57
Revision 00 EN - 01/2021
HP-MSM-HB
35,0(6
13.6.4
Caustic settings (menu
Measurement > Caustic)
Fig. 13.5:
Dialogue window
Caustic settings
Parameters (start number of the plane)
Under Start, the start number at which the measurement is initiated can be entered for the plane. By default,
the start number is generally set to zero and should only be changed when you are measuring in an existing
document and don’t want the existing measurement data to be overwritten. If, for example, you have mea-
sured a caustic with 21 planes and want to magnify the measuring area to the smaller z-values, you can set
the start plane to 21 and modify the measuring area appropriately. The new measuring values will then be
written into the existing document starting with plane 21.
In the Quantity selection field, the number of planes to be measured in the specified z range is set. The fol-
lowing should be considered here:
• Since the LaserDiagnosticsSoftware LDS always sets the measuring plane distances so they are equi-
distant (equal spacing) and the measuring area is almost always situated symmetrically around the focal
point, an odd number of measuring planes should be selected. The focus plane is calculated based on
the measuring plane and displayed in the caustic illustration.
• Beam measurement norm DIN 11146 specifies that at least 10 measuring planes should be measured.
Furthermore, five measurements should also be taken within a Rayleigh length and the other beyond 5
Rayleigh lengths. In order to meet all of the requirements with equidistant distribution, at least 17 mea-
suring planes must be measured in a range of ± 3 Rayleigh lengths.
Mode (automatic and manual settings)
There are two different measuring modes for caustic measurement. In “Automatic” mode, the measuring
system and the LDS determine the ideal measuring window position (x- and y-direction) for each measuring
plane and the optimal measuring window size for the fill factor. Furthermore, the plane location in the z-direc-
tion is also calculated based on the specifications (number of measuring planes, measuring limits z-direction).
Especially when adjusting the measuring window size and the measuring window position in the x-
and y-direction, the number of iterations (max. three per plane) can result in an extended measure-
ment duration.
It is therefore possible to change the measuring mode to “Manual Settings” for recurring measuring tasks
and for repeating measurements. In this case, the measuring system will take the measuring window posi-
tions and measuring window sizes from the previous measurement or from a .ptx file. This reduces the mea-
