Anti-reflective or antireflection (AR) coatings are a type of
optical coating applied to the surface of lenses and other
optical devices to reduce reflection. This improves the
efficiency of the system since less light is lost. In complex
systems such as a telescope, the reduction in reflections also
improves the contrast of the image by elimination of stray
light. This is especially important in planetary astronomy. In
other applications, the primary benefit is the elimination of
the reflection itself, such as a coating on eyeglass lenses
that makes the eyes of the wearer more visible, or a coating
to reduce the glint from a covert viewer's binoculars or
Many coatings consist of transparent thin film structures with
alternating layers of contrasting refractive index. Layer
thicknesses are chosen to produce destructive interference in
the beams reflected from the interfaces, and constructive
interference in the corresponding transmitted beams. This
makes the structure's performance change with wavelength and
incident angle, so that color effects often appear at oblique
angles. A wavelength range must be specified when designing or
ordering such coatings, but good performance can often be
achieved for a relatively wide range of frequencies: usually a
choice of IR, visible, or UV is offered.
Why settle for regular eyeglass lenses when you can have
CrystalCLEAR lenses out-perform regular lenses by helping you to see
better, feel better, and actually look better when you are
wearing your glasses.
These virtually invisible lenses are extremely durable,
scratch resistant, and easy to clean. State-of-the-art,
no-glare properties are combined with double-sided scratch
resistance and a finish that repels water. CrystalCLEAR lenses
eliminate reflections that cause eyestrain and fatigue,
especially from fluorescent lighting and computer screens.
They resist dirt and smudges, so you do not have to clean them
as often. With CrystalCLEAR, you not only look better—you feel
Mirrored lenses reduce the intensity of light to an even
greater extent than regular sunglasses, making them a great
choice for very bright conditions. Mirrors can be opaque or
semi-opaque when viewed from the front, affecting whether or
not others can see your eyes.
Polarized lenses are used in sunglasses to reduce glare from
reflective surfaces such as the surface of a lake or the hood
of a car. They accomplish this feat through a process called
polarization, much like a Venetian blind controls sunlight
through a window.
Sunlight itself is not polarized - light from the sun will
either be absorbed or reflected horizontally, diagonally or
vertically. The problem this causes for fishermen and drivers
lies in the horizontal reflectivity. Sunlight bouncing off a
horizontal surface will strike the viewer's eyes at a similar
angle. This means the glare from the surface of the water or
the road or the car hood will be strong. Polarized lenses have
a laminated surface containing vertical stripes. These stripes
only allow vertically-polarized light to enter the wearer's
eyes. Glare is eliminated because the horizontally-polarized
lightwaves cannot bypass the polarized filter.
Polarized lenses do not provide universal protection from
glare, however. If the wearer tilts his head past 45 degrees
or so, some of the horizontal light can enter and cause some
bright spots. Some wearers who use polarized lenses in snowy
areas may find that they lose some contrast between snow and
shadows. Fishermen and drivers seem to derive the most benefit
from polarized lenses because they deal with mostly horizontal
surfaces. A fishermen wearing polarized sunglasses can see
below the surface of the water to search for schools of fish
or hidden obstacles. Drivers are no longer affected by a
constant reflection of light from their hoods or the road
There are some limitations to the use of polarized lenses,
however. Because the vertical polarizing stripes reduce the
amount of light entering the eye, polarized lenses cannot be
used for regular eyewear with clear lenses. Prescription
sunglasses can be tinted a very light gray to accommodate the
polarized laminate, but most contact lenses cannot. Some
drivers discover that polarized lenses can cause distortions
in liquid crystal displays (LCDs). Onboard clocks and other
instrument displays may be temporarily unreadable.
Both horizontally and vertically-polarized lenses are used to
view three-dimensional movies. Some of the light reflected
from the movie screen is vertically polarized, which means
only a lens with a similar vertical laminate will receive it.
The other lens only receives horizontal light waves. Your brain
takes both of these images and combines them to create a
realistic sense of depth.
Polycarbonate lenses are thinner and lighter than traditional
plastic eyeglass lenses. They also offer 100% ultraviolet (UV)
protection and are up to 10 times more impact-resistant than
regular plastic lenses.
