Article
Chemistry, Multidisciplinary
Soon Wei Daniel Lim, Maryna L. Meretska, Federico Capasso
Summary: This study introduces an alternative metasurface geometry based on high aspect ratio via-holes, designing and characterizing metalenses that focus incident infrared light into a diffraction-limited spot. By engineering both transmitted phase and amplitude profiles simultaneously, the impedance match between the incident and transmitted waves is improved, leading to increased focusing efficiency. The holey platform enhances the accessible aspect ratio of optical nanostructures while maintaining mechanical robustness, paving the way for a generation of high aspect ratio ruggedized flat optics.
Article
Optics
YangLiu Zhang, Xu Wang, ZhouPing Su, HongXiang Pan, XingTao Chen, WenYu Zhang
Summary: The DSCE method can effectively reduce the error of freeform surface construction and improve the imaging quality of the off-axis reflective imaging system, and can be used to design imaging systems consisting of multiple freeform surfaces.
Article
Engineering, Electrical & Electronic
Qiongchan Gu, Jiangtao Lv, Xinwei Mo, Xiaoxiao Jiang
Summary: High aspect ratio metamaterials are crucial in nanotechnology and biotechnology for developing new devices. Overcoming the diffraction limit is essential for high resolution microscopy techniques. Although many theoretical optical devices have been proposed, fabricating special optical components with high aspect ratios is extremely challenging. This article summarizes the commonly used fabrication approaches and reviews the important applications of high aspect ratio metamaterials. Furthermore, it proposes and verifies methods for optimizing device performance by manipulating geometric parameters.
SENSORS AND ACTUATORS A-PHYSICAL
(2022)
Article
Thermodynamics
Ezrann Z. A. Zainal, Mhadi A. Ismael, A. Rashid A. Aziz, Salah E. Mohammed, Masri B. Baharom, Firmansyah, M. Hanif Ibrahim, M. Sahalan, Abdul Qawiy
Summary: This study investigates the effects of different aspect ratios on the operating frequency and power output of the FPLG engine. The medium aspect ratio (AR1.5) is found to be optimal for overall FPLG operation, providing the best balance of operating frequency and power output, especially in lean conditions.
APPLIED THERMAL ENGINEERING
(2021)
Article
Chemistry, Multidisciplinary
Jian-Guan Hua, Shu-Yu Liang, Qi-Dai Chen, Saulius Juodkazis, Hong-Bo Sun
Summary: This work presents a universal and flexible technology for the fabrication of crystalline micro-optics with required shape and surface roughness. By combining femtosecond laser ablation with high-temperature treatment, the rough non-crystalline layer caused by ablation is removed and the surface roughness is reduced to approximately 2 nm without changing the structure shape. This technology offers nanoscale resolution and free-form 3D manufacturing capability for various crystals, providing a new approach to fabricate micro-/integrated-optics and nonlinear optical elements.
ADVANCED FUNCTIONAL MATERIALS
(2022)
Article
Multidisciplinary Sciences
Shi Liu, Jierui Zhang, Yu Zhang, Shuowei Zhang, Songzhou Yang, Guoxing Zou, Liquan Liu
Summary: This study proposes a method for designing a large solar simulator with high irradiation uniformity. By optimizing the concentrator and projection system, it successfully achieves high irradiance uniformity and large irradiation area, providing accurate and reliable solar irradiation for laboratory calibration and performance testing of spacecraft payloads.
Review
Food Science & Technology
Juan Zhang, Xiaoyun Chai, Fenglan Zhao, Guige Hou, Qingguo Meng
Summary: Hawthorn is a medicinal and edible plant with rich bioactive substances, which offer high nutritional and therapeutic value. Its antioxidant, anti-inflammatory, anticancer properties are related to its polyphenols, flavonoids, and pentacyclic triterpenoids.
Article
Chemistry, Physical
Ezrann Z. A. Zainal, Salah E. Mohammed, A. Rashid A. Aziz, M. B. Baharom, Aiman Jaffry, Firmansyah, A. A. Shahrul, Mhadi A. Ismael
Summary: This paper presents an experimental study on the effect of aspect ratio on the performance characteristics of a Free-piston linear generator (FPLG) engine fueled by hydrogen. Results show that aspect ratio 2.0 produces the highest pressure, heat release, and shortest combustion duration, while aspect ratio 1.0 has higher combustion efficiency and operating frequency. The aspect ratio significantly influences the engine performance characteristics.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2021)
Article
Optics
Alex Dorn, Hans Zappe, Caglar Ataman
Summary: This study analyzes the feasibility of using refractive free-form phase plates as an alternative to active alignment in the aperture stop of microscope objectives. By determining the misalignment-induced aberrations at the exit pupil and considering pupil aberrations, the method can restore the imaging performance of passively aligned systems with practical tolerances, although it can only correct for field-independent aberrations.
