Miniaturized interferometric 3-D shape sensor using coherent fiber bundles. (August 2018)

• Record Type: Journal Article
• Authors: Zhang, Hao; Kuschmierz, Robert; Czarske, Jürgen
• Is Part Of: Optics and lasers in engineering. Volume 107(2018)
• Page Start: 364
• Page End: 369
• Publication Date: 2018-08
• Subjects: Shape measurement -- Interferometry -- Coherent fiber bundle -- In-situ -- Image processing -- Speckle; Lasers in engineering -- Periodicals; Optical measurements -- Periodicals; Optics -- Periodicals; Lasers en ingénierie -- Périodiques; Mesures optiques -- Périodiques; Optique -- Périodiques; 621.36605
• DOI: 10.1016/j.optlaseng.2018.04.011
• Languages: English
• ISSNs: 0143-8166

Abstract

Highlights: A novel camera based laser Doppler distance sensor was developed. The sensor allows in-situ, absolute 3-D shape measurements of rotating workpieces in a lathe. A novel speckle separation technique and in-situ fringe distance calibration method were realized for reducing the measurement uncertainty. A coherent fiber bundle was employed to enable a compact sensor head with keyhole access. These methods also can be applied in other optical sensors that are limited by the speckle effect or the thermal effect. Abstract: Mach-Zehnder interferometer based sensors for simultaneous distance and velocity measurement allow for absolute 3-D shape measurements of rotating workpieces for instance in cutting lathes. The achievable shape uncertainty is limited to around one micron due to the speckle effect and temperature drifts, however. In this paper, a laser Doppler distance sensor with phase evaluation (P-LDD sensor) with a camera based scattered light detection is investigated. A novel speckle separation technique and in-situ fringe distance calibration method are realized to reduce the measurement uncertainty. A coherent fiber bundle is employed to forward the scattered light towards the camera. This enables a compact and passive sensor head with keyhole access. Compared with a photo detector based sensor, the camera based setup allows to decrease the measurement uncertainty by the order of one magnitude. As a result, the total shape uncertainty of absolute 3-D shape measurements can be reduced to about 100 nm.