Linear electrostatic modulator

• US 5,661,593 A
• Filed: 09/01/1995
• Issued: 08/26/1997
• Est. Priority Date: 10/01/1992
• Status: Expired due to Fees

• Current Assignee: Craig D. Engle
• Original Assignee: Craig D. Engle
• Inventors: Engle, Craig D.
• Primary Examiner(s): ANDERSON, BRUCE C
• Application Number:
  US08/522,591
• Time in Patent Office: 725 Days
• Field of Search: 359/291, 359/292
• US Class Current: 359/292
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means

Abstract

A plurality of reflective conductors (28) are affixed to an insulating substrate (12). Each reflective conductor (28) overlaps and is separated from a first electrode (18) affixed to the substrate (12) thereby forming a plurality of capacitive pixel elements (32). Each capacitive pixel element (32) is electrically connected to a respective thin film transistor (40) to assist in controlling the potential difference applied to the pixel element (32). Varying each potential difference varies separation between the reflective conductor (28) and first electrode (18) thereby phase modulating a wavefront incident thereon. Thin film transistors (40) are formed on the substrate (12).

Claims

1. An electrostatic spatial light modulator comprising:

an insulating substrate,

a capacitive pixel element comprising;

first electrode means affixed to said substrate,

reflective conductor means affixed to said substrate overlapping and separated from said first electrode means,

an electronic switch,

said electronic switch comprises a first terminal, a second terminal and a third terminal,

said first terminal to said electronic switch is electrically connected to said pixel element,

said electronic switch comprises a device selected from the group consisting of a) thin film transistors formed on said substrate and b) threshold device pairs affixed to said substrate coupled together at said first terminal of said electronic switch in non-opposing series relation, said threshold devices being of the type which provides a low impedance to current flow when forward biased into an on condition,

potential control means for applying to said pixel element a potential difference comprising;

means operatively associated with said control means electrically connected to said second terminal of said electronic switch to enable said potential difference to be dependent on a potential applied to said third terminal of said electronic switch,

whereby varying said potential difference varies separation between said reflective conductor means and said first electrode means of said pixel element thereby modulating a wavefront incident on said reflective conductor means.

2. An electrostatic spatial light modulator comprising:

an insulating substrate,

first electrode means affixed to said substrate,

reflective conductor means affixed to said substrate overlapping and separated from said first electrode means to form a plurality of capacitive pixel elements,

a plurality of electronic switches,

each said electronic switch comprises a first terminal, a second terminal and a third terminal,

said first terminal of each said electronic switch is electrically connected to a respective pixel element,

each said electronic switch comprises a device selected from the group consisting of a) thin film transistors formed on said substrate and b) threshold device pairs affixed to said substrate coupled together at said first terminal of said electronic switch in non-opposing series relation, said threshold devices being of the type which provides a low impedance to current flow when forward biased into an on condition,

potential control means including said electronic switches for applying to each said pixel element a respective potential difference which is dependent upon a first potential applied to said third terminal of said electronic switch electrically connected to said pixel element,

means operatively associated with said control means varying said potential differences which varies separation between said reflective conductor means and said first electrode means of the pixel element thereby modulating a wavefront incident on said reflective conductor means of said pixel element.

3. An electrostatic spatial light modular comprising:

an insulating substrate,

a plurality of pixel elements, each said pixel element comprising;

first electrode means affixed to said substrate, reflective conductor means affixed to said substrate overlapping and separated from said first electrode means,

a plurality of electronic switches,

each said electronic switch comprises a first terminal, a second terminal and a third terminal,

said first terminal of each said electronic switch is electrically connected to a respective pixel element,

each said electronic switch comprises a device selected from the group consisting of a) thin film transistors formed on said substrate and b) threshold device pairs affixed to said substrate coupled together at said first terminal of said electronic switch in non-opposing series relation, said threshold devices being of the type which provides a low impedance to current flow when forward biased into an on condition,

potential control means to apply to each said pixel element a respective potential difference comprising;

means operatively associated with said control means electrically connected to said second terminal of each said electronic switch to enable said potential difference applied to each said pixel element to be dependent on a potential applied to said third terminal of said electronic switch electrically connected to said pixel element,

whereby varying said potential difference applied to each said pixel element varies separation between said reflective conductor means and said first electrode means of the pixel element thereby modulating a wavefront incident on said reflective conductor means of said pixel element.