Multilayer Light Modulator

• US 20100220381A1
• Filed: 02/27/2009
• Published: 09/02/2010
• Est. Priority Date: 02/27/2009
• Status: Active Grant

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Frazier, Gary A.
• Granted Patent: US 7,894,123 B2
• Time in Patent Office: Days
• US Class Current: 359/296
• CPC Class Codes: G02F 1/167 by electrophoresis
• CPC Class Codes: G02F 1/172 based on a suspension of orientable dipolar particles, e.g. suspended particles displays
• CPC Class Codes: G02F 1/21 by interference

Abstract

A multilayer light modulator includes, a light modulating stack operable to transform an electrical control signal into a modulated optical signal. The light modulating stack comprises one or more optically reflecting layers, optically transmitting layers, and optically variable layers. The optically variable layer comprises a plurality of electrophoretic particles supported in a fluid. The multilayer light modulator also includes a bias generator coupled to the optically variable layers. The bias generator is responsive to the electrical control signal, wherein the bias generator creates a bias that changes the reflectance of the light modulating stack by causing the electrophoretic particles to move within the fluid.

Claims

1. A multilayer light modulator comprising:

a light modulating stack operable to transform an electrical control signal into a modulated optical signal, the light modulating stack comprising;

one or more optically reflecting layers;

one or more optically transmitting layers;

one or more optically variable layers, the optically variable layers comprising a plurality of electrophoretic particles supported in a fluid;

a bias generator coupled to the optically variable layers and responsive to the electrical control signal, wherein the bias generator creates a bias that changes the reflectance of the light modulating stack by causing the electrophoretic particles to move within the fluid.

2. The multilayer light modulator of claim 1, wherein the fluid comprises a material selected from the group consisting of water, hexane, decane, isoparaffinic fluid, and methanol.

3. The multilayer light modulator of claim 1, wherein the electrophoretic particles comprise material selected from the group consisting carbon, rutile, silicon, and graphite.

4. A device comprising:

a first layer having a first index of refraction;

a second layer having a second index of refraction;

a fluid having a third index of refraction enclosed between the first layer and the second layer;

a plurality of particles having a fourth index of refraction suspended in the fluid; and

a variable voltage source coupled to the first and second layer and operable to cause the plurality of particles to move within the fluid.

5. The device of claim 4, wherein the plurality of particles are electrically charged.

6. The device of claim 4, wherein the fluid is of a first viscosity, the first viscosity such that the particles move within the fluid when an electrical force is applied to the particles and are suspended when no electrical force is applied to the particles.

7. The device of claim 4, wherein the particles diffuse light.

8. The device of claim 4, wherein the first refractive index is different than the second refractive index.

9. The device of claim 4, wherein the fluid is substantially optically transparent.

10. The device of claim 4, further comprising at least one additional layer having at least one additional index of refraction.

11. The device of claim 4, wherein the first, second, third, and fourth indices of refraction are selected to maximize a change in reflectance of the device upon the particles moving from a first position to a second position.

12. The device of claim 4, wherein the first and second layers comprise a material selected from the group consisting of silicon, germanium, silicon nitride, rutile, and diamond.

13. The device of claim 4, further comprising a layer of capsules arranged between the first layer and the second layer, the capsules operable to contain the fluid between the first layer and the second layer.

14. The device of claim 4, wherein the plurality of particles comprises a plurality of metallic flakes.

15. A method comprising:

receiving an electrical control signal;

adjusting the reflectance of a light modulating stack comprising a plurality of layers by changing the relative location of a plurality of electrophoretic particles with respect to the remainder of the light modulating stack;

receiving light waves from a light source; and

converting the electrical control signal into a modulated optical signal that selectively switches between reflecting or absorbing at least a portion of the light waves.

16. The method of claim 15, wherein adjusting the reflectance of the light modulating stack comprises adjusting a bias applied to at least one layer of the light modulating stack.

17. The method of claim 15, wherein upon the reflectance being adjusted, the bias is no longer applied to the light modulating stack.

18. The method of claim 15, wherein adjusting the reflectance of the light modulating stack comprises creating a layer of electrophoretic particles against an inner surface of one layer of the plurality of layers of the light modulating stack.

19. The method of claim 18, further comprising maintaining the layer of electrophoretic particles until the electrical control signal indicates a change in the reflectance of the light modulating stack.

20. The method of claim 15, wherein receiving an electrical control signal comprises receiving an electrical control signal-indicating the reflectance of the light modulating stack is to produce a modulating optical signal of a predetermined pattern.