FOV
S
V
0
Pixel #1
Pixel #1
W
P
/ ß
CCD Sensor
Scan Object
Camera Control and Performing a Scan
17
Instruction Manual
SK1024U3HU
shar
ed_CameraContr
ol(3)_Sync_ML.indd
Instruction Manual SK1024U3HU © 2019-07 E
Synchronization of the Image Acquisition with the Feed Rate of the Object
A line scan camera produces a two-dimensional image by moving either the object or the camera. The direction of
the translation movement must be orthogonal to the sensor axis of the line scan camera.
In order to obtain an image with the correct aspect ratio, a line synchronous feed is required. With RGB color
sensors, the color sequence of the individual sensor lines must also be taken into account when processing
the sensor data. The software development kits from Schäfter+Kirchhoff contain easy-to-use functions for this
purpose.
If the object speed is variable or the accuracy requirements are high, external synchronization is required. The
various synchronization modes are described in the next section.
The optimal scan speed for a given line frequency is
calculated as follows:
W
P
· f
L
V
O
=
ß
If the scanning speed is fixed, the line frequency must
be adjusted accordingly in order to obtain the correct
aspect ratio in the image:
V
O
· ß
f
L
=
W
P
V
O
= object scan velocity
W
P
= pixel width
f
L
= line frequency
S
=
sensor length
FOV
=
field of view
ß
= magnification factor
=
S / FOV
Example 1:
Calculating the scan velocity for a given field of view and a given line frequency:
Pixel width
=
500 µm
Line frequency
= 13.88 kHz
S
=
12.8 mm
FOV
=
20 mm
12.5 µm · 13.88 kHz
V
O
=
(12.8 mm / 20 mm)
=
271 mm/s
Example 2:
Calculating the line frequency for a given field of view and object scan velocity:
Pixel width
=
500 µm
Scan velocity =
200 mm/s
S
=
12.8 mm
FOV
=
20 mm
200 mm/s · (12.8 mm / 20 mm)
f
L
=
12.5 µm
=
10.2 kHz
