Position Signals, Image Field And X-Y Reference System - Scanlab hurrySCAN 10 Installation & Operation Manual

Position Signals, Image Field and X-Y
Reference System
Position signals are digitally transferred from the
controller to the scan head.
Figure 4 shows the definition of the X-Y reference
system which is used for the position signals trans-
mitted to the scan head. The orientation of the axes
corresponds to the orientation used by the RTC
boards from SCANLAB: The Y axis points in the oppo-
site direction of the entry beam (and the Z axis in the
opposite direction of the exit beam). Consequently:
Scanner 1 deflects the beam in the Y direction,
Scanner 2 in the X direction.
The scan head is calibrated in such a way that for a
scan angle of 0.408 rad optically with excursion in
the negative axis direction the bit-value "1311" has to
be transmitted, for the neutral position (null point)
the bit-value "32768, and for a scan angle of
0.408 rad optically with excursion in the positive axis
direction the bit-value "64225".
The maximum adjustable scan angle is (1 / 0.96)
larger than the calibration angle. The input signal
values for the maximum adjustable image field points
(see figure 4) are listed in the following table.
Position X bit-Value
(CHAN2)
0 32768
1 65535
2 65535
3 32768
4 0
5 0
6 0
7 32768
8 65535
Vignetting can occur at a particular scan angle
dependent on the specific scan head and objective.
The laser beam is then partially blocked within the
scan head or objective, which results in transmission
losses. The higher the power loss, the greater is the
risk of damage to the scan system. In view of this, the
technical specifications page 34
calibration angle, but also the maximum allowed
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hurrySCAN 10, digital, 1064 nm, f = 254 mm
Rev. 2.6 e
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2 The hurrySCAN 10 – Principle of Operation
scan angle. This is not the same as the maximum
adjustable scan angle. To avoid scan system damage,
make sure the maximum allowed scan angle is never
exceeded.
The maximum allowed scan angle is derived from the
geometric and optical data of the employed compo-
nents (see the
ration" on page
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sufficiently small calibration angles, the maximum
allowed scan angle can be larger than the maximum
adjustable angle. In such cases, the specified
maximum allowed scan angle has no practical rele-
vance.
Y bit-Value
(CHAN1)
32768
32768
65535
65535
65535
32768
0
Positions in the image field
0
0
Figure 4
tion of the square image field and shows the orienta-
tion of this distortion with reference to the axes. The
field distortion is caused by the beam path within the
scan head and by the characteristics of the objective.
It must be compensated by the controller.
If you use a SCANLAB RTC
RTC
include not only the
the scan head, the field distortion is compensated
automatically. Before data values are transferred to
the scan head, the values are transformed by the
RTC
section "Customized Optical Configu-
6). In some cases, particularly with
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1
X
2
0
Y
3
4
also depicts the pillow-barrel-shaped distor-
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interface board or an
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SCANalone standalone board for controlling
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boards with the help of a correction table. A
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6
5
4
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