Francis Smethwick ground the first high-quality aspheric lenses and presented them to the Royal Society on February 27, reading and burning glasses also outdid their spherical equivalents.
42.
Convex aspheric curvatures are used in many vari-focal lenses to increase the optical power over part of the lens, aiding in near-pointed tasks such as reading.
43.
Both, more strongly aspherized corrector and, especially, strongly aspherized fast mirror ( into a rather unpopular type of aspheric shape ) of the Wright are a fabrication disadvantage.
44.
However, the Schmidt Cassegrain telescope proved difficult to mass-produce because the models needed Schmidt corrector plate, an advanced aspheric lens, which could be hard to manufacture.
45.
Even at high prescriptions some high myope prescriptions with small lenses may not see any difference, since some aspheric lenses have a spherically designed center area for improved vision and fit.
46.
The range of lens powers available to dispensing opticians for filling prescriptions, even in an aspheric form, is limited practically by the size of the image formed on the retina.
47.
Recognized as an expert in optical instrument design, aspheric optics, interferometry, lasers, and lens testing, Hopkins has been characterized as the " father of optical engineering ."
48.
50 years later, John Hadley developed ways to make precision aspheric and objective mirrors for reflecting telescopes, building the first parabolic Newtonian telescope and a Gregorian telescope with accurately shaped mirrors.
49.
Also, in aphakia or extreme hyperopia, high plus power aspheric lenses can be prescribed, but this practice is becoming obsolete, replaced by surgical implants of intra-ocular lenses.
50.
That allowed opticians to design lenses that are more curved, and as a result, thinner and lighter at the edges-- the so-called " aspheric " lens.
