Recent  

The purpose of our study is to demonstrate the detection of hydrogen in a mixture with natural gas by means of ultrasound measurements. In the coming years, hydrogen will be mixed with natural gas and distributed in the available gas pipeline network; therefore, monitoring the hydrogen content in real time becomes a necessity. We show the implementation of miniature ultrasound transducers (CMUTs) for this purpose by measuring the speed of sound of the mixture.

A very small, anharmonic but periodic signal is separated from a noise background that is orders of magnitude larger than the pure signal. The approach consists of a sequence of filters and transformations and is demonstrated on an interferometric measurement of the high-temperature chemical expansion of a thin film, containing heat haze, thermal length drift, and parasitic vibrations. The displacement is 38 % larger and the uncertainty 35 % lower than when evaluated with previous approaches.

This study introduces four sensors utilizing multiple fiber Bragg grating constellations embedded in a silicon dioxide single-mode fiber for simultaneous pressure, temperature, and bending curvature measurement. By varying grating constellation, dimensions, and materials, researchers optimized sensor performance. Results indicate that the optimal configuration involves a high cladding-to-coating ratio, less-stiff coating, and the combination of two gratings to form a Fabry–Pérot interferometer.

The paper presents a concept for fabricating a biosensor with enhanced long-term stability and offers new options for designing photonics-based microsystems aimed at analysing biosamples. In order to couple the light used to probe samples, a grating is illuminated from the back side, thus realizing an inverted grating configuration. This offers the possibility of designing microsystems that can be operated more conveniently and with a much extended lifetime.

3D thermograms are a good alternative when a single traditional 2D thermal image does not reveal enough information to analyze a complex object. However, the 3D thermography field is still under exploration. This paper shows a comparison of a thermography system operated with two different 3D sensors. The results indicate that the depth sensor with more accurate measurements captures the object geometry better, and therefore the interpretation of the 3D thermograms is improved.

High levels of nitrate can cause negative effects on aquatic plants, fishes and human health. A simple, reusable and sensitive electrochemical sensor based on silver nanoparticles with a modified gold screen-printed electrode has been developed for the detection of nitrate in water.  The sensor exhibited good performances such as high sensitivity, reproducibility, repeatability and selectivity. The proposed approach was successfully used to determine nitrate in freshwater.

In power electronics, materials like silicon carbide (SiC) are increasingly being used instead of silicon. They have a lot of advantages but also require defect inspection with high accuracy. Different defect types on SiC samples are measured with various methods to determine which one is most suitable for which defect. In conclusion, each examined measurement method is sensitive to the studied defects, although they differ in speed and specialized application fields.

Essential steps for the establishment of a data cycle were discussed, boundary conditions were defined and possible technological solutions for the achievement of the objective were presented. The subaspects mentioned are data generation, archiving, database extraction and reuse. A special focus was on the data format DICONDE, whose structuring and archiving techniques primarily address test data. In addition, two examples were presented in which this schema was implemented.

Interferometric form measurement methods display ambiguities between certain form errors and the misalignment of measurement specimens. In this work, we present a concept for improving the accuracy of the form measurement of aspheres and freeform surfaces with a tilted-wave interferometer by introducing absolute distance measurements using a white light interferometer. A description of the laboratory setup and the corresponding data analysis is given together with first distance measurements.

The presented approach allows users to perform measurements of microphone responses directly in the array using the internal hardware and so to characterize the whole signal chain of microphone–preamplifier–ADC. The measurements do not need special equipment and can be carried out in ordinary reverberant locations. A loudspeaker driven by a voltage pulse is used to produce a sound wave with a short first wavefront. Processing only this wavefront suppresses reflected waves that arrive later.

This paper presents a conceptual approach for enhancing the communications between different calibration systems in a calibration ecosystem and enabling data exchange based on the digital calibration certificate (DCC) using the Beamex calibration ecosystem as an example. The presented system architecture concept introduces data exchange and DCC services that would allow the exchange of calibration data between the Beamex ecosystem and third-party systems.

Our research introduces an innovative method to improve the quality control of plastic granules, crucial in industries like manufacturing and automotive. We addressed a common issue: identifying "burn marks" on granules caused by overheating during processing. By combining advanced machine learning and a novel data augmentation technique called "cutout", we significantly enhanced the detection accuracy of these defects.

Greenhouse gas emissions from freshwaters are not well quantified on a global scale. Our prototype monitors aqueous concentrations of CH₄ and CO₂ at relevant timescales. Our low-cost design allows the application of replicated sensors to capture spatial heterogeneity and temporal variability in dissolved gases in highly dynamic ecosystems, thereby addressing a major bottleneck in the reliable estimation of emissions. We provide a detailed prototype description and share software code.