Illumination Area Research Articles

Solar Concentrator Bio-Inspired by the Superposition Compound Eye for High-Concentration Photovoltaic System up to Thousands Fold Factor

We have proposed a fruitful design principle targeting a concentration ratio (CR) >1000× for a typical high concentrating photovoltaics (HCPV) system, on account of a two-concentrator system + homogenizer. The principle of a primary dual-lens concentrator unit, completely analogous basic optics seen in the superposition compound eyes, is a trend not hitherto reported for solar concentrators to our knowledge. Such a concentrator unit, consisting of two aspherical lenses, can be applied to minify the sunlight and reveal useful effects. We underline that, at this stage, the CR can be attained by two orders of magnitude simply by varying the radius ratio of such two lenses known from the optics side. The output beam is spatially minimized and nearly parallel, exactly as occurs in the superposition compound eye. In our scheme, thanks to such an array of dual-lens design, a sequence of equidistant focal points is formed. The secondary concentrator consists of a multi-reflective channel, which can collect all concentrated beams from the primary concentrator to a small area where a solar cell is placed. The secondary concentrator is located right underneath the primary concentrator. The optical characteristics are substantiated by optical simulations that confirm the applicability of thousands-fold gain in CR value, ~1100×. This, however, also reduced the uniformity of the illumination area. To regain the uniformity, we devise a fully new homogenizer, hinging on the scattering principle. A calculated optical efficiency for the entire system is ~75%. Experimentally, a prototype of such a dual-lens concentrator is implemented to evaluate the converging features. As a final note, we mention that the approach may be extended to implement an even higher CR, be it simply by taking an extra concentrator unit. With simple design of the concentrator part, which may allow the fabrication process by modeling method and large acceptant angle (0.6°), we assess its large potential as part of a general strategy to implement a highly efficient CPV system, with minimal critical elaboration steps and large flexibility.

Analysis of X-Ray Beams Irradiation Accuracy Using Collimation Test Tools as Well as Illumination Measurement on the Collimator to the Radiographic X-Ray Machine Conformity Test Results

In the Suitability Test Method there is the Illumination and Collimation Test still using the manual method. This test aims to ensure that the light from the collimator lamp can be seen clearly so that the area of ​​the irradiation field can be identified when irradiating, as well as ensuring that the area of ​​the collimator lamp matches the X-ray beam so that it meets the needs and ensures that the patient does not get an excessive dose. The purpose of this research is to develop the simplest way by which the illumination measurement is carried out simultaneously at four points and the measurement data is directly stored. The contribution of this research is expected to be more testing tools and the data will be stored until the effective time of the next test. This module is designed using the HC-SR04 sensor as a distance meter and the TSL2561 sensor as a lux meter. The TSL2561 sensor allows for precise Lux calculations and can be configured for different gain/timing ranges to detect light ranging from 0.1-40,000+ Lux on the fly. This module is equipped with a display facility in the form of TFT Nextion to display measurement results. In addition, there is also data storage using an SD Card to store display measurement results. In this research, the module has been tested and compared with the suitability test value of the X-ray plane and got an error value of 2.0% with a module efficiency of 98.0% in the illumination test, and an error of 2.2% with a module efficiency of 97.8% in the collimator test. From this research, it can be concluded that the light sensor TSL2561 can be used to measure the illumination area of ​​the collimator lamp.

Optical Imaging and Image Restoration Techniques for Deep Ocean Mapping: A Comprehensive Survey

Visual systems are receiving increasing attention in underwater applications. While the photogrammetric and computer vision literature so far has largely targeted shallow water applications, recently also deep sea mapping research has come into focus. The majority of the seafloor, and of Earth’s surface, is located in the deep ocean below 200 m depth, and is still largely uncharted. Here, on top of general image quality degradation caused by water absorption and scattering, additional artificial illumination of the survey areas is mandatory that otherwise reside in permanent darkness as no sunlight reaches so deep. This creates unintended non-uniform lighting patterns in the images and non-isotropic scattering effects close to the camera. If not compensated properly, such effects dominate seafloor mosaics and can obscure the actual seafloor structures. Moreover, cameras must be protected from the high water pressure, e.g. by housings with thick glass ports, which can lead to refractive distortions in images. Additionally, no satellite navigation is available to support localization. All these issues render deep sea visual mapping a challenging task and most of the developed methods and strategies cannot be directly transferred to the seafloor in several kilometers depth. In this survey we provide a state of the art review of deep ocean mapping, starting from existing systems and challenges, discussing shallow and deep water models and corresponding solutions. Finally, we identify open issues for future lines of research.

