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What is the difference between a laser and a maser?

We’ve all heard of a laser, but what about a maser? What is the difference between the two?


Laser is an abbreviation of Light Amplification by Stimulated Emission of Radiation.


The maser - which stands for Mass Amplified by Stimulated Emission of Radiation - was discovered by the same team of scientists who produced the laser.



Lasers

What does a laser do?


A laser is a device that stimulates molecules or atoms to emit light at particular wavelengths.


It will then amplify that light and typically produce a very narrow beam of radiation.


Lasers are used in several items we use every day.


They include everything from optical disc drives and barcode scanners, to printers and entertainment systems.



What does a maser do?


A maser is a device that produces and amplifies electromagnetic radiation waves, mainly in the microwave region of the spectrum.


The very first maser was built at Columbia University in 1953 by Charles Townes, James Gordon, and Herbert Zeiger.


Masers produce much higher frequency than lasers and, thus, lower wavelengths of electromagnetic radiation.


When the laser was invented, it was actually known as an optical maser. This was then changed later on to what we now know as lasers.



What is an example of a maser?


Let’s look at the hydrogen maser.


Initially, a beam of atomic free radical hydrogen atoms is produced via high-frequency radio waves being introduced to the hydrogen at low pressure.


Next, the state is selected; as with lasers, a maser requires a population inversion of the atoms.


This is done via applying a magnetic field around the beam. It results in the atoms which remain inside and not being pulled from the beam by electromagnetic forces to have incredibly high relative energy states in comparison to ground-state hydrogen atoms, and thus an inversion of energy states from more ground state hydrogens to more excited state hydrogen atoms.


A microwave cavity then confines the microwaves emitted from the hydrogen atoms' emission. This further stimulates the high-energy population in a positive feedback loop, where more microwaves mean more excitation, and more excitation results in more microwaves.


A small fraction of the signal from the microwave cavity is allowed to be released into a coaxial cable (at a 90-degree angle to the beam) to a radio receiver.



What sort of use could we get out of this hydrogen maser?


This maser setup is used to produce atomic clocks. These are independent timepieces that are capable of measuring time without the influence of gravity.


Gravity and the relationship between space and time results in time measuring differently, depending on your distance from a gravitational source. This is of vital importance to code that operates on a time-based system


Imagine putting a million-dollar space exploration vehicle out into the stars, only to realize the code which asked for the collection of data every second in relative terms to earth instead sends back information every 1.5 seconds and fluctuates uncontrollably or something of the sort.