RTC6 boards
Doc. Rev. 1.0.21 en-US
7 Basic Functions for Scan Head Control and Laser Control
174
Image Field Correction Algorithm
For these field distortions, the RTC6 PCIe Board board
internally uses a algorithm to compensate for it. The
algorithm is based on a correction table.
An orthogonal grid of 257 × 257 points is
superimposed on the ideal square Image Field. The
adjusted x and y coordinates for a corrected output
of these grid points are stored in a correction table.
To move the focus to any point within the Image
Field, the RTC6 PCIe Board calculates the corrected
coordinates by interpolating from the grid points in
the correction table.
The correction is executed for every single Microstep,
see also Chapter 7.1.2 ”Microstepping”, page 140.
SCANLAB creates a correction file for every system
type. For this purpose, the correction table is
calculated based solely on general system data (such
as mirror geometry, calibration and the objective
specifications). Standard correction files therefore
reflect neither the unique properties possessed by the
customer’s individual system, nor alignment errors.
For those customers requiring more accurate
correction tables tailored to the unique properties of
their particular scan systems, SCANLAB offers the
correXion program line. These generate RTC
correction files based on test measurement data. For
further information, refer to the corresponding
manual or contact SCANLAB).
Activating Image Field Correction
To activate Image Field correction, at the beginning of
a user program the required correction tables must:
(1) be loaded from the corresponding correction files
into RTC6 PCIe Board memory (by
load_correction_file)
(2) assigned to the used scan head connectors (by
select_cor_table or select_cor_table_list)
2D correction tables activate an Image Field
correction for x and y coordinates,
3D correction tables additionally for z coordinates.
2D and 3D Correction Files
SCANLAB supplies 2D and 3D correction files. They
have the extension
*.ct5
and the following naming
scheme applies:
•
D2_xxx.ct5
for 2D correction files
•
D3_yyy.ct5
for 3D correction files
Here,
xxx
and
yyy
are numbers. Each correction file is
calculated for a specific optical configuration. The
configuration is specified in the accompanying
*_ReadMe.txt
file and in parameters of the
correction file header, see also Section
”ct5 Correction File Header”, page 178.
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