e894a2g

e894a2g - 3 Given an Argon Ion laser running its main green...

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ENSC 460/894 Assignment 2: (Oct. 14 due Oct. 21 2003) 1 For a HeNe laser calculate the ratio of the spontaneous radiation coefficient to the stimulated coefficient (HeNe wavelength is 632.8 nm). (5 marks) 2 A Huygens eyepiece (occular) is a combination of two positive thin lenses of the same glass. If the lenses are separated by half the sum of their focal lengths then chromatic aberration is eliminated. Assume two thin lenses of f values 2.5 cm (field lens - furthest from the eye) and 1.5 cm (eye lens - closest to the user). (a) What is the combined focal length of the eyepiece (3 marks) (b) What is the eyepiece magnification (2 marks) (c) Assume the stated f is for the c line (red colour) of a dense flint (DF-2 in the chart). What would be the change in the f's of the two lenses and the eyepiece for the g line (violet) (5 marks).
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Unformatted text preview: 3 Given an Argon Ion laser running its main green line, with a beam radius of 1 mm design a beam expander to expand the beam radius to 5 mm using a main lens of f = 30 cm. Do both Galilean and Keplerian expander and draw the design. State what f input lens is required and the length of the system (5 marks each) 4 Calculate the Q value for a CO 2 laser (wavelength 10.6 microns) with a 2 m cavity and mirror reflectances of 100% for the rear and 40% for the output window. (5 marks) 5(a) What is the average number of round trips for a photon in a laser with mirror reflectances of 100% for the back mirror and 40% for the front mirror? (2 marks) (b) If the optical cavity length is 1.5 m, with is the cavity lifetime? (2 marks)...
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