Light Diffraction Research Articles

Implementation of a high-resolution micro-grating accelerometer using a subdivision interpolation technique

This paper proposes a subdivision interpolation technique for an optical accelerometer based on diffraction grating interferometry. The diffraction light intensity curve presents a sine shape with the increase of the acceleration. To address the issues of linearization signal processing across the entire range, a subdivision interpolation circuit is employed, in conjunction with a 90° phase shift and high-precision DC bias-voltage techniques, converting an analog signal with sinusoidal characteristics from the photodetector into standard incremental digital signals that vary linearly over the full range. The novel methodology, to the best of our knowledge, ensures that its performance is least affected by the phase imbalance, offset error, and amplitude mismatch induced by fabrication and alignment errors of the grating, achieving high-resolution digital signal output. The experiment results reveal that the optical accelerometer based on grating interferometry achieved a sensitivity of 85.2 V/g, a resolution of 137.6 µg, as well as a subdivision interpolation factor of 45. This work provides a significant guide for the development of high-resolution MOEMS accelerometers in practical applications.

Generation of Isolated Subfemtosecond Electron Bunches by the Diffraction of a Polarization-Tailored Intense Laser Beam.

We propose utilizing a polarization-tailored high-power laser pulse to extract and accelerate electrons from the edge of a solid foil target to produce isolated subfemtosecond electron bunches. The laser pulse consists of two orthogonally polarized components with a time delay comparable to the pulse duration, such that the polarization in the middle of the pulse rapidly rotates over 90° within few optical cycles. Three-dimensional particle-in-cell simulations show that when such a light pulse diffracts at the edge of a plasma foil, a series of isolated relativistic electron bunches are emitted into separated azimuthal angles determined by the varying polarization. In comparison with most other methods that require an ultrashort drive laser, we show the proposed scheme works well with typical multicycle (∼30 fs) pulses from high-power laser facilities. The generated electron bunches have typical durations of a few hundred attoseconds and charges of tens of picocoulombs.

Production of nanocomposite films based on low density polyethylene/surface activated nanoperlite for modified atmosphere packaging applications

The modified atmosphere packaging films based on polyethylene nanocomposites reinforced with perlite nanoparticles were prepared using a blow molding machine. The perlite particles were first reduced to nano dimensions using an abrasive mill, then the porosity of nanoperlite was increased to improve their efficiency in absorbing ethylene gas. For this purpose, 6 normal sodium hydroxide solution at 50°C temperature was used. Finally, perlite nanoparticles were modified by polymethyl hydrogen siloxane silane compound. In each of the stages of grinding and modifying the perlite surface, the necessary tests including dynamic light diffraction test, nitrogen absorption test and ethylene gas absorption test were performed using gas chromatography method. The results showed that the size of perlite particles was reduced to 500 nm by using an abrasive mill, and the surface modification process increased the specific surface area of perlite by 10 times. Based on this, the amount of ethylene gas absorption in perlite nanoparticles with modified surface increased up to 3 times compared to normal perlite. The results of the gas chromatography test showed that the nanocomposite film based on polyethylene reinforced with 6% by weight of modified perlite nanoparticles has several times the efficiency in absorbing ethylene gas compared to the potassium permanganate sachets The results of the mechanical properties tests of nanocomposite film in comparison with pure polyethylene film showed that nanocomposite film has higher properties than pure polyethylene. The results of shelf-life tests of green tomatoes packed in nanocomposite film based on polyethylene reinforced with modified nanoperlite showed that green tomatoes can be stored for two months using the prepared modified atmosphere packaging.

Inkjet Printing of Magnetically Responsive Photonic Crystals

AbstractMagnetic colloidal nanocrystalline clusters (MCNCs) exhibit a color‐changing response to a magnetic field due to their tunable assembly into photonic crystals demonstrating visible light diffraction. The use of this response to obtain a magnetically sensitive color micropattern on the surface of a solid substrate requires appropriate scalable technologies for deposition of MCNCs. Here, inkjet printing of MCNCs onto the surface of a solid substrate coated with uncured polydimethylsiloxane is addressed and demonstrate their capability to form desired patterns with structural colors from blue to red controlled by external magnetic field. The results, thereby, pave the way to semi‐commercial manufacture an anticounterfeiting imaging at a large scale.

Integration of Melt Electrowritten Polymeric Scaffolds and Bioprinting for Epithelial Healing via Localized Periostin Delivery.

