Methane plays an important role in global warming, and tracing its sources requires precise analysis of its isotopic fingerprint. In this study, we demonstrate the foundation of a system based on optical feedback cavity-enhanced absorption spectroscopy that achieves the stability needed for accurate isotope measurements. This work shows the potential of the method for future climate studies and environmental monitoring.

This article describes the determination of ferrite and austenite proportions in the weld zone of duplex steels using image processing and neural networks. These proportions allow conclusions to be drawn about the quality of the weld. For this purpose, neural networks of different architectures were applied to various image data configurations of metallography images. Depending on the architecture and application of the networks, error rates of 2 % to 3 % were achieved, which met expectations.

We present a 3D gas schlieren imaging sensor (3D-GSIS) for reconstructing vehicle exhaust plume density fields. It estimates plume size, laser absorption path lengths, intersection points of lasers, and local densities. Combined with advanced remote emission sensing, it enables direct measurement of pollutant concentrations in exhaust plumes.

A non-contact, optical methodology suitable for high temperatures based on laser-Doppler vibrometry is presented to directly determine piezoelectric constants. LiTaO₃ is chosen as a model material as it is a representative piezoelectric material with applications in sensors and surface acoustic wave devices. The values determined range from 12 pm V^-1 at 21 °C to about 15 pm V^-1 at 400 °C, being in good agreement with the literature. Thus, the proof of concept for this approach has been obtained.

We present an eight-channel evaluation board for ultrasound sonography and photoacoustic imaging. High frame rates enable averaging, improving signal-to-noise ratio. The board integrates a programmable preamplifier and an analog front-end with 12-bit analog-to-digital conversion, with data transmitted via Ethernet for PC evaluation. Gain distribution and its effect on signal-to-noise ratio in a multichannel photoacoustic receive chain are quantitatively characterized at 540 frames per second.

Automation in measurement tracking improves quality management by reducing human interaction and manual data risks. To enable this, all metrological and administrative data in quality certificates must be machine-readable. Digital calibration certificates (DCCs) meet this need and enable fully automated compliance checks. A temperature-monitoring demonstrator illustrates their automation potential. Its code is published for reuse.