High-resolution STEM observation of the dynamics of Pt nanoparticles in a liquid

The dynamics of Pt nanoparticles (NPs) in water are observed by high-resolution scanning transmission electron microscopy with a home-made static sandwich-type liquid cell (LC). Carbon is coated on both sides of the membrane windows of the LC to make them conductive. The slow motion of Pt NPs in thin water droplets enables us to acquire high-resolution scanning transmission electron microscopy images. Using a dose rate of 3 × 105 e nm−2s, some Pt NPs with a diameter of less than 2 nm disappear into the water, some move around, and others repeatedly attach to and detach from each other. The density of Pt NPs larger than 2 nm remains unchanged with further observation. However, by increasing the dose rate to 5.3 × 105 e nm−2s, the Pt NPs gather at the beam illumination area, and then form aggregates with chain network structures. It is also determined that the NPs attach to each other at their {111} surfaces.

Combination of MoS2 nanopetals with Ag nanoparticles decorated graphene oxide for boosting photocatalytic abatement of recalcitrant pollutants under visible light irradiation

Herein, various weight ratios (1:1, 1:3, and 3:1) of MoS2/GO composites decorated with Ag nanoparticles (named as MAG) have been prepared by microwave-assisted route. XRD and XPS investigations indicated the catalyst crystallinity and elemental oxidation states. Morphological analysis revealed presence of small MoS2 nanopetals scattered on GO sheets with Ag NPs dispersed on surface whereas BET-analysis disclosed its excellent surface area (∼88 m2/g). Optical properties of MAG catalysts revealed that they were highly visible-light active, with a bandgap of 2.15 eV and a lower charge recombination rate. Excellent efficiency was observed for TC (90.7%; 0.0186 min−1) and FIP-degradation (85.2%; 0.0177 min−1) with 4 mg MAG (3:1) catalyst at neutral pH under visible-light irradiation owing to high synergistic interaction (∼2.21) in the composite. Effects of catalyst amount, pH, and effective area of illumination on degradation were investigated. High reusable nature of the catalyst (65% (TC) and 58% (FIP) efficiency after 5 cycles) was supported by post-photocatalytic characterization studies. Photodegradation products of TC were determined via LC-MS studies. Holes and hydroxyl radicals were majorly involved in degradation process revealed by trapping studies. High COD (70.4%) and TOC (55.1%) removal rates confirm high photo-mineralization of real-wastewater without any pre-treatment. The current investigation, combined with comparative literature, illustrates real-world potential of MAG catalysts for eradication of resistant pollutants.

Low-to-Zero-Overhead IRS Reconfiguration: Decoupling Illumination and Channel Estimation

Most algorithms developed for the optimization of Intelligent Reflecting Surfaces (IRSs) so far require knowledge of full Channel State Information (CSI). However, the resulting acquisition overhead constitutes a major bottleneck for the realization of IRS-assisted wireless systems in practice. In contrast, in this letter, focusing on downlink transmissions from a Base Station (BS) to a Mobile User (MU) that is located in a blockage region, we propose to optimize the IRS for illumination of the area centered around the MU. Hence, the proposed design requires the estimation of the MU’s position and not the full CSI. For a given IRS phase-shift configuration, the end-to-end BS-IRS-MU channel can then be estimated using conventional channel estimation techniques. The IRS reconfiguration overhead for the proposed scheme depends on the MU mobility as well as on how wide the coverage of the IRS illumination is. Therefore, we develop a general IRS phase-shift design, which is valid for both the near- and far-field regimes and features a parameter for tuning the size of the illumination area. Moreover, we study a special case where the IRS illuminates the entire blockage area, which implies that the IRS phase shifts do not change over time leading to zero overhead for IRS reconfiguration.