Management of skin injuries imposes a substantial financial burden on patients and hospitals, leading to diminished quality of life. Periostin (rhOSF), an extracellular matrix component, regulates cell function, including a proliferative healing phase, representing a key protein to promote wound healing. Despite its proven efficacy in vitro, there is a lack of scaffolds that facilitate the in situ delivery of rhOSF. In addition, there is a need for a scaffold to not only support cell growth, but also to resist the mechanical forces involved in wound healing. In this work, we synthesized rhOSF-loaded mesoporous nanoparticles (MSNs) and incorporated them into a cell-laden gelatin methacryloyl (GelMA) ink that was bioprinted into melt electrowritten poly(ε-caprolactone) (PCL) microfibrous (MF-PCL) meshes to develop mechanically competent constructs. Diffraction light scattering (DLS) analysis showed a narrow nanoparticle size distribution with an average size of 82.7 ± 13.2 nm. The rhOSF-loaded hydrogels showed a steady and controlled release of rhOSF over 16 days at a daily dose of ∼40 ng/mL. Compared with blank MSNs, the incorporation of rhOSF markedly augmented cell proliferation, underscoring its contribution to cellular performance. Our findings suggest a promising approach to address challenges such as prolonged healing, offering a potential solution for developing robust, biocompatible, and cell-laden grafts for burn wound healing applications.

Green Synthesis of Silver Nanoparticles from Anthocyanin Extracts of Peruvian Purple Potato INIA 328-Kulli papa.

In this work, AgNPs were synthesized using an anthocyanin extract from Peruvian purple potato INIA 328-Kulli papa. The anthocyanin extract was obtained through a conventional extraction with acidified ethanolic aqueous solvent. This extract acted as both a reducing and stabilizing agent for the reduction of silver ions. Optimization of synthesis parameters, including pH, reaction time, and silver nitrate (AgNO3) concentration, led to the optimal formation of AgNPs at pH 10, with a reaction time of 30 min and an AgNO3 concentration of 5 mM. Characterization techniques such as X-ray diffraction (XRD) and dynamic light scattering (DLS) revealed that the AgNPs had a crystallite size of 9.42 nm and a hydrodynamic diameter of 21.6 nm, with a zeta potential of -42.03 mV, indicating favorable colloidal stability. Fourier Transform Infrared (FTIR) analysis confirmed the presence of anthocyanin functional groups on the surface of the AgNPs, contributing to their stability. Furthermore, the bacterial activity of the AgNPs was evaluated by determining the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). For E. coli, the MIC was 0.5 mM (0.05 mg/mL) and the MBC was 4.5 mM (0.49 mg/mL). Similarly, for S. aureus, the MIC was 0.5 mM (0.05 mg/mL) and the MBC was 4.0 mM (0.43 mg/mL). These results highlight the potential benefits of AgNPs synthesized from Peruvian purple potato anthocyanin extract, both in biomedical and environmental contexts.

Observation of sunlight diffraction through tree twigs and leaves

This work reports the observation of sunlight diffraction through empty spaces in between twigs and leaves in tree crowns. The diffraction patterns are dominated by red wavelength on front followed by the trail of rest of spectral bands of white light rainbow bursts. Tree crowns act as obstacles and apertures causing diffraction/ interference of solar rays. Separation between leaves and twigs (d) is a few inches and distance between crown and camera (D) is in range of a few meters. Empty spaces in tree crown are much longer than red to violet wavelengths in sunlight therefore scattering, dispersion, reflection, diffraction and interference effects cannot be ruled out. Tree crown deflects solar rays into narrow angles all around to enable interference inside camera lens to create grating structure diffracting light into regular patterns. Diffraction pattern look like red petunia flower having 3 × 3 rose petals. Motorola mobile phone camera was used to record the sunlight diffraction patterns. Mobile camera consists of small focal length (≈5 mm) lens, a fixed opening aperture and an image sensor. Lens consists of few plastic or glass elements and sensor consists of charge coupled device (CCD) or CMOS technology. These diffraction/ interference patterns have potential to increase efficiency of Next Gen solar cells. This paper describes possible theoretical background of light diffraction and multiple ray interference through tree twigs and leaves.

Orbital Hall diffraction and its application for vortex measurement.

We observe significant orbital angular momentum (OAM)-helicity-dependent centroid shifts in the Fraunhofer patterns for the far-field diffraction of optical vortex beams passing through a thin single wire, thus suggesting the orbital Hall effect (OHE) of light in diffraction. Based on the OHE with a thin cross wire, we further experimentally develop a compact and robust alignment-free method to measure the OAM states of light. These findings indicate that not only does the OHE of light offer insights into vortex diffraction with broken rotational symmetry, it may also provide a reliable and efficient way to simplify the vortex measurement for waves of different natures.

