Moiré patterns and carbon nanotube sorting

Moiré patterns (MPs), arising from the superposition of two lattices with close periods, are tightly related to the physicochemical properties of bilayer nanostructures. Here, we develop the theory of complex MPs emerging in twisted bilayer graphene and planar nets of double-walled nanotubes at significant relative twist and/or deformation of layers. The proposed theory clarifies the physicochemical regularities arising at sorting of single-walled carbon nanotubes (SWCNTs) by organic molecules, which self-assemble in regular coatings on both the tubes and planar graphene. We introduce and consider an outer tubular virtual lattice that is a parent structure for the deposited coating and due to this fact, its existence is crucial for the coating formation. As we show, such outer lattices exist only for successfully sorted SWCNTs and the superposition between the outer lattice and SWCNT forms a specific long-period MP. We explain known experimental results of SWCNT sorting by molecules of flavin group, poly(9,9-dioctylfluorene-2,7-diyl) (PFO), and poly [(m-phenylenevinylene)-alt-(p-phenylenevinylene)] (PmPV). Also, our approach points out other organic molecules and polymers suitable for effective CNT sorting.

Directional Moiré Boosting Using Spatial Filtering

Overlapping of two or more grating structures of small frequency differences gives rise to the Moiré patterns. While the overall moiré patterns are widely studied, in many cases – specially in case of a zonal fringe analysis – zone or direction based highlighting or suppression of moiré patterns are very helpful. This paper presents a simple method for directional boosting of moiré patterns, generated using Spatial Light Modulator (SLM) based interferometric setup, using the spatial filtering technique. Keywords: Moiré, Spatial Filter, Directional Boosting, Interferometry, Spatial Light Modulator, Optics

Controlling the Shapes of the Moiré Patterns Generated Using the Interferometry and a Spatial Light Modulator

Moiré patterns are generated by the superposition of two periodic patterns of close frequencies. This present paper proposes a simple method to bridge the conventional gap between interferometry and moiré patterns by generating moiré patterns using straight-line interference fringes from a Michelson interferometer like setup and a circular grating pattern generated on a Spatial Light Modulator (SLM). The visible variation in the geometrical shapes of the moiré patterns by varying the ratio of the periods of the two periodic patterns has also been presented. The experimental results match with the simulation results. Keywords: Moiré, Interferometry, Spatial Light Modulator, Optics, Engineering physics

Scintillating Starbursts: Concentric Star Polygons Induce Illusory Ray Patterns

Here, we introduce and explore Scintillating Starbursts, a stimulus type made up of concentric star polygons that induce illusory scintillating rays or beams. We test experimentally which factors, such as contrast and number of vertices, modulate how observers experience this stimulus class. We explain how the illusion arises from the interplay of known visual processes, specifically central versus peripheral vision, and interpret the phenomenology evoked by these patterns. We discuss how Starbursts differ from similar and related visual illusions such as illusory contours, grid illusions such as the pincushion grid illusion as well as moiré patterns.