Scientists at NUI Galway are developing technologies which mimic the human eye for use in large space telescopes.
This optics research activity is being carried out under a contract awarded by the European Space Agency (ESA ) for €1 million, under the title ‘Active Optics Correction Chain for Large Monolithic Mirrors’, and it is funded by the ESA Technology Research Programme.
The Principal Investigator on the project is Dr Nicholas Devaney of the School of Physics at NUI Galway. He has many years of experience developing adaptive optics systems for different applications, including astronomy, imaging of the human retina, and microscopy.
Over the next four years, Dr Devaney and his colleague, Dr Alexander Goncharov, will design and build a functioning ‘active optics’ system suitable for application to space telescopes. Part of the work will be subcontracted to the prestigious Fraunhofer Institute for Applied Optics in Germany.
According to Dr Devaney: “Active optics might be a solution to the problem of image blurring associated with large telescopes deployed in space. With active optics, the optical elements are adjusted until a sharp image is obtained. This is similar to the way in which our eyes are capable of focusing on both distant objects and objects that are close to us, by adjusting the shape of the lenses in our eyes.”
The researchers believe that even more precise control can be obtained using specialised sensors, called ‘wavefront sensors’.
These are specially designed to measure the deviation of the light waves from their ideal shape, while a ‘deformable mirror’ can be used to correct the light. The team will develop a device which they hope can be a prototype for integration into future, large space telescopes.
The blurring in imagery in large space telescopes is caused by the use of ultra-thin mirrors which are inherently ‘floppy’.
Engineers have developed these thin mirrors to reduce the weight of the telescope, and therefore the cost of launching them into space.
Space telescopes can provide exquisite images of the cosmos, with a new generation of even larger telescopes coming on stream in the coming years. These will carry on the work of the likes of the Hubble Space Telescope, which was launched in 1990. The Herschel space observatory, launched in 2009 by the European Space Agency, had a telescope diameter of 3.5m. The James Webb Space Telescope will be launched by NASA in 2018, and it will have a diameter of 6.5m, almost three times larger than the Hubble Space Telescope.
The European Space Agency is currently exploring enabling technologies for large optical systems in space, for observation of the universe or for observing the Earth itself.
“Active optics has not yet been used in space, and it is necessary to develop it for future space telescopes,” explains Dr Devaney. “This technology has already been developed for telescopes on the ground.
In fact many Earth-based telescopes have systems called ‘adaptive optics’ which even correct for blur caused by atmospheric turbulence.”