While spectacles have increasingly become a style statement, these humble companions are the one object that many of us rely on throughout the day for a very basic need.
There are today many types of frames and styles which is perhaps why we tend to look through the importance of lenses - the key component that makes spectacles what they are.
The convex lenses were the first ones to be made to cure far-sightedness and then came the concave lenses to treat short-sightedness.
A lot goes into the making of lenses.
Knowing more about how lenses are made can help eyewear users appreciate the basic steps involved in choosing the right spectacles.
For instance, did you know that it is important to choose your frames according to your prescription? This is because, lenses are cut according to the frames and certain prescriptions may not go well with small or thick frames.
You'll be able to appreciate this and much more as you read on to find out how your prescription lenses are actually made.
Raw materials In the past, opticians relied on separate optical laboratories to produce lenses.
But now, full-service outlets that make lenses for customers at the same place are the norm.
These outlets get plastic pieces which are injection moulded and look like hockey pucks.
The manufacturing process of lenses involves several steps.
Surfacing and blocking The laboratory technician inputs the optical prescription data into the computer and it provides a print out of the information necessary for producing the required prescription lenses.
The next critical step is when the technician marks the exact position of your pupils while you are wearing the glasses (not yet fitted with the corrected lenses).
This is when a lensometer is used by the technician - to locate the positioning.
Next, a lens lathe is used.
A lathe is any mechanical device that is used to cut an object symmetrically.
The lathe trims the lens from behind to get the desired thickness and precision.
Polishing When it is just out of the lathe, the back of the lens is a bit rough.
So the technician places the lens in a fining machine called a lap, which polishes it.
First, each lens is rubbed against a rough fining pad made of soft sandpaper.
Then the laps are removed from each lens and soaked in hot water for a few minutes.
After that they are attached back to the lenses and placed in the fining machine for polishing.
The machine then rotates the fining pad in a circular motion while a polishing compound is run over the lenses.
Edging After polishing, the lens is much thinner than when it starts out.
But it still needs to be cut down to a smaller size.
The lens is now put into a lens edger along with the frame selected for it.
The edger uses a digital tracer to capture the three-dimensional image of the frame and by using a diamond cutting wheel, cuts the lens to the precise measurements provided by the optician.
Coating This is the final process when the lenses are dipped into a tint container to be coated.
Coating makes lenses resistant to scratching, anti-reflective or able to block UV rays.
The lens usually receives up to 16 ultrathin layers of metal oxide coatings.
After drying, the lens is ready to be inserted into the desired frames.
During the whole production process these spectacle lenses undergo four basic inspections - three of them happening in the laboratory and the fourth one at the optical outlet.
They include checking the optical prescription, verifying the optical centre placement, verifying the frame alignment and visually checking for scratches.
When all these steps are completed, the spectacles are ready for use.
There are today many types of frames and styles which is perhaps why we tend to look through the importance of lenses - the key component that makes spectacles what they are.
The convex lenses were the first ones to be made to cure far-sightedness and then came the concave lenses to treat short-sightedness.
A lot goes into the making of lenses.
Knowing more about how lenses are made can help eyewear users appreciate the basic steps involved in choosing the right spectacles.
For instance, did you know that it is important to choose your frames according to your prescription? This is because, lenses are cut according to the frames and certain prescriptions may not go well with small or thick frames.
You'll be able to appreciate this and much more as you read on to find out how your prescription lenses are actually made.
Raw materials In the past, opticians relied on separate optical laboratories to produce lenses.
But now, full-service outlets that make lenses for customers at the same place are the norm.
These outlets get plastic pieces which are injection moulded and look like hockey pucks.
The manufacturing process of lenses involves several steps.
Surfacing and blocking The laboratory technician inputs the optical prescription data into the computer and it provides a print out of the information necessary for producing the required prescription lenses.
The next critical step is when the technician marks the exact position of your pupils while you are wearing the glasses (not yet fitted with the corrected lenses).
This is when a lensometer is used by the technician - to locate the positioning.
Next, a lens lathe is used.
A lathe is any mechanical device that is used to cut an object symmetrically.
The lathe trims the lens from behind to get the desired thickness and precision.
Polishing When it is just out of the lathe, the back of the lens is a bit rough.
So the technician places the lens in a fining machine called a lap, which polishes it.
First, each lens is rubbed against a rough fining pad made of soft sandpaper.
Then the laps are removed from each lens and soaked in hot water for a few minutes.
After that they are attached back to the lenses and placed in the fining machine for polishing.
The machine then rotates the fining pad in a circular motion while a polishing compound is run over the lenses.
Edging After polishing, the lens is much thinner than when it starts out.
But it still needs to be cut down to a smaller size.
The lens is now put into a lens edger along with the frame selected for it.
The edger uses a digital tracer to capture the three-dimensional image of the frame and by using a diamond cutting wheel, cuts the lens to the precise measurements provided by the optician.
Coating This is the final process when the lenses are dipped into a tint container to be coated.
Coating makes lenses resistant to scratching, anti-reflective or able to block UV rays.
The lens usually receives up to 16 ultrathin layers of metal oxide coatings.
After drying, the lens is ready to be inserted into the desired frames.
During the whole production process these spectacle lenses undergo four basic inspections - three of them happening in the laboratory and the fourth one at the optical outlet.
They include checking the optical prescription, verifying the optical centre placement, verifying the frame alignment and visually checking for scratches.
When all these steps are completed, the spectacles are ready for use.
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