Light Interference Pattern Research Articles

Comparison of visual improvement based on the Potential Visual Test "Retinometry" in patients with Posterior Capsular Opacity Fibrotic and Regenerative types before and after Nd YAG Laser Capsulotomy

Background: Posterior Capsular Opacity (PCO) can disrupt a patient's vision and is a prevalent challenge medical professionals face in restoring visual clarity after cataract surgery. Various evaluation methods can be employed to measure visual improvement and the efficacy of Nd: YAG Laser Capsulotomy. One such method is Retinometry, which harnesses interference patterns of light on the retina as light passes through the pupil to provide patients with relevant information regarding the potential outcomes of Nd: YAG Laser Capsulotomy. This study aims to review the efficacy of the potential vision test "Retinometry" in patients with posterior capsular opacity before and after Nd: YAG Laser Capsulotomy. Methods: Literature searching was conducted using six online databases (PubMed, Scopus, Science Direct, Clinical Key, and Google Scholar). Search terms included a combination of main keywords: "Retinometer", "Posterior Capsulotomy", "Nd: YAG laser", and "Visual Acuity". Results: A total of 5 articles were included in this review. It’s found that the retinometer visual potential test has a function in evaluating the effects that occur and visual function after Nd: YAG laser capsulotomy. Due to the increasing incidence of cataract surgery, the rise of IOL placement will increase the risk of PCO formation and the need for Nd: YAG capsulotomy. Conclusion: Posterior Capsular Opacity (PCO) management remains a significant concern in patients post-cataract surgery, given its potential to disrupt visual acuity. Neodymium-doped Yttrium Aluminum Garnet (Nd: YAG) laser capsulotomy is a practical approach for addressing PCO-related visual impairment. Still, its impact on visual improvement may be modest, especially regarding refractive measurements. The type of lens used does not significantly influence the procedure outcomes. As the incidence of cataract surgery continues to rise, the prevalence of PCO and the need for Nd: YAG capsulotomy are likely to increase.

Using a Diffraction Grid to Measure the Wavelength of a POF Laser

The research has been carried out to determine the wavelength of the POF laser using a diffraction grating. The diffraction grating used consists of three kinds of grid constants, namely 100 lines/mm, 300 lines/mm, and 600 lines/mm. Furthermore, the variation of the distance between the grid and the screen with a length of 40 cm, 60 cm, and 90 cm is carried out. The results showed that the wavelength of the POF laser light was between 664.07 nm-728.31 nm and the red monochromatic light source obtained the interference pattern of light on the screen as well as red monochromatic light. Based on the results of the research, it can be proven that the wavelength obtained from the use of a diffraction grating to measure the wavelength of the red laser is close to the wavelength value of 664.07 nm.

Young’s Electron Experiment Enigma

This paper focuses on a long-standing problem in physics that originated more than two centuries ago. In 1802 Young noticed numerous bright and dark bands formed behind a metal sheet containing a pair of slits, when it was illuminated by candlelight. Advances in understanding the nature of light, the bands could be understood as “light interference patterns.” Nevertheless, in the mid-20th century, another paradox arose when individual electrons fell upon the double slit configuration. It was not clear how individual electrons could create the same banded patterns. Yet the new quantum physics theory was at the peak of physics’ popularity. As a result, a special moniker was created that allowed such idiosyncrasies: “wave-particle duality.” Under its banner, waves could act as particles and vice-versa. This behavior failed “locality,” essentially meaning local reality or relativity, as each electron, considered as an indivisible particle, could not then pass through both slits simultaneously. This paper offers a modern Quantum Field Theory (QFT) approach showing how modern Quantum Field Theory can resolve this electron enigma.

