Photon Focus MV0 3D06 Series, User Manual, Page: 66 / 125

11 Image Data Processing
Figure 11.2: Laser test image
11.5 3D Features
11.5.1 Overview
The MV0 Python 3D06 cameras contain a very accurate laser line detector for laser
triangulation (measurement of 3D profiles) that extracts 3D information in real time. For more
details see Section 11.5.4.
The camera should be placed so that the laser line is located in horizontal direction. The
outputs of the laser detector (LineFinder or COG) are the location coordinate of the laser line,
the width of the laser line and the peak height, representing the signal intensity of the laser
line (see Section 11.5.3).
The camera has a special mode (see 2D&3D mode in Section 11.5.5) for setup and debugging
purposes that allows to view the image and the detected laser line in the same image.
11.5.2 Measuring Principle
For a triangulation setup a laser line generator and a camera is used. There are several
configurations which are used in the laser triangulation applications. Which setup is used in an
application is determined by the scattering of the material to be inspected. There are setups
for highly scattering materials and others for nearly reflecting surfaces.
In addition the penetration depth of light depends on the wavelength of light. The longer the
wavelength the deeper is the penetration of the light. Historically red line lasers with a
wavelength around 630 nm were used. With the modern high power semiconductor line laser
in blue (405 nm), green and also in the near infrared there is the possibility to adapt the
wavelengths according to the inspection needs.
But not only the penetration depth affects the choice of the wavelength of the line laser. For
an accurate measurement, other disturbing effects such as radiation or fluorescence of the
object or strong light from neighbourhood processes have to be suppressed by optical filtering
and an appropriate selection of the laser wavelength. Hot steel slabs for instance are best
inspected with blue line laser because of the possibility to separate the laser line with optical
filters from temperature radiation (Planck radiation) which occurs in red and NIR.
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