Podcast
Questions and Answers
What does the acronym 'laser' stand for?
Light Amplification by Stimulated Emission of Radiation.
What are the primary components of a helium-neon (He-Ne) laser?
A mixture of helium and neon gas and a small bore capillary tube.
At what wavelength does the most widely used He-Ne laser operate?
632.8 nm.
What property of laser light distinguishes it from other light sources?
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What method is used to excite the helium-neon mixture in a He-Ne laser?
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What is the purpose of the output coupler in a He-Ne laser?
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What characteristic allows laser beams to travel over great distances?
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What does the Gaussian intensity profile in laser beam propagation refer to?
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Name one application of lasers due to their properties.
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Why is the wavelength of laser light considered extremely pure?
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Study Notes
Helium-Neon Laser (He-Ne)
- Lasers are devices that produce intense beams of light which are monochromatic, coherent, and highly collimated.
- The term "laser" originated as an acronym for "Light Amplification by Stimulated Emission of Radiation".
- A helium-neon laser (He Ne) laser is a type of gas laser whose gain medium consists of a mixture of helium and neon (10:1) inside of a small bore capillary tube.
- The most widely used He Ne laser operates at a wavelength of 632.8 nm (in the red part of the visible spectrum).
- The He-Ne laser is excited by a DC electrical discharge.
He-Ne Laser Schematic Diagram
- The He-Ne laser consists of a laser bore tube (usually a capillary tube) filled with a 10:1 ratio of Helium and Neon gas.
- The laser bore tube is enclosed in a glass envelope which contains a reservoir of Helium-Neon gas.
- The He-Neon gas is excited by a DC electrical discharge which is applied between an anode and a cathode.
- The laser bore tube is also equipped with a high reflector (a mirror which reflects nearly all of the light that strikes it) and one output coupler (a mirror which allows a small amount of light to pass through it).
- The output coupler is used to couple the laser beam out of the laser cavity.
- The high reflector and the output coupler form a resonant cavity.
- When the He-Ne gas is excited, it emits photons of light.
- The photons then travel back and forth between the high reflector and the output coupler.
- As the photons travel, they stimulate more atoms to emit photons.
- This process is called stimulated emission.
- The stimulated photons are emitted in phase with the original photons.
- These photons are then amplified by the stimulated emission.
- This amplification process creates the laser beam which is emitted from the output coupler.
- The wavelength of the laser beam is determined by the type of gas used, and the length of the resonant cavity.
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Description
Explore the fascinating world of Helium-Neon lasers, their construction, and how they operate. This quiz covers key principles including the gas mixture, operating wavelength, and the process of light amplification. Test your knowledge on the components and functionality of He-Ne lasers.