The Physics Classroom in an Online 3D Virtual World: A Thai High School Teacher Needs Analysis

The study set out to examine the actual and desired needs of Thai high school physics teachers in the 2021 academic year from a sample of 44 teachers in Thailand’s northeastern Surin Province. Also, assessment was undertaken concerning each teacher’s ‘order of needs’ from the 41 items presented for evaluation to the teachers. Moreover, there were three main categories in the study’s assessments. These were the teachers’ opinions on the use of 3-dimension virtual learning (3DVL) teaching media in physics for, 1) a mechanics laboratory, 2) an electromagnetism laboratory, 3) and a wave, sound, and light laboratory. The questionnaire was examined by five experts with a confidence value of 0.97. The data were analyzed using descriptive statistics including the mean and standard deviation. Moreover, a modified version of the priority needs index (PNIModified) was used to assess the ‘order of needs’ of each teacher in teaching a 3DVL. The results of the study revealed that physics teachers believed that the overall readiness in teaching and learning management of the three groups of physics laboratories were at a moderate level. The teachers also felt that the need for computer-assisted teaching materials and 3DVL science and physics laboratories for high school students was at a high level in all three categories. Concerning each teacher’s ‘order of needs,’ it was determined that the top five teaching needs were for the spectral studies of hot gases (1), followed by teaching parallax (2), the need to teach light interference patterns (3), the polarization of light (4) and then light diffraction and diffraction grating (5).

Computing Shor’s algorithmic steps with interference patterns of classical light

When considered as orthogonal bases in distinct vector spaces, the unit vectors of polarization directions and the Laguerre–Gaussian modes of polarization amplitude are inseparable, constituting a so-called classical entangled light beam. Equating this classical entanglement to quantum entanglement necessary for computing purpose, we show that the parallelism featured in Shor’s factoring algorithm is equivalent to the concurrent light-path propagation of an entangled beam or pulse train. A gedanken experiment is proposed for executing the key algorithmic steps of modular exponentiation and Fourier transform on a target integer N using only classical manipulations on the amplitudes and polarization directions. The multiplicative order associated with the sought-after integer factors is identified through a four-hole diffraction interference from sources obtained from the entangled beam profile. The unique mapping from the fringe patterns to the computed order is demonstrated through simulations for the case N=15.

Recording of dynamic and permanent gratings in composite LC cells containing gold nano-island films

The nonlinear optical properties of composite liquid crystal (LC) cells containing gold nano-island film (AuNIF) deposited on one of the cell substrates are studied with the help of dynamic holographic techniques. A dynamic phase grating of a photoinduced change in the refractive index arises in a composite LC cell when the two-wave mixing of laser beams of a cw Nd:YAG laser is used. The nonlinear optical response is caused due to a surface-induced photorefractive effect observed under the simultaneous action of a periodic light interference pattern and a constant voltage. The result of this impact is appearance of an internal electric field (Eint) at the AuNIF-LC interface. This electric field defines the local reorientation of LC molecules. Our experimental studies prove that the Eint value can be controlled by the size and shape of Au nanoparticles in AuNIF. As a result, we obtained a record of either fast dynamic gratings or quasi-stationary gratings in the composite LC cells depending on the morphology of AuNIF.

Biolayer interferometry for DNA-protein interactions.

Biolayer interferometry (BLI) is a widely utilized technique for determining macromolecular interaction dynamics in real time. Using changes in the interference pattern of white light reflected off a biosensor tip, BLI can determine binding parameters for protein-protein (e.g., antibody-substrate kinetics) or protein-small molecule (e.g., drug discovery) interactions. However, a less-appreciated application for BLI analysis is DNA-protein interactions. DNA-binding proteins play an immense role in cellular biology, controlling critical processes including transcription, DNA replication, and DNA repair. Understanding how proteins interact with DNA often provides important insight into their biological function, and novel technologies to assay DNA-protein interactions are of broad interest. Currently, a detailed protocol utilizing BLI for DNA-protein interactions is lacking. In the following protocol, we describe the use of BLI and biotinylated-DNA probes to determine the binding kinetics of a transcription factor to a specific DNA sequence. The experimental steps include the generation of biotinylated-DNA probes, the execution of the BLI experiment, and data analysis by scientific graphing and statistical software (e.g., GraphPad Prism). Although the example experiment used throughout this protocol involves a prokaryotic transcription factor, this technique can be easily translated to any DNA-binding protein. Pitfalls and potential solutions for investigating DNA-binding proteins by BLI are also presented.

