PTU Important Questions----LASERS

                                   Physics:



Important Questions related to chapter --LASERS.


 2-marks/4-marks


Q1. What is laser?
Q2. What is holography?
Q3. Explain how a laser light is different from ordinary light?
Q4. Explain the terms:
      1)Stimulated emission 2) Population Inversion 3) Optical Pumping
      4)Stimulated absorption
Q5. State any four methods of pumping a laser.
Q6. Explain how a hologram differs from phtograph?
Q7. Explain spiking process.
Q8. Differentiate between spatial coherence and temporal coherence.
Q9. Differentiate between 3-level and 4-level laser.
Q10. Are all holograms same?
Q11.write physical significance of Einstein's coefficients.
Q12. Explain the role of Helium in He-Ne laser.
Q13. Differentiate between spontaneous emission and stimulated emission.
Q14.State any two applications of Holography.
Q15. Explain why a 4-level laser is preferred over 3-level laser although it has low efficiency?
Q16. What do you mean by coherance length? write down the expression for it.
Q17. What is the wavelength of He-Ne Laser, Semiconductor Laser?

6-marks/8-marks

Q1. a) Explain the construction, working and the energy level diagram for
           He-Ne laser.
       b) Explain process of spiking in Ruby laser.

Q2. a) Explain the construction, working and the energy level diagram for Ruby laser.
       b) Define Einstein coefficients and give their significance.

Q3. What do you understand by holography? Derive the relationship between
       Einstein coefficients.

image source: lasers.llnl.gov