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05/05/2021 10:10

New 3D sensor scans transparent objects

Desiree Haak Strategie / Marketing / Koordination
Fraunhofer-Institut für Angewandte Optik und Feinmechanik IOF

    A new measurement method for 3D shape acquisition has been developed by researchers at the Fraunhofer Institute for Applied Optics and Precision Engineering IOF. With their “MWIR 3D sensor”, they can scan objects three-dimensionally, regardless of whether they are made of transparent plastic or glass. Even objects with shiny metallic or jet-black surfaces can be detected without any difficulties. Combining different materials is also no problem for the new 3D infrared sensor. In the field of 3D sensor technology, this degree of flexibility in the properties of the object is a first. Applications are conceivable in areas such as quality control in production and robotics.

    Until now, if you wanted to measure reflective, transparent or black surfaces accurately
    with conventional 3D scanners, you first had to treat the surface for this purpose. This
    means that the objects were temporarily coated with varnish for the measurement.
    After the scan, this usually had to be removed again at great effort.

    Glass and transparent objects become visible to machines

    The latest invention by Fraunhofer IOF will make this impractical and time-consuming
    treatment of the object superfluous in the future. Due to the size of the measuring
    field as well as the resolution and speed, the method is also suitable for quality control
    in production processes or for applications in automation.

    This is possible because researchers at the Fraunhofer Institute in Jena, Germany have
    succeeded in making thermal radiation usable for 3D measurement. The researchers
    therefore refer to this method as “3D sensing in the thermal infrared range”. At the
    heart of the system is a high-energy CO2 laser with which the objects are irradiated.

    Using special lenses for high power densities, the laser beam is expanded into a line
    that vertically illuminates the entire object. For a high-resolution measurement result,
    this line is moved over the object in a specially coordinated sequence. The energy of
    the laser light is absorbed by the measured object and partially re-emitted.

    Combination of thermography and triangulation

    Two thermal imaging cameras analyze the thermal signature left by the narrow and
    intense infrared line on the object from two different perspectives. Afterwards, a software developed in-house calculates spatial pixels from the information of the two viewing angles and merges them into the exact dimensions of the measured object.

    The thermal energy introduced for the 3D analysis is so low that the object is not damaged. The temperature difference between heated and non-heated surfaces is typically
    less than 3 °C. For this reason, the method is also suitable for sensitive materials.

    “By switching from a full-surface thermal pattern to a narrow thermal strip, we have
    succeeded in advancing the technology in such a way that we can meet the requirements placed on a 3D sensor in industrial use,” emphasizes Martin Landmann, a researcher of the “Imaging and Sensing” department at Fraunhofer IOF. Together with
    his team and a group of researchers of the innovation alliance “3Dsensation”, he has
    been working on the system since 2017.

    “With adaptive mirror optics, we have succeeded in focusing the power of the laser on
    a much smaller surface, thus providing the necessary contrast for the thermal imaging
    cameras much faster. Only this made it possible to achieve an accuracy of less than 10
    µm for the 3D coordinates with a field of view width of 160 mm," he explains.

    Conceivable applications in robotics

    Following the successful scientific demonstration of the new measurement method, the
    researchers are now working intensively to make the measurement principle ready for
    the market: “For us, it is now a matter of transferring the system from the laboratory
    to practical use,” explains Landmann. He already has concrete areas of application in
    mind: “The parameters of our system allow us to optimize it for different application
    scenarios. If we reduce the resolution to below 50 µm, we can record a stereoscopic
    data set in under a second and are thus fast enough for applications in robotics.”

    At Fraunhofer IOF, researchers are currently developing various systems based on the
    MWIR 3D measurement method. In addition to optimizing the method for various
    measurement scenarios and applying it in industrial plants, the team led by Martin
    Landmann and group leader Dr. Stefan Heist is working on a system for use in robotics.
    This system focuses on transforming the laboratory setup into a prototype that is as
    compact and robust as possible. In this way, robots can be enabled to recognize and
    grasp transparent objects.

    First MWIR 3D system "Glass360Dgree" presented at "Control-Virtual"

    The first application-oriented system to use this MWIR 3D measurement principle is
    "Glass360Dgree". The system is specifically designed for inspecting glass bodies in
    optics manufacturing and will also be used by research partners in the further course of
    testing how the measurement method can be integrated into a wide variety of robotic
    processes. The Fraunhofer IOF researchers will present "Glass360Dgree" to the public
    for the first time at "Control-Virtual", the international trade fair for quality assurance,
    starting May 3.

    Trade journal “inVISION” honors new sensor as “Top Innovation 2021”

    The new 3D measurement method in the thermal infrared region was recently selected
    as “Top Innovation 2021” by the magazine “inVISION” - a trade journal for the topics
    of image processing, embedded vision and measurement technology. “We are very
    pleased about the inVISION award,” says group leader Dr. Stefan Heist. “This is a wonderful confirmation of our intensive work over the past years and a great motivation to
    keep enhancing our 3D thermal system.”

    Contact for scientific information:

    Dr. Stefan Heist

    Fraunhofer IOF
    Imaging and Sensing
    Albert-Einstein-Straße 7
    07745 Jena

    Phone: +49 (0) 3641 807-214

    More information: Press release (incl. images and video demonstration) on the website of Fraunhofer IOF 3D measuring systems at the Fraunhofer IOF Imaging and Sensing at Fraunhofer IOF


    The system works with thermal radiation for the 3D detection of transparent objects
    The system works with thermal radiation for the 3D detection of transparent objects
    Walter Oppel
    Fraunhofer IOF

    "Glass360Dgree" visualization of the 3D scanning process
    "Glass360Dgree" visualization of the 3D scanning process
    Walter Oppel
    Fraunhofer IOF

    attachment icon Press Release: New 3D sensor scans transparent objects

    Criteria of this press release:
    Journalists, Scientists and scholars
    Materials sciences, Physics / astronomy
    transregional, national
    Research results, Transfer of Science or Research


    The system works with thermal radiation for the 3D detection of transparent objects

    For download


    "Glass360Dgree" visualization of the 3D scanning process

    For download



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