Televisions, monitors, books have created generations of people with impaired vision. The development of technology has given the world contact lenses, but glasses continue to hold the lead. The most important part of glasses is the lenses. Read on to learn about the process of making them.
What are they made of?
Lenses are made of glass or optical polycarbonates.
Important! Each material has a number of advantages and disadvantages.
Glass has a higher hardness and, as a result, is highly resistant to scratches and chemical-thermal effects. The downside will be high fragility (a piece of glass near the eye is not the brightest prospect for a bespectacled person) and greater weight compared to plastic. The latter is light, durable, easier to process and cheaper.
Convex, concave, what else?
Based on their shape, lenses are divided into spherical and aspherical. Spherical (single-focal - with one focus) have one grounding curve and are divided into:
convex - to correct farsightedness;- concave - for myopic people.
Aspherical ones are thus designed to correct the astigmatism defect and have more grounding curves. There are also bifocal subtypes, which are divided in half - for working at a long distance and near, which is convenient with the onset of age-related changes. Progressive ones, in turn, have three surface areas - for long, medium and short distances.
Types of lens coatings
Important! Plastic lenses can be given more useful properties by applying various coatings.
The impact-resistant coating compensates for the original softness of the plastic and increases its resistance to scratches. from exposure to cleaning materials and hard objects.- Anti-reflex (brightening) - improves image clarity, neutralizes glare from the outside and inside.
- The hydrophobic (water-dirt-repellent) layer is obtained by applying the thinnest silicone film, from which water and dirt roll off (The effect of “glasses fogging” disappears when moving from a cold to a warm room).
- The antistatic coating eliminates the possibility of a static charge arising from contact with skin and various tissues, which attracts dust (removing it scratches the surface of the glasses).
- Multifunctional - includes 4 of the above coatings.
- Mirror application has only an aesthetic function; it makes the eyes indistinguishable behind lenses of different shades.
Glass lens production technology
The principle of lens production has remained virtually unchanged since the invention of glasses; processing accuracy has improved, manufacturing time has decreased and the process has become automated.
A blank (about 10–14 cm) is taken as a basis, and the number of its diopters is measured with a special device.- The next step is to scan the glasses frame in order to match the frames and lenses, then they will be aligned without additional adjustment.
- Then the lens is placed in an automatic machine, where the required shape is given by grinding with the necessary force (during the entire grinding stage, its surface is washed with an aqueous solution with aluminum particles for cooling, removal of removed particles and a more effective effect of the grinding material on its surface).
- Before fitting into the frame, its edges are additionally ground to obtain the required chamfer.
How is product quality controlled?
High quality of the product is ensured by inspection at all stages:
- checking diopters with their value printed on the packaging;
- reconciliation of values when scanning the shape of the rim of the frame;
- alignment of the optical center when setting the interpupillary distance after scanning the form.
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