Comparing laser and polychromatic confocal optical displacement sensors for the 3D measurement of cylindrical artefacts containing microscopic grooved structures

Abstract

A scanning system has been developed for measuring the surface of early cylinder mechanical sound recordings to high precision, both for surface preservation and for post-processing of the data to recover the sound encoded in the grooves. Research has identified that high sensor axial resolution is required to resolve the smallest amplitude groove modulations contained on typical cylinder artefacts resulting in the selection of confocal laser and white light (polychromatic) confocal sensors as suitable sensing technologies. This paper presents data acquired by the two confocal sensor technologies, comparing the measured surface profiles with data obtained using a stylus profilometer. We investigate limitations of the sensors, relating their characteristics to the ongoing development of the scanning system.

Characterization of the main error sources of chromatic confocal probes for dimensional measurement

“…Calibration is achieved by comparing the confocal measurement with a more accurate measurement serving as a reference in order to ensure measurement traceability. In this context, Boltryk et al [9,10] investigate the behaviour of chromatic confocal probes when performing measurement on cylindrical artefacts with sinusoidal grooves. The results reveal that the confocal measurements depend on the depth of the grooves and the inclination of the flanks.…”

Chocolate Swelling during Storage Caused by Fat or Moisture Migration

“…The technique is regularly implemented in the production industry as a tool to control thickness, dimensions, and locations of different products (Micro‐Epsilon 2008). In scientific literature, the CCDS technique has been applied to monitor the thickness of wavy water (Zhou and others 2009) or silicone fluid films (Lel and others 2005) and to generate surface profiles (Boltryk and others 2009). The latter application is of particular interest for quantitative investigations of swelling in chocolate as the CCDS technique offers the possibility to scan the height profile of a sample prior to and after migration from filling components.…”