„Werk:Horocycles of Light in a Ferrocell“ – Versionsunterschied
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Figure 1. Static arrangement of magnets and light pattern from a Ferrocell. Arrangement of twelve magnets with their respective isopotentials in (a) to demonstrate the applied magnetostatic field used in (b), where we have a luminous pattern obtained with a Ferrocell with the illumination of various colors in a circular arrangement. | Figure 1. Static arrangement of magnets and light pattern from a Ferrocell. Arrangement of twelve magnets with their respective isopotentials in (a) to demonstrate the applied magnetostatic field used in (b), where we have a luminous pattern obtained with a Ferrocell with the illumination of various colors in a circular arrangement. | ||
Version vom 11. März 2026, 08:26 Uhr
Über diese Seite Werk
- Condensed Matter
- DOI: 10.3390/condmat6030030
- License CC BY 4.0
- Lab: Soft Matter Lab
Soft Matter Lab, School of Arts, Sciences and Humanities, University of São Paulo, São Paulo 03828-000, Brazil; tufaile@usp.br
Space Science Center, 235 Martindale Drive, Morehead State University, Morehead, KY 40531, USA; msnyder@pic2mag.com
Correspondence: atufaile@usp.br
(PDF) Horocycles of Light in a Ferrocell. Available from: https://www.researchgate.net/publication/353803975_Horocycles_of_Light_in_a_Ferrocell [accessed Mar 11 2026].
Abstract:
We studied the effects of image formation in a device known as Ferrocell, which consists of a thin film of a ferrofluid solution between two glass plates subjected to an external magnetic field such as diffraction gratings or photonic crystals leading to scattering resonances. However, some curious phenomena can be easily observed with the Ferrocell. In this article, in the presence of a light source. Following suggestions found in the literature, we compared the we will discuss one of the concepts that most confuses some people in optics: the concept Ferrocell light scattering for some magnetic field configurations with the conical scattering of light of diffracted rays [16–19], which is present at Ferrocell that is related to directional scatby thin structures found in foams known as Plateau borders, and we discuss this type of scattering tering. The name itself brings an oxymoron: rays in optics are often found in reflections with the concept of diffracted rays from the Geometrical Theory of Diffraction. For certain magnetic and refractions, while diffraction is a characteristic seen in waves when they are deflected field configurations, a Ferrocell with a point light source creates images of circles, parabolas, and by obstacles. When faced with this phenomenon, some people may have a cognitive hyperboles. We interpret the Ferrocell images as analogous to a Möbius transformation by inversion conflict, because the concepts of wave and ray are commonly used in separate scenarios, of the magnetic field. The formation of circles through this transformation is known as horocycles, being considered only as an approximation to each other, but they cannot coexist, in the which can be observed directly in the Ferrocell plane.
Keywords: ferrofluid; magnetism; magneto-optics; hyperbolic geometry; optics
problem of diffracted rays arises when Young analyzes Huygens‘ principle
1. Introduction
We can observe a curious case of directional light scattering in a Hele-Shaw cellfilled with a ferrofluid solution known as Ferrocell as shown in Figure 1. The Ferrocell issubjected to a static external magnetic field, and for the specific case of ferrofluids, themagnetic field can alter structures formed by the agglomeration of nanoparticles that canscatter light [1–6]. In this way, we can have different conditions leading to diffraction,refraction, and reflection, for different configurations of magnetic fields, using field in-tensity and direction as control parameters, as well as cell thickness.
Systems similar to this one have been studied in the area of photonics in disorderedmedia [7,8] for solar panels, in which diffraction patterns of polymeric wires formingdifferent geometries present information on the distribution of wires. In these systems,effects such as Anderson localization are studied [9], where multiple scattering createsmodes with a high level of spatial confinement, and has been reported in optical systemswith ferrofluids. Other effects that can be explored for the case of light transport in thestructures formed by ferrofluids when subjected to an applied magnetic field are light inphotonic crystals [10,11], light polarization [12,13], and magnetic fluidic optical gratings[14,15], in which localized modes couple to transmission channels.
The understanding of light scattering in systems with ferrofluids, such as the case ofFerrocell, can lead to applications in the paint industry or new types of light sources suchas Random lasers, leading to the development of new possibilities for fundamental re-search and the engineering of new devices [8]. Which leads to the question: what is themain mechanism in the light scattering in ferrofluids? For the case of ferrofluids sub-jected to an external magnetic field interacting with light, in general, we have a classiclight scattering caused mainly by electric dipoles in the form of micro-needles that arealigned to an external magnetic field. Light scattering may be beyond disordered. Gaussian scattering due to the fact that we have structures ordered by the magnetic field,such as diffraction gratings or photonic crystals leading to scattering resonances. How-ever, some curious phenomena can be easily observed with the Ferrocell. In this article,we will discuss one of the concepts that most confuses some people in optics: the conceptof diffracted rays [16–19], which is present at Ferrocell that is related to directional scat-tering. The name itself brings an oxymoron: rays in optics are often found in reflectionsand refractions, while diffraction is a characteristic seen in waves when they are deflectedby obstacles. When faced with this phenomenon, some people may have a cognitiveconflict, because the concepts of wave and ray are commonly used in separate scenarios,being considered only as an approximation to each other, but they cannot coexist, in thesame way, as biologists who studied the platypus for the first time, were baffled by theobservation of features of birds and mammals in the same animal. Historically, theproblem of diffracted rays arises when Young analyzes Huygens‘ principle and ends upwith Joseph Keller’s Geometrical Theory of Diffraction, in which along with the conceptof a ray of geometrical optics, we have the concept of diffracted ray governed by rulesanalogous to those of reflection and refraction, in order to determine the resultant fields.This theory was later extended as the Uniform Theory of Diffraction [20,21], as a methodfor solving scattering problems for small discontinuities. This is a classic differential lightscattering problem, in which different components of electrical and magnetic moments oflight interacting with a material create anisotropic effects in the direction of the scatteredlight. The analysis of these effects is made by comparing some characteristic factors of thesystem with the wavelength of light, such as material properties and the scale of thescatterers. In some cases of scattering using Keller’s theory, light is considered to sliparound obstacles.
Figure 1. Static arrangement of magnets and light pattern from a Ferrocell. Arrangement of twelve magnets with their respective isopotentials in (a) to demonstrate the applied magnetostatic field used in (b), where we have a luminous pattern obtained with a Ferrocell with the illumination of various colors in a circular arrangement.