Room-Temperature Persistent Luminescence in Metal Halide Perovskite Nanocrystals for Solar-Driven CO 2 Bioreduction

Room-Temperature Persistent Luminescence in Metal Halide Perovskite Nanocrystals for Solar-Driven CO ₂ Bioreduction

Fault classification based on computer vision for steel wire ropes

Abstract As an actual steel material application, steel wire rope (SWR) is widely used in various industrial cases. However, in real cases, SWRs are inevitably damaged by erosion, friction, etc. Therefore, it is of great importance to monitor SWRs’ surface conditions in case of accidents. In recent years, computer vision recognition of SWR’s surface has been extensively studied. Based on it, we propose an image-processing method to detect local flaws of SWRs, which extracts the features from the illumination area on the surface of the SWR. Firstly, a three-feature dimension descriptor is constructed by combining the edge grayscale value gradient of the illumination area and morphological features of the illumination area. Then, the KNN (k-nearest neighbour) algorithm is used as a classification method to distinguish the local flaws. According to the experiment results, our proposed method has a high accuracy which is about 94.35%, and low time cost. It can be used in future local flaw detection.

Feasibility of In-Line Raman Spectroscopy for Quality Assessment in Food Industry: How Fast Can We Go?

Raman spectroscopy is a viable tool within process analytical technologies due to recent technological advances. In this article, we evaluate the feasibility of Raman spectroscopy for in-line applications in the food industry by estimating the concentration of the fatty acids EPA + DHA in ground salmon samples (n = 63) and residual bone concentration in samples of mechanically recovered ground chicken (n = 66). The samples were measured under industry like conditions: They moved on a conveyor belt through a dark cabinet where they were scanned with a wide area illumination standoff Raman probe. Such a setup should be able to handle relevant industrial conveyor belt speeds, and it was studied how different speeds (i.e., exposure times) influenced the signal-to-noise ratio (SNR) of the Raman spectra as well as the corresponding model performance. For all samples we applied speeds that resulted in 1 s, 2 s, 4 s, and 10 s exposure times. Samples were scanned in both heterogenous and homogenous state. The slowest speed (10 s exposure) yielded prediction errors (RMSECV) of 0.41%EPA + DHA and 0.59% ash for the salmon and chicken data sets, respectively. The more in-line relevant exposure time of 1 s resulted in increased RMSECV values, 0.84% EPA + DHA and 0.84% ash, respectively. The increase in prediction error correlated closely with the decrease in SNR. Further improvements of model performance were possible through different noise reduction strategies. Model performance for homogenous and heterogenous samples was similar, suggesting that the presented Raman scanning approach has the potential to work well also on intact heterogenous foods. The estimation errors obtained at these high speeds are likely acceptable for industrial use, but successful strategies to increase SNR will be key for widespread in-line use in the food industry.

Spectroscopic thermo-elastic optical coherence tomography for tissue characterization

Optical imaging techniques that provide free space, label free imaging are powerful tools in obtaining structural and biochemical information in biological samples. To date, most of the optical imaging technologies create images with a specific contrast and require multimodality integration to add additional contrast. In this study, we demonstrate spectroscopic Thermo-elastic Optical Coherence Tomography (TE-OCT) as a potential tool in tissue identification. TE-OCT creates images based on two different forms of contrast: optical reflectance and thermo-elastic deformation. TE-OCT uses short laser pulses to induce thermo-elastic tissue deformation and measures the resulting surface displacement using phase-sensitive OCT. In this work we characterized the relation between thermo-elastic displacement and optical absorption, excitation, fluence and illumination area. The experimental results were validated with a 2-dimensional analytical model. Using spectroscopic TE-OCT, the thermo-elastic spectra of elastic phantoms and tissue components in coronary arteries were extracted. Specific tissue components, particularly lipid, an important biomarker for identifying atherosclerotic lesions, can be identified in the TE-OCT spectral response. As a label-free, free-space, dual-contrast, all-optical imaging technique, spectroscopic TE-OCT holds promise for biomedical research and clinical pathology diagnosis.

