1.LASER.pdf

LASER Dr. Ankur Pandya Physics Department Dr. Ankur Pandya IT,NU  LASER Light Amplification by Stimulated Emission of Radiation Dr. Ankur Pandya APPLICATIONS OF LASER..? Dr. Ankur Pandya  Turkey is preparing laser weapon for countering warshi...

LASER Dr. Ankur Pandya Physics Department Dr. Ankur Pandya IT,NU  LASER Light Amplification by Stimulated Emission of Radiation Dr. Ankur Pandya APPLICATIONS OF LASER..? Dr. Ankur Pandya  Turkey is preparing laser weapon for countering warships and destroying unmanned vehicles Dr. Ankur Pandya Dr. Ankur Pandya Virtual Key Board Using LASER Dr. Ankur Pandya  ALSO FOUND IN Laser Printer Cutting Rocks CD Writing Dr. Ankur Pandya MEDICAL FIELD APPLICATIONS Dr. Ankur Pandya ENGRAVING USING LASER Dr. Ankur Pandya WHY THESE APPLICATIONS ARE POSSIBLE……? Highly monochromatic Unidirectional Highly intense High degree of coherency Less divergent Dr. Ankur Pandya LASER:DIFFERENT FROM TRADIATIONAL SOURCES….. ? Dr. Ankur Pandya TRADITIONAL SOURCES ARE… ? Dr. Ankur Pandya  Plan of Talk Types of Optical LASER Resonator Pumping and its types Theoretical Aspects Time Line Dr. Ankur Pandya  Time Line 1954 –C. Townes and A.Schawlow 1961 – Ali 1974 - the first 1917 – invented the 1960 – T. public laser - 1978- 1982 – Laser Javan Dr. Albert maser using Maiman – barcode laserdisc utilized in CD ammonia gas Ruby Laser – He – Ne scanner at the player player Einstein and Laser supermarkets. microwave radiation Dr. Ankur Pandya THEORETICAL ASPECTS Dr. Ankur Pandya PROPOSED BY………(1917) Dr. Ankur Pandya Interaction between Atom & Input Energy Energy Spontaneous Absorption Emission A  h A* A* A  h N ab  B12 N1Qt N sp  A21 N 2 t Dr. Ankur Pandya Stimulated Emission N st  B21 N 2 Q t Dr. Ankur Pandya  Einstein's Coefficients N ab  B12 N1Qt N sp  A21 N 2 t N st  B21 N 2Qt Abbreviations N1 – No. of atoms in the Ground State N2 – No. of atoms in the Excited State Nab – No. of atoms participating in absorption Nsp - The probability of spontaneous emission Nst - The probability of stimulated emission Q – Spectral Energy Density (the photon density per unit frequency range ) A21 , B12 , B21 -----Dr. Ankur Einstein's Pandya Coefficients Conditions for Amplification N ab  N sp  N st B12 N1Q  A21 N 2  B21 N 2Q stimulated transitions B21 N 2Q B21   Q spon tan eous transition A21 N 2 A21 stimulated transition B21 N 2Q N 2   absorption transition B12 N1Q N1 Dr. Ankur Pandya  PumPing -“ process by which the atoms are energized from the ground state to the excited state” Types of Pumping optical pumping electrical direct conversion ( Solid State discharge (Semiconductor Laser) (Gas Laser) Laser) Dr. Ankur Pandya  Optical Pumping 1. Input energy is in terms of radiation 2. Applicable to solid state lasers (e.g. Ruby Laser) Dr. Ankur Pandya  Electric Discharge GAS LASERS Dr. Ankur Pandya Direct Conversion Dr. Ankur Pandya  Pumping Schemes Three Level Pumping Scheme Four Level Pumping Scheme Two Level Pumping Scheme Dr. Ankur Pandya Three Level Pumping Scheme Dr. Ankur Pandya Four Level Pumping Scheme Dr. Ankur Pandya Optical Resonator 2 L  mm Dr. Ankur Pandya Optical Resonator Dr. Ankur Pandya  Different Laser Systems Ruby Laser (Solid State Laser) He Ne Laser( Gas Laser) Co2 Laser Semiconductor Lasers Nd: YAG Laser Dr. Ankur Pandya Ruby Laser Dr. Ankur Pandya  Ruby Laser: Salient Features Al2o3 + Cr+3 (0.05%) Ruby Laser First visible laser system Red Laser beam (6943 Ǻ) Pulsed form output Dr. Ankur Pandya Energy level diagram Dr. Ankur Pandya He Ne Laser Potential Difference – 2000 V Dr. Ankur Pandya He Ne Laser Dr. Ankur Pandya He Ne Laser: Working Process Electron- He Atoms Collisions Field De- Emission Atomic Excitation Collisions: of Ne of He & Ne Electrons Excitation of Ne Atoms Dr. Ankur Pandya EnErgy LEvEL Diagram Dr. Ankur Pandya Dr. Ankur Pandya  Salient Features: He Ne Laser Power Production: 10- 40 mW highly stable Used in Holography due to mode stability long operating lifetime :> 20,000 hours Dr. Ankur Pandya  LIMITATIONS Limited to low power applications only Less Efficient: 0.1% Dr. Ankur Pandya HOLOGRAPHY Dr. Ankur Pandya HOLOGRAPHY Dr. Ankur Pandya HOLOGRAPHY Dr. Ankur Pandya Dr. Ankur Pandya Dr. Ankur Pandya Dr. Ankur Pandya Dr. Ankur Pandya HOLOGRAPHY Dr. Ankur Pandya