Showing papers by "K. A. Suresh published in 1997"

The pancharatnam phase as a strictly geometric phase: A demonstration using pure projections

Abstract: We describe an interferometer based on the Pancharatnam phase in which the extra phase introduced is of purely geometric origin, with no contributions from the dynamic phase. We use a cholesteric liquid crystal film as a circular analyser, and a sheet polarizer as a linear analyser, to project each polarization state on the next one. This experiment can also be viewed as a demonstration of Berry's phase arising from quantum measurements.

Formation of Liquid Crystalline Phases from a Langmuir Monolayer

Abstract: We report the transformation of a two-dimensional monolayer at the air−water interface into three-dimensional liquid crystalline phases on continuous tuning of the surface molecular density. On compressing a 4‘-n-octyl-4-cyanobiphenyl monolayer, at room temperature, we obtain multilayer domains whose thicknesses range from a few layers to hundreds of layers. Above 28 °C, these domains undergo a phase transition and change to much thicker lenslike domains. On expansion, these domains revert to the monolayer. Although these domains originate from a monolayer, we find that they exhibit features typical of liquid crystals.

Optics of Some Chiral Liquid Crystals

Abstract: Although the optics of chiral systems like cholesterics has been studied for well over one hundred years, the subject is still very relevant in view of new and different chiral systems that have been realised in the laboratory in recent times. These systems are associated with novel optical properties and have drawn considerable attention. Here, we consider the optics of ferrocholesterics, absorbing cholesterics, chiral smectic C, absorbing and non-absorbing twist grain boundary smectics and a tapered soliton lattice. In particular, we deal with reflection, transmission and diffraction properties of these systems.

Phase Diagram of a Liquid Crystal Siloxane Polymer at Air Water Interface

Abstract: We have carried out surface manometry and epifluorescence microscopic studies on a polymeric liquid crystal, siloxane polymer of 1-methyl propyl 4 (4′-hexyloxy benzoyloxy) benzoate, n ∼ 40 at the air water interface. At room temperature, on compression, the usual liquid-expanded (LE) phase transforms to a different structure consisting of small bright domains. On further compression, these join to form striations which in turn change to a melted stripe structure. At 35°C, on compression, the LE phase changes to a new structure which appears as large irregularly shaped bright domains. On cooling, these domains change to the melted stripe structure.