Physics & Astronomy ETDs

Publication Date

5-21-1971

Abstract

It was undertaken to investigate the intensity ratio of refracted light polarized parallel and perpendicular to the plane of incidence. The primary object of the experiment was to obtain this ratio for light incident at very nearly the critical angle on a water-air interface, the light having first passed through the water. A laser was used to produce the light beam and the experimental results were compared with the theory propounded by Fresnel for infinite plane waves and elsewhere asserted to hold for bound plane waves. As this theory predicted a ratio of the square of the refractive index (n) for the water and the ratio calculated was smaller than this by some 23-24%, further data were taken. The water ratio was within several percent of n, so similar measurements were made with a prism of dense glass, having a much higher refractive index. This ratio was even less in agreement with the theory, being almost 35% smaller. However, it was about 12% larger than the n obtained for the glass, so the experimental ratio is apparently not simply n. The intensity ratio was investigated with the glass prism for angles of incidence some degrees less than the critical angle. These measurements differ from the theory for the first several degrees away from the critical angle, but the later figures are quite close to those expected. Shifting the experimental curve one degree further from the critical angle would greatly improve the agreement with the theoretical curve. Several checks were made to see if the angles at which the data were taken were not actually somewhat smaller than they were believed to be, but it appears that these angles should, indeed, be fewer than three minutes from the critical angle. This is an extreme upper limit, and would not lower the theoretical ratio more than 5 or 6%. It has been suggested that the two polarizations may be differentially absorbed by the glass and water. The distilled water used held large amounts of dust in suspension, and the glass prism could well contain similar inhomogeneities. This would be worth investigating, particularly as the attenuation due to this water has been shown to be over 50% of light intensity in a distance of one meter.

Degree Name

Physics

Level of Degree

Masters

Department Name

Physics & Astronomy

First Committee Member (Chair)

Howard Carnes Bryant

Second Committee Member

Christopher Pratt Leavitt

Third Committee Member

David Solomon King

Language

English

Document Type

Thesis

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