Scanlab RTC6 PCIe Board - Wobbel Shapes - Important Notes on Choosing Appropriate Parameter Values; Classic Wobbel Shapes

RTC6 boards
Doc. Rev. 1.0.21 en-US
8 Advanced Functions for Scan Head Control and Laser Control
234
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8.4.1 Wobbel Shapes – Important
Notes on Choosing
Appropriate Parameter Values
“Classic” Wobbel Shapes
“Classic” wobbel shapes are defined by
set_wobbel_mode or set_wobbel.
Only assign hardware appropriate values to the
Transversal , Longitudinal and Freq parameters.
Rule of thumb to estimate appropriate maximum
values:
(1) Maximum frequency: F = 1/(10
 T)
where T = Tracking Error
(1)
(2) Wobbel amplitude
(2)
: A = T  V
where V = typical positioning speed
(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
Path
= 2    A  F.
• Make sure that the combination of the used
values and the trajectory
(3)
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 systems
(4)
you can also
read out the present temperatures of
galvanometer scanners 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°
mechanical
) at ±503,316 bit.
– This is an angle control AC of
 1.44  10
6
bit/rad
optical
 50,300 bit/°
mechanical
).
• Calibration factor
(5)
K = 5,000 bit/mm.
• Typical positioning speed
V
rad
= 100 rad
optical
/s.
– Converted to control values this corresponds to
a typical positioning speed of
V = V
rad
 AC
 1.44  10
8
bit/s = 1,440 bit/10 µs.
– In the Image Field this corresponds to a typical
positioning speed of V/K =28.8 m/s.
Notice!
• Too big values define control situations where
very high waste heat is produced.
Galvanometer scanner 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
galvanometer scanners may not be able to
follow the nominal curve. This may lead to
unexpected marking results.
(1) See technical specifications in the scan head manual.
(2) At the maximum frequency estimated with (1).
(3) See Glossary entry on page 30.
(4) See Glossary entry on page 27.
(5) See *_ReadMe.txt file of correction file or
get_table_para.