Python Notes for mca i year students osmania university.docx
What are polycarbonate lenses
1.
2. Polycarbonate lenses are one of
the lightest, thinnest and safest
lenses on the market today.
Most all lenses are now made
from polycarbonate polymer.
3. The polycarbonate material was developed
in the 1970’s to be used for aerospace
usage. Polycarbonate is still the
preferred material used for space shuttle
windshields and helmet visors of the
astronauts. It wasn’t until 1980 when
polycarbonate was introduced into
eyeglass lenses because of the demand
for lightweight and impact resistant
lenses.
4. The lenses typically considered ‘coke bottle
bottoms’ are considered to be the past
generations of lenses. One remedy to use this
new material is because these lenses are
typically thinner and lighter than most
conventional glass or plastic and is the
preferred choice in most eyewear. Previous
lenses were made from a molding process
where the liquid plastic was molded and baked
for a long period of time. The liquid would
harden and would eventually create the lens.
5. Polycarbonate lenses on the other hand though
start out as solid materials which are shaped
like pellets. These are then heated until they
melt. After the pellets have melted, the liquid is
then inserted into the molds of the lenses which
are compressed and cooled. Instead of this
process taking multiple hours, the process to
create polycarbonate lenses only takes
minutes. This process is called Injection
molding as opposed to the cast molding
process.
6. Another important feature of
polycarbonate lenses is their
ultraviolet light inhibiting value.
With these lenses one doesn’t have
to pay extra for UV treatment to
protect eyes from potentially
harmful rays.
7. Nothing can compare to the impact resistance and safety of
polycarbonate lenses. This material has been used in
‘bullet-proof’ windows in cars and airplane windshields.
Because of the materials used, most safety glasses and
children’s eyewear use ‘polycarb’ because of the
incredible safety features. In fact, polycarbonate lenses
are up to ten times more impact-resistant than typical
plastic or glass lenses. Polycarbonate lenses are also
used in rimless eyewear glasses because of the
lightweight and due to the frame components.
Polycarbonate lenses tend to be 10% thinner than the
plastic or trivex plastic material lenses.
8. The benefits of a polycarbonate lens far
surpasses the older generations of
lenses benefits. Polycarbonate lenses
not only offer a lighter, more impact-
resistance and UV protection, but it also
offers a wider variety of lens designs.
One now can use progressive and
multifocal lenses on polycarbonates.
