We present the results of simplified polarimetric methods for detecting disturbances on a fibre-optic link in a quantum key distribution system. The proposed methods use a polarisation coupler and a single polariser as a polarisation-sensitive detection system. The effectiveness of the disturbance detection was considered in a plug-and-play quantum key distribution system with phase encoding. This paper compares the performance of two simplified methods for determining changes in the state of polarisation in response to three types of disturbances, including touching, bending, and inserting a clip-on coupler. Also, the results of an experiment involving the entire procedure of introducing eavesdropping into a telecommunications fibre-optic cable are presented. The results of the measurements indicate the subsequent steps when attacking a fibre-optic cable. This article shows that a simplified polarisation-sensitive sensor can be implemented into a quantum key distribution system to detect disturbances and eavesdropping attempts, as well as enhance the security of the system.

Many manufacturers offer resins that are advertised as transparent. Transparent 3D printed parts are not only visually attractive, but this feature is often required for practical use, for example, in optical parts. The manufacturers themselves point out that achieving optimal light transmittance requires appropriate post-processing. In this study, we evaluate the transparency of 10 types of commercial 3D printing resins by measuring their light transmittance. Each resin was used to print sample tiles that were post-processed in eight different ways. The light transmittance of each sample was then measured using a commercial spectrophotometer to determine which post-processing methods yielded the best transmittance properties for flat objects printed using different resins. We also evaluate the impact of post-processing methods on the chromaticity measures and surface roughness of the sample tiles. Finally, we assess the effect of samples' exposure to direct sunlight by comparing light transmittance measurements taken at two different time points. Our results show that to ensure the highest level of transparency, it is crucial to coat the parts with a layer of clear varnish. For such samples, transmittance averages nearly 24% higher than for the unvarnished ones.

The potential of near-infrared, fluorescence and Raman spectroscopy for early-phase sealice sensing is investigated, targeting its detection in water prior to their parasitic life stage, allowing early alerts and reducing food waste.

Blue Phase (BP) liquid crystals are self-assembled 3D photonic structures that uniquely combine optical isotropy with ultrafast electro-optical switching. Their cubic symmetry enables polarization-independent behavior, while sub-millisecond response times make them highly attractive for dynamic photonic applications. However, their practical use has typically been limited by their tendency to form disordered polycrystalline domains, resulting in scattering and poor optical performance. In this work, we realized large-area monocrystalline BP structures with a photonic stopband positioned entirely outside the visible range. This eliminates structural coloration and enables a fully transparent, broadband operation without parasitic reflection. The cubic symmetry ensures the system remains optically isotropic, supporting polarization-independent modulation. We demonstrate a fast phase modulator based on this monocrystalline BP platform. The device achieves phase modulation with sub-millisecond response times and polarization independence, representing a significant advancement over traditional LCs. Our findings position monocrystalline BPs as a robust and versatile platform for reconfigurable optics. The combination of fast response, polarization independence, and optical transparency opens new pathways for advanced applications in adaptive optics, beam steering, dynamic holography, and transparent optical systems such as AR/VR and laser-based technologies.

Scientists involved in building quantum computers are currently facing many physical difficulties. Creating qubits, manipulating them and reading their state requires a lot of experience. This paper describes an optical laser system as a test platform for quantum-optical control that enables effective manipulation of an emulated quantum bit. Importantly, it is a reproduction of the system controlling the optical path in real ion traps. This solution makes it possible to study the phenomena occurring in such systems and to learn about the wide range of problems that a designer and an operator of quantum systems may encounter, even before they start building them. The optical system presented in the article uses, among others, a 532 nm laser, acousto-optic modulators (AOMs), ultrafast light detectors, and a programmable FPGA chip. The entire optical system was then attached to the QUBIT emulator and thoroughly tested. The article describes the design and operation of the proposed optical system and shows an example of how to control it using a Python script.

