Gentec-EO Beamage-3.0 - Manual (Page 36)

Beamage-3.0 User Manual Revision 6.0 35
5.1.1. Main Controls
The “Main Controls” section allows the user to set the desired beam diameter definition and crosshair
position. Use the drop-down menu to select the desired setting.
5.1.1.1. Beam Diameter Definition
By default, the beam width definition is set to “4 sigma (ISO)” which respects the ISO-11146-1:2005 and
ISO11146-2:2005 standards (refer to Annex A ISO11146 and iso11670 Definitions). This definition takes
the entire image to compute the beam parameters slowing the computation time and reducing the frame
rate.
The
“FWHM along crosshairs (50%)” finds the crosshair’s Full Width Half Maximum (FWHM). The
algorithm will return the width corresponding to the curve’s first half maximum and the curve’s last half
maximum. Because the beam definition only takes into account a slice of the beam, the computation time
is much faster and higher frame rates can be achieved.
The
“1/e2 along crosshairs (13.5%)” finds the crosshair’s width corresponding to 1/e 2
(about 13.5%) of its
maximum. Similarly to the FWHM, this beam definition will increase the frame rate.
The
“86% effective diameter (D86)” computes the circular beam containing 86% of the total intensity. This
definition assumes the beam is circular.
5.1.1.2. Crosshair Definition
The crosshair is defined by its center (intersection of the 2 crosshairs) and its orientation. The crosshair
center can be set to the beam’s centroid as defined by the ISO-11146-1:2005 and ISO-11146-2:2005
standards,
the beam’s peak position or at a user defined fixed position. If many pixels correspond to the
peak value, the crosshair ’s center will be set to the first peak.
The crosshair’s orientation is set to “Auto Orient” by default, which aligns it to the beam’s orientation as
defined by the ISO-11146-1:2005 and ISO-11146-2:2005 standards. It can also be set to a fixed 45
o
or 0
o
angle.
Warning
The crosshair definition will affect the XY Display (refer to section 6.36.3)
and the beam width if it is defined by the FWHM or 1/e
2
along crosshair
5.1.2. Measure
The “Measure” section presents the beam’s diameter and centroid information according to the selected
beam definition (refer to section 5.1.1.1).
The computation algorithm first determines an approximate beam diameter (13.5% clip level). The
algorithm will consider that all pixels outside 2 times the approximate beam diameter are the outside area.
The
outside area’s average will become the baseline, which will be subtracted from the area containing
the beam. Only the area containing the beam will be used to compute the diameter. This means that a
smaller beam will have a smaller area which will decrease the computation time and increase the frame
rate. If the beam is larger and all pixels contain the area containing the beam, there will be no baseline
subtraction and the frame rate will be slower.