Fresnel Effects Research Articles

A tutorial on the physics of light and image shading.

This paper provides an overview of the many different ways that light interacts with surfaces in the natural environment to provide useful information for visual perception. It begins with a discussion of how the concept of light has evolved over the course of human history. It then considers a wide variety of optical phenomena including Lambert's laws of illumination, the effects of microscopic surface structure on patterns of reflection, the bidirectional reflectance distribution function, the refraction of transmitted light, chromatic dispersion, thin film interference, sub-surface scattering, the Fresnel effects, indirect illumination from multiple reflections, caustics, and the structure of the light field. The primary goal of this discussion is to provide the necessary background information to help students and young researchers more easily understand the scientific literature on the perception of 3D shape and material properties from patterns of image shading.

High-efficiency continuous-wave Tm-doped fiber laser with a single fiber Bragg grating at 1942 nm

We report a continuous-wave Tm-doped fiber (TDF) laser with a single fiber Bragg grating (FBG). The Fresnel effect presenting in the passive fiber end-face and high-reflectivity FBG established the resonator. The peak wavelength of the laser was 1942.25 nm with a spectral linewidth of 194 pm. The maximum output power was 37.5 W, corresponding to a slope efficiency of 63.7% with a beam quality factor of M 2 ∼ 1.51. To the best of our knowledge, this is the highest slope efficiency of a TDF laser pumped by 793 nm laser diode.

In-orbit calibration of the pyramid coarse sun sensor using Lyapunov-based conical maneuvers of the satellite: A new framework

Due to the lightweight, inexpensive, and simplicity, coarse sun sensors (CSS) are an interesting part of the small satellites with low-earth orbit. However, the CSS drawbacks such as low accuracy and nonlinear distribution of the error contours through the sensor Field of View (FOV) apply a notable limitation in its application. This forces the literature to focus on laboratory or in-orbit calibration methods. The excellence of the in-orbit calibration in comparison with the laboratory cases is clear; however, the difficulty is to achieve enough data when the satellite is launched. To solve that, in this paper, a conical maneuver based on the Lyapunov theory is designed which causes the sunlight to cover the sensor FOV. After that, using the achieved rich data pack, the CSS calibration process, including the sensor misalignment, solar cells misalignment, and solar cells characteristic curve (Fresnel effect), is accomplished. Moreover, the results show that the combination of the new calibration methods with the iterative least square (ILS) algorithm leads to 0.89° accuracy through the FOV of 120°.

Acoustic scattering from rough elastic cylinders partially insonified by directional sonars: Effects of rms roughness and correlation length

A modal-series-based model for acoustic scattering from smooth and rough elastic cylinders insonified by directional sonars is derived. Sonar directivity, Fresnel zone effects, spherical spreading of the incident field, and axially propagating guided waves excited by this spreading are included while end-effects are assumed to be negligible. The performance of the scattering model is evaluated against laboratory monostatic and bistatic measurements of scattering from both smooth and rough elastic cylinders. Three aspects of scattering — overall scattering levels, resonance frequencies, and resonance shapes — are analyzed both theoretically and experimentally. The roughness on the cylinder has a Gaussian distribution and is characterized by a random variation of the cylinder radius along its length. Effects of various statistical properties of this one-dimensional roughness, such as different rms roughness for a given correlation length and different correlation lengths for fixed rms roughness, are investigated.

Next-generation active telescope for space astronomy

We present a design for an active telescope for space astronomy. The telescope is capable of both exoplanet work and general astronomy over wavelengths from ∼100 nm up to 5 μm. The primary mirror is 6 m in diameter, formed by 16 mirror segments that are precisely phased and supported on rigid body actuators and with segment optical surface figures fine-tuned using surface figure actuators. The active primary forms a large deformable mirror (DM) with wavefront error (WFE) correction at the entrance pupil. Thus the largest source of WFE can be removed at the source and is corrected over the entire field of view. This enables diffraction-limited performance at 400 nm and a more efficient optical system over a broader wavelength range than could be achieved by a small DM at a downstream relayed pupil. The telescope is passively cooled to below 100 K at Sun–Earth L2, enabling astronomical-background-limited observations out to 5 μm. Launched on a SpaceX Starship or alternatively National Aeronautics and Space Administration’s Space Launch System, the telescope requires minimal deployments. A 72-m-diameter starshade provides a contrast ratio better than 10 − 10 for exoplanet science. Near the visible region, with a 108% working bandwidth from 300 to 1000 nm, a working distance of 120 Mm provides a 51-mas inner working angle (IWA). This band can be moved to shorter or longer wavelengths by adjusting the starshade range from the telescope. Our first-ever thermal analysis of such a starshade shows that a temperature below 100 K can be achieved over a broad range of observing directions, permitting the possibility of working into the infrared. We model the yield in exoplanets that can be observed. A starshade and associated spectrograph offer significant advantages for exoplanet characterization. They enable a much broader instantaneous spectral bandwidth (here 108%) than current coronagraphs (∼10 % to 20% bandwidth), allow both polarizations to be observed simultaneously, and have higher throughput. The IWA is twice as small as can be achieved with a coronagraph and there is no outer working angle. These differences are particularly pronounced in the UV, where coronagraph performance would be strongly affected by throughput losses, wavefront aberrations, Fresnel polarization effects at surfaces, and thermal instability.

