Scanlab RTC 5 PC Interface Board - 8.4.1 Wobbel Shapes - Important Notes on Choosing Appropriate Parameter Values; “Classic” Wobbel Shapes

RTC
®
5 PC Interface Board
Rev. 1.9 e
8 Advanced Functions for Scan Head and Laser Control
168
innovators for industry
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 command. 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 = maximum 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 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 you can also
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°
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
(3)
K = 5,000 [bit/mm].
• Maximum positioning speed
V
rad
= 100 [rad
optical
/s].
– Converted to control values this corresponds to
a maximum 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 maxi-
mum positioning speed of V/K =28.8 [m/s].
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.
(1) See technical specifications in the scan head manual
(2) At the maximum frequency estimated with (1)
(3) See ReadMe file of correction file or get_table_para