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Trends in Physics, Budapest, Hungary

Trends in Physics, Budapest, Hungary. Electro-optical solution for visual acuity and contrast sensitivity modeling. Roberts Paeglis and Maris Ozolinsh. University of Latvia, Dept. of Optometry and Vision Science. European Comission Centre of Excellence. Outline.

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Trends in Physics, Budapest, Hungary

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  1. Trends in Physics, Budapest, Hungary Electro-optical solution for visual acuity and contrast sensitivity modeling Roberts Paeglis and Maris Ozolinsh University of Latvia, Dept. of Optometry and Vision Science EuropeanComissionCentre of Excellence

  2. Outline • Light scattering in human eyes • Electro-optic ceramics in an eye model • “Single-pass”experiments • “Double-pass”experiments • Final remarks

  3. 7 of 10 people over 65 have opacities in the eye lens(es). For 2 of the 7 opacities cause problems, the cataracts Opaque eye lens (B.Masters, 2001) What happens in the eye? During the lifetime, light scattering in the human eyes increases 2 to 3 times

  4. Why modeling? Modeling of light scattering could promote understanding of physical and physiological changes in the eye How? In this way we could also assess the limits of diagnostical methods without a threat to harm or exhaust volunteers

  5. Where we are… • Light scattering in human eyes • Electro-optic ceramics in an eye model • “Single-pass”experiments • “Double-pass”experiments • Final remarks

  6. We used PLZT…. PLZT ceramics is largely transparent for the visible light. Applied electric field, however, induces formation of polar regions that cause considerable light scattering By changing the electric field that we apply, we can vary the amount of scattering induced PLZT stands for Pb0.91La0.09Zr0.65Ti0.35O3

  7. To keep an eye on... Scattering in the PLZT materialis sensitive to the changes in temperature The increase of scattering is reversible Golden electrodes are applied in tiny islets on the surface. The plate with electrodes has stronger absorption in the blue spectrum. So does the cataract in the human eye, however

  8. Where we are… • Light scattering in human eyes • Electro-optic ceramics in an eye model • “Single-pass”experiments • “Double-pass”experiments • Final remarks

  9. Microscope& CCD Microscopewithout the ocular & the CCD without the objective 1301 Single-pass method... incoherent light PLZT ceramics & lens Resolution test Voltagegenerator

  10. Microscope& CCD Microscopewithout the ocular & the CCD without the objective 1301 Single-pass method... laser source PLZT ceramics & lens Laser(633 nm) Double slit Voltagegenerator

  11. As a result…. Changes in the quality of images were observed starting from E=5…7 kV/cm. The range used does not harm the PLZT

  12. Clinical applications Alterations in intensity and contrast of the digital images were registered. At E=9 kV/cm the interference patterns for the conventional “good vision” (V=1.0 or 20/20) could be resolved no more. Evaluation of reliability and comparison of diagnostic methods could be made

  13. 1 I 2 3 Pixels Changes can be visualised... One bit scans of interference images:E=0; E=8.4 kV/cm;E=9.0 kV/cm Interference patterns are used in clinics to evaluate the neural functions of the eye with a cataract

  14. Standard tests can be tried... The system can visualize the changes in contrast and intensity of contrast sinusoids and bright incoherently illuminated objects (Vistech Consultants, Inc.)

  15. Where we are… • Light scattering in human eyes • Electro-optic ceramics in an eye model • “Single-pass”experiments • “Double-pass”experiments • Final remarks

  16. Double-pass optical set-up In collaboration with the Laboratory of Optics, the University of Murcia, Spain

  17. 1302 Double-pass scheme Eyepositioning Focusing system L3 L4 M2 M3 CCD M1 M4 Aperture L2 Beam splitter PLZT ceramics & lens Spatialfilter Laser (543 nm) L1 Voltagegenerator Courtesy of H.M.Bueno

  18. E=8,0 kV/cm E=6,7 kV/cm E=0 kV/cm E=8,3 kV/cm E=5,4 kV/cm E=8,7 kV/cm E=4,0 kV/cm E=7,7 kV/cm E=7,3 kV/cm The centre loses energy... Intensity distribution of a point image Electric field

  19. …higher spatial frequencies gain the energy We can register the “migration” of energy to the tails...

  20. Light maintains polarisation... Depolarisation of light in the model and the eye differ…

  21. Where we are… • Light scattering in human eyes • Electro-optic ceramics in an eye model • “Single-pass”experiments • “Double-pass”experiments • Final remarks Finis coronat opus

  22. In brief, A device consisting of PLZT ceramics, a +55.6 D lens, a microscope and a CCD can visualize the changes in images that are caused by light scattering Reliability and the limits of interferometry diagnostics can be studied

  23. Furthermore… Interdependence of scattering and ocular aberrations, and their impact on the image can be explored with a PLZT plate in the double-pass setup Light of high energy can be used to see the effects more profoundly

  24. However... Resolution can be limited by high aberrations of the optical device (chromatic aberrations, coma), CCD geometry and digital processing Scattering effects are temperature-dependent

  25. Thank you! HAVE I LEFT ANY TIMEFOR QUESTIONS?

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