Adaptive polymer fiber neural device for drug delivery and enlarged illumination angle for neuromodulation

Objective. Optical fiber devices constitute significant tools for the modulation and interrogation of neuronal circuitry in the mid and deep brain regions. The illuminated brain area during neuromodulation has a direct impact on the spatio-temporal properties of the brain activity and depends solely on the material and geometrical characteristics of the optical fibers. In the present work, we developed two different flexible polymer optical fibers (POFs) with integrated microfluidic channels (MFCs) and an ultra-high numerical aperture (UHNA) for enlarging the illumination angle to achieve efficient neuromodulation. Approach. Three distinct thermoplastic polymers: polysulfone, polycarbonate, and fluorinated ethylene propylene were used to fabricate two step-index UHNA POF neural devices using a scalable thermal drawing process. The POFs were characterized in terms of their illumination map as well as their fluid delivery capability in phantom and adult rat brain slices. Main results. A 100-fold reduced bending stiffness of the proposed fiber devices compared to their commercially available counterparts has been found. The integrated MFCs can controllably deliver dye (trypan blue) on-demand over a wide range of injection rates spanning from 10 nl min−1 to 1000 nl min−1. Compared with commercial silica fibers, the proposed UHNA POFs exhibited an increased illumination area by 17% and 21% under 470 and 650 nm wavelength, respectively. In addition, a fluorescent light recording experiment has been conducted to demonstrate the ability of our UHNA POFs to be used as optical waveguides in fiber photometry. Significance. Our results overcome the current technological limitations of fiber implants that have limited illumination area and we suggest that soft neural fiber devices can be developed using different custom designs for illumination, collection, and photometry applications. We anticipate our work to pave the way towards the development of next-generation functional optical fibers for neuroscience.

Photoacoustic Carbon Nanotubes Embedded Silk Scaffolds for Neural Stimulation and Regeneration.

Neural interfaces using biocompatible scaffolds provide crucial properties, such as cell adhesion, structural support, and mass transport, for the functional repair of nerve injuries and neurodegenerative diseases. Neural stimulation has also been found to be effective in promoting neural regeneration. This work provides a generalized strategy to integrate photoacoustic (PA) neural stimulation into hydrogel scaffolds using a nanocomposite hydrogel approach. Specifically, polyethylene glycol (PEG)-functionalized carbon nanotubes (CNT), highly efficient photoacoustic agents, are embedded into silk fibroin to form biocompatible and soft photoacoustic materials. We show that these photoacoustic functional scaffolds enable nongenetic activation of neurons with a spatial precision defined by the area of light illumination, promoting neuron regeneration. These CNT/silk scaffolds offered reliable and repeatable photoacoustic neural stimulation, and 94% of photoacoustic-stimulated neurons exhibit a fluorescence change larger than 10% in calcium imaging in the light-illuminated area. The on-demand photoacoustic stimulation increased neurite outgrowth by 1.74-fold in a rat dorsal root ganglion model, when compared to the unstimulated group. We also confirmed that promoted neurite outgrowth by photoacoustic stimulation is associated with an increased concentration of neurotrophic factor (BDNF). As a multifunctional neural scaffold, CNT/silk scaffolds demonstrated nongenetic PA neural stimulation functions and promoted neurite outgrowth, providing an additional method for nonpharmacological neural regeneration.