Article
Thermodynamics
Enderaaj Singh, Sukanta Roy, Ke San Yam, Ming Chiat Law
Summary: This paper presents a numerical study on the power production efficiency of a three-bladed H-Darrieus vertical axis wind turbine using S-1046 airfoil under accelerated wind conditions of the cooling tower exhaust system. The results show that the turbine with a smaller aspect ratio of 0.44 achieves a better power coefficient of 0.294 at TSR 2.5. Flow field analysis and a comparative study with free-stream flow conditions are provided to discuss the turbine's performance, indicating that the turbine performs better under exhaust flow systems.
Article
Optics
Shaoliang Yu, Luigi Ranno, Qingyang Du, Samuel Serna, Colin McDonough, Nicholas Fahrenkopf, Tian Gu, Juejun Hu
Summary: This work presents a new fiber-to-chip coupling scheme based on free-form reflective micro-optics. The scheme achieves low coupling loss and high bandwidth density, and has large alignment tolerance and solder reflow compatibility. It is a promising optical packaging solution for applications such as wavelength division multiplexing communications, broadband spectroscopic sensing, and nonlinear optical signal processing.
LASER & PHOTONICS REVIEWS
(2023)
Article
Engineering, Marine
Leila N. Azadani, Mojtaba Saleh
Summary: The study investigated the effect of blade aspect ratio on the power generation of paired straight-bladed vertical axis wind turbines. The results showed that increasing the blade aspect ratio led to an increase in power generation and a decrease in wake recovery rate.
Article
Automation & Control Systems
Zhaoyu Li, Kai Tang, Pengcheng Hu, Lihua Huang
Summary: This paper introduces a new trochoidal sweep scanning path for freeform surface inspection, which solves the problem of oscillation in current scanning paths and significantly improves the kinematic performance of the inspection device. Both computer simulation and physical inspection experiments demonstrate the feasibility and superiority of the proposed method in terms of inspection stability and efficiency compared to traditional oscillating sweep scanning paths.
IEEE TRANSACTIONS ON AUTOMATION SCIENCE AND ENGINEERING
(2023)
Article
Chemistry, Physical
Zhitian Shi, Konstantins Jefimovs, Antonino La Magna, Marco Stampanoni, Lucia Romano
Summary: By introducing metal electric field modulators, controlled tilted etching can be achieved by modifying the near sample surface potential, thereby changing the incident angle of ions and obtaining a tilted profile.
APPLIED SURFACE SCIENCE
(2022)
Article
Multidisciplinary Sciences
Brandon Y. Feng, Haiyun Guo, Mingyang Xie, Vivek Boominathan, Manoj K. Sharma, Ashok Veeraraghavan, Christopher A. Metzler
Summary: We propose a scanning-free wavefront shaping technique called neural wavefront shaping (NeuWS) that integrates maximum likelihood estimation, measurement modulation, and neural signal representations to reconstruct diffraction-limited images through strong static and dynamic scattering media without guidestars, sparse targets, controlled illumination, nor specialized image sensors.
Article
Engineering, Electrical & Electronic
Agnieszka Gierej, Kurt Rochlitz, Adam Filipkowski, Ryszard Buczynski, Sandra Van Vlierberghe, Peter Dubruel, Hugo Thienpont, Thomas Geernaert, Francis Berghmans
Summary: We have prepared and characterized microstructured biodegradable and biocompatible polymer optical fibers using commercially available poly(D,L-lactic acid) (PDLLA). The preparation of preforms by transfer molding and fiber manufacturing was reported and the influence of polymer processing on the molar mass decrease of PDLLA was investigated. The in vitro degradation of the fabricated fibers in phosphate buffered saline (PBS) was studied, showing molar mass loss of 21%, 25%, and 43% over 105 days for fibers with diameters of 400, 200, and 100 μm, respectively. Cutback measurements revealed an attenuation coefficient of 0.065 dB/cm at 898 nm for a microstructured fiber with a diameter of 219 +/- 27 μm. After immersion in PBS at 37 degrees C, the optical loss increased by 0.4 dB/cm at 950 nm after 6 h and by 0.8 dB/cm after 17 h.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2023)
Article
Materials Science, Ceramics
Wendy Meulebroeck, Mathilde Patin, Karin Nys, Hugo Thienpont
Summary: There is a need to understand the link between the optical spectrum and technology parameters of silver-staining. The study conducted experiments on samples with known fabrication conditions, comparing optical and chemical methods to identify the measures that match material properties. The research resulted in a flowchart scheme for non-destructive assessment of silver-staining technology and its potential application in different glass families.
