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.

In the field of tissue engineering, spherical phosphorescent microprobes are well suited to quantify the oxygen content in close proximity to the cells during their growth phase. When using standard seed trays like glass dishes, probe excitation and signal acquisition can be realized by applying a fluorescence microscope. However, when using a bulky bioreactor a custom-built optics system with a laser as the excitation source had to be employed. Here we describe the basic principles of spherical optical oxygen microprobes for use in standard cell cultures and the system modifications with a laser, which were required in order to perform similar measurements from a distance in bioreactor cultures.

Wide field Raman imaging using the integral field spectroscopy approach was used as a fast, one shot imaging method for the simultaneous collection of all spectra composing a Raman image. For the suppression of autofluorescence and background signals such as room light, shifted excitation Raman difference spectroscopy (SERDS) was applied to remove background artifacts in Raman spectra. To reduce acquisition times in wide field SERDS imaging, we adapted the nod and shuffle technique from astrophysics and implemented it into a wide field SERDS imaging setup. In our adapted version, the nod corresponds to the change in excitation wavelength, whereas the shuffle corresponds to the shifting of charges up and down on a Charge-Coupled Device (CCD) chip synchronous to the change in excitation wavelength. We coupled this improved wide field SERDS imaging setup to diode lasers with 784.4/785.5 and 457.7/458.9 nm excitation and applied it to samples such as paracetamol and aspirin tablets, polystyrene and polymethyl methacrylate beads, as well as pork meat using multiple accumulations with acquisition times in the range of 50 to 200 ms. The results tackle two main challenges of SERDS imaging: gradual photobleaching changes the autofluorescence background, and multiple readouts of CCD detector prolong the acquisition time.

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.

Astrophysicists use Integral Field Spectroscopy to record spectrally resolved images of faint galaxies. Transferred to imaging Raman spectroscopy, this technique significantly accelerates the capture of Raman images as the simultaneous acquisition of multiple spectra makes scanning procedures obsolete. Furthermore, sequentially collected Raman images result in image sequences thus allowing to monitor Raman features in the spatial dimension over time. However, long readout times of the required large-area charge coupled device detectors slow down the acquisition rate. Here we report how the acquisition frequency of Raman images can be enhanced with on-chip windowing and binning readout. The potential of this approach is demonstrated with Raman image sequences of polystyrene beads in motion in a micro-fluid environment.

Raman spectroscopy has been successfully applied to medical applications and emerged as a powerful non-invasive technique able to provide information to identify tissue diseases and guiding during image surgery. Of particular interest for medical diagnosis are Raman images in which a complete Raman spectrum is acquired for each pixel of the image enabling the generation of chemical maps. However, Raman images are usually recorded in a time consuming step-by-step scanning process that may take several minutes or even hours. Integral field Spectroscopy (IFS) is a technique used in Astronomy that reduces the recording time by combining imaging and spectroscopic capabilities in a single instrument. Both, spatial and spectral information are provided simultaneously without scanning procedure and with outstanding light collection efficiency [1]. IFS is based on slicing the image using a mirror stack or a bundle of optical fibers and stringing the slices together in front of the slit of a multiplex spectrograph. Raman SERDS (Shifted Excitation Raman Differential Spectroscopy) images of large-area porcine skin patches and the basic principles for a pseudo-real-time video Raman imaging have already been reported using this technique [2].

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.

Step-by-step, time-consuming scanning of the sample is still the state-of-the-art in imaging Raman spectroscopy. Even for a few 100 image points the measurement time may add up to minutes or hours. A radical decrease in measurement time can be achieved by applying multiplex spectrographs coupled to imaging fiber bundles that are successfully used in astronomy. For optimal use of the scarce and expensive observation time at astronomical observatories, special high-performance spectrograph systems were developed. They are designed for recording thousands of spatially resolved spectra of a two-dimensional image field within one single exposure. Transferring this technology to imaging Raman spectroscopy allows a considerably faster acquisition of chemical maps. Currently, an imaging field of up to 1 cm2 can be investigated. For porcine skin the required measurement time is less than 1 min. For this reason, this technique is of particular interest for medical diagnostics, e.g., the identification of potentially cancerous abnormalities of skin tissue.

A three-dimensional computational fluid dynamics-(CFD-) model based on a differential pressure laminar flow bioreactor prototype was developed to further examine performance under changing culture conditions. Cell growth inside scaffolds was simulated by decreasing intrinsic permeability values and led to pressure build-up in the upper culture chamber. Pressure release by an integrated bypass system allowed continuation of culture. The specific shape of the bioreactor culture vessel supported a homogenous flow profile and mass flux at the scaffold level at various scaffold permeabilities. Experimental data showed an increase in oxygen concentration measured inside a collagen scaffold seeded with human mesenchymal stem cells when cultured in the perfusion bioreactor after 24 h compared to static culture in a Petri dish (dynamic: 11% O-2 versus static: 3% O-2). Computational fluid simulation can support design of bioreactor systems for tissue engineering application.

We present a new method for noninvasive real-time oxygen measurement inside three-dimensional tissue-engineered cell constructs in static and dynamic culture settings in a laminar flow bioreactor. The OPAL system (optical oxygen measurement system) determines the oxygen-dependent phosphorescence lifetime of spherical microprobes and uses a two-frequency phase-modulation technique, which fades out the interference of background fluorescence from the cell carrier and culture medium. Higher cell densities in the centrum of the scaffolds correlated with lower values of oxygen concentration obtained with the OPAL system. When scaffolds were placed in the bioreactor, higher oxygen values were measured compared to statically cultured scaffolds in a Petri dish, which were significantly different at day 1-3 of culture. This technique allows the use of signal-weak microprobes in biological environments and monitors the culture process inside a bioreactor.

