Shutters for infra red communication at moderate bandwidths

1. A modulating corner-cube retroreflector, wherein the modulating corner-cube retroreflector is used for remote communications, comprising:

a solid corner-cube retroreflector comprising a front surface and three mutually perpendicular surfaces, wherein the three mutually perpendicular surfaces include a first surface, a second surface and a third surface;

a thin membrane disposed relative to at least one of the first surface, second surface, and third surface, wherein the thin membrane covers at least a portion of the surface; and

a modulator adapted to cause the thin membrane to vibrate;

wherein:

the solid corner-cube retroreflector is configured to receive an incident beam of light from a source along a first path and is configured to return a reflected beam of light back towards the source along a second path that is substantially parallel to the first path;

the thin membrane is configured to substantially frustrate total internal reflection of the incident beam of light when the thin membrane is moved relative to at least one surface of the retroreflector; and

the modulator creates an electric field between at least one surface of the retroreflector and the thin membrane.

2. The modulating corner-cube retroreflector of claim 1 , further comprising an optical filter, wherein the optical filter permits a substantially narrow wavelength band of light to enter the corner-cube retroreflector.

3. A modulating corner-cube retroreflector, wherein the modulating corner-cube retroreflector is used for remote communications, comprising:

a solid corner-cube retroreflector comprising a front surface and three mutually perpendicular surfaces, wherein the three mutually perpendicular surfaces include a first surface, a second surface and a third surface;

a thin membrane disposed relative to at least one of the first surface, second surface, and third surface, wherein the thin membrane covers at least a portion of the surface; and

a modulator adapted to cause the thin membrane to vibrate;

wherein:

the solid corner-cube retroreflector is configured to receive an incident beam of light from a source along a first path and is configured to return a reflected beam of light back towards the source along a second path that is substantially parallel to the first path;

the thin membrane is configured to substantially frustrate total internal reflection of the incident beam of light when the thin membrane is moved relative to at least one surface of the retroreflector; and

the thin membrane comprises a first thin membrane, the modulating corner-cube retroreflector further comprising one or more additional thin membranes.

4. A modulating corner-cube retroreflector, wherein the modulating corner-cube retroreflector is used for remote communications, comprising:

a solid corner-cube retroreflector comprising a front surface and three mutually perpendicular surfaces, wherein the three mutually perpendicular surfaces include a first surface, a second surface and a third surface;

a thin membrane disposed relative to at least one of the first surface, second surface, and third surface, wherein the thin membrane covers at least a portion of the surface; and

a modulator adapted to cause the thin membrane to vibrate;

wherein:

the solid corner-cube retroreflector is configured to receive an incident beam of light from a source along a first path and is configured to return a reflected beam of light back towards the source along a second path that is substantially parallel to the first path;

the thin membrane is configured to substantially frustrate total internal reflection of the incident beam of light when the thin membrane is moved relative to at least one surface of the retroreflector; and

the modulator comprises a sound conducting tube.

5. A modulating corner-cube retroreflector, wherein the modulating corner-cube retroreflector is used for remote communications, comprising:

a solid corner-cube retroreflector comprising a front surface and three mutually perpendicular surfaces, wherein the three mutually perpendicular surfaces include a first surface, a second surface and a third surface;

a thin membrane disposed relative to at least one of the first surface, second surface, and third surface, wherein the thin membrane covers at least a portion of the surface; and

a modulator adapted to cause the thin membrane to vibrate;

wherein:

the solid corner-cube retroreflector is configured to receive an incident beam of light from a source along a first path and is configured to return a reflected beam of light back towards the source along a second path that is substantially parallel to the first path;

the thin membrane is configured to substantially frustrate total internal reflection of the incident beam of light when the thin membrane is moved relative to at least one surface of the retroreflector; and

the thin membrane comprises silicon carbide.

