121
Revision 00 EN - 01/2021
HP-MSM-HB
35,0(6
24.3.11 Option (advanced user only) (menu
Measurement > Option
)
Fig. 24.11: Dialog window
Option
Enable beam find process
The Beam Find function must be used for caustic measurement. This involves an algorithm that separates
the measuring signal from the measurement artifacts (e.g. noise) via an adjustable trigger threshold and
adapts the size of the measuring window to this signal. This algorithm is only executed in the beam search
plane (Dialog window
Caustic
). On all other measuring planes, the measuring window size is determined us-
ing the fill factor.
If this function is deactivated, the beam search plane must be manually “premeasured” in the measuring
system. Otherwise the measuring system might end up positioning the measuring window on the edge of the
measuring area where there is no measuring signal. This makes it impossible to take a meaningful measure-
ment.
If you turn the Beam Find function off and have the measuring measure the beam search plane system be-
fore each caustic measurement, you can save about 20 sec of measuring time per caustic measurement.
Summary: This function should be activated by default and only deactivated by experienced users. Turning
off this function can shorten the time for caustic measurements by about 15 %.
Fill factor
The fill factor is the quotient of the beam diameter and the length of the sides of the measuring window. As
long as the measuring signal is not cut off and there are no noise components in the measuring result and
now errors in the offset determination, the fill factor won’t influence the accuracy at all. But since every real
measuring signal is tainted with noise and since the precision with which the zero level of a measuring signal
can be determined is finite, very small fill factors can lead to a high level of accuracy. Depending on how
substantial the RMS noise is and the errors in the zero level determination of a measuring plane, the optimal
fill factor value to produce the best possible mathematical result will be different.
