Horocycles of Light in a Ferrocell

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 in the presence of a light source. Following suggestions found in the literature, we compared the Ferrocell light scattering for some magnetic field configurations with the conical scattering of light by thin structures found in foams known as Plateau borders, and we discuss this type of scattering with the concept of diffracted rays from the Geometrical Theory of Diffraction. For certain magnetic field configurations, a Ferrocell with a point light source creates images of circles, parabolas, and hyperboles. We interpret the Ferrocell images as analogous to a Möbius transformation by inversion of the magnetic field. The formation of circles through this transformation is known as horocycles, which can be observed directly in the Ferrocell plane.

Exploring the Polarization of Light in Ferrofluids with Mueller Matrices

“…Now let usrelate how the light at each point of the polarization pattern is related to its respective Stokes vector for the case of a dipole magnetic field applied to the plane where the thin film of ferrofluid is located in Figure 3. As discussed in our previous works [1,14], ferrofluid particles are oriented by the applied magnetic field, as if forming the field lines of Figure 3a. For the case of a system with a linear polarizer and linear analyzer, we have determined that the orientation of the polarization is perpendicular to these field lines.…”

“…This includes material characterization [7,8] used to characterize chiral films that have been processed from bacterial cellulose. The matrix calculus is also used in optical device development [9], such as in polarimetric imaging analysis of optical components for the generation of cylindrical vector beams, and in astrophysics [10], where the polarization state of the radiation provides much more astrophysical information than just the light intensity; it is also used in remote sensing [11] as a tool to enhance the information available in a variety of remote sensing applications, as well as in astrobiology [12], in the study of entopic phenomenon [13], to elucidate the perception of Haidinger brushes and horocycles of light [14], which shows some of the connections between topology and optics. Mueller matrices are also used in many other areas [15].…”

Complex Functions, Multipoles and Light Polarization in a Ferrocell

“…Our experimental system is based on a system with two crossed polarizers, with the ferrofluid film between them [6]. When the magnetic field is applied to the ferrofluid, we can observe the formation of light patterns.…”

“…With the device known as a Ferrocell [2], we can observe certain light patterns when the ferrofluid in this device reacts to light in the presence of a magnetic field generated by a magnet, as shown in Figure 1. The main concept here is magneto-optics, which is the use of magnetism to influence light propagation [3][4][5][6][7].…”

Finding the Right Angles of a Ferrocell

“…Upon application of an external magnetic field, the nanoparticles between the two pieces of glass self-organize into needle-like filaments which are in the order of 100 µ m in length [5]. These micro-needles then align with the magnetic field to minimize dipolar interactions as seen under the microscope in Figure 1.…”