Liquid mirror shows promise for adaptive optics Jul 24, 2008 3
comments Researchers in Canada have built the first deformable
liquid mirror from a magnetic liquid or “ferrofluid”, which
could someday be used to compensate for distortion in the images
of telescopes and other optical devices. Liquid mirrors are
nothing new. The Large Zenith Telescope in Canada, for example,
has a 6 m-diameter mirror that is a rotating dish filled with
mercury. As the mercury spins around, its profile forms a
perfect parabola. While such mirrors can be made large and
essentially defect-free, they do have two important limitations:
they can only point straight up; and the shape of the mirror
cannot be adjusted dynamically. Dynamic adjustment is important
because astronomers are keen on using adaptive optics systems
that change the shape of the mirror to correct for aberration
caused by the atmosphere. In 1994 researchers came up with an
idea whereby magnetic coils change the shape of a mercury mirror
containing an electric curren