This combination of lightweight comfort, UV protection and
impact resistance makes polycarbonate lenses an excellent
choice for children's glasses, sports eyewear and safety
Polycarbonate was developed in the 1970s for aerospace
applications, and is currently used for the helmet visors of
astronauts and for space shuttle windshields. Eyeglass lenses
made of polycarbonate were introduced in the early 1980s in
response to a demand for lightweight, impact-resistant lenses.
Since then, polycarbonate lenses have become the standard for
safety glasses, sports goggles and children’s eyewear. Because
they are less likely to fracture than regular plastic lenses,
polycarbonate lenses are also a good choice for rimless
eyewear designs where the lenses are attached to the frame
components with drill mountings.
Progressive lenses, sometimes referred to as no-line bifocals,
not only provide visual correction for distances that
traditional bifocals can't, but they also hide the fact that
you even need reading glasses. No one else has to know whether
you're sporting a pair of glasses just for fashion — or
because your arms have "grown too short" to allow you to see
Progressive lenses are the closest to how natural vision is
(before the onset of presbyopia) that you can get in a pair of
prescription eyeglasses. They are more than just a defined
near and distance correction in one lens. Rather, progressives
provide a smooth transition from distance through intermediate
to near, with all the in-between corrections included as well.
This constant graduation of the prescription means that you
can look up to see in the distance, look ahead to view your
computer in the intermediate zone, and drop your gaze downward
to read and do fine work comfortably close up.
You get the best vision through the lens when looking directly
at the object of focus. There is a "corridor" of optimum
vision that runs vertically down each lens. Your eye care
practitioner will measure both eyes in relation to the
position of the frame in order to place the corridor in just
the right location for you. So you'll get the best vision when
you point your nose directly at whatever you want to see.
A great number of curves are present in the lens in order to
achieve the progression from one area of focus to the next.
These curves are graduated vertically in the center and
brought out to the sides of the lenses to be "blended"
together. Although most of that blended area is eliminated
when the lenses are cut down to fit the eyeglass frame, the
side areas that remain do not provide the best vision.
Transitions lenses change, so you don’t have to.
* If light conditions remained as constant as they are in
your eye care professional’s exam room, you wouldn’t need
anything more than clear lenses in your glasses. But think
about how many times you move from indoors to outdoors and
from sunny skies to overcast. Each and every time you do, your
eyes must try to adapt to that changing light, often making it
difficult to see objects clearly and making your eyes feel
tired and uncomfortable. That’s why we recommend Transitions lenses … lenses that conveniently and
automatically change as light changes, so you can see better
everywhere you go – without ever having to change eyeglasses
* Transitions lenses are photochromic lenses.
"Photochromic" means the lenses change from clear to dark in
the presence of ultraviolet (UV) radiation, such as when
exposed to sunlight. Indoors and at night, Transitions lenses
are as clear as regular clear lenses. Outdoors, when exposed
to the sun’s UV rays, they turn sunglass dark, enhancing the
quality of vision by reducing glare (thereby minimizing eye
strain and fatigue) and improving contrast in all light
conditions. And it’s all automatic.
* UV 400 ProtectionBut Transitions lenses don’t stop at
improving visual quality and visual comfort.
Like your skin, your eyes need sun protection too.
Transitions lenses provide UV400 protection, blocking 100% of
damaging UVA and UVB radiation and helping to preserve your
long-term eye health.
* Convenience and protection can be fashionable, too.
Transitions lenses are compatible with virtually all frames
and are available in a wide range of lens materials and
prescriptions. Chances are, if your prescription is available
in a clear lens, it’s also available in a Transitions lens.
Everyday lenses that can help you see better today … and
tomorrow. If you ever have to squint or strain your eyes in
sunlight, or have trouble seeing objects clearly in bright
sunlight, chances are your everyday eyeglasses could do a
better job of providing you with all-day, automatic visual
quality, comfort and long-term protection. Ask your eyecare
professional about lenses that can help you see better today
and tomorrow. Simply put, Transition lenses are not just as
good as clear lenses, they’re clearly better.