Bidirectional confocal measurement of a microsphere.

This paper presents the bidirectional confocal measurement of a microsphere, which enables the simple measurement of the sphere with a similar number of measuring points taken on its upper and its lower hemispheres. The innovative measuring strategy is the placement of the sphere above a mirror and the subsequent measurement of the upper hemisphere on the real sphere and the lower hemisphere on the mirrored sphere. While theoretical explanations are given first, the main focus of the paper is the presentation of the idea itself and the very promising empirical findings.

Fringe Projection Profilometry in Production Metrology: A Multi-Scale Comparison in Sheet-Bulk Metal Forming.

Fringe projection profilometry in combination with other optical measuring technologies has established itself over the last decades as an essential complement to conventional, tactile measuring devices. The non-contact, holistic reconstruction of complex geometries within fractions of a second in conjunction with the lightweight and transportable sensor design open up many fields of application in production metrology. Furthermore, triangulation-based measuring principles feature good scalability, which has led to 3D scanners for various scale ranges.

Virtual cleaning and unwrapping of non-invasively digitized soiled bamboo scrolls.

In ancient China, symbols and drawings captured on bamboo and wooden slips were used as main communication media. Those documents are very precious for cultural heritage and research, but due to aging processes, the discovered pieces are sometimes in a poor condition and contaminated by soil. Manual cleaning of excavated slips is a demanding and time-consuming task in which writings can be accidentally deleted.

Browsing through sealed historical manuscripts by using 3-D computed tomography with low-brilliance X-ray sources.

Severely damaged historical documents are extremely fragile. In many cases, their secrets remain concealed beneath their cover. Recently, non-invasive digitization approaches based on 3-D scanning have demonstrated the ability to recover single pages or letters without the need to open the manuscripts.

High-speed focal-distance-modulated fiber-coupled confocal sensor for coordinate measuring systems.

This article presents a new robust, precise, high-frequency focal-distance-modulated confocal point sensor for probing in coordinate measuring systems (CMSs). While maintaining the known advantages of the confocal measurement principle, the sensor represents an innovative combination of a fiber-coupled confocal illumination and detection with a tuneable, acoustically driven gradient-index fluid lens for modulation of the focus distance and a novel signal processing utilizing a lock-in amplifier. The new arrangement is able to achieve an approximately linear characteristic curve for the optimized feedback control of the CMS in scanning sample mode.

Nanotopographic characterization of spotted micro arrays on polyvinyl alcohol films by high-resolution long-range nanoprofiling.

The nanopositioning and nanomeasuring machine was applied for the nanotopographic characterization of polymer micro spot arrays of fluorimetric chemochips. Chemochips are arrays of fluorescence dyes in a hydrogel matrix with different response behaviors of chemical components determination of chemical and physico-chemical properties of analytes by a pattern recognition approach. For the characterization and quality control of the spots, a nanometer resolution is needed over a scan range of several millimeters.