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

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

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.

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

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

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

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)

Figure 1 1 Active Medium (Here Ruby Crystal) 2 Pumping Scheme (Optical means) 3 & 4 Feedback system ( Mirror) 5 Output i.e. LASER light

Figure 2: Population Inversion

Figure 3

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

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.

In 3D Technology

In 3D technology contd.

In Defense

Eye Surgery Fig A Fig B http://www.life123.com/bm.pix/bigstockphoto_close_up_of_eye_surgery_catar_2264267.s600x600.jpg

Skin Resurfacing

In Jewellery

In Industry

In Communication

Thank you