Looking Into Space Is Good For The Eye

The Lund Telescope Group works on the mechanical and optical design of next-generation astronomical telescopes. Today´s astronomers need ever more powerful optical telescopes, with ever-increasing resolution, in order to study stars and stellar systems, with the emphasis on our own galaxy the Milky Way.

One area of particular interest today is the investigation of planetary system formation. The goal is to image and in-vestigate the characteristics of planets of similar size to the Earth. However, this requires very high resolution, as planetary systems are formed out of spinning discs of material in which planets are extremely hard to resolve, using today´s techniques.

The presence of such planets is mainly detected through indirect measurement of the 'wobble´ of the star as the planet orbits, and the reduction of light emission from the star as the planet transits it.

A hot topic

Astronomers are also very keen to look out to extremely distant galaxies to investigate how the very first galaxies were formed. With a high-resolution optical telescope, the process of galaxy formation could be more accurately investigated by imaging through time (from distant to near).

"The formation of galaxies and plane-tary systems are two very hot topics for astronomy and astrophysics," says Professor Arne Ardeberg of the Lund Observatory. "But we have come about as far as we can with today´s telescopes. The kind of resolution astronomers are looking for requires optical telescopes with extremely large mirrors."

Today´s state-of-the-art optical telescopes have primary mirrors of between eight and ten metres in diameter. The sorts of studies that astronomers want to carry out on stellar systems demand telescopes with mirrors several times this size. While optical polishing techniques have advanced sufficiently to produce mirrors of this size, handling them would be a problem.

These issues are being overcome in the proposal for a European extremely large telescope - known as Euro 50 - by building the primary mirror in segments. The segmented optical and infrared telescope will have 618 two-metre mirrors, and will employ advanced adaptive optics systems to correct distortion.

One in the eye for astronomy

"It´s fair to say that the construction of this telescope would revolutionize astro-nomy and advance our knowledge of how galaxies and planetary systems like ours came into being," says Arne Ardeberg.

But there´s another more earthly spin-off benefit of the adaptive optical techniques being developed for Euro 50. Arne Ardeberg´s colleague at the Lund Observatory, Dr Mette Owner-Petersen, is working with the Ophthalmology Department of SahlgrenskaUniversityHospital to apply the adaptive optical techniques to studies of the eye for medical research and treatment.

"To get useful information about the retina while the person is still living requires non-invasive techniques of very high resolution," says Dr Petersen.

"The trouble is, today´s adaptive optical tech-niques can only resolve a very small area of the retina at a time, making complete studies time-consuming and uncomfortable for the patient. By employing the adaptive optical techniques we have developed for astronomy, we can correct for the distortions at the periphery of vision and obtain a wide-field retinal image."

One of the researchers responsible for developing the technique Sahlgrenska University Hospital, Dr Zoran Popovic, is equally enthusiastic:

"Spatial resolution, or visual acuity is an important measure of visual function. We can perform psycho-physical experiments to study how this is affected by retinal neural circuitry when a patient looks through the system. The new adaptive optical techniques we are developing will also enable us to minimize aberrations over a wide field of view and will greatly help calculate more accurate diagnoses of retinal conditions. For example, during the tests, patients´ contrast vision is improved five-fold, meaning we can apply finer test scales to the patient."

Lund Observatory has also benefited from this collaboration, as it has been able to trial and improve its techniques in a real-life test-bed.

Perhaps, thanks to the scientists of the Lund Observatory, we´ll all get a better view of space in the future - with or without a telescope.