Capturing Transparent Objects in Three Dimensions

I recall a related problem for the detection of errors in manufacturing process.   Its broad use in this kind of application?

Fraunhofer at the Hannover Messe Preview 2022

Research News / March 16, 2022  in Fraunhofer

Capturing transparent objects in three dimensions is a major challenge. Researchers at Fraunhofer Institute for Applied Optics and Precision Engineering IOF have developed a sensor that is able to solve this problem. The system has now been successfully tested for the first time with a robot. Applications in large-scale industrial manufacturing processes such as the semiconductor or automotive industry could be possible. The sensor will be featured at the Hannover Messe Preview on March 16 and at the German trade fairs Control from May 3 – 6, as well as Hannover Messe from May 30 – June 2, 2022.

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

Transparent objects have their drawbacks: It is not without reason that we have stickers of birds’ silhouettes on big glass windows in order to protect their real-life conspecifics from colliding with the transparent barrier. Just as these animals have difficulties recognizing transparent surfaces, robots are also limited in their capabilities: They cannot “see” glass or other so-called “uncooperative surfaces” – i.e., surfaces that are glossy metal, extremely reflective, or jet-black. Especially in an industrial environment, this has been impeding the use of robots in the past. Many projects of automatization stagnate because uncooperative surfaces could only be detected too slowly or too inaccurately in 3D measurement.

Thermographic 3D sensor makes transparent objects visible to robots for the first time

A new 3D measurement technique, developed by researchers at Fraunhofer IOF last year, solves this problem: The “MWIR 3D Sensor” – also called “Glass360Dgree” – can detect objects with reflective or light-absorbing surfaces spatially and reliably for the first time. For this purpose, the system combines infrared laser projection and thermography: After locally heating up the object to be measured, two thermal imaging cameras determine the resulting temperature distribution on the object’s surface. Contrary to conventionally used sensors, the newly developed system does not require additional measurement aids or special, temporarily applied markings, for example in the form of (spray) paint.

High measurement speed for applications in large-scale industrial processes

Production processes are often about speed combined with high quality. This means: The more work steps a system can perform per minute without producing defective products, the more profitable is the production. The researchers at Fraunhofer IOF have taken this self-image of industry as an opportunity to adapt “Glass360Dgree” to various production scenarios. In recent months, the researchers from Jena have succeeded in increasing the measurement speed accordingly and optimizing the parameters of the measurement field.

“Our research group has been cooperating for years with companies from a wide range of production fields,” explains Dr. Stefan Heist, head of the “3D Sensors” research group at Fraunhofer IOF. “Among them are companies from semiconductor manufacturing, the automotive industry and aviation. We looked at joint projects from the past and analyzed how our 3D glass sensor could achieve better results than conventional sensors in various application scenarios,” explains the researcher, who has been working vigorously on new methods for 3D measurement for years. “We were able to identify three key starting points to make our system ready for potential use in a large-scale industrial manufacturing facility.”.... '