Effect of laser pulse energy deposition method on nanosecond laser scanning ablation of SiCp/AA2024 composites

The control of the thermal stress and heat accumulation is major issue faced in the laser precision machining, and plays a key role in the laser machining of composite materials. In this pursuit, the present study envisaged the effect of pulse energy deposition method on the processing of particulate reinforced aluminum alloy matrix composites SiCp/AA2024. Specifically, by modulating the combination of the spot overlap ratio (SOR) and the area scanning passes, a variety of pulse energy deposition methods with the same number of received pulses per unit area were designed and applied on a target. The influence of the pulse energy deposition on processing was evaluated by measuring and comparing the ablation depth and surface roughness. The results showed that by using multiple scanning passes with small spot overlap ratios led to a good processing with a high ablation depth. Furthermore, the influence of SOR and scanning passes on the machining was studied using the control variable method. The influence of energy deposition method was studied from the aspect of nanosecond laser ablation mechanism, Fresnel reflection effect and heat accumulation.

Measuring the Hubble constant with double gravitational wave sources in pulsar timing

ABSTRACT Pulsar timing arrays (PTAs) are searching for gravitational waves from supermassive black hole binaries (SMBHBs). Here we show how future PTAs could use a detection of gravitational waves from individually resolved SMBHB sources to produce a purely gravitational wave-based measurement of the Hubble constant. This is achieved by measuring two separate distances to the same source from the gravitational wave signal in the timing residual: the luminosity distance DL through frequency evolution effects, and the parallax distance Dpar through wavefront curvature (Fresnel) effects. We present a generalized timing residual model including these effects in an expanding universe. Of these two distances, Dpar is challenging to measure due to the pulsar distance wrapping problem, a degeneracy in the Earth-pulsar distance and gravitational wave source parameters that requires highly precise, sub-parsec level, pulsar distance measurements to overcome. However, in this paper we demonstrate that combining the knowledge of two SMBHB sources in the timing residual largely removes the wrapping cycle degeneracy. Two sources simultaneously calibrate the PTA by identifying the distances to the pulsars, which is useful in its own right, and allow recovery of the source luminosity and parallax distances which results in a measurement of the Hubble constant. We find that, with optimistic PTAs in the era of the Square Kilometre Array, two fortuitous SMBHB sources within a few hundred Mpc could be used to measure the Hubble constant with a relative uncertainty on the order of 10 per cent.

Freeform surface for light shaping by iterative design via Fourier domain.

We extend our previous work [Yang et al., Opt. Express29, 3621 (2021)10.1364/OE.415649] and propose an iterative algorithm to design a freeform surface for far-field light shaping. The algorithm alternately performs a wavefront phase design step and a freeform surface construction step. The smooth wavefront phase is designed by the mapping-type Fourier pair synthesis method, and the freeform surface is constructed by using the obtained wavefront phase. The algorithm provides a solid approach that ensures the introduction of the required wavefront phase manipulation for light shaping. Moreover, the related physical effects such as the Fresnel effect and polarization effect are included in the algorithm. We demonstrate the flexibility of the algorithm by examples.

Perceived roughness of glossy objects: The influence of Fresnel effects and correlated image statistics.

The roughness of a shiny surface determines how sharp the reflected image of the surroundings is, and thus whether the surface appears highly glossy or more or less matte. In a matching experiment, subjects were asked to reproduce the perceived roughness of a given surface (standard) in a comparison stimulus (match), where the standard and the match could differ in both shape and illumination. To compare the effect of the reflection model on the accuracy of the settings, this was done for two different reflectance models (bidirectional reflectance distribution function [BRDF]). The matching errors were smaller, that is, the constancy under shape and illumination changes higher, when Fresnel effects were physically correctly reproduced in the reflectance model (Fresnel-BRDF) than when this was not the case (Ward-BRDF). The subjects’ settings in the experiment can be predicted very well by two image statistics, one of which is based on the mean edge strength and the other on a local discrete cosine transform. In particular, these predictions also reflect the empirically observed advantage of the Fresnel-BRDF. These results show that the constancy of perceived roughness across context changes may depend on the BRDF used, with Fresnel effects playing a significant role. The good prediction of subjects’ settings using the two image statistics suggests that local brightness variance, which affects both image statistics, can be used as a valid cue for surface roughness.

