Trial_final

# Trial_final - Trial Final Exam ECE 4300 Time Limit 2 hours...

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Trial Final Exam ECE 4300 Time Limit: 2 hours 1 . A Galilean telescope consists of two lenses of focal lengths f1 and f 2 , but the focal length f 1 is negative, meaning that this lens is a diverging lens. To avoid sign confusion, write it as f1 = -| f 1 |. Also, the lens spacing is no longer f 1 + f 2 but f 2 -| f 1 |. (a) Write the ABCD matrix for this telescope, from the input surface of the first lens to the output surface of the second lens (i.e., not accounting for any propagation distance before and after the telescope). (b) By applying the ABCD law to a collimated input beam with a Rayleigh range, z0, much larger than | f 1 |, show that the beam coming out of this telescope is not focused, but that it is magnified transversely in the ratio of M = f 2 /| f 1 |, i.e., its radius is M times larger than the radius of the input beam. 2. In ray optics, a beam may be focused an arbitrary distance away from a lens. However, there is an upper limit to how far from a lens a Gaussian beam may be focused.

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## This note was uploaded on 07/09/2009 for the course M&AE 326 taught by Professor Psiaki during the Spring '08 term at Cornell.

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Trial_final - Trial Final Exam ECE 4300 Time Limit 2 hours...

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