Prediction of drug-induced toxicity is complicated by the failure of animal models to extrapolate human response, especially during assessment of repeated dose toxicity for cosmetic or chronic drug treatments. In this work, we present a 3D microreactor capable of maintaining metabolically active HepG2/C3A spheroids for over 28 days in vitro under stable oxygen gradients mimicking the in vivo microenvironment. Mitochondrial respiration was monitored using two-frequency phase modulation of phosphorescent microprobes embedded in the tissue. Phase modulation is focus independent and unaffected by cell death or migration. This sensitive measurement of oxygen dynamics revealed important information on the drug mechanism of action and transient subthreshold effects. Specifically, exposure to antiarrhythmic agent, amiodarone, showed that both respiration and the time to onset of mitochondrial damage were dose dependent showing a TC50 of 425 μm. Analysis showed significant induction of both phospholipidosis and microvesicular steatosis during long-term exposure. Importantly, exposure to widely used analgesic, acetaminophen, caused an immediate, reversible, dose-dependent loss of oxygen uptake followed by a slow, irreversible, dose-independent death, with a TC50 of 12.3 mM. Transient loss of mitochondrial respiration was also detected below the threshold of acetaminophen toxicity. The phenomenon was repeated in HeLa cells that lack CYP2E1 and 3A4, and was blocked by preincubation with ascorbate and TMPD. These results mark the importance of tracing toxicity effects over time, suggesting a NAPQI-independent targeting of mitochondrial complex III might be responsible for acetaminophen toxicity in extrahepatic tissues.

Until now, spatially resolved Raman Spectroscopy has required to scan a sample under investigation in a time-consuming step-by-step procedure. Here, we present a technique that allows the capture of an entire Raman image with only one single exposure. The Raman scattering arising from the sample was collected with a fiber-coupled high-performance astronomy spectrograph. The probe head consisting of an array of 20 × 20 multimode fibers was linked to the camera port of a microscope. To demonstrate the high potential of this new concept, Raman images of reference samples were recorded. Entire chemical maps were received without the need for a scanning procedure.

In many biological and environmental applications spatially resolved sensing of molecular oxygen is desirable. A powerful tool for distributed measurements is optical time domain reflectometry (OTDR) which is often used in the field of telecommunications. We combine this technique with a novel optical oxygen sensor dye, triangular-[4] phenylene (TP), immobilized in a polymer matrix. The TP luminescence decay time is 86 ns. The short decay time of the sensor dye is suitable to achieve a spatial resolution of some meters. In this paper we present the development and characterization of a reflectometer in the UV range of the electromagnetic spectrum as well as optical oxygen sensing with different fiber arrangements.

L'invention concerne une optode pour determiner des parametres chimiques d'un echantillon, l'optode comportant une matrice polymere qui comprend une polyetherethercetone sulfonee (SPEEK) dans laquelle un colorant de detection est immobilise ou plusieurs colorants de detection sont immobilises, au moins un des colorants de detection etant sensible au pH. La presente invention concerne egalement un procede pour determiner la valeur du pH d'un echantillon, dans lequel l'optode selon l'invention est utilisee.

Pioneered by Clark's microelectrode more than half a century ago, there has been substantial interest in developing new, miniaturized optical methods to detect molecular oxygen inside cells. While extensively used for animal tissue measurements, applications of intracellular optical oxygen biosensors are still scarce in plant science. A critical aspect is the strong autofluorescence of the green plant tissue that interferes with optical signals of commonly used oxygen probes. A recently developed dual-frequency phase modulation technique can overcome this limitation, offering new perspectives for plant research. This review gives an overview on the latest optical sensing techniques and methods based on phosphorescence quenching in diverse tissues and discusses the potential pitfalls for applications in plants. The most promising oxygen sensitive probes are reviewed plus different oxygen sensing structures ranging from micro-optodes to soluble nanoparticles. Moreover, the applicability of using heterologously expressed oxygen binding proteins and fluorescent proteins to determine changes in the cellular oxygen concentration are discussed as potential non-invasive cellular oxygen reporters.

Known as gas of life, molecular oxygen is a crucial metabolic factor. Especially in the field of cell biol- ogy, the content of ambient oxygen determines proliferation and differentiation. Therefore, it is a mandatory step to monitor and to control the oxygen concentrations in bioreac- tors for three-dimensional tissue engineering. From experi- ence, the oxygen content of the culture medium does not reflect the circumstances within the cell tissue. Hence, it is important to develop advanced measurement techniques, which indicate the oxygen concentration within the cell carrier. To avoid interferences of the flow conditions and cell growth non-invasive or at least minimal-invasive detec- tion techniques are strongly preferable. In this paper we will describe the principle of the oxygen determination, results from measurements in biological samples.

The occurrence of hypoxic conditions in plants not only represents a stress condition but is also associated with the normal development and growth of many organs, leading to adaptive changes in metabolism and growth to prevent internal anoxia. Internal oxygen concentrations decrease inside growing potato tubers, due to their active metabolism and increased resistance to gas diffusion as tubers grow. In the present work, we identified three hypoxia-responsive ERF (StHRE) genes whose expression is regulated by the gradual decrease in oxygen tensions that occur when potato tubers grow larger. Increasing the external oxygen concentration counteracted the modification of StHRE expression during tuber growth, supporting the idea that the actual oxygen levels inside the organs, rather than development itself, are responsible for the regulation of StHRE genes. We identified several sugar metabolism-related genes co-regulated with StHRE genes during tuber development and possibly involved in starch accumulation. All together, our data suggest a possible role for low oxygen in the regulation of sugar metabolism in the potato tuber, similar to what happens in storage tissues during seed development.