Nanoengineered parabolic liquid mirrors

Abstract

We give a progress report on an application of a new class of versatile optical elements pioneered by our laboratory: By coating liquids we create reflective surfaces that can be shaped by rotation into a parabolic mirror. Coated ferrofluids can also be shaped with magnetic fields.Low cost is what makes rotating mercury LM Telescopes interesting. However, they are limited by the fact that they cannot be tilted. We are now working on a new generation of LMs that can be tilted. The goal is to produce large inexpensive LMTs that can be tilted by at least twenty degrees. Early work demonstrated a tilted LM that used a high viscosity liquid. An extrapolation law, confirmed by our experiments, shows that it should be possible to tilt LMs by twenty degrees, assuming a liquid having a few times the viscosity of glycerin. Rotating nanoengineered LMTs are interesting even without tilting, since their lower weight would make then less costly than Hg mirrors and high viscosity makes them less sensitive to winds.We have made two major recent technological breakthroughs: We have made a robotic machine which is capable of producing the large quantities of coating material required for large mirrors. We have also developed a technique that allows us to coat the appropriate class of liquids by simply spraying the nanoengineered coating on them. In this contribution, we present optical tests of our liquids as well as optical shop tests of rotating mirrors.

On the Photometric Variability of Very Sharp-lined Cool mCP Stars

“…data for this group of stars, as is seen in the figures. This provides further support for the idea (e.g., Borra et al 1985) that magnetic braking is the primary cause of the slow rotation periods of the cool mCP stars and that most, if not all, of this process must occur in the pre-main sequence stages of these stars, since their longer periods would require a much more efficient braking mechanism than could occur during the main sequence stage (e.g., see Glagolevskij 2003).…”

Magnetically Deformable Liquid Mirrors from Surface Films of Silver Nanoparticles

“…The majority of commercial ferrofluids, however, are oil-based and therefore do not exhibit the high surface energies required for the facile spreading of the nanoparticles as a surface film. [15,32,33] Aqueous ferrofluids are known [34][35][36] but are not suitable for the preparation of stable magnetic mirrors because of the relatively rapid evaporation of water. In order to meet, simultaneously, the criteria of low vapour pressure and high surface tension, we have identified ethylene glycol as an appropriate carrier liquid.…”

Ethylene Glycol Based Ferrofluid for the Fabrication of Magnetically Deformable Liquid Mirrors

“…Highly reflective surface films of silver nanoparticles can be spread on water, ethylene glycol, and several other hydrophilic liquids . The majority of commercial ferrofluids, however, are oil based and therefore do not have sufficiently high surface energies to permit the facile spreading of surface films.…”