The most mature quantum key distribution systems available on the market is the class of prepare-and-measure systems which are vulnerable to eavesdropping attacks. Therefore, monitoring optical properties of such a system should be enhanced. This paper presents a measurement methodology, characterisation, and testing of a four-channel Stokes polarimeter implemented into the send-and-return quantum key distribution system with faint pulses. The developed polarimetric setup is a complete amplitude-division Stokes polarimeter, the main objective of which is to define changes in the polarization state of light pulses. The measurement method is based on intensity measurements of four selected polarization components. The four-channel Stokes polarimeter was characterised and its performance was compared with a commercial instrument. At this stage of the polarimeter development, different signal processing paths were proposed. The influence of fibre infringement was observed as a rapidly changing polarisation state and, as a result, intrusion threshold levels were determined for the analysed signals for the quantum key distribution fibre-optic link tested.

The results obtained for new dual-cladding optical fiber tapers surrounded by liquid crystal (LC) doped with Fe3O4 nanoparticles in a specially developed glass cell are presented. The created structures are sensitive to changes in refractive index values in the surrounding medium caused by modifying external environment parameters. In this investigation, cells are filled with nematic LCs 6CHBT and with the same mixture doped with 0.1 wt% and 0.5 wt% of magnetic nanoparticles (Fe3O4 NPs). The taper is made on a standard single-mode telecommunication fiber, stretched out to a length of 20.0 ± 0.5 mm, and the diameter of the tapers is approximately 15.0 ± 0.3 μm, with a loss lower than 0.5 dB @ 1,550 nm. Measurements are carried out in a wide range covering the visible and infrared ranges in two setups: 1) without a magnetic field, with steering only by voltage and 2) with an applied magnetic field. The presented spectrum results are divided into two ranges according to the parameters of optical spectrum analyzers: 350–1,200 nm and 1,200–2,400 nm. For all investigations, a steering voltage is chosen from the range of 0 to 200 V, which allows for establishing the influence of dopants on transmitted power and time response at different arrangements. Due to the sensitivity of LCs to temperature changes, this paper focuses on measuring at room temperature the effect of the magnetic field on propagation in a fiber optic taper. The proposed solution demonstrates the technology for creating advanced components as a combination of fiber optic technology, LCs, and nanoparticles. The presented results show the possibility of creating new sensors of various external factors such as magnetic or electric fields in miniaturized dimensions.

Intensive research is currently being conducted on wire arc additive manufacturing (WAAM) processes.Previous studies have demonstrated the impact of current parameters on altering the structure and properties of 316L stainless steel.However, there is a lack of comprehensive information in the literature regarding the influence of electrode extension length (contact to tube distance) on changes in the structure and geometry of parts made of 316L steel using the cold metal transfer (CMT) method.This parameter was often assumed to be constant in research experiments.The study aimed to determine how the length of the electrode extension affects the geometric properties of steel walls produced in the WAAM CMT additive manufacturing process.The experiment used 316LSi stainless steel to build 3D structures in the shape of straight walls.The chosen shape of the parts yielded the most benefits for preparing samples from the resulting structures for destructive testing.The research demonstrated that the length of the electrode extension is a crucial parameter in the additive manufacturing process of structures using the WAAM method.Modifying the electrode extension length in the WAAM process with a CMT machine impacts the bead geometry and, consequently, the overall model geometry.A 6 mm increase in the electrode extension length resulted in a model that was over 8 mm taller, despite using the same number of layers.

An Adaptive Spiral Phase Plate (ASPP) based on liquid crystal (LC) and the transmission electrode technique is theoretically and experimentally demonstrated. This ASPP design enables the generation of high-quality optical vortices with topological charges ranging from ±1 to ±4 using a single device, with higher charges being directly achievable by employing higher-birefringence LC or thicker cells. The continuous reconfigurability of the optical phase shift, achieved through a simple control mechanism involving only two low voltages and 100 electrodes that distribute the voltage, sets this device as an accurate approximation to a continuous ASPP. The measured conversion efficiency ranges between almost 100% and 95% for the first and fourth topological charges, respectively. This device offers remarkable advantages, such as complete reconfigurability, allowing adjustment of operating wavelengths and topological charges. The fabrication process mirrors that of a standard LCD cell, ensuring a cost-effective and reliable solution. In summary, the proposed ASPP is a key advancement, providing superior light conversion efficiency, simplicity, and the capability for on-the-fly reconfiguration in various optical applications.

