travel distance of the sleigh during the measurement. The travel distance can
range from 5 mm to the full length of the stage.
Min. Data Points is the (minimum) number of Z positions at which measurements will be
made.. The actual number depends also on the Scan Method .
Timeout is the max. waiting time for a valid camera image. This is to allow the Auto exposure
function to obtain a valid camera image.
Scan Method
The software provides two different kinds of scan
methods, the
Normal Scan and the Coarse
Scan .
The Coarse Scan just moves the translation
stage from Start to Stop positions (or vice versa
depending on the position prior to start the measurement). The number of recorded beam
widths equates exactly to the entered number of
Data Points .