6. A modulating corner-cube retroreflector, wherein the modulating corner-cube retroreflector is used for remote communications, comprising:

a solid corner-cube retroreflector comprising a front surface and three mutually perpendicular surfaces, wherein the three mutually perpendicular surfaces include a first surface, a second surface and a third surface;

a thin membrane disposed relative to at least one of the first surface, second surface, and third surface, wherein the thin membrane covers at least a portion of the surface; and

a modulator adapted to cause the thin membrane to vibrate;

wherein:

the solid corner-cube retroreflector is configured to receive an incident beam of light from a source along a first path and is configured to return a reflected beam of light back towards the source along a second path that is substantially parallel to the first path;

the thin membrane is configured to substantially frustrate total internal reflection of the incident beam of light when the thin membrane is moved relative to at least one surface of the retroreflector; and

the thin membrane is doped with metal.

7. The modulating corner-cube retroreflector of claim 6 , wherein the metal is selected from the group consisting nickel and chromium.

8. A modulating corner-cube retroreflector, wherein the modulating corner-cube retroreflector is used for remote communications, comprising:

a solid corner-cube retroreflector comprising a front surface and three mutually perpendicular surfaces, wherein the three mutually perpendicular surfaces include a first surface, a second surface and a third surface;

a thin membrane disposed relative to at least one of the first surface, second surface, and third surface, wherein the thin membrane covers at least a portion of the surface;

a modulator adapted to cause the thin membrane to vibrate; and

a substance between the thin membrane and the retroreflector, wherein the substance prevents the thin membrane from adhering to the retroreflector;

wherein:

the solid corner-cube retroreflector is configured to receive an incident beam of light from a source along a first path and is configured to return a reflected beam of light back towards the source along a second path that is substantially parallel to the first path;

the thin membrane is configured to substantially frustrate total internal reflection of the incident beam of light when the thin membrane is moved relative to at least one surface of the retroreflector.

9. The modulating corner-cube retroreflector of claim 8 , wherein the substance comprises oil.

10. A modulating corner-cube retroreflector, wherein the modulating corner-cube retroreflector is used for remote communications, comprising:

a solid corner-cube retroreflector comprising a front surface and three mutually perpendicular surfaces, wherein the three mutually perpendicular surfaces include a first surface, a second surface and a third surface;

a first thin membrane disposed relative to at least one of the first surface, second surface, and third surface, wherein the thin membrane covers at least a portion of the surface;

a modulator adapted to cause the first thin membrane to vibrate;

a second thin membrane, wherein the second thin membrane is disposed relative and substantially parallel to one of the first surface, second surface, and third surface;

wherein:

the solid corner-cube retroreflector is configured to receive an incident beam of light from a source along a first path and is configured to return a reflected beam of light back towards the source along a second path that is substantially parallel to the first path;

the first thin membrane is configured to substantially frustrate total internal reflection of the incident beam of light when the first thin membrane is moved relative to at least one surface of the retroreflector.

11. The modulating corner-cube retroreflector of claim 10 , wherein the modulator is adapted to move the second thin membrane.

12. The modulating corner-cube retroreflector of claim 10 , further comprising a third thin membrane, wherein the third thin membrane is disposed relative and substantially parallel to one of the first surface, second surface, and third surface.

13. The modulating corner-cube retroreflector of claim 12 , wherein the modulator is adapted to move the third thin membrane.

14. A method for receiving a first beam of light along a first path and returning a second beam of light along a second path, wherein the second path is substantially parallel to the first path, the method comprising steps of:

receiving the first beam of light with a solid corner-cube retroreflector, wherein the first beam of light travels along the first path;

reflecting light with the solid corner-cube retroreflector;

vibrating a thin membrane disposed near a surface of the retroreflector to intermittently frustrate total internal reflectance of the first beam of light to produce the second beam of light; and

returning the second beam of light, wherein:

the second beam of light travels along the second path,

the vibrating step causes modulation of information on the second beam of light, and

the vibrating step is caused by sound pressure.