Seasonal changes in the content of plastid pigments in the hametophyte of dominant mosses in forest ecosystems of Ukrainian Roztochchya

Poikilohydric mosses, as one of the most sensitive groups of plants to the influence of habitat conditions, responding to environmental factors, demonstrate adaptations, which differ from vascular plants, for the prediction of changes in the natural environment. The changes in the content of photosynthesis pigments and their ratio in dominant deciduous epigeal species of mosses depending on changes in stand crowns, insolation intensity, water-temperature regime of soil and air in local ecosystems of Ukrainian Roztochchya were analyzed. Due to the significant projective cover and closed crowns in the area of ancient forests, the 30-50% lower indicators of light intensity, 8-12% of substrate temperature under moss turf, and 43-50% higher indicators of its humidity compared to pine plantations were identified. Anthropogenic impact in the area of stationary recreation was conditioned by the intensive trampling, which led to a decrease in the closure of the tree crowns (up to 0,4-0,5), an increase in light intensity by 2,5 times, and a decrease in soil moisture under moss turf by 2-4 times. The shade-tolerant Polytrichastrum formosum, Atrichum undulatum and Plagiomnium affine mosses compensated the limited amount of light energy available for growth by intensively increasing of the content of pigments (chlorophylls a and b), light-harvesting complexes and reducing of the chlorophylls a/b ratio to 1,6-2,1. A significant variability in the ratio of chlorophylls to carotenoids from 5 to 9 was found. Significant limits of variation in the content of carotenoids and the ratio of chlorophylls to carotenoids served as an indicator for assessing the edapho-climatic changes in the living conditions of bryophytes in forest ecosystems. Significant variability in the ratio of chlorophylls a/b (2,35-4,25) in autumn in comparison with such indicators in summer is associated with increased illumination of the experimental areas and the activity of the reactions of mutual transformations of chlorophylls a and b. The increase in the values of the ratio of chlorophylls a/b caused by the activation of pigment metabolism indicates their adaptation to both light and shadow. In autumn, the decrease in the ratio of chlorophylls to carotenoids (in the range of 4,31-5,08) is associated with the intensity of synthesis and decomposition of chlorophylls a and b, and carotenoids, which can be used as an important indicator of plant adaptation ability to the changes in light intensity, humidity, and temperature.

Passive near-field optical scanning imaging based on semiconductor nanowire/tapered microfiber probe

<sec>In this paper, we propose a passive near-field scanning imaging system by using the structure of cadmium sulfide (CdS) nanowire/tapered microfiber probe, which combines the near-field scanning structure and the nanowire/microfiber coupling technology. In the passive near-field scanning imaging system, a passive nanoprobe is adopted to detect the intensity change of the reflected light field on the sample surface, which not only retains the advantage of the nanoprobe for the strong restriction of the reflected light on the sample surface, but also reduces the interference of strong excitation light during detection. Through the high efficiently evanescent field coupling between the CdS nanowire and the tapered microfiber, the collected light signal is transmitted to the photodetector in the far field, and finally the imaging of the target sample morphology can be realized.</sec><sec>At first, the light field model of the nanowire/tapered microfiber probe structure is verified by the finite element analysis method. The calculated collection efficiency from the sample to the probe is about 4.65‰ and the transmission efficiency from the nanowire to the tapered microfiber is about 74.47%. The collection efficiency is improved by an order of magnitude compared with traditional metal-coated near-field probe. In the experiments, a scanning step of 20 nm and a probe-sample distance of 230 nm are selected. The nanowire/tapered microfiber probe and traditional tapered fiber probe are both used to measure the widths of different CdSe nanoribbons samples, and the atomic force microscopy measurement is used as the benchmark to calculate their measurement error, which is increased about 3 times. By changing the angle <i>θ</i> between the probe and the sample, it is found that the resolution obtained using the designed nanowire/microfiber probe is always higher than only using the tapered microfiber probe. Comparing with the tapered microfiber probe scheme, the measurement error is reduced to a value less than 7.2%.</sec><sec>In addition, compared with the active luminescence probe scheme, this passive near-field scanning scheme reduces the preparation complexity of the optical probe and the detection structure complexity of the optical system. The large microscopic illumination area can avoid the influence of the small laser spot size on imaging, and the imaging range is determined only by the travel distance of the linear stage. Therefore, our work may provide an attractive approach for developing new near-field scanning microscopy systems in the future.</sec>

A new photoelectrochemical reactor designed for solar hydrogen fuel production: Experimental study

