Method and apparatus for controllable frustration of total internal reflection

• US 5,999,307 A
• Filed: 09/04/1997
• Issued: 12/07/1999
• Est. Priority Date: 09/04/1997
• Status: Expired due to Term

• Current Assignee: Concord HK International Education Limited
• Original Assignee: University of British Columbia
• Inventors: Tiedje, J. Thomas, Whitehead, Lorne A., Coope, Robin John Noel
• Primary Examiner(s): Spyrou, Cassandra
• Assistant Examiner(s): WINSTEDT, JENNIFER E
• Application Number:
  US08/923,431
• Time in Patent Office: 824 Days
• Field of Search: 359/222, 359/298, 359/318, 359/320, 359/896, 156/155
• US Class Current: 359/298
• CPC Class Codes: B29C 2035/0827 using UV radiation
• CPC Class Codes: B29C 59/16 by wave energy or particle radiation , e.g. infrared heating B29C59/007 takes precedence
• CPC Class Codes: B29K 2021/00 Use of unspecified rubbers as moulding material
• CPC Class Codes: G02B 26/02 for controlling the intensity of light G02B26/004 takes precedence

Abstract

A method and apparatus for facilitating controllable switching an interface between a reflective state in which light incident upon the interface undergoes total internal reflection, and a non-reflective state in which total internal reflection is prevented at the interface. The apparatus incorporates a member (preferably an elastomer) which is deformable with respect to the interface. The member'"'"'s Young'"'"'s Modulus in portions of the member adjacent the interface is substantially greater (i.e. stiffer) than the member'"'"'s Young'"'"'s Modulus in portions of the member away from the interface. The stiffened portion of the member adjacent the interface may be in the form of a microstructure. A pair of electrodes coupled to a voltage source can be provided to controllably deform the member into optical contact with the interface, within a continuously variable range of optical contact values, to produce the non-reflective state in selectably varying degrees.

Claims

1. Apparatus for controllably switching an interface between a reflective state in which light incident upon said interface undergoes total internal reflection and a non-reflective state in which said total internal reflection is prevented at said interface, said apparatus comprising a member deformable with respect to said interface, said member'"'"'s Young'"'"'s Modulus in portions of said member adjacent said interface being substantially greater than said member'"'"'s Young'"'"'s Modulus in portions of said member away from said interface, wherein E>

a/d, where E is said member'"'"'s Young'"'"'s Modulus at portions of said member adjacent said interface, a is the bond energy per unit area due to the Van der Waals force between said interface and said member, and d is a dimension characteristic of roughness of said interface.