Cu3BiS3/MXenes with Excellent Solar-Thermal Conversion for Continuous and Efficient Seawater Desalination.

Two-dimensional materials with unique physical and chemical properties have recently attracted widespread attention in the field of solar thermal conversion. However, affected by the Fresnel effect, traditional two-dimensional materials such as MXenes, graphene, transition metal disulfide often have relatively significant light reflection losses at the solid-liquid or gas interface. So how to improve the light absorption of the two-dimensional material performance has become a new challenge in photothermal conversion. Here, we use an improved thermal-injection method to uniformly grow Tricopper(I) Bismuth Sulfide (Cu3BiS3, CBS) on the surface of Ti3C2 nanosheets in a nonaqueous polar solvent environment. A three-dimensional nanoflower-nanosheet structure CBS-Ti3C2 for photothermal conversion has been constructed successfully. Owing to the excellent photothermal performance of Cu3BiS3 in the near-infrared region, the good thermal conductivity of Ti3C2, and the unique porous structure of the composite material, the composite achieves broadband absorption of light (more than 90% in the visible light region, more than 80% in the near-infrared region), which optical model and finite element simulation have theoretically verified. The composite material has obtained higher solar-to-heat conversion performance than similar material systems, and the steady-state temperature can reach 62.3 °C under 1 sun incident light intensity. CBS-Ti3C2 is expected to become a light-absorbing layer material for solar vapor generation devices due to its excellent light-to-heat conversion performance and good material flexibility. It still guarantees a reasonably high steam generation rate (1.32 kg·m-2·h-1) even with a thinner material thickness (0.48 mg·cm-2) and a comprehensive conversion efficiency higher than 90%. Besides, CBS-Ti3C2 also exhibits the characteristics of resisting surface salt accumulation, which is conducive to maintaining the long-lasting photothermal seawater evaporation process. The material's electronic structure and the charge transfer process of the heterojunction interface have been studied with the first-principles calculation. The high light absorption performance and good thermal conductivity of the composite material are theoretically explained and supported.

Efficient framework for the examination of the field of view sensitivity of a field-widened birefringent interferometer.

An efficient approach is presented that allows the field of view sensitivities of a field-widened birefringent interferometer constructed from several stacked birefringent slabs to be examined. The approach utilizes a Jones matrix framework that is valid for birefringent slabs that have their optic axis parallel to the surface of the slab. It neglects Fresnel effects and multiple reflections, but accounts for birefringent splitting and does not neglect higher-order angular effects. The simplified approach allows the angular sensitivity of the optical path difference near the field-widened configuration to be examined in the presence of misalignment and mismatches between the components. Understanding these effects is critical to developing wide-field interferometers that can be utilized for imaging purposes. Here, we present the developed framework and apply it to examine the field of view effects of a three-element field-widened static birefringent interferometer that is being developed for the measurement of upper atmospheric winds. We examine the sensitivity of the device to rotational misalignment, mismatches, and wavelength shifts. Comparisons among the modeled interference fringes, output from Zemax optical design software, and lab observations are used to validate the approach. It is also shown that the approach accurately simulates parasitic fringes associated with unwanted coupling between extraordinary and ordinary waves at the interfaces.

High contrast at small separation – II. Impact on the dark hole of a realistic optical set-up with two deformable mirrors

ABSTRACT Future large space- or ground-based telescopes will offer the resolution and sensitivity to probe the habitable zone of a large sample of nearby stars for exo-Earth imaging. To this end, such facilities are expected to be equipped with a high-contrast instrument to efficiently suppress the light from an observed star to image these close-in companions. These observatories will include features such as segmented primary mirrors, secondary mirrors, and struts, leading to diffraction effects on the star image that will limit the instrument contrast. To overcome these constraints, a promising method consists in combining coronagraphy and wavefront shaping to reduce starlight at small separations and generate a dark region within the image to enhance the exoplanet signal. We aim to study the limitations of this combination when observing short-orbit planets. Our analysis is focused on SPEED, the Nice test bed with coronagraphy, wavefront shaping with deformable mirrors (DMs), and complex telescope aperture shape to determine the main realistic parameters that limit contrast at small separations. We develop an end-to-end simulator of this bench with Fresnel propagation effects to study the impact of large phase and amplitude errors from the test-bed optical components and defects from the wavefront shaping system on the final image contrast. We numerically show that the DM finite stroke and non-functional actuators, coronagraph manufacturing errors, and near-focal-plane phase errors represent the major limitations for high-contrast imaging of exoplanets at small separations. We also show that a carefully defined optical set-up opens the path to high contrast at small separation.

