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Title: GR9677.058
Post by: conantee on December 08, 2010, 03:17:59 AM
58. A collimated laser beam emerging from a commercial HeNe laser has a diameter of about 1 millimeter. In order to convert this beam into a well-collimated beam of diamter 10 millimeters, two convex lenses are to be used. The first lens is of focal length 1.5 centimeters and is to be mounted at the output of the laser. What is the focal length, f, of the second lens and how far from the first lens should it be placed?
     f    Distance
(A) 4.5 \mbox{ cm}   6.0\mbox {cm}
(B) 10 \mbox{ cm}   10 \mbox{ cm}
(C) 10 \mbox{ cm}    11.5 \mbox{ cm}
(D) 15 \mbox{ cm}    15 \mbox{ cm}
(E) 15 \mbox{ cm}   16.5 \mbox{ cm}