Green Synthesis of ZnO Nanostructures and Their Antibacterial Activity Against Catfish Pathogen

Due to its antibacterial activity against clinical bacterial pathogens at the time of tissue development, zinc oxide (ZnO) is considered one of the most important metal oxide nanostructured materials. In this study, ZnO nanostructures were prepared using Aloe vera gel juice, which is easy, inexpensive, and ecofriendly. The nanostructures of ZnO were characterized using a variety of analytical techniques, including scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and dynamic light scattering (DLS). As a result of the XRD study, the hexagonal phase of ZnO with the structure of wurtzite has been identified. ZnO material with high heterogeneity morphology has been observed by SEM analysis. As-prepared ZnO nanostructures were tested for their antibacterial activity against the newly discovered pathogen of catfish. A ZnO sample prepared with a high concentration of Aloe vera gel possessed an inhibition zone of 13.21±0.04 mm, whereas a ZnO sample prepared with a low concentration of Aloe vera juice had an inhibition zone of 6.23±0.02 mm and a pure ZnO sample had an inhibition zone of 3.31±0.03 mm. Furthermore, we examined the effectiveness of the ZnO nanostructures on bacterial strains based on the type of nanoparticles applied to the commercial strains. In addition to their modified surface properties, small particle size, and highly toxic effects for the killingof bacterial cell growth, the Aloe vera juice assisted ZnO nanostructures demonstrated excellent antibacterial activity against the catfish pathogens.

Electrically tunable total reflection of light by oblique helicoidal cholesteric

An oblique helicoidal state of a cholesteric liquid crystal (ChOH) is capable of continuous change of the pitch P\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$P$$\\end{document} in response to an applied electric field. Such a structure reflects 50% of the unpolarized light incident along the ChOH axis in the electrically tunable band determined by P\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$P$$\\end{document}/2. Here, we demonstrate that at an oblique incidence of light, ChOH reflects 100% of light of any polarization. This singlet band of total reflection is associated with the full pitch P\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$P$$\\end{document}. We also describe the satellite P/2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$P/2$$\\end{document}, P/3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$P/3$$\\end{document}, and P/4\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$P/4$$\\end{document} bands. The P/2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$P/2$$\\end{document} and P/4\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$P/4$$\\end{document} bands are triplets, whereas P/3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$P/3$$\\end{document} band is a singlet caused by multiple scatterings at P\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$P$$\\end{document} and P/2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$P/2$$\\end{document}. A single ChOH cell acted upon by an electric field tunes all these bands in a very broad spectral range, from ultraviolet to infrared and beyond, thus representing a structural color device with enormous potential for optical and photonic applications.Impact statementPigments, inks, and dyes produce colors by partially consuming the energy of light. In contrast, structural colors caused by interference and diffraction of light scattered at submicrometer length scales do not involve energy losses, which explains their widespread in Nature and the interest of researchers to develop mimicking materials. The grand challenge is to produce materials in which the structural colors could be dynamically tuned. Among the oldest known materials producing structural colors are cholesteric liquid crystals. Light causes coloration by selective Bragg reflection at the periodic helicoidal structure formed by cholesteric molecules. The cholesteric pitch and thus the color can be altered by chemical composition or by temperature, but, unfortunately, dynamic tuning by electromagnetic field has been elusive. Here, we demonstrate that a cholesteric material in a new oblique helicoidal ChOH state could produce total reflection of an obliquely incident light of any polarization. The material reflects 100% of light within a band that is continuously tunable by the electric field through the entire visible spectrum while preserving its maximum efficiency. Broad electric tunability of total reflection makes the ChOH material suitable for applications in energy-saving smart windows, transparent displays, communications, lasers, multispectral imaging, and virtual and augmented reality.Graphical

Effects of Leaching Agents on Pb and Cd Immobilization in Battery Waste Contaminated Soils Amended with Bare and Stabilized Zero-Valent Iron Nanoparticles

