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Tuesday, 25 September 2012

Applied Optics-For MSc/B.E/B.Tech/M.Tech

1(a) What is luminescence? Differentiate between fluorescence and phosphorescence. (10 Marks)
(b) Explain three processes that take place during interaction of radiation with matter. (10 Marks)
2(a) What is population inversion? (4 Marks)
(b) Derive the relations between various Einstein co-efficients. (6 Marks)
(c) What are the basic requirements for an active medium in a laser system? (6 Marks)
(d) Determine the ratio of spontaneous to stimulated emission and A21/B21 if wavelength is 1390 nm and temperature 300K.     (4 Marks)
3(a) Explain in detail any 4 pumping mechanisms. (8Marks)
(b) What are the configurations possible for cavity resonators in a laser system? (6 Marks)
(c) Determine the  number of modes of standing waves in the resonant cavity of length 1m of  He-Ne laser operating  at wavelength 6328 Å.(6 Marks)
4(a) Explain with examples three-level and four-level laser systems. Mention advantages and disadvantages. (6 Marks)
(b) What is coherence? (6 marks)
(c) What is mode coupling? (4 Marks)
(d) What is a metastable state? (4 Marks)
5(a) With neat figures, explain the working of Ruby laser. (10 Marks)
(b) Explain the working of Nd:YAG laser. (10 Marks)
6(a) With the help of energy level diagram, explain the working of He-Ne gas laser. (10 Marks)
(b) Explain the working of C02 laser. (6 Marks)
(c) Calculate on the basis of Einstein’s theory the number of photons emitted per second by He-Ne laser source emitting light of wavelength 6328Å with an optical power 10 mW. (04 Marks)
7(a) Explain how lasers are used in cutting, drilling and welding operations in industry. (6 Marks)
(b) Write a short not on sensors developed by using lasers. (6 Marks)
(c) What is LIDAR? Explain. (4 Marks)
(d) What is the role of laser in ophthalmology? (4 Marks)
8 (a) Explain the construction of hologram using laser. Mention some applications of holography. (8 Marks)
(b) With a neat block diagram, explain fiber optic communication. (8 Marks)
(c) A fiber 500m long has an input power of 8.6 mw and output power 7.5 mw. What is the loss specification in cable? (4 Marks)

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