The error in three-dimensional (3-D) scans by a 3-D measurement system based upon fringe projection on translucent objects is presented. The dependencies on different material parameters are shown. A model describing the cause of the measurement error is introduced and the possibility of error compensation by shifting measurement points in a normal direction is demonstrated
The Abbe School of Photonics (ASP) provides photonics education of graduate and doctoral students at the Friedrich Schiller University in Jena, Germany. The main instrument for training students in optical sciences is a Master's degree program, which is open to international students, research-oriented and supported by German photonics industry. In this context, a conceptually new open lab Makerspace for photonics was established to support both the internal students in the realization of innovative and creative processes, as well as to build a strong and curious community of like-minded people from outside of the university. The photonics Makerspace provides all tools and materials needed to setup state-of-the-art optical instruments. Furthermore, it provides technical mentoring, open workshops and lectures. Partners from the photonics industry corroborate the process of making by well-established open innovation schemes and are integrated into the Makerspace with hackathon and innovation camp formats where the Makerspace users work on industry challenges. Finished and ongoing projects are transformed into freely accessible, open source hardware while a commercial exploitation of the projects is supported. Out of the broad topical spectrum of ongoing projects, two quite advanced examples are a low-cost smartphone-based 3D-scanner with a cloud-based, free software and a high-resolution microscope built of 3D-printed modules. For these projects, apart from hardware and software, also workshops and lectures are available. Other examples include a drone for medical applications in search and rescue, a smartphone-based lithography setup, a Raman-spectrometer, a camera array for meteorite detection, and many more. All activities of the Makerspace are scientifically investigated with special attention on the interaction between open innovation approaches and the Maker scene. Here, we will share our insights into potentials and opportunities offered by this novel educative approach.
In many application areas, stereo vision-based active triangulation systems are used to reconstruct the three-dimensional (3-D) surface shape of measurement objects. Typically, in order to solve the correspondence problem and increase the accuracy of the pixel assignment, a sequence of patterns is projected onto the object's surface and simultaneously recorded by two cameras. Most 3-D measurement systems are limited to static objects. In order to enhance their speed, it is necessary to use fast cameras as well as fast projection systems. Although high-speed camera systems are available, pattern projection at high frame rates is a difficult task and only a few techniques exist at the moment. In this contribution, we compare two different projection approaches, a laser-based speckle projection unit and an LED-based multi-aperture projection system, with regard to the achievable point cloud completeness and accuracy
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