This study compared the effectiveness of bare zero-valent iron nanoparticles (B-nZVI) and starch-stabilized zero-valent iron nanoparticles (S-nZVI) in immobilizing Pb and Cd from lead-acid battery waste soils. Both B-nZVI and S-nZVI were prepared in almost identical manner using the technique of reducing ferric chloride with sodium borohydride. X-ray diffraction (XRD) and dynamic light scattering (DLS) analyses confirmed that polydisperse B-nZVI and S-nZVI were synthesized. XRD and DLS analyses showed that B-nZVI and S-nZVI had different surface properties. To assess the immobilization capability of B-nZVI and S-nZVI, a composite soil sample was collected from an automobile lead-acid battery waste dumpsite. The soil sample had a pH of 3.85 and Pb and Cd levels of 16,674 mg/kg and 41 mg/kg, respectively. Single extraction procedures using 0.01M CaCl2, 0.1 M HCl, and 0.05 M EDTA were used to simulate phytoavailable Pb and Cd in the soil studied. Batch immobilization analysis showed that Cd was mobile in the control but immobile in B-nZVI and S-nZVI treated soils. Pb was however not immobile in either the control or treated soils. The mobility of Pb however decreased with increasing doses of S-nZVI and 0.003 g of S-nZVI was needed to make Pb completely immobile in soil. Batch immobilization also showed that S-nZVI was 1.8-2.49 times more efficient in immobilizing Pb than B-nZVI. Simulated phytoavailability of Pb was in the order of EDTA > HCl > CaCl2 > H2O while simulated photoavailable Cd was in the order of HCl > EDTA > H2O > CaCl2.

Effect of an inquiry-based teaching sequence on secondary school students’ understanding of wave optics

Wave optics is a mandatory part of Croatian secondary school physics curriculum for students in the final year of secondary school (age 18–19). Many physics education research studies have shown that it is a difficult physics topic for both university and secondary school students. An inquiry-based teaching sequence on wave optics, designed for eight 45-min teaching periods, was developed by the authors. The sequence included four investigative students’ experiments on the topics of interference, diffraction, and polarization of light, as well as several teacher demonstrations. The experimental group included six classes of students from six different Croatian urban secondary schools, who underwent the teaching intervention with the new inquiry-based sequence on wave optics, whereas the control group consisted of six classes from the same schools, taught in a predominantly lecturing way. Both groups were post-tested with the same instrument, the Conceptual Survey on Wave Optics (CSWO), to evaluate the research hypothesis that the new sequence might improve students’ conceptual understanding better than the traditional teaching. The results of the experimental and control groups were analyzed and compared using the Rasch analysis. The results show that the experimental group outperformed the control group in four out of five conceptual areas probed by the CSWO, suggesting that the new inquiry-based teaching sequence may contribute to stronger development of secondary school students’ conceptual understanding of wave optics, especially concerning typical wave optics patterns, reasoning from experiments, and explaining basic wave optics phenomena. A questionnaire on attitudes toward the teaching intervention was administered to students and it was found that students generally liked the inquiry-based teaching intervention and expressed positive attitudes to interactive, experimental, and collaborative aspects of physics teaching. The results are very promising, but their generalization may be limited by the selection of the students, as well as by the short duration of the teaching intervention and the relatively small breadth of the covered topics. Published by the American Physical Society 2024

Image optimization of a computer-generated hologram by reusing zero-order beams and reflectors vibration.

In computer-generated holography, spatial light modulators are predominantly used for image reconstruction. However, the quality of the reconstructed images is often compromised by laser speckle and zero-order light diffraction. To address these problems, we propose the reuse of the zero-order beam, which not only eliminates the interference caused by zero-order diffraction in the reconstructed images but also considerably enhances image brightness. Moreover, we propose the use of vibrating reflectors in the proposed structure for reusing the zero-order beam to reduce speckle, thereby suppressing the speckle contrast in reconstructed images to less than 4%.

Diffraction of laser light by a Ferrocell and ferrofluid layers: A comparison

In a previous study, we conducted a comparative analysis of laser light extinction using both a Ferrocell and ferrofluid layers. Specifically, we examined the diffraction of laser light by these devices. The Ferrocell was positioned between an electromagnet and a He-Ne-laser beam, and diffraction patterns were recorded with and without the application of a magnetic field. Subsequently, the experiment was replicated using a glass cuvette filled with a ferrofluid. We investigated the power spectra of these diffraction patterns and analyzed temperature variations. Our findings reveal significant distinctions between the diffraction patterns produced by the ferrofluid and the Ferrocell. Further investigations into these differences are currently underway.

Introducing wave-particle duality with low-cost quantitative experiments on light diffraction

We present a quantitative optical low-cost experiment aimed at introducing students to wave-particle duality from a phenomenological point of view. The experiment, focused on light diffraction, clearly shows the intermediate crossover regime which characterize the transition from geometric optics (in which light behaves like a stream of particles) to the Fraunhofer diffraction regime (where the wave aspects are most evident). It can also be considered for introducing students to the uncertainty relations through diffraction of light waves. The experiments do not require expensive materials or specific laboratory instruments and employ the sensors and camera of common mobile devices. The experiments were tested with master students in mathematics and physics, who aim at becoming high school teachers.

