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.