Glossary - Schäfter+Kirchhoff SK6288GKOC-L Instruction Manual

Glossary

Exposure period
is the illumination cycle of a line scan sensor. It is the 
integration time plus the additional time to complete the
read-out of the accumulated charges and the output
procedure. While the charges from a finished line scan
are being read out, the next line scan is being exposed.
The exposure period is a function of the pixel number and
the  pixel frequency. The minimum exposure period of
a particular line scan camera determines the maximum
 line frequency that is declared in the specifications.
Integration control
Cameras with integration control are capable of curtailing
the  integration time within an  exposure period.
This performs an action equivalent to a shutter mechanism.
Integration time
The light-sensitive elements of the photoelectric sensor
accumulate the charge that is generated by the incident
light. The duration of this charge accumulation is called
the integration time. Longer integration times increase
the intensity of the line scan signal, assuming constant
illumination conditions. The complete read-out of
accumulated charges and output procedure determines
the minimum  exposure period.
Line frequency, line scan frequency
is the reciprocal value of the  exposure period. The
maximum line frequency is a key criterion for line scan
sensors.
Optical resolution
Two elements of a line scan camera determine the optical
resolution of the system: first, the pixel configuration of
the line sensor and, secondly, the optical resolution of the
lens. The worst value is the determining value. In a phased
set-up, both are within the same range.
The optical resolution of the line sensor is primarily deter-
mined by the number of pixels and secondarily by their
size and spacing, the inter-pixel distance. Currently
available line scan cameras have up to 12 000 pixels,
ranging from 4 to 14 µm in size and spacing, for sensors
up to 56 mm in length and line scan frequencies up to
83 kHz.
During a scanning run, the effective resolution perpendi-
cular to the sensor orientation is determined by the
velocity of the scan and by the  line frequency
© 2015
Schäfter + Kirchhoff GmbH • Hamburg
Pixel frequency
The pixel frequency for an individual sensor is the rate of
charge transfer from pixel to pixel and its ultimate
conversion into a signal.
Shading correction
 White Balance and Shading Correction, p. 16
SCM
Shading Correction Memory,
 White Balance and Shading Correction, p. 16
SOS
Start of scan,
 4.2 Advanced Synchronization Control, p. 24
SkLineScan
is the software application by Schäfter + Kirchhoff to
control the line scan cameras,
 3.1 Software: SkLineScan, p. 12
Synchronization
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 a constant object velocity have to be
compatible with each other.
For more accurate requirements or with a variable object
velocity then external synchronization is necessary.
SK6288GKOC-L Instruction Manual (06.2015)
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