OPHIR BeamSquared, User Manual

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Chapter 4 Operation
Operating Modes 4.1
BeamSquared has five operating modes which give the user control over the measurement process, and
provide short cycle times for making M
2
measurements. The first four are found in the Configuration wizard,
while the fifth is only accessible after an M
2
test is complete.
Automated Stepping 4.1.1
The Automated Stepping method allows the user to make a
minimum number of input settings and obtain a reasonably fast set of
M
2
results. The user sets the range over which the beam samples are
acquired and the basic step distance between data points in the Z value
edit controls.
Cycle times can be quite long if the user does not optimize Z Start , Z
Stop , and Z Step . Making M
2
runs with 20 to 50 data points (much
more than the 11 required by ISO) takes a significant amount of time
to complete. Excessive samples may degrade the results.
This is the primary intended use of the BeamSquared system and
provides the most accurate results that are ISO compliant.
Automated ISO Setup 4.1.2
The Automated ISO Setup method was introduced for users desiring
guidance in setting up the point locations for an M
2
run that conforms
to the minimum ISO requirements. This method does not require any
inputs from the user as it performs an initial scan of the beam
propagation path to determine the point locations needed to conform to
the minimum ISO requirements.
If the minimum ISO requirements can be determined with the current
configuration, the
Automated ISO Setup method will populate the
Step Table with the recommended 11 points. The points are
distributed according to the ISO 11146 specification with five points
taken around the waist, five points taken beyond two Rayleigh lengths,
and one point at the focal length of the lens. The user may modify the
Step Table , if desired, before starting the run. Additional information
on adjusting the Step Table is described in section 4.1.4.
If the minimum ISO requirements cannot be determined during the
initial scan, the
Automated ISO Setup method will populate the
Automated Stepping inputs with the recommended Z Start , Z Stop ,