Dynamic holographic display with cantilever

• US 5,266,531 A
• Filed: 04/28/1992
• Issued: 11/30/1993
• Est. Priority Date: 01/30/1991
• Status: Expired due to Fees

• Current Assignee: PDACO LIMITED
• Original Assignee: Cordata, Inc.
• Inventors: Kikinis, Dan
• Primary Examiner(s): Chaudhuri, Olik
• Assistant Examiner(s): OJAN, OURMAZD
• Application Number:
  US07/876,061
• Time in Patent Office: 581 Days
• Field of Search: 437/228, 156/644, 156/662, 148/DIG. 73
• US Class Current: 438/29
• CPC Class Codes: G03H 1/22 Processes or apparatus for obtaining an optical image from holograms G03H1/26 - G03H1/34 take precedence
• CPC Class Codes: G03H 1/2294 Addressing the hologram to an active spatial light modulator
• CPC Class Codes: G03H 2225/24 Having movable pixels, e.g. microelectromechanical systems [MEMS]

Abstract

A dynamic holographic display has an array of reflective surfaces formed on cantilever structures substantially parallel to the surface of a substrate, such as a silicon wafer. A holographic image is formed by controlling electrical currents passed through the cantilever structures to position the reflective surfaces of the cells in the array so the topography forms a hologram, and reflected light interferes to form a holographic image. In a preferred embodiment, control is by computer and positions of reflective surfaces are determined by calculation from dimensional data available to the control computer.

Claims

1. A method of forming a movable reflective surface on a substrate for making a dynamic holographic display device comprising the steps of:

etching and undercutting a U-shaped trench in a surface of said substrate such that a cantilever structure is formed that extends in a direction substantially parallel to said substrate surface;

forming a reflective coating to at least a portion of said cantilever structure to form said movable reflective surface; and

providing electrical contacts to said substrate and to said cantilever structure so that passing an electrical current through said cantilever structure heats said cantilever structure, as a result deforming said cantilever structure to thereby move said movable reflective surface.

2. A method as in claim 1 wherein said substrate comprises a doped semiconductor substrate.