Showing papers by "Richard Kowarschik published in 2010"
TL;DR: A high-speed projection system that is able to project statistical speckle patterns at a rate of 500Hz to generate structured light for a real-time photogrammetry stereo vision setup and compares it with widely used stripe projection methods, qualitatively and quantitatively.
Abstract: We propose a high-speed projection system that is able to project statistical speckle patterns at a rate of 500Hz. Its purpose is to generate structured light for a real-time photogrammetry stereo vision setup. As conventional digital light projector (DLP) projection setups are limited in their maximum projection rate to 250Hz for gray-value patterns, stripe projection systems are usually applied for real-time three-dimensional (3D) measurements. However, these techniques can only be used on steady surfaces as phase unwrapping has to be done. In contrast, the proposed setup is able to measure the shape of multiple spatially separated objects at once. We compare the speckle setup with a system using a DLP projector and with other fast 3D shape measurement setups, like the widely used stripe projection methods, qualitatively and quantitatively.
112 citations
TL;DR: The calibration process is presented, and first quantitative results of a shape measurement are shown and discussed, to demonstrate its universal use.
Abstract: We propose what we believe to be a novel approach to measure the 3D shape of arbitrary diffuse-reflecting macroscopic objects in holographic setups. Using a standard holographic setup, a second CCD and a liquid-crystal-on-silicon spatial light modulator to modulate the object wave, the method yields a dense 3D point cloud of an object or a scene. The calibration process is presented, and first quantitative results of a shape measurement are shown and discussed. Furthermore, a shape measurement of a complex object is displayed to demonstrate its universal use.
26 citations
TL;DR: In this article, the phase difference between the Fourier spectrum is corrected by subtracting the phase values of the overlapping areas and plotting them into a histogram, and the amplitude adjustment between different spectral sections is demonstrated.
20 citations
8 citations
TL;DR: In this paper, an extended array interferometer is presented, which allows for more sensitive measurements for the determination of the area of coherence for holographic microscopy, which can be adapted and measured in micrometer scale.
Abstract: Zusammenfassung Interferometrische Mess- und Abbildungsverfahren sind häufig durch kohärentes Rauschen begrenzt. Eine Anpassung des Kohärenzvolumens an die Messbedingungen kann das Rauschen verringern. Für die holografische Mikroskopie müssen Kohärenzparameter im Mikrometerbereich eingestellt und gemessen werden. Das klassische Young´sche Doppelspalt-Interferometer ist dabei oft zu unempfindlich. Ein erweitertes Array-Interferometer liefert deutlich empfindlichere Messungen für die Bestimmung der Kohärenzfläche. Abstract Interferometric measurement and imaging techniques are often impaired by coherent noise. An adjustment of the volume of coherence can be adjuvant. For holographic microscopy the coherence parameters have to be adapted and measured in micrometer scale. The classic Young´s double-pinhole interferometer´s sensitivity is often too low for this case. An extended array interferometer is presented here, which allows for more sensitive measurements for the determination of the area of coherence.
4 citations
TL;DR: In this paper, a partially coherent illumination was proposed to suppress the coherent noise and optimize the imaging quality. But, it is shown that the illumination can not be used in a high coherent laser light source, which causes coherent noise.
Abstract: Holographic micro-imaging setups commonly use high coherent laser light sources, which cause coherent noise It is shown how a partially coherent illumination suppresses the coherent noise and optimizes the imaging quality
2 citations