Spatial light modulator with full complex light modulation capability

• US 5,148,157 A
• Filed: 09/28/1990
• Issued: 09/15/1992
• Est. Priority Date: 09/28/1990
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Florence, James M.
• Primary Examiner(s): Oberley, Alvin E.
• Assistant Examiner(s): Liang, Regina
• Application Number:
  US07/590,405
• Time in Patent Office: 718 Days
• Field of Search: 340/783, 340/763, 340/764, 340/825.27, 350/6.5, 350/6.6, 350/486, 350/487, 350/374, 350/269, 358/206, 358/208, 330/4.3, 359/392, 359/391, 359/317, 359/318, 359/259, 359/277, 359/279
• US Class Current: 345/84
• CPC Class Codes: G02B 26/001 based on interference in an adjustable optical cavity interference filters G02B5/28; devices or arrangements using multiple reflections in spectrometry or monochromators G01J3/26
• CPC Class Codes: G02B 26/06 for controlling the phase of light G02B26/08 takes precedence , measuring optical phase difference G01J9/00
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: G09F 9/372 the positions of the elements being controlled by the application of an electric field
• CPC Class Codes: G09G 2300/0443 with several sub-pixels for the same colour in a pixel, not specifically used to display gradations G09G3/364 takes precedence
• CPC Class Codes: G09G 3/346 based on modulation of the reflection angle, e.g. micromirrors micromirrors devices per se G02B26/0833

Abstract

It is possible to control the amplitude and phase modulation of light independently and simultaneously. The invention described here details how to do so by dividing a picture element into smaller modulating elements, providing independent addressing for each element, setting the necessary angle for each element and then resolving them into the picture element. The invention also show one embodiment of the invention.

Claims

1. A method for full complex modulation of light comprising the following:

a) dividing a picture element into a number of modulating elements;

b) providing addressing circuitry for each of said modulating elements;

c) selecting a net phase and amplitude of modulation;

d) calculating angles to achieve said net phase and said amplitude of modulation;

e) addressing said modulating elements to achieve said angles for independent control of said amplitude and net phase in the picture element response; and

f) resolving said modulation elements as said picture element.

2. The method of claim 1, wherein:

a) said addressing circuitry is made up of activation electrodes, one electrode corresponding to one modulating element.

3. The method of claim 1, wherein:

a) said addressing of said modulating elements consists of applying a perdetermined voltage to an electrode; and

b) locating said electrode directly under said modulating element.

4. A spatial light modulator, comprising:

a) a plurality of picture elements formed in a layered structure, each pixel being divided in half along a common horizontal axis, said layer structure further comprising;

i) a substrate;

ii) a reflecting layer divided into said plurality of said picture elements, said picture elements being suspended over a well;

iii) electrodes in said well, such that one electrode corresponds to one half of each said picture element being divided in half; and

b) electrical addressing circuitry such that each said half is independently addressable for full complex modulation.

5. The modulator of claim 4, wherein:

a) said modulator is divided into two halves;

b) spacers are positioned at either end of the gap between the two halves;

c) said halves are independently deflectable providing the application of an electrostatic force; and

d) said electrostatic force is applied by activation of respective electrodes under each of said halves.