1. A Brief Account of LASER & Its Application
Jayanta Kumar Majhi
Assistant Professor
UG & PG Department of Physics
B.B.College, Asansol, West.Bengal

2. After this lesson you will learn
Brief history of laser
What is Laser?
Difference between ordinary light and LASER
Basic Principle & Requirements
Few Properties & Applications

3. Introduction
In 1917 Einstein Predicted the idea of Stimulated Emission
The idea was first used by Townes in1954 in the construction of a device called MASER
This principle was later extended to optical frequencies by Schawlow and Townes in 1958.
This led to the construction of new device called LASER
The first successful operation of laser was demonstrated by Maimann in 1960 using Ruby crystal.

4. Light Amplification by Stimulated Emission of Radiation
What is a LASER?
Light Amplification by Stimulated Emission of Radiation

5. Difference Between Ordinary Light and Laser Light
Spontaneous Emission
No Amplification
Stimulated Emission
Light Amplification

6. Basic Principle of Laser
Triggering Photon
Atom in Excited State E2 E2 E2 E2 E1 E1 E1
Atom in Ground State E1
Stimulated Emission take place in a particular direction
Spontaneous emission
take place in any direction
Absorption

7. Basic Requirements of Laser
There are three basic components of a Laser
Active Medium ( Solid, Liquid and Gas)
Pumping Mechanism to have PI (Optical or Electrical)
Feedback System (Optical Resonator)

8. Figure 1 1 Active Medium (Here Ruby Crystal)
Pumping Scheme (Optical means)
3 & Feedback system ( Mirror)
Output i.e. LASER light

9. Figure 2: Population Inversion

10. Figure 3

11. Properties of LASER Light
Highly monochromatic (i.e. Single color)
Highly coherent ( i. e. highly systemic)
Highly directional (No Spreading)
Highly intense (Energy is very high)
Smallest divergence & highest power density
Smallest spot size or beam diameter

12. Applications In holography i.e. to produce and reproduce 3D image
Read hologram
Barcode Scanning
Bleeding less Surgery
Retinal attachment and detachment in eye surgery
Remote monitoring in defense, Fibre Optics and Communication system
In Engineering works : Cutting, drilling and welding
In jewellery etc.

13. In 3D Technology

14. In 3D technology contd.

15. In Defense

16. Eye Surgery
Fig A
Fig B

17. Skin Resurfacing

18. In Jewellery

19. In Industry

20. In Communication

21. Thank you