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Efficient Refraction of Light Incident at Near the Critical Angle

IP.com Disclosure Number: IPCOM000096808D
Original Publication Date: 1963-Nov-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 26K

Publishing Venue

IBM

Related People

Nethercot, AH: AUTHOR

Abstract

Light, approaching the interface between media having different indices of refraction, undergoes total internal reflection from it. This is when its angle of incidence is equal to or greater than the critical angle. When the angle of incidence is less than, but still near, the critical angle, only negligible amounts of light are transmitted across the interface. The rate of change of the angle of refraction of such transmitted light with respect to the rate of change of its angle of incidence is very great. Thus, an interface oriented to receive the output beam of a conventional beam deflector at an angle of incidence near the critical angle operates as a passive, high gain amplifier of changes in the angle of deflection of the output beam.

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Efficient Refraction of Light Incident at Near the Critical Angle

Light, approaching the interface between media having different indices of refraction, undergoes total internal reflection from it. This is when its angle of incidence is equal to or greater than the critical angle. When the angle of incidence is less than, but still near, the critical angle, only negligible amounts of light are transmitted across the interface. The rate of change of the angle of refraction of such transmitted light with respect to the rate of change of its angle of incidence is very great. Thus, an interface oriented to receive the output beam of a conventional beam deflector at an angle of incidence near the critical angle operates as a passive, high gain amplifier of changes in the angle of deflection of the output beam. When constructed of conventional optical materials, however, such an interface exhibits a prohibitively low transmission efficiency.

To construct an interface having a high transmission efficiency for light incident at near the critical angle, it is necessary to employ interface media having widely differing indices of refraction. Such media form an optical interface which has a polarizing angle closely approaching its critical angle. The polarizing angle is that angle of incidence at which light linearly polarized in the plane of incidence is totally transmitted across the interface.

For example, rutile (n~3) and air (n~1) form an interface having a polarizing ...