Fiber-optic reading magnifiers for the visually impaired.
We describe fiber-optic stand magnifiers specifically designed for use as low-vision reading aids. Application of this technology results in better optical and ergonomic properties. The fiber-optic magnifiers (tapers) provide bright, uniformly illuminated, distortion-free images. The reading material can be scanned without the user's having to bend directly over the magnifier. One can further increase the scanning field by slanting the taper to tilt the image toward the observer. Tilting the upper face of the taper by cutting the smaller lower face on a bias is shown to increase the scanning range substantially and to provide better control of illumination. The scanning range of such tilted tapers is approximately double that of the equivalent lens magnifiers. To increase the contrast transfer through the magnifiers, we have developed lower-resolution tapers with an increased core-to-cladding ratio. The increase in contrast transfer is reported for representative tapers. The lower-resolution design is also helpful in reducing the manufacturing cost of taper magnifiers.
D015350:Contrast Sensitivity; D004867:Equipment Design; D005336:Fiber Optic Technology / Q000295:instrumentation*; D006801:Humans; D007909:Lenses; D008027:Light; D008433:Mathematics; D055100:Optical Fibers; D055095:Optics and Photonics; D011932:Reading; D015354:Vision, Low / Q000628:therapy*