Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Eye - ground: The truth in a distorting mirror

23.10.2007
Exclusive opportunities are provided to ophthalmologists by the device recently designed by specialists of the Institute of Problems of Laser Technologies (Russian Academy of Sciences) and their colleagues from the Faculty of Physics (Lomonosov Moscow State University).

It is the so-called digital fundus-camera equipped with the real-time aberrometer. In fact, two devices are combined in it – one of them enables to see the eye-ground and the other corrects distortions caused by the optical medium of the specific patient’s eye.

As a matter of fact, physicians have been using fundus-cameras for a long time, i.e. diagnostic devices for eye-ground investigation (fundus or more precisely fundus oculi – is the eye-ground). The first similar devices appeared back in the middle of the century before last, and constituted the optical system of lenses, mirrors and light bias, with the help of which it was possible to see blowup of the retina and the vessels feeding it. Since that time, fundus-cameras have been repeatedly improved and became digital – like digital cameras, however, the researchers failed to make the picture sufficiently distinct (at micron definition). It is the eye itself that impeded – its optical medium absorbs light, and its component “details” - cornea, lens and so on, including the eyeball per se – repeatedly change light waves’ direction, thus “blurring” the final image. Physicists call this phenomenon aberration – imperfection of the optical system.

Moreover, astronomers have long ago learned to successfully overcome this phenomenon, which distorts the light of faraway stars – with the help of, broadly speaking, distorting mirrors. It is necessary to know how the light waves’ direction changes on the way from their source through to the observer and how to correct the image – as though to “distort it back”. Physicists decided to apply this particular technique to the fundus-camera design: to measure the distortion and to correct it accordingly. An additional infrared laser and a special “ruby” mirror allowed to implement the idea.

So, an ordinary laser (or several lasers, if the image is needed in different spectral regions) illuminates the eye-ground, the light is reflected and when it is going through the optical system of the device it gets onto the camera matrix – this is how the “picture” is obtained, i.e. the image of the retina and the vessels feeding it, which the ophthalmologist needs to see for making a precise diagnosis. A moment prior to the laser starting operation, the aberration correction system is switched on. It means that the infrared laser (which is absolutely safe) will send its ray of light to find out how its intensity and direction will change on the way “down to the bottom and back”.

The sensors, having recorded these changes, send a signal to the “distorting mirror”, which in response distorts it exactly in such a way that compensates for the changes not for the infrared ray but for visible light – the one that allows to obtain the proper image. Only after the mirror gets “tuned up” accordingly, taking into account individual peculiarities of the eye under investigation, the ordinary laser is switched on and sends an impulse of light, which, having been reflected from the eye-ground and having been “corrected” with the help of the “ruby” mirror, gets onto the digital camera matrix.

As a result, one can get the eye-ground image several times more distinct as compared to the ones provided by ordinary, also digital fundus-cameras: the image at a micron definition. Habitually blurred picture of the retina and vessels on the computer display of the camera acquires unprecedented sharpness, which allows the ophthalmologist to quickly (at the rate of one shot per second) get an excellent image of the object in question, without spoiling his/her eyes in attempt to sort out “shadows and mists” of the pictures obtained with the help of any other fundus-cameras. Ophthalmologists and patients highly appreciate the Russian physicists’ invention.

Nadezda Markina | alfa
Further information:
http://www.informnauka.ru

More articles from Medical Engineering:

nachricht A first look at interstitial fluid flow in the brain
05.07.2018 | American Institute of Physics

nachricht A sentinel to watch over ocular pressure
04.07.2018 | Fraunhofer Institute for Microelectronic Circuits and Systems

All articles from Medical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Machine-learning predicted a superhard and high-energy-density tungsten nitride

18.07.2018 | Materials Sciences

NYSCF researchers develop novel bioengineering technique for personalized bone grafts

18.07.2018 | Life Sciences

Why might reading make myopic?

18.07.2018 | Health and Medicine

VideoLinks
Science & Research
Overview of more VideoLinks >>>