FOV
S
V
0
Pixel #1
Pixel #1
W
P
/ ß
CCD Sensor
Scan Object
Page 14
3. Camera Control and Performing a Scan
Schäfter + Kirchhoff © 2014 • Line Scan Camera SK1024U3PD Manual (05.2014) • shared_CameraControl(2)_Adjustments_USB-mc.indd (05.2014)
The optimum object scan velocity is calculated from:
W
P
·
f
L
V
O
=
ß
If the velocity of the object carrier is not adjustable
then the line frequency of the camera must be
adjusted to provide an image with the correct aspect
ratio, where:
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
= S / FOV
Synchronization of the Imaging Procedure and the Object Scan Velocity
• A two-dimensional image is generated by moving either the object or the camera. The direction of the translation
movement must be orthogonal to the sensor axis of the CCD line scan camera.
• To obtain a proportional image with the correct aspect ratio, a line synchronous transport with the laterally
correct pixel assignment is required. The line frequency and the constant object velocity have to be adapted to
each other.
• In cases of a variable object velocity or for particular high accuracy requirements then an external synchroni-
zation is necessary. The various trigger modes are described below.
The optimum object scan velocity is calculated from:
W
P
·
f
L
V
O
=
ß
If the velocity of the object carrier is not adjustable
then the line frequency of the camera must be
adjusted to provide an image with the correct aspect
ratio, where:
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
= S / FOV
Example 1:
Calculating the object scan velocity for a given field of view and line frequency:
Pixel width = 10 µm
Line frequency = 45 kHz
S = 10.24 mm
FOV = 20 mm
10 µm · 45 kHz
V
O
=
(10.24 mm / 20 mm)
= 879 mm/s
Example 2:
Calculating the line frequency for a given field of view and object scan velocity:
Pixel width = 10 µm
Object scan velocity = 800 mm/s
S = 10.24 mm
FOV = 20 mm
800 mm/s · (10.24 mm / 20 mm)
f
L
=
10 µm
= 41 kHz
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