The unambiguous identification of persons is one of the key aspects of police work. Biometric data find their application here due to the uniqueness of personal characteristics, which has a decisive impact on the certainty of identification of a person under investigation. Both the expansion of the set of biometric characteristics and advances in the quality (accuracy) of their representation in archives affect the correctness of identification and increase the chances of identification based on even fragmentary data. Through the practical application of modern technology, we can achieve significant advances in the effectiveness of person identification for forensic purposes and the search for missing persons.StreszczenieJednoznaczna identyfikacja osób jest jednym z kluczowych aspektów pracy policji. Dane biometryczne znajdują tu swoje zastosowanie ze względu na niepowtarzalność cech osobowych, co ma decydujący wpływ na pewność identyfikacji badanej osoby. Zarówno poszerzanie zbioru cech biometrycznych, jak i postęp w jakości (dokładności) ich odwzorowania w archiwach wpływają na poprawność identyfikacji i zwiększają szanse na identyfikację na podstawie nawet fragmentarycznych danych. Dzięki praktycznemu zastosowaniu nowoczesnych technologii jesteśmy w stanie osiągnąć znaczący postęp w skuteczności identyfikacji osób na potrzeby kryminalistyki i poszukiwań osób zaginionych.ResumenLa identificación inequívoca de las personas es uno de los aspectos fundamentales del trabajo policial. Los datos biométricos encuentran aquí su aplicación debido a la unicidad de los rasgos personales, que tiene un impacto decisivo en la certeza de la identificación de la persona investigada. Tanto la ampliación del conjunto de características biométricas como los avances en la calidad (precisión) de su reproducción en los archivos afectan a la corrección de la identificación y aumentan las posibilidades de identificación a partir incluso de datos fragmentarios. Gracias a la aplicación práctica de la tecnología moderna, podemos hacer avances significativos en la eficacia de la identificación de personas para la ciencia forense y la búsqueda de personas desaparecidas.ZusammenfassungDie eindeutige Identifizierung von Personen ist einer der wichtigsten Aspekte der Polizeiarbeit. Biometrische Daten finden hier ihre Anwendung aufgrund der Einzigartigkeit der persönlichen Merkmale, die einen entscheidenden Einfluss auf die Sicherheit der Identifizierung der untersuchten Person hat. Sowohl die Erweiterung der Menge biometrischer Merkmale als auch die Fortschritte bei der Qualität (Genauigkeit) ihrer Wiedergabe in den Archiven beeinflussen die Richtigkeit der Identifizierung und erhöhen die Chancen der Identifizierung auf der Grundlage selbst bruchstückhafter Daten. Durch die praktische Anwendung moderner Technologien sind wir in der Lage, die Effizienz der Personenidentifizierung in der Forensik und bei der Suche nach vermissten Personen erheblich zu steigern.РезюмеОднозначная идентификация личности - это один из ключевых аспектов работы полиции. Биометрические данные находят здесь свое применение благодаря уникальности персональных черт, что оказывает решающее влияние на уверенность в идентификации человека. Как расширение набора биометрических характеристик, так и повышение качества (точности) их воспроизведения в архивах влияют на правильность идентификации и повышают шансы на установление личности на основе даже фрагментарных данных. Практическое применение современных технологий позволяет значительно повысить эффективность идентификации личности в криминалистике и поиске лиц, пропавших без вести.

We present the implementation of the Four-Channel Stokes Polarimeter for continuous monitoring of the state of polarization of light in QKD system, to detect disturbance of the fiber link integrity in the single photon regime.

Polymer microtips manufactured at the end face of standard optical fibers have been used for effectively coupling with a selected antiresonant fibers (ARFs). Four tested ARFs had similar geometry, 7 capillaries placed around the central air core. It was shown how such coupling structure modified the ARFs spectral characteristics. Applying polymer microtip successfully excited additional bands. Illumination of the ARF with a microtip that operates as a microlens causes a change in numerical aperture and mode number.

