On May 16, the world marks the International Day of Light. 

The creation of high-speed Internet, alternative energy sources, as well as technologies of diagnosing and treating disease would have been inconceivable without studying light, which is considered the source of life (by way of photosynthesis). 

The research of light properties started back from book Kitab al-Manazir (Book of Optics) by Ibn al-Haytham, which came out in 1015. The works by Einstein in early 20th century changed our perception of time and light. 

it was the first successful demonstration of laser deigned by physicist and engineer Theodore Maiman that made a real revolution. It happened on May 16, 1960. This very date was chosen for the International Day of Light which has been marked for several years already. 

Nowa laser machine at the Lawrence Livermore Laboratory and T. Maiman with his first laser

Nowa laser machine at the Lawrence Livermore Laboratory and T. Maiman with his first laser

Source: https://oko-planet.su/science/scienceclassic/68517-lazery-bolshoy-moschnosti.html

On May 16, 1960, the scientist demonstrated the first optical quantum generator – laser. He used the crystal of artificial ruby (aluminum oxide Al2O3 with a slight admixture of chrome Cr) an active medium, and made of it a rod in the form of cylinder 1 cm in diameter and 2 cm long. In the course of operation, the laser was exposed to radiation of flash discharge lamp. Fabry-Perot resonator served as resonator. It was formed of silver mirror coating applied onto the rod butts. The laser was working in pule mode emitting light with wavelength of 694.3 nm.




American physicist Theodore Maiman made a breakthrough in the field of optical frequencies. It was a rise by 10,000 in frequency and 1 million times in power, though nobody had ever thought at that time that this leap could be made so soon. The inventor owed his success to the use of uncommonly new working body – ruby crystal, moreover, without cryogenic cooling. Thank to such a bold solution, Maiman wrote his name into the history of mankind and made a step to the era of modern instrument-making.




The launch of the first solid-state laser was as follows: the ruby cylindrical rod (active element inside the device) played the role of trigger, while the excitement was achieved due to optical pumping (flash bulbs). To ensure population inversion of energy levels inside the ruby crystal, the lamps were working in the mode of super-bright short pulses. Silver coating on the butts of artificial ruby rod served as resonator. 

At present, lasers are used in not only telecommunications sphere, but the fields of space communication and medicine. It is also used in everyday life. The issue in question is about barcode scanners that can be met at the stores, as well as office laser scanners or printers, or even laser shows. Laser ha firmly entrenched in many spheres of our life including science, technology, medicine, and entertainment industry.

That is why the establishment of holiday on the initiative of UNESCO looks obvious. The establishment of memorial date was preceded by the idea of holding The International Year of Light and Light-based Technologies (IYL2015) in 2015. The initiative turned out to be successful, so the state members considered the resolution on establishment of annual holiday. In 2015, 147 countries organized over 13,000 events devoted to the role of light in human life.

Photo on the page: https://w-dog.ru/search/лампочка+красная+синяя+желтая/page/13/

Photo on the homepage: https://digital-foto.no/fototeknikk/perspektiv/juks-med-bildeperspektivet