When were glasses invented? Detailed answer

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When were glasses invented? Detailed answer

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When were glasses invented?

Take a look around and you will see that a significant number of people wear glasses. We are so used to seeing people with glasses that it is hard to imagine a time when they were not. People with poor eyesight had to cope with this as best they could. No one knows for sure when glasses were invented. In 1266, Roger Bacon, an English monk who did many interesting experiments, found a way to enlarge the letters in a book to make them easier to read. He just put a piece of glass ball on top of the book! Of course, it didn't help in the way glasses do.

The first glasses can be seen in the portrait of the cardinal, which was painted in 1352 in Italy. It had two framed lenses connected by a crossbar. When printed books began to appear, glasses became a necessity for many people and their use became widespread. In the XNUMXth century they were made in large numbers in northern Italy and southern Germany.

In 1784, Benjamin Franklin invented bifocals, which are two different types of lenses in the same frame. To understand how glasses help a person see better, you need to know what the eyes are. The eye is spherical in shape with a slight bulge in front. In the center of this bulge is the pupil, through the opening of which a beam of light penetrates into the dark interior of the eye. A beam of light passes through the hole in the pupil to the lens. The lens focuses light, giving an image of a visible object at the back of the eyeball. There is a septum of light-sensitive cells called the retina.

In some people, the eyeball is slightly extended from front to back; in others, the eyeball is too short and the lens cannot focus a clear image onto the retina. Glasses give the eye an additional lens, which corrects the work of the lens of the eye so that a clear image is focused on the retina. And you see better!

Author: Likum A.

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Technology for measuring time with an accuracy of up to zeptoseconds 02.01.2023

How fast do electrons move between atoms within the same molecule? Most often, they require only a few attoseconds (10^-18 seconds or a millionth of a billionth of a second). Keeping track of such fast processes is challenging, and a team of Australian scientists recently developed a new interference technology capable of measuring time delays with zeptosecond (10^-21 seconds, or trillionth of a billionth of a second) resolution.

As a test, this technology was used to measure the delay between two pulses of light emitted by different hydrogen isotopes, normal hydrogen (H2) and deuterium (D2), which were simultaneously exposed to a single pulse of laser light. The measured delay was less than three attoseconds, and its cause is the difference in the dynamics of motion of lighter and heavier nuclei of hydrogen isotope atoms.

Light was emitted by hydrogen atoms through a process called high harmonic generation (HHG). This process occurs when an electron is knocked out of an atom by a powerful stream of light, which also accelerates the electron to a higher energy (speed). When the electron returns to the "bosom" of the atom, a quantum of hard ultraviolet light (extreme ultraviolet, XUV) is emitted. The frequency, intensity and phase of the secondary radiation strongly depend on the parameters of the wave functions, so all atoms and molecules emit hard ultraviolet with their own unique parameters.

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The obtained simulation results match the experimental data very well, and this suggests that in the future this technology can be used to study and measure ultrafast processes in atoms and molecules with unprecedented time resolution.

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