# Lab5 - photodiode and record the data with the computer. 1....

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1 Lab 5: Diffraction Introduction We will look at the wave nature of light in a set of experiments where diffraction and interference patterns are produced when laser light is incident on various obstacles. Background - see Pedrotti^3, Chapter 11 The general arrangement that will produce a diffraction pattern is illustrated schematically in the figure above. At a distance D from the obstacle, the intensity of the diffracted light will be measured as a function of the x coordinate. The diffraction patterns are relatively simple in the far field limit, where 1 / 2 << λ D a , where a is the characteristic dimension of the obstacle (such as the width of a slit) and is the wavelength of light. This is the Fraunhofer diffraction limit, and the diffraction patterns are simply Fourier transforms of the diffracting object. Experiment In the following experiments, you will scan the diffraction patterns with a linearly driven
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Unformatted text preview: photodiode and record the data with the computer. 1. Measure the diffraction patterns from single and multiple slits. In the far field limit, you should be able to extract the slit parameters by analysis of your diffraction patterns. Determine the slit widths for at least two single slits, and the slit width and spacing for at least one double slit. Compare your results with a measurement of the slit widths with the microscope. 2. Using Babinets principle (which relates the diffraction pattern of a mask to its complement), measure the diameter of a human hair (your own if you have one to spare!). 3. Using a razor blade (BE CAREFUL! Do not cut yourself!), cut a slit in aluminum foil and measure the diffraction pattern. From it, deduce the slit width. Compare to the width from microscopy. Repeat with two closely-spaced slits you cut into the foil....
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## This note was uploaded on 12/29/2011 for the course PHYSICS 375 taught by Professor Eno during the Spring '11 term at Maryland.

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