Physics & Astronomy ETDs

Publication Date

5-14-1967

Abstract

The purpose of this investigation was to continue the study of surface wave phenomena initiated by Woodward and Bryant. [l], [2] Woodward, using an experimental arrangement similar to that shown in Fig. 3, observed that the intensity of light measured above, but parallel to, the reflected beam was a very sharp function of the incident beam angle at the critical angle. They also observed that the light intensity above the reflected beam decreased exponentially as the detector was moved away from the reflected beam in the plane of incidence. They reported characteristic lengths for the exponential decay constant of 9.6 ± 1.5 mm for the electric vector, Ē, oriented parallel to the plane of incidence and 6.2 ± 1.5 mm for Ē normal to the plane of incidence. It was desired to verify these results, since these authors con­sidered their detection system somewhat inadequate. They used a non-linear photoconductive cell which required calibration, but more importantly perhaps, the sensitivity of their detector was relatively low, requiring a large aperture optical system. Although Woodward demonstrated analytically the size of the telescope aperture would not affect the characteristic length, his aperture was of such an extent that it was effectively averaging light over distances greater than the characteristic lengths being measured. It was felt that initially, in this investigation attention should be directed towards improving the quality of the detection system.

Other investigators have observed at least qualitatively similar phenomena as that described by Woodward and Bryant. For instance, Osterberg and Smith [3] in experiments with glass plates and prisms observed that light incident at the critical angle could be detected some distance away from the incident beam by placing another prism on the glass surface. If the glass plates and prisms were homogeneous, (i.e. free of internal strains) the distance light could be detected from the incident beam, was short, on the order of a few millimeters. In certain cases where the glass was inhomogeneous, they were able to detect light that had traveled nearly a meter along the surface. They presented a simple diffraction theory to explain the transmission of light along the surface when the incident beam is at the critical angle. In somewhat similar experiments, Maecker [4] using spherical waves and a photographic detection technique, observed a "comet tail" of light along the surface of a glass prism. He measured the intensity of light as a function of distance from the incident beam and observed that it decreased as the inverse cube of the distance, which apparently agreed with his theoretical predictions. The work of Maecker seems of fundamental importance and it would be very interesting to repeat his experiments using a laser as the light source and a photomultiplier as well as a camera to detect the surface light intensity. Another surface wave effect, which may be at least peripherally related to the results described by the above mentioned authors, is that reported by Goos and Hanchen [5]. By studying multiple reflections in glass plates they were able to determine that the reflected ray was translated a very short distance (a few microns) parallel the plane of incidence. One of the more interesting theoretical ideas connected with the phenomenon of total internal reflection is that of Fedorov [6], who suggested that for incident light of arbitrary polarization relative to the plane of incidence, the refracted beam would be shifted laterally out of the plane of incidence.

In the context of the somewhat incomplete knowledge of surface wave properties, it was believed that an investigation of the influence of the optical medium on such properties might prove enlightening. Also, if possible, it was desired to verify experimentally the lateral shift of electromagnetic energy out of the plane of incidence as predicted theoret­ically by Fedorov.

Degree Name

Physics

Level of Degree

Masters

Department Name

Physics & Astronomy

First Committee Member (Chair)

Howard Carnes Bryant

Second Committee Member

Seymour Samuel Alpert

Third Committee Member

Derek B. Swinson

Fourth Committee Member

Colston Chandler

Language

English

Document Type

Thesis

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