In the newer glasses, Peli and his co-inventor Dr. Vargas-Martin from the University of Murcia, Spain, designed a wide-field telescope made of straight and curved mirrors built completely within the spectacle lens,
The Journal of Biomedical Optics article describes the process that Peli and his team went through as they created and tested various prototypes of telescopes leading to the design that would be most effective and comfortable for patients with low vision. They started with a telescope made with mirrors and lenses to prove the image shifting principle. To embed the whole telescope inside the spectacle lens they had to obtain the magnifying power from curved mirrors instead of lenses, as mirrors maintain their power when embedded inside the spectacle lens, while the lenses lose their power when not in the air. Regular spherical mirrors can not be tilted without loss of focus, so they constructed a version made with tilted parabolic mirrors. The latter worked well and was in focus, but the images were distorted enough due to the parabolic shape to cause a disturbing effect during head movements. The latest design they constructed is based on spherical and flat mirrors with the flat mirrors implemented as tilted beam splitters that use polarization to reduce light loss.
Says Peli, "The short height of the actual magnifier, its position, and inclusion of a small tilt of the last flat mirror (the one closest to the user's eye), enables the wearer to simultaneously view the magnified field above the unmagnified view of the uninterrupted horizontal field.
Not only will the new glasses improve the cosmetics and usefulness of
this type of device, the in-the-lens design will make it possible to
mass-produce the telescopic magnifier as a standard
|SOURCE Schepens Eye Research Institute|
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