Question

Describe LASER under the following points:
(a) Meaning
(b) Basic Principle
(c) Uses.

Answer 1

(a) Meaning of Laser: It is a device by which an intense, monochromatic, parallel and highly coherent radiation is obtained. Laser means 'Light amplification by stimulated emission of radiation'.

(b) Basic principle: Some atoms have definite exciting energy state in which the atoms may remain for longer time (about ${10}^{-3}$ sec.) as compared to higher energy state. This state is called metastable state.

(c) Uses: Some uses of laser are as follows:

1. Medical science: A laser ray can produce a very narrow beam with very high intensity. This property is used in treatment of detached retina. Laser beams are also used in surgery controlling bleeding at the time of surgery, in the treatment of skin cancer and surgery of brain.

2. Communications: The ability of laser beam to travel long distances without spreading makes tool for signal and in radio communications.

3. Technology: The property of high intensity is used to cut hard metals, very fine drill in diamond, to cut the so many layers of clothes at a time. The infrared laser is used to erase spots of ink.

4. Meteorology: The weather informations are collected with the help of Radar, an instrument based on the properties of Laser.

5. Long distance measurement: The laser rays are parallel and do not spread, this property is used in the measurement of long distance. The distance of moon from earth is measured by laser device.

6. War field: To detect and destroy the rockets of enemy by laser. In observing the enemies at night.

7. Space science: To control the rockets, spaceship and satellites.

8. Holography: Laser is used to prepare hologram where three-dimensional pictures are produced. Three dimensional photography is known as holography.