What are lenses? Detailed analysis

The article describes what lenses are, for which they are used, where applicable, and in particular on 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. Another thing contributed to this, such as the development of the glass industry, and in particular, lenses. Approximately in 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 used for? In this we will understand.

Definition

According to official terminology, the lens is a piece of transparent material with two surfaces that refract light rays. 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, and the like. But we will analyze the optical ones. What are lenses, we disassembled, but how do they work?

It's all in their surface. Simply put, one of their surfaces collects light, and the second because of its shape refracts it. Or vice versa. Also, in such a process, both sides can participate simultaneously: one, accepting, dissipating, and the second gathering in a bundle, etc.

With magnifying lenses, probably everyone knows, especially the boys, who in the summer, collecting them light, turned it into a tiny and hot spot. And, by the way, an interesting fact: a similar method of breeding fire is mentioned in Aristophanes' play "The Cloud", dated 424 BC. E. In the Roman Empire, for the first time, a method of vision correction using a lens was applied: the emperor Nero looked at the gladiator fights through a concave emerald. Probably, he 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 are those in which the middle is thicker than the edges, and to 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 the lens focus?

In simplified terms, this is the point where the rays of light gather through the lens. And the term "focal length" denotes the length from the center of the optical lens to the point of focusing. You can also explain this with the example of a children's game with a magnifying glass and the sun: in order for the rays of the latter to gather at a hot spot, you need to find the right distance between light and the surface. It also manifests itself when wearing glasses - if they are too close or detached from the eyes, the image will be blurred. So now we know what the lens focus is.

Areas of use

With the discovery of the possibility of changing the length of the light wave through lenses (magnification of the image), humanity quickly estimated it according to merit. It all began with simple telescopes and telescopes. And the last long time was an indicator of the status of the ship's captain or researcher, since they cost a lot of money and they were often encrusted with precious stones and metals.

And later the first microscopes allowed to open the veil of the macrocosm. True, some modern models, acting on the probing type, have almost no lenses. But they allow you to build three-dimensional and raster images of small objects.

Different devices with lenses are also an integral part of the modern world: they are in cameras of mobile phones, photos and video cameras, even ordinary door eyes contain lenses. But they do not use the method of magnification, but rather the diffusion of light, through which a small hole allows you to see the entire staircase.

Also, when it comes to the question of what an optical lens is, one can not help but mention the glasses. This simple device was invented in the Middle Ages and changed little, but it greatly facilitates the life of people with visual impairment. Their first prototypes were used even in Ancient Rome, but then they were just flat pieces of glass with a convex or concave shape, which were rarely used, for example, for reading or for studying distant objects.

Contact us

But what are contact lenses? The principle of their action is the same as in conventional, but the size is much smaller. They are made of soft plastic and put directly on the cornea of the eye. Despite the advantages over conventional glasses, they did not completely replace them, as the inventors predicted. Such lenses are more difficult to "wear", they need frequent care, and long weariness tires and irritates the eyes. In addition, their service life is less than usual points, and the price is sometimes higher.