Lasers
Claimed by Sam Manley: 4/20/2022
Lasers
Lasers have become a very useful invention and have been used in a variety of applications throughout the world, ranging from medical procedures such as laser-eye surgery to simply using a laser to engrave one's initials onto an item of value. The word laser is actually an acronym that stands for light amplification by stimulated emission of radiation, which essentially describes the process by which lasers work.
There are many types of lasers - each with their own distinct features. Often times, the laser is named after the lasing medium that is used. The lasing medium is used to excite the atoms into their excited state; when in their excited state, these atoms release energy in the form of photons, thus creating the laser beam.
Laser Light
To create laser light, there are some conditions that need to be satisfied: the atoms in the lasing-medium must have electrons in an excited state from which they can drop, producing a photon with energy (and thus wavelength) equal to the electron's change in potential energy as it fell, and the light used to stimulate the emission must be that exact same wavelength. This means that all the light emitted by the laser is monochromatic, meaning the photons are all of only one wavelength. [1]
Another difference between laser light and normal light is its state when shone. Laser light is very directional, which explains why when a laser is shone, the beam is very concentrated and organized - there is no or very little scattering of the light. This feat is extremely helpful when considering the applications such as laser-eye surgery where focusing and precise energy is needed.
Here you can find a link to a simulation of a laser that allows you to adjust the parameters of the experiment.
History
The theory of stimulated emission was first suggested by Albert Einstein in 1917. [2] The first person to witness stimulated emission was Rudolf Ladenburg, a german physicist, in 1928. He saw no practical uses for it at the time though, so he effectively dismissed it and lasers went unstudied for over 20 years. [2] This streak came to an end in 1951, when Charles Townes came up with a way to stimulate emission of light in the microwave region of frequencies, and he created a working device in 1953 that he called a "maser" (for microwave amplification through stimulated emission of radiation). [2] Aleksandr M. Prokhorov and Nikolay G. Basov described that theory of the maser independently, ad in 1964, Townes, Prokhorov, and Basov earned the Nobel prize for their work.[2] Townes mentioned the idea of extending the capabilities of the maser to produce stimulated emission of shorter wavelengths of light to his brother-in-law, Arthur Schawlow, and Gordon Gould, who took their research in different directions (Schawlow and Townes began researching optical masers while Gould had more militaristic goals in mind). [2] Gould was the man that came up with the term "laser" but he is not credited with inventing the first one. [2] The first laser was created by Theodore H. Maiman in May of 1960, when he made a laser that used synthetic ruby as the lasing-medium. [2]
Types of Lasers
Ruby Lasers
Ruby lasers have a flash tube and two mirrors. In this case, the lasing medium is the ruby rod. When light is flashed, the atoms in the ruby get excited and some of these atoms emit photons, which bounce off the mirrors and are eventually emitted as monochromatic and directional laser.
Solid-state Lasers
In solid-state lasers, the lasing medium is distributed in a solid matrix such as ruby.
Gas Lasers
The Lasing medium in this case is usually either helium or helium-neon. They usually have an output color of red. Carbon dioxide is used as a lasing medium when the lasers are being used to cut hard materials.
Semiconductor Lasers
These are also called diode lasers and are different from solid-state lasers. They are usually very small and use a very small amount of power. These lasers are incorporated into a larger arrays.
Connectedness
Lasers are a very unique invention because they have so many applications, as mentioned before. They can be used as a method to decorate objects and have also been applied to the medical field -laser-eye surgery. The concept and process by which lasers work is directly related to physics, specifically the idea of energy emission in the form of photons. This may not have a direct relationship to chemical engineering, but the basic principles of chemistry - atoms and energy - play a large part in the manufacturing of lasers. Industrial applications range from cameras, firearms, scientific techniques such as spectroscopy, and also daily use during presentations. An interesting recent application of lasers is the laser focus that is implemented in LG G3 phone camera. Click on the link below to read more about this feature.
See also
This link has more information about the laser used in the LG G3 phone camera. [ http://www.trustedreviews.com/opinions/how-the-lg-g3-laser-af-camera-focus-works]
References
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