Multi-Wavelength Optical Patterning for Multiscale Materials Design

Laser interferometry is a consolidated technique for materials structuring, enabling single step and large area patterning. Here we report the investigation of the morphological modification encoded on a thin film of a photosensitive material by the light interference pattern obtained from a laser operating in multiline mode. Four lines with equal intensity are retained, with the same p linear polarization. An azopolymer is exploited as medium for the holographic recording. Optical microscopy and profilometer measurements analyze the modification induced in the bulk and on the surface of the irradiated area. We show that the intensity profile of the interference patterns of two laser beams is the one obtained assuming each line of the laser as an independent oscillator of given intensity and wavelength, and how these light structures are faithfully replicated in the material bulk and on the topography of the free surface. Patterns at different length scales are achievable in a single step, that can be traced back to both interference fringes and wave envelopes. The proposed multi-wavelength holographic patterning provides a simple tool to generate complex light structures, able to perform multiscale modifications of photoresponsive materials

Student recognition of interference and diffraction patterns: An eye-tracking study

Previous studies have demonstrated that students have difficulties in applying the wave model of light to explain single-slit diffraction and double-slit interference patterns. In this study, we investigated if students could recognize typical interference and diffraction patterns at all. Eye movements of high-school students were measured while they were identifying patterns produced by monochromatic light on a double slit, single slit, and diffraction grating, and by white light on a diffraction grating. Most students had difficulties with recognizing double-slit interference pattern and diffraction grating pattern of monochromatic light. Identification of the single-slit diffraction pattern was easier probably due to its distinguishable central maximum. The easiest task for students was recognizing the diffraction pattern of white light on an optical grating. Eye-tracking data suggested that even students who incorrectly answered this question were aware that the diffraction grating separates white light into colors. Additionally, eye tracking revealed that students who identified patterns correctly attended more the correct pattern than other options, thus corroborating previous findings. Overall, the results indicate that the recognition of interference and diffraction patterns is quite demanding for students, suggesting that more attention should be paid to observing and understanding basic wave optics phenomena.

Mid-infrared microfiber Bragg gratings.

We report mid-infrared (mid-IR) Bragg gratings fabricated on sub-wavelength-diameter chalcogenide glass (ChG) microfibers. ChG microfibers with diameters around 3 µm are tapered drawn from As2S3 glass fibers, and the mid-IR microfiber Bragg gratings (mFBGs) are inscribed on microfibers using interference patterns of near bandgap light at a 532 nm wavelength. At a wavelength of about 4.5 µm, the mFBG has an extinction ratio of 15 dB and a positive photo-induced refractive index change of 2×10-2. The dependence of the grating formation on accumulated influence of exposure power density and time is investigated. The mid-IR mFBGs demonstrated here may be used as building blocks for micro-photonic circuits or devices in the mid-IR spectral range.

Acousto-optic imaging using focused and plane wave ultrasound pulses

Acousto-optic imaging exploits the effects of modulation of light by acoustic waves propagating in an optically scattering medium to determine its optical properties. The imaging resolution is determined by the acoustic pressure field distribution inside the sample. In the ideal case, this distribution should be limited to a relatively small, strictly defined volume within which the light modulation occurs. Practical applications of this technique impose specific requirements on transducers configuration which constitute additional limitations on shaping the acoustic pressure field characteristics. We investigate the possibilities of improving performance of an acousto-optic imaging system utilizing a linear ultrasound array by comparing results obtained using plane wave and focused pulses and different apodization patterns. Acoustic pressure field distributions were determined numerically and with hydrophone measurements. We introduce an ultrasound focus quality coefficient in order to describe and compare the confinement of the expected light modulation volume. Acousto-optic images were obtained experimentally by measuring contrast decrease of the interference patterns of a laser light transmitted through samples and recorded by a camera. The results show that for focused pulses the off-focal pressure field components have significant influence on the determined values, and that this issue can be mitigated by using plane wave imaging.