JOURNAL OF NON-CRYSTALLINE SOLIDS
(2023)
Article
Engineering, Biomedical
Alejandro Madrid-Sanchez, Fabian Duerr, Yunfeng Nie, Hugo Thienpont, Heidi Ottevaere
Summary: The characteristics of high porosity, microscale features, and pores interconnectivity make scaffolds suitable for human tissue substitutes. However, these characteristics often limit the scalability of different fabrication approaches, especially in bioprinting techniques. In this study, an alternative vat photopolymerization technique called light sheet stereolithography (LS-SLA) is proposed to fabricate centimeter-scale scaffolds with high resolution. The LS-SLA technology allows the modification of voxel profiles using laser beam shaping and enables the production of complex three-dimensional scaffolds.
INTERNATIONAL JOURNAL OF BIOPRINTING
(2023)
Article
Construction & Building Technology
Jeroen Cerpentier, Nick Rondelez, Nathan Slembrouck, Stef Gielen, Paula Acuna, Youri Meuret
Summary: This paper proposes a compact adaptive lighting fixture that utilizes an embedded system and camera for autonomous beam adjustment based on computer vision. It detects painting frames and adjusts the light beam direction and spot size accordingly. This integration between computer vision and adaptive light fixtures for indoor lighting represents a first demonstration.
BUILDING AND ENVIRONMENT
(2023)
Article
Engineering, Electrical & Electronic
Ikuo Arata, Hirotoshi Terada, Michael Vervaeke, Dries Rosseel, Hugo Thienpont
Summary: In this study, a gallium arsenide (GaAs) aspherical solid immersion lens (SIL) has been developed for semiconductor failure analysis. The SIL significantly increases the numerical aperture and spatial resolution of a microscopy system by attaching it to the backside of the device-under-test. To improve the spatial resolution, a shorter wavelength light source is used. The use of GaAs as SIL material enables the use of shorter wavelengths, and an aspherical design corrects spherical aberration, resulting in diffraction limited performance for semiconductor failure analysis.
MICROELECTRONICS RELIABILITY
(2023)
Article
Chemistry, Multidisciplinary
Bega Karadza, Pieter Schiettecatte, Hannes Van Avermaet, Leila Mingabudinova, Luca Giordano, Dobromil Respekta, Yu-Hao Deng, Igor Nakonechnyi, Kim De Nolf, Willem Walravens, Youri Meuret, Zeger Hens
Summary: Researchers have demonstrated green, amber, and red LEDs formed using InP-based quantum dots as on-chip color converters for blue LEDs. The implementation of QDs with high photoluminescence efficiency results in efficient color conversion, minimal intensity roll-off, and rejection of blue light. This on-chip color conversion technology using InP-based QDs provides spectrum-on-demand LEDs, including monochromatic LEDs that bridge the green gap.
Article
Chemistry, Analytical
Lien Smeesters, Jef Verbaenen, Luca Schifano, Michael Vervaeke, Hugo Thienpont, Giancarlo Teti, Alessio Forconi, Filippo Lulli
Summary: This study proposes a novel five-channel multispectral camera design suitable for autonomous and continuous crop monitoring. It covers visible, near-infrared, and thermal wavelength bands, allowing the sensing of various vegetation indices. The wide-field-of-view imaging design exceeds 164 degrees, providing a larger field of view compared to drone-sensing systems.
Article
Chemistry, Analytical
Olga Rusyakina, Thomas Geernaert, Mederic Loyez, Maxime Lobry, Karima Chah, Pawel Mergo, Hugo Thienpont, Christophe Caucheteur, Francis Berghmans, Tigran Baghdasaryan
Summary: We address the challenge of spectral multiplexing of biosensors in a single optical fiber by combining photonic crystal fibers (PCF) with fiber Bragg grating technology. We utilize the optical transmission spectrum of a straight fiber Bragg grating in a PCF to excite cladding mode resonances, enabling plasmonic label-free biodetection of HER2 protein. Our PCF sensor can detect a protein concentration of 8.62 nM with high reproducibility.
