Experiment 2 - Geometrical Optics 1Experiment 2Geometrical Optics1 IntroductionIn this experiment, we will continue to explore geometrical optics bystudying the optics of simple curved mirrors and lenses.2 Background - see Pedrotti3, Sections 2-6 to 2-9When studying the geometrical optics of mirrors or lenses one considersthe following three quantities: object distance so, image distance si,and focal length f. These quantities are related by the equation1so+1si=1f(1)There is a convention to be followed in the definition of these quantities.For lenses, a converging lens (convex) has f > 0 while a diverging lens(concave) has f < 0. For mirrors, f > 0 for concave mirrors, and f < 0for conve x mirrors. Also by convention, we place the object to the leftof the lens, with so> 0. If si> 0, it is on the right of the lens and isa real image. If si< 0 it is to the left of the lens (same side as object)and is a virtual image. One can consider the mirror as a folded overversion of the lens: sois positive and on the left, but now a si> 0 ison the left (the opposite of the lens) and si< 0 is on the right, behindthe mirror, and a virtual image.The focal le ngth of a spherical mirror is simply f = R /2, where R isthe radius of the mirror, and the focal length of a thin lens is given by1f= (n − 1)1R1−1R2, (2)where n is the index of refraction, and Riare the radii of curvature ofthe two surfaces.Experiment 2 - Geometrical Optics 23 ExperimentYou are supplied with a concave mirror, and two lenses. Your chal-lenge is to find the focal lengths of the optics as accurately as possible.A first start is to use an object at infinity (or close to it). Thewindows in the hallway are a good place to start.You have available the laser as a source of rays to do ray tracing.Think about what happens to the rays as they pass through a lens, orbounce off a mirror. Also available is a scanning photodiode, which willallow you to use the computer to acquire beam position and sizes.Using two (or more) optics, build a compound lens device, and mea-sure its
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