An Adaptive Reference Scheme to Extend the Functional Range of Optical Backscatter Reflectometry in Extreme Environments

Optical frequency domain reflectometry (OFDR) measurements are performed by recording the interference pattern of light backscattered by density fluctuations or Bragg gratings along the length of an optical fiber. Changes in local temperature or strain in the fiber cause shifts in the backscattered light spectrum, which can be calibrated to the applied temperature or strain. Comparing the backscattered optical spectra from each reflection site with a reference (unstrained) spectrum allows for quantification of local spectral shifts. While mature OFDR-based technologies can provide high-precision spatially distributed measurements over kilometer lengths, the post-processing approaches used to recover spectral shifts from raw optical intensity data can limit the use of OFDR in harsh environments. This paper presents a novel approach to post-processing OFDR data which extends the usability of optical fibers exposed to harsh environments. This approach is the first to use the spectral shift quality, calculated for two OFDR measurements, to identify an appropriate reference scan from which the spectral shift can be determined. Three experimental data sets are used to test the algorithm: (1) an optical fiber heated to >950°C, (2) an aluminum-embedded optical fiber under strain from differential thermal expansion, and (3) an optical fiber exposed to a total neutron flux of $2\times 10^{13}$ n/cm2/s over 40 hours in a nuclear test reactor. Results show that using a metric of quality to select an appropriate reference measurement extends the functional range of OFDR strain and temperature sensors. Furthermore, this algorithm can be applied to existing OFDR data.

Light interference pattern measurements from automated low-cost Young’s double-slit experiments

Light interference pattern measurements from automated low-cost Young’s double-slit experiments

Bio-Layer Interferometry Analysis of the Target Binding Activity of CRISPR-Cas Effector Complexes.

CRISPR-Cas systems employ ribonucleoprotein complexes to identify nucleic acid targets with complementarity to bound CRISPR RNAs. Analyses of the high diversification of these effector complexes suggest that they can exhibit a wide spectrum of target requirements and binding affinities. Therefore, streamlined analysis techniques to study the interactions between nucleic acids and proteins are necessary to facilitate the characterization and comparison of CRISPR-Cas effector activities. Bio-layer Interferometry (BLI) is a technique that measures the interference pattern of white light that is reflected from a layer of biomolecules immobilized on the surface of a sensor tip (bio-layers) in real time and in solution. As streptavidin-coated sensors and biotinylated oligonucleotides are commercially available, this method enables straightforward measurements of the interaction of CRISPR-Cas complexes with different targets in a qualitative and quantitative fashion. Here, we present a general method to carry out binding assays with the Type I-Fv complex from Shewanella putrefaciens and the Type I-F complex from Shewanella baltica as model effectors. We report target specificities, dissociation constants and interactions with the Anti-CRISPR protein AcrF7 to highlight possible applications of this technique.

Dual-axis optical spatial heterodyning angle measurements using CMOS sensor color crosstalk

A simple, yet precise, optical angle measurement device was developed by analyzing the light interference pattern from a modified Lloyd’s mirror interferometer combined with a CMOS camera sensor. The resulting spatially heterodyned signal was very sensitive to small angle changes from an incident low-power laser beam, with an accuracy better than 8.9 arcsec over a range of 1.47 degrees. Measurement dead zones, estimated to have an angular span of ± 0.96 arcmin, occurred in the middle of the device’s measurement range at a critical angle where the pitches of the light interference pattern and the CMOS sensor array were equal. Also, a proof-of-concept test successfully demonstrated the use of this device for dual-axis angle measurements using a single CMOS sensor.

Light interference pattern measurements from automated low-cost Young’s double-slit experiments

Young’s double-slit experiment is commonly used in undergraduate physics laboratory to show the wave nature of light. As an alternative to expensive commercial kits, here we present an automated, low–cost light intensity measurement setup that allows real-time visualization of the interference pattern. The light intensity is measured by a light dependent resistor placed on the head of a dot matrix printer. The head motion is controlled by an Arduino which also collects the data and send them to a computer. The interference pattern obtained by the setup is in agreement with a model that includes the degree of the coherence of the light source and the effective size related to the light collecting area of the resistor. The apparatus allows quantitative data analysis from the measured light patterns and is suitable to be used in undergraduate physics laboratories.

