Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

Tunnel Light Modulator

IP.com Disclosure Number: IPCOM000094839D
Original Publication Date: 1965-Jun-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

French, WK: AUTHOR

Abstract

It is known that at the interface between two media of different optical densities total reflection will occur if the sine of the angle of incidence is greater than N2/N1 where N1 and N2 are the respective indices of refraction of the two media. If the second medium is a very thin layer, the thickness of which is a fraction of the wavelength of the incident ray, total reflection does not occur. Part of the ray continues through the second medium without any change in direction. If a third medium follows the second medium, the portion of the ray transmitted by the second medium is refracted in the third medium according to the relative index of refraction of the first and third medium. The percentage of transmitted and reflected energy will in any case be determined by the thickness of the low-density layer.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 71% of the total text.

Page 1 of 2

Tunnel Light Modulator

It is known that at the interface between two media of different optical densities total reflection will occur if the sine of the angle of incidence is greater than N2/N1 where N1 and N2 are the respective indices of refraction of the two media. If the second medium is a very thin layer, the thickness of which is a fraction of the wavelength of the incident ray, total reflection does not occur. Part of the ray continues through the second medium without any change in direction. If a third medium follows the second medium, the portion of the ray transmitted by the second medium is refracted in the third medium according to the relative index of refraction of the first and third medium. The percentage of transmitted and reflected energy will in any case be determined by the thickness of the low- density layer.

The foregoing phenomenon, which is an application of Snell's Law, is used by the apparatus shown. Entrance prism 10 has its surface 10A cut at an angle to cause entering light rays 11, preferably from a laser source, to be totally reflected along path 12. Quartz plate 13 is disposed with surface 13A slightly off-parallel with respect to surface 10A and spaced by distance of one quarter wavelength. Surface 13A and its opposite parallel surface can be partially silvered. This permits an electrostatic field to be generated across the quartz crystal-causing it to expand under the piezoelectric effect and thus modulate the air gap between fa...