November 14, 1967 - The first laser in the world to be patented

For several decades since the 1960s, lasers were no longer a science fiction idea, a rare item in the research room, an expensive thing.

November 14, 1967 - Theodore Maiman signs a patent for the world's first laser

Ruby lasers, a solid laser, were first created in 1960, by American physicist Theodore Maiman at the Hughes Laboratory in Malibu, California. This is considered the first laser in the world and Maiman registered a patent on November 14, 1967. Rubies form aluminum oxide and chromium. When chromium absorbs green and green light rays, it leaves only the pink light emitted.

Realistic picture of ruby ​​laser.

Laser is the acronym for Light Amplification by Stimulated Emission of Radiation in English, and means " amplify light by stimulated emission ". Natural light and artificial light are normally emitted by energy changes at the atomic and molecular levels that occur without external interference. However, the second type of light exists and occurs when the atom or molecule still retains its excess energy until it is forced to emit energy in the form of light. Laser was built to create and amplify this form of forced light into intense and focused beams. The special nature of laser light makes laser technology an essential tool in almost every aspect of everyday life, such as telecommunications, entertainment, manufacturing and medicine.

Albert Einstein casually took the first step in laser development with the possibility of having two types of emission. In an article published in 1917, he was the first to propose the existence of forced emission . For many years, physicists thought that the spontaneous emission of light was the most likely and dominant form, and any forced emission must be much weaker. It was not until after the Second World War that people began to search for the necessary conditions for dominant forced emission, and caused an atom or molecule to excite other atoms or molecules, creating light emission amplification effect.

Theodore Maiman - the father of the world's first laser.

Electrons exist at separate energy levels in an atom. The energy levels can be understood to correspond to the individual orbits of electrons around the nucleus. The outer electron will have a higher energy level than the inner electrons. When there is physical or chemical impact from the outside, these electrons can also jump from low energy levels to high energies or vice versa. These processes can generate or absorb light rays (photons) according to Albert Einstein's hypothesis. The wavelength (hence the color) of the light ray depends on the energy difference between the levels.

Lasers are emulated by maser, a device that has a similar mechanism but produces microwave rays rather than light radiation.Maser is the acronym for Microwave Amplification by Stimulation Emission of Radiation and means " Amplifying micro-wave by stimulated emission" . Maser and laser have the same mechanism of action, except that the maser operates with photon frequencies in the microwave region and the laser works in ultraviolet, light or infrared. The first Maser was created by Charles H.Townes with the help of two recent graduate students, JPGordon and HJZeiger, in 1953. That first Maser did not produce continuous waves.

At the same time, two scientists, Nikolay Gennadiyevich Basov and Aleksandr Mikhailovich Prokhorov of the Soviet Union, worked independently in the field of vibrating quantum and created a continuous beam system by using more than two energy levels. . The system can release continuous rays without letting the particles down to normal energy levels, thus keeping the frequency. In 1964, Charles Townes, Nikolai Basov and Aleksandr Prokhorov both received the Nobel Prize in physics for the foundation of the field of quantum electronics, leading to the creation of oscillators and magnifiers based on maser-laser theory.

Maiman's ruby ​​laser emits intense intense red light pulses with a wavelength of 694 nanometers, in a narrow, highly concentrated beam that is typical of the characteristics expressed by many lasers today. The first laser used a small ruby ​​rod with two silver-plated heads to reflect light, surrounded by a spiral flash, and small enough to hold in hand. Interestingly, the photographer was commissioned by the Hughes Laboratory to advertise the new invention that the actual laser was too small and the Maiman posing with a larger laser until later did not work. The picture of Maiman with the 'more spectacular' laser still circulated and used in many publications.

Description of ruby ​​laser.

The presence of lasers in sci-fi works, or action movies, as well as general commentary leads to false thoughts. For example, contrary to what appears in movies like Star Wars, lasers are never seen in a vacuum, because the vacuum has no light scattering. In the air, the laser can collide with dust or obstructions on the road and scatter, creating flashes of light; Similar to the sun shines in dusty environments. This technique applies to visible lasers, such as in photographic purposes, by increasing the number of particles in the air, such as using a spray bottle.

High intensity laser beams can be seen in the air thanks to Rayleigh scattering or Raman scattering . For more intense rays, concentrated at a small point, the air can be heated up to the plasma state, so the laser can be seen by radiation from this plasma. However, a sudden increase in pressure when the air is quickly heated can produce a loud explosion, and create a laser beam response to damage the device (depending on the design of the laser). In sci-fi movies, special effects often describe laser weapons that travel a few meters per second, contrary to the fact that lasers move at the speed of light, so fast that it cannot see movement. transfer of laser. Some scenes depicting the safety system using red lasers, can be disabled by characters by using mirrors, when the person sees the laser by spraying white dust into the air. In fact, safety systems can use infrared lasers rather than visible lasers.

Laser ruby ​​cut steel.

For several decades since the 1960s, lasers were no longer a science fiction idea, a rare item in the research room, an expensive thing. It has become a valuable tool in certain scientific applications , it has become an essential item in everyday work, and is so popular that it can be purchased in grocery stores, some people use it. Measure the size of the room to paste the paper on the wall. Any list of major technological achievements of the 20th century has a laser name on the top. The penetration of lasers into all aspects of current life can be best appreciated by the scope of application of laser technology. On the spectacular side of this range are military applications, including the use of lasers as weapons against missile attacks. In another area, daily activities such as listening to music on a CD, and printing or copying paper documents. Laser bars sold for hundreds of dollars each are considered inexpensive parts, both carpenters also use lasers, and simple measuring devices also have lasers attached.