Photonic Lanterns (PLs) play a crucial role in astrophotonic technologies, converting multi-mode inputs to single-mode outputs while being theoretically low loss. Despite technical advancements, the reproducibility of PLs remains unexplored. We present a study characterizing multiple PLs to address the challenges of mass production. Initial results indicate high taper rate consistency, vital for PL stability and their integration into astrophotonic instruments. Beyond taper measurements, our comprehensive evaluation includes throughput, near-field, and chromatic analysis, ensuring mass produced PLs meet stringent telescope requirements.
Imaging Raman spectroscopy can be used to identify cancerous tissue. Traditionally, a step-by-step scanning of the sample is applied to generate a Raman image, which, however, is too slow for routine examination of patients. By transferring the technique of integral field spectroscopy (IFS) from astronomy to Raman imaging, it becomes possible to record entire Raman images quickly within a single exposure, without the need for a tedious scanning procedure. An IFS-based Raman imaging setup is presented, which is capable of measuring skin ex vivo or in vivo. It is demonstrated how Raman images of healthy and cancerous skin biopsies were recorded and analyzed.
After having demonstrated that an IFU, attached to a microscope rather than to a telescope, is capable of differentiating complex organic tissue with spatially resolved Raman spectroscopy, we have launched a clinical validation program that utilizes a novel optimized fiber-coupled multi-channel spectrograph whose layout is based on the modular MUSE spectrograph concept. The new design features a telecentric input and has an extended blue performance, but otherwise maintains the properties of high throughput and excellent image quality over an octave of wavelength coverage with modest spectral resolution. We present the opto-mechanical layout and details of its optical performance.
Spatially resolved sensing of molecular oxygen is important for many biological and environmental applications. For this
purpose, time-resolved fluorescence measurements were combined with optical time domain reflectometry (OTDR), a
technique which was primarily developed for inspections of optical fiber lines. To achieve spatial resolution of some
meters, which are typical for commercial OTDR instruments, the lifetimes of the sensor dyes must be within the range of
some nanoseconds, which is much shorter than the decay times of common phosphorescent oxygen probes. Therefore,
the measurements were performed with a novel fluorescent triangular-[4]phenylene sensor dye. The fluorescence decay
times are around 80 ns in absence of oxygen and around 20 ns in the presence of air. The [4]phenylene sensor dye was
applied in toluene solution as well as immobilized in a polymer film. Using a branched model fiber line, oxygen
measurements were carried out in a micro- to millimolar concentration range. Oxygen-dependent fluorescence decay
times measured with OTDR in toluene were verified by use of time-correlated single photon counting (TCSPC). The
Stern-Volmer plots obtained for fluorescence quenching of sensor dyes dissolved in toluene solution and polymer-based
sensor spots show good linearity.
Optical measurements of molecular oxygen are based on phosphorescent dyes with decay times dependent on the
ambient oxygen content. Additionally, the phosphorescence decay times are affected by the temperature. In this work,
we present miniaturized fiber optical probes, which are able to determine both ambient oxygen content and temperature
simultaneously.
Two examples of our biophotonic research utilizing nanoparticles are presented, namely laser-based fluoroimmuno analysis and in-vivo optical oxygen monitoring. Results of the work include significantly enhanced sensitivity of a homogeneous fluorescence immunoassay and markedly improved spatial resolution of oxygen gradients in root nodules of a legume species.
Machine dyes are frequently used as nonlinear optical (NLO) chromophores. In the case of our dyes, both, the substitution of the methine proton by a cyano group and the substitution of the methine carbon by nitrogen, lead to a strong bathochromic shift. In this work the influence of these modifications to the first hyperpolarizability is systematically investigated.
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