working, history and construction of laser.

2. 

3.  WHAT IS LASER
 INTRO TO LASER AND ITS HISTORICAL DEVELOPMENT.
 CHARACTERISTICS OF LASER
 BASIC CONDITIONS FOR LASER ACTION
 COMPONENTS OF LASER DEVICES
 VISUALIZATION OF LASER ACTION

4.  A LASER(Light Amplification by Stimulated Emission of Radiation) is a
device that emits light through a process of optical amplification based
on the stimulated emission of EM radiation.

5.  There can be no doubt that the laser represents one of the most remarkable
scientific and technical milestones of the 20th century. The dramatic growth of
laser technology began in 1960, when the first successful laser was reported. Lasers
are now used in the most diverse fields: biology and medicine, cybernetics and
computer circuitry, communications and radar systems, industrial processes, and
measurements of various types.

6. HISTORICAL DEVELOPMENT
 Sir Albert Einstein, in 1917 ,predicted the process of stimulated emission which later
become the base of LASER.
 C. Townes and his Co-workers in U.S.A and N. Basov et. al in USSR, in 1954 discover
MASER(Microwave Amplification by Stimulated Emission of Radiation).
 The concept of light amplification by an optical mirror resonant cavity was put
forward in 1958 by C. Townes and N. Basov et. al which was the actual base of LASER
action.
 T. Maiman, in 1960, produced the first LASER using ruby crystal.
 He-Ne LASER was developed by A. Javan et. al, in 1961.
 Thereafter various other LASER devices were discovered in the coming years.

7. CHARATERISTICS OF LASER
 High Directionality
 High Intensity
 Extraordinary Mono-Chromaticity
 High Degree Of Coherence

8.  There must be some metastable states
 To achieve population inversion
 To trigger stimulated emission by first few randomly emitted spontaneous
photons
 The stimulated emitted photons produce more stimulation and consequently
light gets amplified as more and more photons gets multiplied.

9.  The LASER Medium or Active Medium:- It is the material in which the LASER action take
place. It may be solid(Ruby), liquid() or gas(He-Ne).
 Pumping Device:- The process by which atoms(active centers) are raised from lower energy
level to upper energy level is called pumping. It is required to achieve population inversion.
 (a) Optical Pumping: In optical pumping light is used to excite the atoms.
 (b) Electrical Pumping: It is used for gas LASERs. In this electrical discharge tube is used to
supply the necessary energy to the active medium(gas).
 (c) Chemical Pumping: The energy given by a chemical reaction to excite the atoms of
active medium.
 (d) X-ray Pumping: In this process the X-ray is used to excite the medium.

10.  The Resonator or Optical Resonant Cavity:- It consist of of a pair of plane or
spherical mirrors having common principal axis. The reflection coefficient of one
of the mirror is very near to 1 and that of other is kept somewhat less than 1. It is
just like a feedback device which make photons to follow back and forth motion
through medium

11. NOW
LETS VISUALIZE THE LASER

13. Thank You Very Much
For your Kind Attention..