Diffraction of light by a slit in anisotropic media with closed and open wave vector surface

Fraunhofer diffraction of an electromagnetic wave by a slit on an opaque screen located between vacuum and an anisotropic medium with closed and open wave vectors surface is considered. A formula for diffraction in a material medium is obtained, including the case of diffraction into a uniaxial anisotropic medium in the absence of absorption, and the formation of diffraction minima and maxima is studied.

Particle Sizing and Surface Area Measurements: A Comparative Assessment of Commercial Air Permeability and Laser Light Diffraction Instruments

Six different commercial powders, finer than 45 μm, were used for examining the effects of particle characteristics on mean particle size and specific surface area. The measurements were carried out using the most commonly used air permeability- and laser light diffraction (scattering) techniques. As the air permeability method has been used as a benchmark for decades in the powder metallurgy (P/M) industry, the physical phenomena that govern the passage of gas through the powder bed under laminar flow conditions were also presented. The experimental data indicate that both methods give similar results for spherical powders. The advantage of laser light systems over gas permeameters is the ability to provide additional information on particle size distribution. Irregularly shaped powders should be analyzed by both techniques, relying on gas permeametry for surface area measurements and on laser light diffraction for the estimation of mean particle size and size distribution. Application of scanning electron microscopy as a complementary technique was found very helpful in the interpretation of data through visualization of individual particles.

Production of Coal Fines in Deep Coal Seam via Morphologic, Flow-Channel, Mineral Analyses: Evidence from Coalbed Methane Wells in the Qinshui Basin.

During the development of deep coalbed methane (CBM), the production of coal fines is common and suppresses the yield of CBM. This work takes the deep CBM wells in the Qinshui Basin as a case study, and the output, composition, morphology, and sources of coal fines were investigated through scanning electron microscopy, X-ray diffraction, proximate analysis, and particle size measurement including image analysis, laser diffraction, and dynamic light scattering. The results indicate that, in comparison with shallow CBM wells, deep wells produce a greater quantity of coal fines which are darker in color and have smaller particle sizes, with the majority being less than 10 μm. The coal fines exist predominantly as aggregates that contained the iron-bearing and clay minerals. Based on the Liddinger particle settling model, the water production volume required for the coal fines to return to the surface in the Wuxiang block was calculated to be 8.55 m3/d. This work can provide a scientific basis for the prevention and control of coal fines in deep CBM wells.

Ptychographic imaging with a fiber endoscope via wavelength scanning

Ptychography has become a popular computational imaging method for microscopy in recent years. In the present work we employ a wavelength scanning ptychography technique enhanced by neural networks for imaging with a fiber endoscope. Illumination of the object at various wavelengths is achieved using a single mode fiber, while a multicore fiber collects diffracted light from a distance. Using a U-Net multilayer convolutional neural network, the diffraction pattern is recovered at the far end of the multicore fiber from the recorded intensity pattern at the proximal end. With the recovered diffraction pattern in place, the phase object can be reconstructed using the ptychography algorithm. The quality of the object reconstruction improves with the number of wavelengths used. Comparison with an end-to-end neural network highlights the effectiveness and practicality of this two-step hybrid system. This alternative and simplified ptychographic endoscopy setup delivers noticeable improvements through neural networks and wavelength scanning.

University students’ recognition of typical wave optics patterns

The recognition and distinction of typical interference and diffraction patterns are among the expected learning outcomes of studying wave optics. Previous studies have reported high school students’ difficulties with this task. In this study, we investigated university students’ ability to distinguish typical wave optics patterns obtained by the double slit, single slit, and diffraction grating. We also used eye tracking to obtain an insight into the distribution of students’ visual attention during the task. The results showed that university students had similar difficulties in recognizing wave optics patterns as high school students. They mostly struggled with identification of the double-slit interference patterns and diffraction grating patterns of monochromatic light while they were more successful in recognition of the diffraction pattern of white light on an optical grating and single-slit diffraction patterns. The eye-tracking data also revealed that students spent more time attending colourful than grey patterns in questions regarding diffraction of white light on an optical grating, thus suggesting that they were aware that the diffraction grating separates white light into colours. In questions regarding monochromatic light patterns, students overall mostly attended the single-slit diffraction pattern probably because of its distinct central maximum. Furthermore, the longer fixation duration for patterns compared to the text implies that students found it easier to extract information from the text than from the patterns. No prior research has compared the number of transitions during problem solving with the accuracy of the answers. In this study, we observed that students who incorrectly solved a task demonstrated a significantly higher number of gaze transitions between the question and the options, as well as among different options. The results of this study indicate that the recognition of typical wave optics patterns is also difficult for university students, thus suggesting that more attention should be paid to systematic observation and identification of key features of basic wave optics phenomena in lecture demonstrations and student laboratories.