3 October 1995 New active 3D vision system based on rf-modulation interferometry of incoherent light
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Abstract
Presently there is still a remarkable gap between the requirements and the capabilities of 3D- vision in the field of industrial automation, especially in manufacture integrated 100%-quality control. For these and a lot of other applications like security and traffic control a new extremely fast, precise and flexible 3D-camera concept is presented in this paper. In order to obtain the geometrical 3D information, the whole 3D object or 3D scene is illuminated simultaneously by means of rf-modulated light. This is realized by using optical modulators such as Pockels cells or FTR optical components (FTR: Frustrated Total Reflection). The back scattered light represents the depth information within the local delay of the phase front of the rf-modulated light intensity. If the reflected wave front is mixed again within the whole receiving aperture using the same optical 2D-modulation components and the same rf- frequency, an rf-interference pattern is produced. A CCD camera may be applied to sample these rf-modulation interferograms. In order to reconstruct the 3D-image a minimum of three independent interferograms have to be evaluated. They may be produced either by applying three different rf-phases or three different rf-frequencies. This procedure will be able to deliver up to some tens of high resolution 3D images per second with some hundred thousand voxels (volume elements). Such a remarkable progress can be achieved by means of three key important steps: Firstly by separating the opto-electronic receiver device from real-time requirements by using homodyne mixing of CW-modulated light. Secondly by applying the rf- modulation signal as an optical reference signal to the receiving optical mixer. And thirdly by using a throughout 2D layout of the transmitted illumination, further, of the optical mixer in the receiving aperture, and of the optoelectronic sensing element, e.g., a CCD-chip.
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Rudolf Schwarte, Horst-Guenther Heinol, Zhanping Xu, Klaus Hartmann, "New active 3D vision system based on rf-modulation interferometry of incoherent light", Proc. SPIE 2588, Intelligent Robots and Computer Vision XIV: Algorithms, Techniques, Active Vision, and Materials Handling, (3 October 1995); doi: 10.1117/12.222664; https://doi.org/10.1117/12.222664
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