Physics & Astronomy ETDs

Publication Date



Theory predicts that the diffraction pattern of a conduction straight edge will show deviations from the diffraction pattern of a non-conductor, and further, that these deviations will depend upon the polarization of the incident light. In this experiment the diffraction of polarized, coherent light from a monochromatic source by a metallic straight edge was studied in a region near the edge of the geometrical shadow. Two orientations of the polarization were used: one with the E vector of the polarized light parallel to the diffracting edge, and the other with the E vector perpendicular to the diffracting edge. Three different straight edges were used: one with a sharp edge, another with a sharp edge that had been blackened in a solution of nitric acid and alcohol, and a third with a blunt edge. The light source used was a ruby laser, which produced a bean of highly coherent, monochromatic, polarized light. The diffraction patterns were photographed on glass spectroscopic plates; and after the plates were developed, their densities were measured with a photodensitometer. The intensity of the diffraction pattern as a function of distance along the plates perpendicular to the edge of the geometrical shadow was obtained from the density measurements. Experimental results were compared with the theoretical predictions of born and Wolf, and with those of Sommerfeld and the Raman and Krishnan modification of the Sommerfeld theory. This experiment was suggested by the results of the thesis experiment of Robert Lawrence Berger in which a large polarization effect as noted in the diffraction pattern of a sharp straight edge in the geometrical shadow. Berger’s experiment was not, however, primarily concerned with intensities in the shadow region, and further work seemed desirable.

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Level of Degree


Department Name

Physics & Astronomy

First Committee Member (Chair)

Howard Carnes Bryant

Second Committee Member

Christopher Dean

Third Committee Member

Victor H. Regener



Document Type