Vectorial physical-optics modeling of Fourier microscopy systems in nanooptics.

Fourier microscopy, which makes direct observation of the angular distribution possible, is widely used in the nanooptics community. The theory of such systems is typically based on ideal lenses. However, the real lenses in the typical complex lens systems have an impact on the image quality in the experiment. Therefore, it is desirable to have a model of the entire system, which is capable of predicting such phenomena, in order to conduct a preliminary detailed analysis of the setup before building it in the lab. In this work, we perform a vectorial physical-optics simulation of Fourier microscopy systems, which considers the real lenses; it also includes the nanostructure (e.g., photonic crystal). The systems are used to image the emission diagram of a single molecule as well as to analyze the angular-spectral property of a photonic crystal. We analyze various effects of the entire systems, e.g., Fresnel effects of the real lens surfaces, diffraction, polarization, chromatic aberration, and the effects of misalignment. We find that the above-mentioned effects have an influence on the final results, which should be taken into account when performing similar real-life experiments.

Fresnel prism effect and chromatic aberration produced by posterior capsular folds after intraocular lens implant

We present a previously unreported positive dysphotopsia of an alternating green and red diagonal line after developing posterior capsular folds following uneventful cataract surgery and its management. A 73-year-old man presented complaining of seeing multicolored ray of light obliquely across luminous sources from his left eye 3 weeks after phacoemulsification. He was found to have 3 folds on the posterior capsule, which were perpendicular to the axis of the line of the red and green rays. This was managed with routine Nd:YAG laser posterior capsulotomy, after which his symptoms instantly resolved. To our knowledge, there is no other published report of this multifaceted visual aberration due to posterior capsular folds. Through our case, we highlight that a thorough examination can find a simple solution for a seemingly complex presenting complaint and can avoid unnecessary investigations and invasive procedures.

Investigation on femtosecond laser ablative processing of SiCp/AA2024 composites

This study presents experimental results of femtosecond laser (λ = 1030 nm, τ = 800 fs) ablation of AA2024, sintered SiC, and SiC-particulate-reinforced aluminum metal matrix (SiCp/AA2024) composites using a scanning method. The aim is to determine the mechanism of femtosecond laser ablation of SiCp/AA2024 composites by a comparative study. Scanning electron microscopy and energy-dispersive spectroscopy reveal the morphological changes in the ablated surface with increasing pulse fluence. The ablation depth and surface roughness measured by a 3D surface profiler indicate interfacial interaction between the AA2024 matrix and SiC particles. Two-temperature modeling (TTM) was applied to analyze the ablation behavior of Al and SiC. The experimental results and TTM analysis indicate that the femtosecond laser ablation of the SiCp/AA2024 composites and the interface interaction in the composites under laser irradiation are due to matrix ablation enhanced by the Fresnel effect and electromagnetic interaction (rather than thermal interaction) at the particle/matrix interface.

The influence of Fresnel effects on gloss perception.

Glossy surfaces reflect a mirror image of the environment. The perceived gloss depends (a) on the blurriness of this mirror image, which is a function of surface roughness, and (b) the strength of the mirror reflection, which, according to Fresnel's equations, is a function of the material's refractive index and the angle of the incident light. Investigations on gloss perception often used simplified reflection models, e.g., the Ward model (Ward, 1992), which do not correctly account for Fresnel effects. Here, possible perceptual consequences of this simplification are investigated in three experiments, in which the gloss impression produced by a physically more plausible reflection model (Fresnel-bidirectional reflectance distribution function [BRDF]) is compared to the gloss produced by two variants of the Ward model under identical conditions. The results show that it is, in general, not possible to match the gloss impression elicited by a Fresnel-BRDF with a Ward-BRDF. Furthermore, compared with the Ward-BRDF, the gloss impression produced with the Fresnel-BRDF under identical conditions is, in general, stronger, more vivid, and more realistic. Gloss constancy is also improved, i.e., the gloss impression depends less on the type of illumination, the presence and properties of a floor, and surface shape. These differences are especially evident with relatively homogeneous illuminations. The results of a fourth experiment, which tested gloss constancy under changes in illumination and shape with a matching task, confirm an improved gloss constancy with a Fresnel-BRDF. Together, these findings suggest that Fresnel effects are used as a cue in gloss perception.

