Laser

By Jacklyn

Have you ever seen a laser or wonder how does the laser works? Well, laser is a special form of light that does not exist in nature but only human technology. They are a powerful beams of electromagnetic radiation. Their beams can be made from x-rays, ultraviolet light, infrared light, or visible light. If you ever watch "Star Wars", "Star Trek", or "Battlestar", those are a role in science fiction movies or books.

Laser

Lasers are really useful. Think about CD & DVD player, bar code reader, machine for cutting metals, and other more stuffs. They are made with lasers. How could laser do we those? :


  • CD & DVD player, it use laser when you want to watch movie / TV or listen music and others.
  • In stores, you may see the bar codes reader to calculate the total payment with bar codes reader; used by laser.
  • TV & Telephones use signals over the cables with lasers. You may call people, watch TV, connect with TV and play games, and others.
  • Also, surgeon use the laser for eye surgery; it is painless because the laser pass through patient's eyes.


Also, the laser stands for Light Amplification by Stimulated Emission of Radiation

How is laser light different from natural light?

First, what is natural light?

Natural light is a light that has many different types and colours of wavelengths. The light waves spread out in all direction. When they combine altogether, it will produce white light. For example, when white light shines through the triangular prism, the light separated and form a rainbow.

Differences...

Unlike natural light, it is all in one wavelength; contains only one colour. They are same phase, lined up, same direction, very narrow, and all the energy is focused to make a small point. The laser is useful for cutting and welding metals, can be control, and make it do all kinds of useful things.

How do laser works?

  1. A high-voltage electric supply makes the tube flash on and off.
  2. Every time the tube flashes, it produce energy into the ruby crystal. It makes the flashes put energy into the crystal in the form of photons.
  3. Atoms in the ruby crystal soak up this energy. This process is called absorption. When an atom absorbs a photon of energy, one of its electrons jumps from a low to higher level of energy; puts the atom in excitement but makes it unstable because the electron can stay in the higher energy level for a few milliseconds. It goes back to its original level; giving off the energy it absorbed. This process is called spontaneous emission.
  4. The photons that atoms give off, zoom up and down inside the ruby crystal, traveling like a light traveling speed.
  5. Every so often, one of these photons hits an excited atom. Then, the excited atom gives off two photons. This is called stimulated emission. Now one photon has produced two, so the light has been bigger.
  6. A mirror at one end of the laser tube keeps the photons bouncing back and forth inside the crystal.
  7. A partial mirror at the other end of the tube bounces some photons back into the crystal but lets some escape.
  8. The escaping photons make a very narrow, bright beam of laser light.
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Summary of my Findings

What I found out is that the laser, unlike the natural light, has different wavelength; lined up, same colour, same direction with same speed, and this is useful for other inventions.

Bibliography - Research