A novel photoanode configuration of meshy type dome design is examined to exploit the maximum accessible light during available sun time at any solar rays angle due to its unique structure. This photoanode shape aims to receive the maximum light quantity by utilizing the possible illumination area. Also, the meshy design lets the solar ray spread into the body of the dome photoanode at any solar rays angle. Titanium dioxide is prepared to coat the stainless steel photoanode using the sol–gel dip-coating method. Two concentrations of potassium dioxide solution are used to study the electrolyte solution conductivity effects on the hydrogen production rate and the associated energy and exergy efficiencies. The vertical and tilted light boundaries are studied to evaluate the enhancement of the hydrogen production rate and the corresponding system efficiencies due to the new dome mesh photoanode design. The present experimental results indicate that increasing the solution concentration significantly affects the hydrogen production rates and associated system efficiencies. The greatest hydrogen mass production rates produced at 0.25 M KOH under artificial tilted (45°) and vertical light boundaries are 31.55 µg/s and 32.22 µg/s, respectively. The overall energy and exergy system efficiencies can be reached to be 5.98% and 4.08% under vertical light, while it is 5.89% and 4.02% at tilted light boundaries. The development of the hydrogen production rate obtained at artificial tilted light boundaries changes between 74% and 80% compared to the enhancement which occurred at vertical artificial light boundaries.

A simple design of uniform LED illumination using catadioptric collimator and freeform lenslet array

We introduce a compact lenslet array principle that takes advantage of freeform optics to deploy a light distributor, beneficial for highly efficient, inexpensive, low energy consumption light-emitting diode (LED) lighting system. We outline here a simple strategy for designing the freeform lens that makes use of an array of the identical plano-convex lenslet. The light is redistributed from such lenslet, hinging on the principle of optical path length conservation, and then delivered to the receiver plane. The superimposing of such illumination area from every lenslet occurs on the receiver plane, in which the non-uniform illumination area located in the boundary should have the same dimension as the size of the freeform lenslet array. Such an area, insofar, is negligible due to their small size, which is the crux of our design, representing a large departure from the former implementations. Based on simulations that assess light performance, the proposed design exhibited the compatibility for multiple radiation geometries and off-axis lighting without concern for the initial radiation pattern of the source. As simulated, the LED light source integrated with such proposed freeform lenslet array revealed high luminous efficiency and uniformity within the illumination area of interest were above 70% and 85%, respectively. Such novel design was then experimentally demonstrated to possess a uniformity of 75% at hand, which was close to the simulation results. Also, proposed indoor lighting was implemented in comparison with the commercial LED downlight and LED panel, whereby the energy consumption, number of luminaires and illumination performance were assessed to show the advantage of our simplified model.

Low‐temperature synthesis of ZnO/ZnS/CuS heterojunction based on solution‐processed nanosheet array with enhanced photocatalytic activity

AbstractZnO/ZnS/CuS net‐like nanosheet (NS) heterojunction array was fabricated via a simple solution method at a low temperature. Morphology and structure of ZnO/ZnS/CuS NS were characterized by scanning electron microscope (SEM) and Transmission electron microscope (TEM). With tiny particles attaching on the rough surface, the thin ZnO/ZnS/CuS NS grew vertically and arranged regularly on Al substrate, providing large effective illumination area and massive active sites. Elemental composition and valence state were confirmed with energy dispersive X‐ray spectrometry and X‐ray photoelectron spectroscopy (XPS), respectively. The UV–vis absorbance spectra indicated that the absorption range of ZnO NS was expanded to the visible region effectively, and the original absorption intensity in the ultraviolet region was also improved after being coated with ZnS and CuS. Photocatalytic activity tests of ZnO, ZnO/ZnS, and ZnO/ZnS/CuS NS were carried out with methyl orange as a simulated pollutant, in which ZnO/ZnS/CuS heterojunction showed great enhancement when making comparison with pure ZnO and ZnO/ZnS NS. After five reuse cycles, photocatalytic performance could still be maintained well, indicating the good catalytic stability. Finally, a probable photocatalytic mechanism was also discussed.

