The article talks about what lenses are, what are they used for, where are they used, and in particular about optical and contact lenses.
Development of science
At all times there were those who were interested in the true structure of the world and natural phenomena. Especially human attention was attracted to the sky and stars. The first telescopes were invented back in the Middle Ages, and their appearance served as a series of astronomical discoveries. This was also facilitated by such a thing as the development of the glass industry, and in particular lenses. Around the same years, the first microscopes were invented, which were constantly improved and also helped scientists to learn the secrets of the macrocosm. So what are lenses, how are they arranged, where are they used and what are they for? This we will understand.
Definition
According to official terminology, a lens is a part made of a transparent material with two surfaces that refract the rays of light. They are made of glass, plastic or other similar optical material. Also, this term can be applied to other phenomena, for example, an air lens, an underground lake lens, etc. But we will analyze optical ones. What are the lenses, we disassembled, but how do they work?
It's all about their surface. Simply put, one surface collects light, and the second, due to its shape, refracts it. Or vice versa. Also, both parties can participate in a similar process at once: one, receiving, scatters, and the second collects in a beam, etc.
Probably everyone is familiar with magnifying lenses, especially the boys who, in the summertime, collecting light, turned it into a tiny and hot spot. And, by the way, an interesting fact: a similar method of lighting a fire is mentioned in the play of Aristophanes “Clouds”, dated 424 BC. e. In the Roman Empire, a lens correction method was also first used: the emperor Nero looked at the gladiators' battles through a concave emerald. He probably suffered from myopia. So now we know what lenses are.
Classification
According to the technical principle of action, they can be divided into two groups - scattering and collecting. The first includes those whose middle is thicker than the edges, and the second those whose edges are thicker than the middle. This definition applies only to their simple type.
They are also characterized by their optical power, which is measured in diopters, and focal length. But what is a focus lens?
In simple terms, this is the point where the rays of light that pass through the lens gather. And the term “focal length” refers to the length from the center of the optical lens to the very place of focusing. This can also be explained by the example of a children's game with a magnifying glass and the sun: in order for the rays of the latter to gather in a hot spot, you need to find the right distance between the light and the surface. This also manifests itself when wearing glasses - if they are too close or distant from the eyes, the image will be blurred. So now we know what a lens focus is.
Areas of use
With the discovery of the possibility of changing the light wavelength through lenses (image enlargement), mankind quickly appreciated it according to its merits. It all started with simple telescopes and telescopes. And the latter has long been an indicator of the status of the captain of a ship or explorer, as it cost a lot of money and is often encrusted with precious stones and metals.
And later, the first microscopes made it possible to open the curtain of the macrocosm. True, some modern models operating according to the probing type have almost no lenses. But then they allow you to build three-dimensional and raster images of small objects.
Various devices with lenses are also an integral part of the modern world: they are in the cameras of mobile phones, photos and video cameras, even ordinary door eyes contain lenses. But they do not use the method of increasing, but rather the diffusion of light, thanks to which a small hole allows you to see the entire landing.
Also, when asked about what optical lenses are, one cannot but mention glasses. This simple device was invented in the Middle Ages and has not changed much, but it greatly facilitates the lives of people with visual impairments. Their first ancestors were used even in Ancient Rome, but then they were simply flat pieces of glass with a convex or concave shape, which were rarely used, for example, for reading or for studying distant objects.
Contact
But what are contact lenses? The principle of their action is the same as in ordinary ones, but the size is much smaller. They are made of soft plastic and are worn directly on the cornea of the eye. Despite the advantages over ordinary glasses, they did not completely displace them, as the inventors predicted. Such lenses are more difficult to "put on", they need frequent care, and long wearing wears and irritates the eyes. In addition, their service life is less than ordinary points, and the price is sometimes higher.