Wobbel Shapes - Important Notes On Choosing Appropriate Parameter Values; Classic" Wobbel Shapes - Scanlab RTC 5 PC Interface Board Installation And Operation Manual

8.4.1 Wobbel Shapes – Important
Notes on Choosing Appro-
priate Parameter Values

"Classic" Wobbel Shapes

"Classic" wobbe shapes are defined using the
set_wobbel_mode or set_wobbel
assign hardware appropriate values to the
Transversal, Longitudinal and Freq parameters.
Caution!
• Too big values define control situations where
very high waste heat is produced. Galvanometer
and digital control board/amplifier board
overheating and permanent damage may occur
even in short-term operation (overload!).
Take the highest possible dynamics of scan head
and laser into account.
• If the frequency values are too high the galva-
nometers may not be able to follow the nominal
curve. This may lead to unexpected marking
results.
Rule of thumb to estimate appropriate maximum
values:
(1) Maximum frequency: F = 1/(10
where T = tracking error
(2)
(2) Wobbel amplitude : A = T
where V = maximum positioning speed
(1) See technical specifications in the scan head manual
(2) At the maximum frequency estimated with
®
RTC 5 PC Interface Board
Rev. 1.9 e
8 Advanced Functions for Scan Head and Laser Control
command. Only

T)
(1)

V
(1)
(1)
Notes
• Also take the path velocity on the wobbel shape
itself into account. For circular wobbel shapes it is
calculated as follows:
  
(3) Path velocity V = 2
Path
• Make sure that the combination of the used
values and the trajectory velocity are suitable for
a long-term operation without causing damages
(process safety!).
• Check the temperature status already during an
evaluation period (see get_head_status) in order
to recognize potential overload situations at an
early stage. With iDRIVE
read-out the present temperatures of galvanom-
eters and/or digital control boards (see
control_command).
Example of Use
System Specification
• Tracking error T = 0.33 [ms].
• Calibration ±0.349 rad
optical
(= 10° ) at ±503,316 [bit].
mechanical
– This is an angle control AC of
 
6
1.44 10 [bit/rad
optical

50,300 [bit/°
mechanical
(3)
• Calibration factor K = 5,000 [bit/mm].
• Maximum positioning speed
V = 100 [rad /s].
rad optical
– Converted to control values this corresponds to
a maximum positioning speed of

V = V AC
rad
 
8
1.44 10 [bit/s] = 1,440 [bit/10 µs].
– In the image field this corresponds to a maxi-
mum positioning speed of V/K =28.8 [m/s].
(3) See ReadMe file of correction file or

A F.
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get_table_para
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