Rapid detection of Mycoplasma synoviae (MS) in a flock is crucial from the perspective of animals’ health and economic income. MS are highly contagious bacteria that can cause significant losses in commercial poultry populations when its prevalence is not limited. MS infections can cause losses associated with a range of clinical symptoms related to the respiratory, mobility and reproductive systems. Lesions related to the reproductive system and changes in the eggshell result in losses associated with infection or embryo death or complete destruction of the eggs. The authors propose using spectral measurements backed up by an AI data processing algorithm to classify eggs’ origin: from healthy hens or MS-infected ones. The newest obtained classification factors are F-scores for white eggshells of 99% and scores for brown eggshells of 99%—all data used for classification were obtained using a portable multispectral fibre-optics reflectometer. The proposed method may be used directly on the farm by staff members with limited qualifications, as well as by veterinary doctors, assistants, or customs officers. Moreover, this method is scalable to mass production of eggs. Standard methods such as serological tests require either specialized staff or laboratory equipment. Implementation of a non-destructive optical measurement method, which is easily adapted for use on a production line, is economically reasonable.

Abstract This work presents the application of an experimental nematic liquid crystal (LC) mixture (1929) in a large aperture lens. The LC material is composed of terphenyl and biphenyl derivatives compounds with an isothiocyanate terminal group and fluorinated lateral substituents. The substitution with a strongly polar isothiocyanate group and an aromatic rigid core provides $$\pi$$ π -electron coupling, providing high birefringence ( $$\Delta n = 0.3375$$ Δ n = 0.3375 at 636 nm and 23 °C) and low viscosity ( $$\eta$$ η = 17.03 mPa s). In addition, it also shows high values of birefringence at near infrared (0.318 at 1550 nm). The synthesis process is simple when comparing materials with high melting temperatures. The excellent properties of this LC mixture are demonstrated in a large aperture LC-tunable lens based on a transmission electrode structure. Thanks to the particular characteristics of this mixture, the optical power is high. The high birefringence makes this LC of specific interest for lenses and optical phase modulators and devices, both in the visible and infrared regions.

Previous measurements have shown that the changes in reflective properties of chicken eggshells allow the classification of their origin: healthy or Mycoplasma synoviae (M.S.) infected hens. The presented portable multispectral optical fiber reflectometer can be used for early M.S. detection in a flock by back-reflected light measurement using a multispectral system.

The proper classification of the origins of food products is a crucial issue all over the world nowadays. In this paper, the authors present a device-a multispectral portable fibre-optic reflectometer and signal processing patch-together with a machine-learning algorithm for the classification of the origins of chicken eggshells in the case of Mycoplasma synoviae infection. The sensor device was developed based on previous studies with a continuous spectrum in transmittance and selected spectral lines in reflectance. In the described case, the sensor is based on the integration of reflected spectral data from short spectral bands from the VIS and NIR region, which are produced by single-colour LEDs and introduced to the sample via a fibre bundle. The measurement is carried out in a sequence, and the reflected signal is pre-processed to be put in the machine learning algorithm. The support vector machine algorithm is used together with three different types of data normalization. The obtained results of the F-score factor for classification of the origins of samples show that the percentages of eggs coming from Mycoplasma synoviae infected hens are up to 87% for white and 96% for brown eggshells.

Today, multispectral optical sensors are extensively studied in non-contact and remote imaging systems. However, our previous experimental studies have shown that the changes in the reflective properties of chicken eggshells allow for the classification of their origin as either healthy or Mycoplasma synoviae (MS)-infected hens. MS is a pathogen affecting poultry that may have a significant economic impacts on poultry breeding. In this work, we present the portable optical fiber reflectometer, which can be used for early MS detection in a flock by the measurement of back-reflected light in a multispectral system. The designed reflectometer consists of control and optical modules. The control module is responsible for the light source and photodetector modulation, the synchronization and the power supply, as well as data recording. The main part of this module is a microcontroller used to ensure flexibility in creating the research sequence during operation. The optical module is based on a fiber bundle with six light outputs and a single detection line. The loose end of the fiber bundle is integrated with an optical head, which shapes the illuminating beam to obtain measurement conditions. The same optical head collects a back-reflected beam that propagates through the detection line to the detector. The application of the optical fiber decreases the weight of the whole system and enables the flexible operation of the optical head, making this system portable. In order to classify the test objects, the collected data were subjected to numerical analysis by means of machine learning.

