Chris Ryser s new
Saturday, March 24, 2018
Opticians dispense "anti-reflection lenses" because the
decreased reflection makes them look better, and they produce
which is particularly noticeable when driving at
night or working in front of a
computer monitor. The decreased glare means that
often find their eyes are less tired, particularly at the end of
the day. Allowing more light to pass through the lens also
contrast and therefore increases visual acuity.
Antireflective ophthalmic lenses should not be confused with
polarized lenses, which decrease (by absorption) the visible
of sun reflected off of surfaces such as sand, water, and
roads. The term "antireflective" relates to the reflection from
surface of the lens itself, not the origin of the light that
reaches the lens.
Many anti-reflection lenses include an additional coating
grease, making them easier to keep clean.
coatings are particularly suited to high-index
lenses, as these reflect more light without the coating than a
lower-index lens (a consequence of the
Fresnel equations). It is also generally easier and cheaper
to coat high index glasses.
There are two separate causes of optical effects due to coatings, often
called thick film and thin film effects. Thick film effects arise
because of the difference in the
index of refraction between the layers above and below the coating (or
film); in the simplest case,
these three layers are the air, the coating,
and the glass. Thick film coatings do not depend on how thick the coating is, so
the coating is much thicker than a wavelength of light. Thin film
effects arise when the thickness of the coating is approximately
the same as a
quarter or a half a wavelength of light. In this case, the reflections of a
steady source of light can be made to
add destructively, and hence reduce reflections by a separate mechanism. In
addition to depending very much on the thickness
of the film, and the wavelength of light, thin film coatings depend on the angle at which the light strikes the
Top layer is Hydrophobic, that is easy to clean on newer lenses
The problems i 2 years down the
road..........................when the lenses have some scratches, a
and could still be useful if someone could fix them up. As
long as the warranty was valid they got fixed up or even
many retailers that is a good reason to sell you a new pair.
These lenses can be saved without having
to purchase new ones.
If you can not find a
local source to strip your defective coating you can do it on line
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