Shape-shifting magnetic mirrors could clear the skies for astronomers

London, Nov 8 : Scientists have developed a morphing mirror that can be reshaped using magnets, and would help clear the blurry image of celestial objects seen by astronomers using mirrors in ground-based telescopes.

According to a report in New Scientist, the new shape-shifting mirror, developed at Laval University in Quebec, is made from a magnetic liquid - a ferrofluid - that can be easily reshaped using magnetic fields.

Ground-based telescopes currently use flexible mirrors with complex actuators underneath to correct for atmospheric distortion and keep a steady focus.

They can even match the resolution of the Hubble Space Telescope.

But, the technology is expensive, and has a limited range of motion. Liquid mirrors are cheaper, and should be able to make larger corrections.

Making mirrors from ferrofluids is not simple, as they are not usually reflective; and the normally oily liquid base can only with difficulty be coated with a reflective top layer of silver nanoparticles.

Water-based ferrofluids hold the reflective layer more effectively, but water evaporates so quickly that the mirror could disappear within hours.

Now, Laval University chemist Anna Ritcey and colleagues have cracked those problems by suspending magnetic iron particles in ethylene glycol, the basis of automotive antifreeze.

It can support a reflective film of silver nanoparticles and has negligible evaporation, creating an optical-quality surface that remains stable for more than 70 days, in part thanks to a new coating added to stabilise the iron particles.

Ferrofluid mirrors also have the advantage of not being limited to lying flat.

The first telescope with a bowl of spinning mercury for a mirror will start working next year, but can only look straight up.

However, with the right mix of magnetic fields, a ferrofluid mirror could even be held upside down if necessary.

Mirrors able to change shape on command could also see uses elsewhere - such as in diagnosing eye disease.

A ferrofluid lens could be rapidly adjusted as necessary to compensate for the large distortions in diseased eyes during eye exams or treatment, Ritcey told New Scientist.

According to Ritcey, another major application could be in testing optics with aspheric surfaces, which are widely used in inexpensive cameras, and optical disk players because of their low cost and high performance.

ANI