The backside of this lens blank is cut to order to fit the exact parameters required. This is done with the aid of a computer to ensure the lens power is exact. It used to be that people with very strong prescriptions could only wear thick, heavy lenses capable of achieving that level of refractive correction. Fortunately, at Payne Glasses, our 1. Polishing tools — designed in all possible optical curvatures — are employed to machine-polish the lens prior to its being cut to fit the frame.
The type of polishing automation varies among manufacturers. Before cutting, special lens treatments are applied. Therefore, if the order involves tinting or some other type of coating, the polished lens is dipped into various solutions to achieve these features.
On this note, Payne has been a North American forerunner in offering light-responsive blue light blocking lenses that protect the eyes from high energy visible light HEV radiated by the sun and electronic devices such as computers and cell phones.
These specialty lenses also adjust their tint to accommodate all types of outdoor lighting. After specialty treatment, the lens undergoes a computerized measurement in order to prepare and trace it for cutting, according to the axis measurements needed for the lens within the selected frame.
The lens is then blocked for glazing, or cutting. Finally, a machine accurately cuts the shape and finishes the edges, with workers supervising quality and order adherence along the way.
Making glasses at large scale, however, is always much quicker and involves batch production. Numerous glasses frames and temples arms are processed at once using semi-automated or even fully automated production processes. The spectacles and components are taken through these stages more quickly and more consistently with less human intervention.
The earliest glasses frames were thought to have been made at the turn of the 12th century from naturally abundant materials such as bone, ivory, leather and wood. Back then, these natural materials would have been hand-carved to accept the very basic and round lenses of that era.
These glasses were usually made of two separate lens-holder, similar to two magnifying glasses joined together. In more recent iterations, spectacles and sunglasses began to benefit from material developments such as polymers. The college of optometrists has put together an informative article about the history of the earliest spectacle frames which you can read here.
Although glass provides the best optical quality, it has been predominantly outdated by several different types of plastic used to make glasses lenses.
These include composite, standard plastic, mid-index plastic, high-index plastic, polycarbonate and high-definition plastic. You can read about these in more detail via the article by The Vision Council. Different colours of tint can be applied to the lens which generally consists of brown, green, blue or grey. Gradient tints can be achieved by from inverse dip-times in the bath. Upside-down, the top of the lens is immersed for longer than the lower region of the lens to create the tinted gradient.
For consistency, both lenses are dipped together which can be assisted with the aid of a dipping-arm machine. How are glasses made? In winter, we still use our table saw but there's a lot of sweeping afterwards This method yields very small, accurate lettering on the inside of our uni-piece temples. Glass blowers would make lenses of different thickness based on rudimentary vision testing.
As these glasses became more popular, the Italian creations spread throughout Europe, mostly available to the wealthy. Because scholarship was a prized attribute during the Renaissance, glasses were status symbols of intelligence and prosperity.
The technology might have remained stagnant for several centuries, because the next clear historical picture of spectacles comes during the s. Benjamin Franklin added to the versatility of glasses by inventing the bifocal lens, which allowed a person with both near and far-sighted affectation to use one pair of glasses instead of two. He did this at first by cutting lenses in half and putting them together into one frame. Some men did not enjoy wearing glasses full time, so these were the answer: pocket glasses that could be folded up on a hinge like a pair of scissors.
As the 19th century dawned, glasses were still handcrafted and not available to everyone. But the industrial revolution was right around the corner, and mass production of both frames and lenses made it much simpler for working men and women to obtain the necessary eye correction.
The early s also saw the introduction of peculiar cylindrical lenses for correcting astigmatism. After the lenses are dipped in a coat of UV treatment and tint, if desired, they are ready to be placed in the frame and worn by the patient.
To ensure each pair of glasses crafted in the U. Further, the National Optical Association requires all optical laboratories to be licensed and adhere to a variety of quality and safety standards. There are four basic quality assurance steps performed throughout the crafting process:. The process of crafting a pair of prescription glasses requires a great deal of precision and expertise — from your eye exam to the moment you place your glasses on your face.
Edina Eye Physicians provides a wealth of comprehensive vision care services, including eye wear.
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