Eco-friendly sun lamp for railway facilities

The paper considers the possibility of using a pulsed discharge in cesium as an environmentally friendly high quality light source for lighting industrial premises of railway transport facilities. The use of cesium filling of standard sapphire burners of high-pressure sodium lamps and a pulsed mode of electric power supply of the discharge to create a light source has been substantiated. A mathematical model of a high-pressure pulsed discharge in cesium is formulated on the basis of the radiative gas dynamics equations. The discharge was simulated and it was shown that it is possible to create a plasma with a temperature 4000 -7000 K and a pressure of 0.5 - 1.5 at m with the power supplied to the discharge ∼ 100 W/cm in the steady-state combustion mode. The dependence of the discharge lighting characteristics on the amplitude of the current pulses and the amount of cesium in the gas discharge tube is analyzed. It is shown that in a wide range of currents and plasma densities, the color rendering index of the discharge radiation Ra> 95 with luminous efficacy ηV ∼ 70lm/W and more. The average luminous flux emitted per unit length of the discharge column is ∼ 104 lm/cm. The color temperature of the discharge radiation can vary over a wide range of values Tc∼ 3000÷4500 K. It is shown that the color coordinates Xc,Yc of discharge radiation are close to the values Xc,Yc of a blackbody. The use of such a source in conditions of a short daylight hours will make it possible to create practically solar illumination of large production areas.

Wide Area Uniform Illumination Scheme Using LED Matrix for Optogenetic Cardiac Pacing

Control of heart rhythm is vital in the case of arrhythmia. Cardiac optogenetics is a promising technique to replace electrical stimulation in a next generation of pacemakers and defibrillators. Therefore, further research towards optimizing light delivery methods is essential. A major requirement is the uniform stimulation of all cells in the area of interest while reducing side effects such as photodamage. Here, a 2 × 2 blue (470 nm, InGaN-based) light-emitting diode (LED) optoelectronic module for uniform ex vivo cardiac muscle illumination is demonstrated. It satisfies two important requirements in optogenetics, which are high illumination homogeneity and high irradiance. CCD camera images show an average 90% homogeneity over the central illumination area of close to 38 mm2 at 1 cm distance from the light source. The module is used to perform physiological experiments on channelrhodopsin 2-expressing Langendorff-perfused mouse hearts. Successful ventricular pacing is obtained for an optical power density threshold below 2 mW/mm2 with light pulses as short as 1 ms. For 10 ms long pulses, the threshold was below 0.2 mW/mm2. The large homogeneous illumination area enabled optogenetic pacing with less than half the optical power of previous attempts with smaller areas of 2 mm2 and thus, presumably, will result in less phototoxicity.

An Impact Analysis of Artificial Light at Night (ALAN) on Bats. A Case Study of the Historic Monument and Natura 2000 Wisłoujście Fortress in Gdansk, Poland.

The artificial light at night (ALAN) present in many cities and towns has a negative impact on numerous organisms that live alongside humans, including bats. Therefore, we investigated if the artificial illumination of the historic Wisłoujście Fortress in Gdańsk, Poland (part of the Natura 2000 network), during nighttime events, which included an outdoor electronic dance music (EDM) festival, might be responsible for increased light pollution and the decline in recent years of the pond bat (Myotis dasycneme). An assessment of light pollution levels was made using the methods of geographical information system (GIS) and free-of-charge satellite remote sensing (SRS) technology. Moreover, this paper reviewed the most important approaches for environmental protection of bats in the context of ecological light pollution, including International, European, and Polish regulatory frameworks. The analysis of this interdisciplinary study confirmed the complexity of the problem and highlighted, too, the need for better control of artificial illumination in such sensitive areas. It also revealed that SRS was not the best light pollution assessment method for this particular case study due to several reasons listed in this paper. As a result, the authors’ proposal for improvements also involved practical recommendations for devising suitable strategies for lighting research and practice in the Natura 2000 Wisłoujście Fortress site located adjacent to urban areas to reduce the potential negative impact of ALAN on bats and their natural habitats.