Quality assurance and machine vision for inspection

Levi, Paul

doi:10.1007/bfb0014787

Cited by 1 publication

(2 citation statements)

References 18 publications

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“…This will simply result in different directions of propagation, causing a lateral shift across the common Fourier plane of the imaging system in which an aperture is located, as shown in Figure 1b. Such large variations in the illumination direction will violate the small illumination angle assumption used for Equation (1).…”

Section: Increasing the Illumination Aperturementioning

confidence: 99%

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Extended-Aperture Shape Measurements Using Spatially Partially Coherent Illumination (ExASPICE)

Agour,

Falldorf,

Bergmann

2024

Sensors

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We have recently demonstrated that the 3D shape of micro-parts can be measured using LED illumination based on speckle contrast evaluation in the recently developed SPICE profilometry (shape measurements based on imaging with spatially partially coherent illumination). The main advantage of SPICE is its improved robustness and measurement speed compared to confocal or white light interferometry. The limited spatial coherence of the LED illumination is used for depth discrimination. An electrically tunable lens in a 4f-configuration is used for fast depth scanning without mechanically moving parts. The approach is efficient, takes less than a second to capture required images, is eye-safe and offers a depth of focus of a few millimeters. However, SPICE’s main limitation is its assumption of a small illumination aperture. Such a small illumination aperture affects the axial scan resolution, which dominates the measurement uncertainty. In this paper, we propose a novel method to overcome the aperture angle limitation of SPICE by illuminating the object from different directions with several independent LED sources. This approach reduces the full width at half maximum of the contrast envelope to one-eighth, resulting in a twofold improvement in measurement accuracy. As a proof of concept, shape measurements of various metal objects are presented.

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Section: Increasing the Illumination Aperturementioning

confidence: 99%

“…Accurately measuring the geometry of technical parts is crucial for improving and streamlining the manufacturing process [1]. To ensure quality during production, 3D shape profiling is essential for many applications.…”

Section: Introductionmentioning

confidence: 99%