Production technologies for different spectacle lenses

Lenses are an important part of glasses, on which the comfort of wearing it and the clarity of a person’s vision depend. Thanks to modern equipment, the process of making corrective glasses has become much easier and faster.

Tuya additionally plans to extend its impression in the US and Europe.

Manufacturing

In general, there are two different processes: regardless of the manufacturer, individual high-precision lenses (so-called “glasses with diopters”) are almost always made using FreeForm technology. This is a state of the art manufacturing technology used by briotweco and has been licensed to the entire spectacle lens industry. Unlike prescription lenses, stock “off-the-shelf” are produced by injection molding. Spectacle lenses are made using special equipment. What would later become a plastic lens is initially a large, convex-shaped plastic disc. The manufacturing process consists of several stages:

1. A protective film is applied to the convex part of the workpiece. This is done in order not to damage the surface during the processing of the concave part.
2. The milling machine thins the disc, reduces its diameter and gives the correct bend. Next comes the grinding.
3. The lens is carefully removed from the blocking device. Then it is cleaned, dried with a stream of air. If necessary, the lens is darkened.
4. To make the lens scratch resistant, it is varnished. It is applied to the plastic lens during the dipping process, strengthening it.
5. It remains only to insert the lenses into the frame. Usually, the lenses are inserted by the master optician. This process requires micrometer precision.

 If earlier only glass was considered the best material for lenses, now manufacturers are increasingly opting for plastic. And this is not surprising. After all, plastic is flexible, lighter and more convenient in the manufacturing process, and lenses have increased resistance to mechanical damage.

Features of the production of bifocal lenses 

Bifocal glass lenses combine 2 lenses: one for distance, the other for near. They are interconnected, have the form of a rounded pocket in the lower part of the glasses closer to the nose, or the lower part is different from the upper one. They can increase or decrease the size of the object in question – it depends on the optical power. A glass bifocal lens is produced as follows:

• The first step is to grind the back of the accessory lens to give it a smooth texture. After that, the side with a bend moved into the recess made in the main lens.
• The machine now remelts and grinds the secondary lens along with the primary until only one visible lens remains.

Making bifocals out of a plastic mixture is much easier. In order to increase the area of near vision, no other devices are needed. The corresponding area is bent in a specific way and more strongly. This is possible thanks to durable molds, which are filled with a liquid plastic lens blank.

How are varifocal lenses made

Varifocal (progressive) lenses combine the ability to see at any distance: the upper part of the lens is responsible for distance vision, the middle part for medium distances, and the lower part for work at close range. The decisive factor in the development is its purpose:

• For children – lenses should be lightweight, impact resistant and preferably scratch resistant.
• For drivers – for this case, there are several types of lenses used in various weather conditions.
• For PC operators – lenses with anti-computer coating, protection from electromagnetic radiation.

The calculated design of semifinished spectacle lenses is created using a special grinding machine. To optimize the varifocal lens, many tests are carried out, after which it is released to the market and enters mass production.

What will be the production of glasses depends on the individual case of the person. The more precise the lens manufacturing process determines how the wearer of the glasses will see the world around them, the more accurate the process will be.