Realization of a compact cross-grating spectrometer and validating experimental tests.

Echelle inspired cross-grating spectrometers offer the potential to bridge the gap between classical high-end echelle spectrometers and curved-grating single-element instruments. In particular, the cross-grating approach offers the possibility to simultaneously achieve a high spectral resolution and a wide accessible spectral range in compact dimensions and without moving parts. We report on the complete realization and implementation details of an all-reflective cross-grating spectrometer based on a modified Czerny-Turner configuration including a folded beam path and a toric-convex mirror for aberration compensation. The applicability of the cross-grating spectrometer is demonstrated by test measurements including the recording of the spectra of different plant leaves. For the cross-grating spectrometer, with an accessible wavelength range between 330 and 1100 nm, a spectral resolution of 0.6 nm at 589 nm was achieved.

Variable diameter CO2 laser ring-cutting system adapted to a zoom microscope for applications on polymer tapes.

This paper presents the conception and implementation of a variable diameter ring-cutting system for a CO2 laser with a working wavelength of 10.6 µm. The laser-cutting system is adapted to an observation zoom microscope for combined use and is applicable for the extraction of small circular areas from polymer films, such as forensic adhesive tapes in a single shot. As an important characteristic for our application, the variable diameter ring-cutting system provides telecentricity in the target area. Ring diameters are continuously tunable between 500 µm and 2 mm. A minimum width of less than 20 µm was found for the ring profile edge. The basic characteristics of the system, including telecentricity, were experimentally evaluated and demonstrated by cutting experiments on different polymer tapes and further exemplary samples.

Dual-mode pushbroom hyperspectral imaging using active system components and feed-forward compensation.

Among the methods developed for hyperspectral imaging, pushbroom spatial scanning stands out when it comes to achieving high spectral resolution over a wide spectral range. However, conventional pushbroom systems are usually realized using passive system components, which has limited their flexibility and adaptability and narrowed their application scenarios. In this work, we adopt a different approach to the design and construction of pushbroom systems based on using active internal components. We present a new system concept utilizing an internal line scanning unit and a rotating camera mechanism. This enables a dual-mode imaging system that allows switching between 2D spatial imaging and spectral imaging. The line scanning unit, which consists of a narrow slit mounted to a linear piezo motor, facilitates the spatial scanning of the target while eliminating the laborious relative motion between the target and the imaging system, which is needed in conventional spectrographs. A software is developed for the automation and synchronization of the active components, which enables a novel feed-forward compensation function to compensate the shift in the diffraction angle due to the scanning motion of the slit and provide higher flexibility in data acquisition.