Mycoplasma synoviae (MS) is a pathogen that causes economic losses in the poultry industry. It can be transmitted, amongst others, via the respiratory tract and spread relatively quickly. As such, MS infections are mainly controlled by maintaining MS-free breeder flocks. Routine diagnosis for the detection of MS may be based on serological, culture, and molecular tests. Here, we propose an optical solution where AI-based analysis of spectral data obtained from the light reflected from the eggshells is used to determine whether they originate from healthy or Mycoplasma synoviae-infected hens. The wavelengths proposed for spectral MS detection are limited to those of VIS and NIR DPSS lasers, which are freely accessible on market. The results are satisfactory: for white eggshells, the F-score is over 95% for five different combinations of wavelengths (using eight or nine wavelengths); for brown eggshells, the F-score is above 85%, also for five different combinations of 6–9 wavelengths.

BACKGROUND:The production of honey, and especially the unifloral varieties, is limited by factors such as weather conditions or the availability of nectar flow and honeydew. This results in a deficit in supply leading to the adulteration of honey. If they are not properly labeled, customers cannot distinguish artificial / synthetic products from real honey. Currently, the basic, commonly used method for determining the varieties of honey (botanical origin) is palynological analysis. However, this procedure is quite difficult owing to the dearth of experienced staff in the field of melissopalynology. RESULTS:A method for identifying and classifying natural honey accurately based on its botanical origin has therefore been proposed. This analysis would rely on the visible light spectra transmitted through a relatively thin layer of the substance of interest, regardless of deviations in thickness. We present algorithms for analyzing the transmittance spectra-parametrization based on polynomial approximation (PMA) and applying a method for spectra selection and reduction (SSR) and a classical classification model (decision tree). A comparison is presented of the classification of four varieties of honey, confirmed by pollen analysis, obtained from the analysis of optically measured transmittance spectra of the samples. The algorithms that are compared contain a decision tree that uses raw data, data reduced by principal component analysis (PCA), and data after calculations based on the proposed algorithms alone (PMA and SSR) and together with the PCA method. CONCLUSION:This novel method produced outstanding results in comparison with the standard PCA method and is helpful in identifying the botanical origin of honey effectively. © 2021 Society of Chemical Industry.

Mycoplasma synoviae (MS) is a major pathogen in chicken and turkeys, causing subclinical infection. MS infections are highly prevalent and may potentate and be involved in sinovitis, respiratory syndromes, as well as lead to eggshell apex abnormality (EAA). A deformed, inhomogeneous eggshell is susceptible to cracks and breaks through which microbes get in and additionally entails higher water loss in the egg during the entire incubation process. Not all eggs with eggshell apex abnormality possess characteristic deformation and that is why some eggs may be incorrectly classified during a visual inspection. To minimize the above risk, the spectral VIS technique and the analysis based on the classification tree method-CTM is proposed. The method makes use of specially defined parameters extracted from the shape of transmittance spectra of eggshells. Directional coefficients of the lines adjusted to the specific ranges of the transmittance spectrum are used in the process of classifying samples as those from MS-carrying hens and from healthy hens. Three CTM-based classifiers were created for a group of white, brown, and mixed shells. After comparing, it can be concluded that the best results were obtained for the group of brown shells (accuracy 88%, specificity 88%, and false negative rate 13%). The authors present a non-invasive spectral method that utilizes eggshells, i.e., the natural waste from chicken farms. The method enables entering data into the classifiers described in the article. The process provides an opportunity to correctly assign, the examined shell to the group of shells with increased risk-with approx. 86% accuracy. This means that, if a few of such results are registered, the herd is eligible more specific studies targeting MS bacteria. Regular spectral testing can support the detection of egg lesions in MS positive flocks.