Generating variable shapes of salt geobodies from seismic images and prior geological knowledge

We have developed an implicit method to automatically generate several possible models of salt top surfaces with varying geometries and topologies. This method can be conditioned to available data such as well markers and seismic picks. Because seismic imaging of salt is prone to velocity uncertainty and Fresnel zone effects, the input of the method is a seismic image that is segmented into three regions: salt, sediments, and uncertain. The uncertain region contains the salt boundary, and all further computations focus within this zone. A monotonic scalar field, ranging from zero on the edge of the certain salt body to one on the maximal possible salt boundary, defines the cumulated probability for a point to be outside the salt body. A random scalar field, also bounded between zero and one, is then used as a threshold for the first scalar field. The salt boundary is implicitly defined by the zero isovalue of the difference between the two fields, and it can be further extracted using marching cubes. The random field parameters have a geometric and topological impact on the simulated salt volumes. They can be adapted to reproduce specific geological features, but their inference remains difficult. The application of the method for the reconstruction of diapir boundaries from a set of partly interpreted sections indicates that it is well-suited to honor numerous constraining data while proposing different possible structural scenarios in the uninterpreted parts.

Performance Improvement of GaN-Based Light-Emitting Diodes With a Microhole Array, 45° Sidewalls, and a SiO2 Nanoparticle/Microsphere Passivation Layer

The characteristics of GaN-based light-emitting diodes (LEDs) with a hybrid structure incorporating a microhole array, 45 sidewalls, and an appropriate SiO2 nanoparticle (NP)/microsphere (MSs) passivation layer are studied and reported. The use of a SiO2 NP/MSs passivation layer causes a remarkable reduction in reverse-biased leakage current. The employment of this hybrid structure leads to substantial enhancements in optical properties without any degradation in electrical performance. In addition, a lower content of SiO2 NP in the mixed SiO2 NP/MSs solution leads to enhanced optical behavior due to the improved transmittance. Experimentally, as compared with a conventional LED (Device A), the studied Device E shows 50.6%, 50.9%, 48.4%, and 49.9% enhancements in light output power, luminous flux, luminous efficacy, and wall-plug efficiency, respectively. These advantages are mainly attributed to the increased scattering probability and the opportunity to find photon escape cones as well as the reduced total internal reflection and Fresnel reflection effects. Therefore, the studied hybrid structure provides a promise for high-performance GaN-based LED applications.

Simulation of water surface using current consumer-level graphics hardware

Water surface visualization is an important research topic in computer graphics. This paper presents a novel method of water surface simulation by Secondary Distorted Textures (SDT), which realistically simulates and visualizes the reflection and refraction of calm water in real-time using current consumer-level hardware. The proposed method renders water surface using two stages of texture maps. 1. The first texture map stores the 3D geometries’ perspective reflection with respect to 3D perspective view; 2. The second texture map stores the distortion results of the first reflection map with lighting effects. Perlin noise is used to generate random height map. Reflection and refraction are obtained and stored in the secondary distorted texture map with Fresnel effects for each frame. At rendering pass, the SDT is directly tiled on water surface. This paper also discussed the rendering of transparent geometry, which have view-dependent of lighting effects features. Experimental results demonstrated that our method can render realistic geometry nearby dynamic water surface at the frame rates of 70-100 FPS by NVIDIA Quadro k5000 graphic card. The existing texture mapping and bump mapping methods were compared for illustrating that our method produced high realistic water surface without aliasing reflection.

Scattering by multiple cylinders located on both sides of an interface

The solution for scattering by multiple parallel infinite cylinders located in adjacent half spaces with dissimilar refractive index is presented in this paper. The incident radiation is an arbitrarily polarized plane wave propagating in the upper half space in the plane perpendicular to the axis of the cylinders. The formulation of the electromagnetic field vectors utilized Hertz potentials that are expressed in terms of an expansion of cylindrical wave functions. It accounts for the near-field multiple scattering, Fresnel effect at the interface, and interaction between cylinders in both half spaces. Analytical formulas are derived for the electromagnetic field and Poynting vector in the far-field. The present solution provides the theoretical framework for deducing the solutions for scattering by cylinders located on either side of an interface irradiated by a propagating or an evanescent incident wave. Deduction of these solutions from the present formulation is demonstrated. Numerical results are presented to illustrate the frustration of total internal reflection and scattering of light beyond the critical angle by nanocylinders located in either or both half spaces.