Laser & Maser: Definition, Differences & Uses

Instructor: Michael Blosser

Michael has a Masters in Physics and a Masters in International Development. He has over 5 years of teaching experience, teaching Physics, Math, and English classes.

This lesson will introduce the reader to the world of lasers and masers, define what they are, how they work, how they are different, and their various uses in everyday applications.

Science Fiction Reality?

We have all seen the laser battles that take place in space in our favorite science fiction movies. These laser weapons capture our imagination of what lasers and other futuristic technology will be able to do. Is this laser technology realistic? What are lasers and what are the actual uses of lasers in our world today?


Laser
Laser Image


Laser

The word LASER is actually an acronym for Light Amplification by Stimulated Emission of Radiation. In 1960, the first fully functional laser was completed, but the technology of the laser goes back to Einstein's study of blackbody radiation in 1917. Blackbody radiation refers to a cavity that absorbs all the radiation that falls upon it and re-emits part of this radiation in a proportion of quantized energy. Max Planck made this discovery. It was one of the founding discoveries in quantum physics (the physics of the subatomic world). This study of blackbody radiation led Einstein to discover the phenomenon of stimulated emission.

Stimulated emission is when electrons absorb energy from an electric current or other source of electromagnetic waves and become 'excited,' meaning they jump from a lower energy level to a higher energy level. When the electrons return to their original energy state they give off a photon (electromagnetic radiation). This light is different from the normal light spectrum that we can see because the photons emitted are all the same wavelength, focused, and directional. This stimulated emission of photons from excited electrons is the main principle of how lasers work.

Maser

The word MASER, an acronym as well, stands for Microwave Amplification by Stimulated Emission of Radiation. Masers were invented in 1953 by two scientists, Charles Townes and Arthur Schawlow. Masers use microwaves, hence the M in its acronym. Microwaves are a type of electromagnetic radiation that fall on the long wavelength side of the electromagnetic spectrum. Microwaves have a shorter wavelength than radio waves but a longer wavelength than the colors we see in visible light.

Since microwaves have very long wavelengths, they have a low frequency and therefore are low energy. Microwaves are not nearly as dangerous as ultraviolet or gamma rays which have very short wavelengths and high frequencies. Masers, like lasers, also use stimulated radiation emission as the essential principle of how they work. The electrons in masers are hit by some form of electromagnetic waves which excite the electrons to a higher energy level, and when the electrons move down to a lower energy level, they emit a photon with a longer wavelength and lower frequency (less energy) than a laser. These are known as microwaves.

Differences

Lasers and masers both emit photons in what is called a stimulated radiation emission. The photons that the laser and maser emit are the result of an electron being excited to a higher energy level. The photons emitted either have high energy and frequency and short wavelengths (laser), or low energy and frequency and longer wavelength (maser) when the electrons return to their original state.

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