LASER Light Diagram Construction Working Advantages Disadvantages Applications and types of Laser

LASERS :
Construction and Working of LASER :

• Laser means "Light Amplification by Simulated Emission of Radiation".
• Consider an atom when external energy (electromagnetic) is applied to it electron jumps from lower energy state to higher energy state.
  

• This electron emits electromagnetic radiation and light The colour of the light depends on frequency and wavelength.
• The energy released is known as photon energy. This process is called absorption. After a short time, the electron again goes to previous lower energy state emitting photon in the process.
• This is known as spontaneous emission. If a photon passes near to this electron, it causes the electron to decay.
• This causes emission of photon. Both photons are in the same phase. The above action described is fundamental for laser action.

• Under desired conditions, if atom undergoes stimulated emission, the atoms releases more photons. The action is cumulative and a chain reaction is formed which releases lot of photons.
• A large amount of energy is released. The wavelength of all photons is same. This process is known as amplification by simulated radiation.
• figure shows arrangement for production laser light energy.
• It consists of external source in the form of flashing light source, two mirrors, laser rod.
• The full reflecting mirror has high reflecting capacity (about 99 %). The other mirror has less reflectivity.

• External source is in the form of flashing light. When light flashes on laser rod, stimulated emission takes place. The photons travel back and forth due to mirrors.
• The amplification takes place. When energy released is greater than certain limit , laser light comes out in the form of sharp beam. The laser beam comes out from partially reflecting mirror.
• The laser beam intensity depends on-size of laser rod, optical cavity, location reflectivity of mirrors.

There are many Types of LASER. These and below :

1. Gas lasers
2. Liquid lasers
3. Chemical lasers
4. Optically pumped solid state lasers
5. Semiconductor lasers
6. X - ray lasers.

Advantages of LASER :

1. Laser beam can travel long distance.
2. Can be used for beautification.
3. Can be used in medical equipment.
4. Can be used in metal processing industries.

Disadvantages of LASER :

1. Operating equipment, control gear is required.
2. Cost is more.
3. High intensity may cause damage to organs.
4. Strict safety precautions are necessary.

Applications of LASER :

1. Special light effects required for media work.
2. In metal works for cutting of metals, welding of metals.
3. Medical field - Many surgical instruments are laser based.These are used in surgery.
4. Laser beam arrangement is used in CD drive of computer for reading/writing data on CD.
5. In missile launchers and other defense applications.