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|for glass tubes|
|for image acquisition|
Image acquiring scanner
Compared to camera based systems, OPOS' s scanner for automatic
visual inspection and measurement of transparent objects provide
a huge depth of focus, hence, are suited ideally to the inspection
of 3d- extended glass objects with large depth expansion. For
example, fluffs, hair and scratches can be detected in objects
with a depth expansion of 300 mm automatically.
Different scanner dimensions with measurement fields starting with 30 mm are available. In a special configuration refracting transparent objects (e.g., glass pipes) are also checkable completely in one movement through the inspection area.
For big 3d-vast glass objects a modular scanner system was developed in 2009 by OPOS. It bases on addable scanner modules with an inspection line of 380 mm. They provide a bright field channel for the to the detection of defects with an expansion greater 0.3 mm and a dark field channel for the detection of smaller defects from approx. 10 µm of expansion. The scanner module permits the detection of these defects in objects with a depth expansion up to 300 mm. The scanners dispose of a CameraLink interface and can be connected therefore to every framegrabber (similar to a line scan camera).
The Fraunhofer Institute IOSB developed inspection systems on the basis of these scanners and introduced them in industry. For example, glass ingots can be inspected and sorted automatically in one movement through the inspection line. Defects are detected automatically in ingots with up to 300 mm of depth expansion - no matter whether they are on the front, back or in the volume. The software of the IOSB is adaptably on different product sizes and compensates deviations of the product position in the measuring field. Further on different test zones, defect classes and defect thresholds can be defined. With it the user can adapt the test criteria for different products and product qualities.
Example of an image acquired with the software of the Fraunhofer
The patented optical arrangement of the scanner allows also the inspection of refracting objects like glass pipes and cylinders. The inspection quality is similar to the inspection of non refracting objects like glass ingot or bent flat glass. An complete inspection of vast glass pipes or cylinders can occur in a biaxial arrangement. The scan rate of the standard modules of 2.2 kHz permits a check step-holding with the production of vast glass pipes up to speeds of 0.7 m/s. Customised adaptations are possible any time. As an example of the defects which can be shown in glass pipes with the dark field channel of the scanner the picture above shows an image acquisitin of a pipe with a node line. The automatic detection and classification of nodes with the help of such images is easily possible.
Original (dual channel) image of a pipe with node line. The bright field channel permits (red) the measurement of transparency profiles and the recognition of larger defects
The dark field channel permits the recognition of finer defects as well as defects which lead to diffraction of the laser beams. The image shows clearly the node line in a glass pipe.
German Patent Application DE 198 06 288 A 1 ,(16.02.1998)
If you are interested in further information, a demonstration, an adaptation of this sensor or a development of a solution of your measurement problem, please contact:
firstname.lastname@example.org or write or phone to:
OPOS Optical On Line Sensors
D-76187 Karlsruhe / Germany
Tel +49 (721) 97130-50
Fax +49 (721) 97130-51
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