Magnetic motion of biogenic guanine crystal plate combined with Fe2O3 nanoparticles

To reduce the magnetic field amplitude required to orient guanine crystal plates, we have attached magnetic nanoparticles to these guanine crystal plates. Fe2O3 nanoparticles are mixed with the guanine crystal plates, which are dispersed in water. Observation by optical microscopy confirmed that the large particles, which are nanoparticle aggregates, attach preferentially to the side edges of the guanine crystal plates. The individual crystal plate surfaces show clear, undisturbed light interference patterns, which mean that each plate’s optical properties have been maintained. The magnetic orientation experiments of these guanine crystal plates with different numbers of optically observed particles are conducted under both in-plane and vertical magnetic fields. The positions of the attached particles do not change, even when the magnetic field is applied. In these experiment, it was difficult to align the crystal direction with the magnetic field direction because the magnetic orientation characteristics are strongly affected by the positions and numbers of the attached particles. However, in-plane rotation and an increased tilt angle are achieved for the guanine crystal plates using magnetic fields of several millitesla.

Penentuan Indeks Bias Kaca Berdasarkan Pola Interferensi Cahaya Laser Terhambur Menggunakan Cermin Datar “Berdebu”

Experiment on Interference Pattern of Laser Light Scattered Analysis using a "Dusty" Plane Mirror aims to determine the glass refractive index value. The dust samples used in this experiment are baby powder, chalk, rice flour, wood powder and beauty powder. The dust samples sprinkled over a clean mirror, so it will produce an interference pattern that can be seen on the screen. The results of the interference pattern are circular because the screen is perforated with a diameter of 0.01 m. Dust particle sample variation only affects the brightness level of interference patterns. Analysis of interference patterns using red laser pointers or green laser pointers will get the brightest interference patterns when using baby powder compared to other dust samples. Based on the resulting interference pattern, the refractive index value of the glass using a red laser pointer is 1.62 ± 0.04 and the weighted average value of the glass refractive index is 1.68 ± 0.02, whereas the refractive index value of glass using a green laser pointer is 1.74 ± 0.07 and the weighted average value of the refractive index of the glass is 1.79 ± 0.02

Interference effects in quantum-optical coherence tomography using spectrally engineered photon pairs

Optical-coherence tomography (OCT) is a technique that employs light in order to measure the internal structure of semitransparent, e.g. biological, samples. It is based on the interference pattern of low-coherence light. Quantum-OCT (QOCT), instead, employs the correlation properties of entangled photon pairs, for example, generated by the process of spontaneous parametric downconversion (SPDC). The usual QOCT scheme uses photon pairs characterised by a joint-spectral amplitude with strict spectral anti-correlations. It has been shown that, in contrast with its classical counterpart, QOCT provides resolution enhancement and dispersion cancellation. In this paper, we revisit the theory of QOCT and extend the theoretical model so as to include photon pairs with arbitrary spectral correlations. We present experimental results that complement the theory and explain the physical underpinnings appearing in the interference pattern. In our experiment, we utilize a pump for the SPDC process ranging from continuous wave to pulsed in the femtosecond regime, and show that cross-correlation interference effects appearing for each pair of layers may be directly suppressed for a sufficiently large pump bandwidth. Our results provide insights and strategies that could guide practical implementations of QOCT.

When topological derivatives met regularized Gauss-Newton iterations in holographic 3D imaging

We propose an automatic algorithm for 3D inverse electromagnetic scattering based on the combination of topological derivatives and regularized Gauss-Newton iterations. The algorithm is adapted to decoding digital holograms. A hologram is a two-dimensional light interference pattern that encodes information about three-dimensional shapes and their optical properties. The formation of the hologram is modeled using Maxwell theory for light scattering by particles. We then seek shapes optimizing error functionals which measure the deviation from the recorded holograms. Their topological derivatives provide initial guesses of the objects. Next, we correct these predictions by regularized Gauss-Newton techniques devised to solve the inverse holography problem. In contrast to standard Gauss-Newton methods, in our implementation the number of objects can be automatically updated during the iterative procedure by new topological derivative computations. We show that the combined use of topological derivative based optimization and iteratively regularized Gauss-Newton methods produces fast and accurate descriptions of the geometry of objects formed by multiple components with nanoscale resolution, even for a small number of detectors and non convex components aligned in the incidence direction.