Image Engineering
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3 OPERATING INSTRUCTIONS HARDWARE
GEOCAL / GEOCAL XL
After switching on, GEOCAL / GEOCAL XL is ready for use. No warm-up phase is required.
Diffractive Optical Element (DOE)
A diffractive optical element (DOE) is used to split the incoming light beam and generate a calibration grid
of evenly distributed light spots with a wavelength of 633 nm. The DOE is mounted on the front of the
GEOCAL / GEOCAL XL device (visible glass plate mounted in circular cutout, see Figure 2).
Camera settings
Set the camera to manual exposure mode. If manual mode is not available, use the automatic exposure
mode. The image should be saved in a lossless format for best results. TIFF format is recommended, and
PNG and JPEG (lossy) are also supported. If you convert RAW image data to another format, ensure the
image is debayered in the process.
The autofocus must be turned off. Since GEOCAL / GEOCAL XL uses a collimated light beam virtually
originating from infinity, the appropriate focus distance will be near infinity. Using manual focus, ensure
the camera is focused on the light points.
Exposure program
Manual
Aperture
No default value
ISO Speed
Lowest value (e.g.,100)
Autofocus
Off
File type
TIFF is recommended. PNG
and JPEG are also supported
DOE
Figure 1: Calibration grid
(the brightest spot marks the center)
Figure 2: Location of the DOE
