OPHIR BeamSquared, User Manual

Page: 51 / 112

Beam Width
Beam Width Basis
defines the method of how the beam
width is calculated. Only beam width measurements that
emulate the second moment are ISO approved for
propagations analysis (D4σ and ESPA Programmable).
Knife Edge methods provide strong results and may be
used when the standard beam width measurement
methods appear to produce anomalous results. In some
cases the caustic may not re-draw unless the beam width
basis is changed.
M
2
Calculations
The Wavelength , Laser Location , and Focal Length
values are entered in the Configuration wizard. They are
repeated here for reference and can be updated here if a
value is entered incorrectly.
Check the Fitted Divergence box to calculate the
divergence from the curve fit rather than the actual data
point at the lens focal length. If the focal length is not
accessible, the software automatically uses the fitted
divergence. When enabled, the divergence result name
changes to
Fitted Divergence to indicate that the results
were from the fit and not from a direct measurement.
Units
Select the desired units for calculating width results,
distance results, and angle results. Changing the width and
distance units also updates the
Measured Caustic
Display axes.
BeamSquared obtains the lens focal length and other lens information from a RFID feature that is
integrated into the lens holder. If the system is operated at a different wavelength than where the
lens was measured, the software automatically corrects and applies the corrected focal length
information to the M
2
measurement application.
Positional Stability 3.7.6
Some laser beam centroids can drift over time. The Positional Stability chart is a 2D histogram
plot of the movement of the centroid location. This type of chart can convey the relative motion
of the beam in space. The chart granularity, or bucket, is sized based on the dimensions of the
camera pixel. The colors indicate the number of times (frequency) that the computed centroid
falls within the area of a pixel. The color palette follows what is selected in the
2D Beam
Display window. However, the palette is automatically ranged where the highest color intensity
(usually white) is always applied to the bucket with the greatest population, and lower valued
populations are proportionally spaced across the lower colors.