OPHIR BeamSquared, Руководство пользователя

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Data Collection 5.8
The number of collected data points depends on how the operator configures the system. The operator can
program the Z
2
axis data points along the Z axis in a number of different ways. Although collection of a frame
exhibiting quality issues is permitted, it is discouraged as measurement accuracy could be degraded. If the
frame contains anomalous, or otherwise suspect data points (referred to as “outliers”), the operator should
remove these data points from the analysis. For more information on frame quality issues in BeamSquared,
refer to the
Frame Quality step in section 4.2.2.
Once enough data points are collected, the propagation parameters for the input laser beam are calculated, as
well as astigmatism and asymmetry ratios. The sampled X and Y beam widths versus the distance from the
lens are plotted and the hyperbolic curve fits are drawn. Using this information, measurements are obtained
for the actual propagation of the laser (1 space) and the beam formed by the focusing optic (2 space).
To obtain a more accurate measurement, data points should be taken with smaller step sizes near the waist,
and larger step sizes in the far field. One measurement should be performed at the focal length of the lens.
This provides the focal length divergence results. The number of samples collected affects the time it takes to
perform a run.
A standard sample step size of 1/10 the focal length of the lens is suggested to comply with the ISO
standard’s recommendation:
“… measurements at at least 10 different z positions shall be taken. Approximately half of the measurements
shall be distributed within one Rayleigh length on either side of the beam waist, and approximately half of
them shall be distributed beyond two Rayleigh lengths from the beam waist.”
Experimentation has shown that at least five samples should be collected in the near field (within one Rayleigh
length), and at least three should be collected in each of the two far field regions (beyond ±2 Rayleigh
lengths).