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Camera Performance and Features
Adjusting Responsivity
See the section Camera Control Category in Appendix A for GenICam features associated with this
section and how to use them.
Relevant Features:
It is desirable for camera performance to always use the maximum exposure time possible based
on the maximum line rate of the inspection system and any margin that may be required to
accommodate illumination degradation. However, it will be necessary to adjust the responsivity to
achieve the desired output from the camera. The camera has a gain feature that can be used to
make the necessary adjustment to the responsivity.
There are two gain adjustments available: sensor row gains, which can be set independently for
each sensor row; and the system gain, which is applied to all sensor rows.
Image Response Uniformity & Flat Field Calibration
See the section Flat Field Category in Appendix A for GenICam features associated with this section
and how to use them
Related Features:
Calibration Target
It is common to find that an image has a lower
response at the edges of the camera’s field of view
compared to its center. This is typically the result of a combination of lens vignetting (cos
4th
) roll-
off and the beam structure of the illumination source. Using a more diffused light may reduce the
roll-off effect. However, if decreasing the lens aperture improves the edge roll-off, then barrel
vignetting (a shadow cast on the sensor by the focus helical or extension tubes) may also be
present.
The camera can compensate for edge roll-off and other optical non-uniformities by using flat field
calibration.
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When performing Flat Field (PRNU) calibration, the camera should be imaging a front
illuminated white target or rear bright field illumination source. The optical setup should be
as per the inspection system, including lens magnification, aperture, and illumination
intensity, spectral content, plus illuminator beam structure.
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Flat field calibration should be performed when the camera temperature has stabilized.
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When the camera is asked to run a flat field calibration it will adjust all pixels to have the
same value as that of the peak pixel value or target level, as per the calibration mode
selected.
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If the flat field calibration is set to a target level that is lower than the peak value and the
system gain is set to a low value, then it is possible that the sensor will maximize its output
before the camera’s output reaches 255 DN. This can be seen when a portion of the output
stops increasing before reaching 255 DN with increasing illumination and the PRNU
deteriorates. This effect can be resolved by decreasing the light level or exposure control
time.
Following a flat field calibration, all pixels should be at their un-calibrated peak value or target
value. Changing gain values now allows the user to make refinements to the operating responsivity
level.
Summary of Contents for ML-FM-16K07A
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Page 18: ...18 Linea ML Multiline Monochrome HDR CMOS Cameras Figure 9 Linea ML HM 16K Camera Mechanical ...
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