SENSORS AND ACTUATORS B-CHEMICAL
(2023)
Article
Food Science & Technology
Lien Smeesters, Thomas Kuntzel, Hugo Thienpont, Ludovic Guilbert
Summary: Aflatoxins pose a significant threat to food and feed safety, but current methods of detection are not well-suited for identifying their presence in the food chain. In this study, we developed a non-destructive optical sensing technique based on fluorescence spectroscopy, resulting in a novel compact fluorescence sensing unit. Testing showed that the unit had high sensitivity and successfully classified naturally contaminated maize kernels. This sensing methodology has the potential to greatly enhance food safety.
Article
Chemistry, Analytical
Sara Abbasi, Mehdi Feizpour, Ilse Weets, Qing Liu, Hugo Thienpont, Francesco Ferranti, Heidi Ottevaere
Summary: Identifying hemoglobinopathies is crucial for managing clinical diseases. This study demonstrates the potential of Raman spectroscopy in combination with high-performance liquid chromatography for accurate identification of different hemoglobin types.
MICROCHEMICAL JOURNAL
(2023)
Proceedings Paper
Education, Scientific Disciplines
Astghik Chalyan, Tine De Pauw, Nathalie Debaes, Hugo Thienpont
Summary: More than 10 years ago, the Photonics Explorer Kit (PEK) was developed as an educational tool to inspire students towards photonics. It has been widely used by physics teachers and optics-related organizations, reaching over 200,000 students annually. The PEK aims to promote the understanding and impact of light technologies in schools, universities, and companies worldwide.
SEVENTEENTH CONFERENCE ON EDUCATION AND TRAINING IN OPTICS AND PHOTONICS: ETOP 2023
(2023)
Article
Optics
Jeroen Cerpentier, Bega Karadza, Hannes van Avermaet, Luca Giordano, Pieter Schiettecatte, Zeger Hens, Youri Meuret
Summary: Solid-state light-emitting diodes (LEDs) have high visual performance in terms of efficiency and color quality. The lighting industry is now considering the non-visual, biological effects of light. This paper presents a simulation-based design method for single-chip InP-based quantum dot on-chip white LEDs that achieve state-of-the art circadian performance while maintaining visual performance. These results are experimentally replicated by fabricating single-chip QD-LEDs with 3 types of InP-based QDs that set a new standard for spectral circadian performance.
OPTICS AND LASER TECHNOLOGY
(2023)
Article
Optics
Artem Shcheglov, Yunfeng Nie, Hugo Thienpont, Heidi Ottevaere
Summary: Recently, there is a growing trend for cost-effective, portable spectrometers to be applied in various fields, including scientific research, food safety, and air pollution analysis. In this study, we propose a miniaturized, two-channel, broadband spectrometer based on variable-spacing concave gratings, which integrates imaging optics and diffraction gratings into a single component. The design allows for a small volume and high spectral resolution, and simulation results demonstrate optical resolutions of less than 1.6 nm in the visible channel and less than 3.1 nm in the near-infrared channel. To validate the feasibility for mass production, we successfully manufactured the variable-spacing concave gratings using diamond tooling and hot embossing replication. The fabricated grating replicas exhibit high diffraction efficiency in both channels. Experimental results of the prototype show a good match in spectral resolution with the nominal design.
JOURNAL OF OPTICAL MICROSYSTEMS
(2023)
Article
Optics
Tommaso Fontanot, Ujjayanta Bhaumik, Ravi Kishore, Youri Meuret
Summary: This paper presents a new Python library called POCAL (Python Optical Coating Analysis Library). POCAL allows for easy design of optical coatings, including single layer and multilayer stack, monitoring a wide variety of optical properties, and automatically refining multilayer designs to achieve desired optical goals. The library is open source and can be easily integrated with various Python-based ray tracers or libraries for more complex simulations. Extensive testing has shown the results to be comparable to those obtained using commercial software.
Article
Optics
Nick Rondelez, Karel Desnijder, Wouter Ryckaert, Youri Meuret
Summary: Freeform optics can generate accurate illumination patterns from compact light sources. This paper presents a novel algorithm for calculating smooth phase shift patterns to generate arbitrary target patterns under non-paraxial conditions. Experimental analysis shows that applying these phase shift patterns to spatial light modulators can create programmable freeform optics. The possibilities and limitations of generating accurate prescribed target patterns are critically discussed in terms of angular extent, spectrum, and etendue.
