Liquid-lens based optical steering system for free-space laser communication

Patent metadata

Field	Value
Publication number	US-10826609-B2
Application number	US-201916447648-A
Country	US
Kind code	B2
Filing date	Jun 20, 2019
Priority date	Jun 20, 2018
Publication date	Nov 3, 2020
Grant date	Nov 3, 2020

Abstract

A beam steering system for a free-space laser communication system in a satellite includes a laser that emits a laser beam, a liquid lens assembly with at least one liquid lens to change the direction of the laser beam, and an amplifying optic to amplify the change in direction of the laser beam. The beam steering system may be used to steer a laser beam transmitted to another satellite or received from another satellite. In one example, a satellite may include two beam steering systems, disposed at opposing ends of a frame, where each steering system is configured to cover a hemisphere such that together, the steering systems can transmit and/or receive a laser beam over a 4π steradian sphere. The beam steering system may include a transmit feedback system and a reception system to monitor the direction and signal of the transmitted beam and the received beam, respectively.

First claim

The invention claimed is:

1. A spacecraft, comprising:
a first laser communication transmitter to transmit a first steered laser beam from the spacecraft, the first laser communication transmitter comprising a first plurality of liquid lenses to steer a first source laser beam to provide the first steered laser beam,
wherein:
the first source laser beam propagates along a first optical axis;
at least one liquid lens of the first plurality of liquid lenses is offset from the first optical axis; and
a focal length of the at least one liquid lens is adjusted in response to an applied voltage to deflect the first source laser beam from the optical axis.

2. The spacecraft of claim 1 , wherein the spacecraft does not include a gimbal or mechanical actuator to steer the first source laser beam so as to provide the first steered laser beam.

3. The spacecraft of claim 1 , wherein the first plurality of liquid lenses steer the first source laser beam independently of a position and/or an orientation of the spacecraft, such that no pointing of the spacecraft is required to steer the first source laser beam so as to provide the first steered laser beam.

4. The spacecraft of claim 1 , wherein the first plurality of liquid lenses comprises:
a first liquid lens offset in a first direction perpendicular to the first optical axis; and
a second liquid lens offset in a second direction perpendicular to the first direction and to the first optical axis.

5. The spacecraft of claim 4 , wherein:
at least one of the first liquid lens or the second liquid lens deflects the first source laser beam to provide a first deflected laser beam; and
the first laser communication transmitter further comprises a fisheye lens to amplify an angular deflection of the first deflected laser beam to provide the first steered laser beam from the spacecraft.

6. The spacecraft of claim 5 , wherein:
a first focal length of the first liquid lens is controlled via a first applied voltage to deflect the first source laser beam along a first axis perpendicular to the optical axis; and
a second focal length of the second liquid lens is controlled via a second applied voltage to deflect the first source laser beam along a second axis perpendicular to the first axis and the optical axis,
so as to point the first steered laser beam from the spacecraft in one direction of a plurality of directions over a hemisphere.

7. The spacecraft of claim 6 , wherein at least one of the first liquid lens or the second liquid lens is controlled so as to vary a beam divergence of the first steered laser beam to provide a wider beamwidth and a narrower beamwidth.

8. A satellite, comprising:
a first laser communication transmitter to transmit a first steered laser beam over a first hemisphere from a first end of the satellite independently of a position and/or an orientation of the satellite; and
a second laser communication transmitter to transmit a second steered laser beam over a second hemisphere from a second end of the satellite independently of the position and/or the orientation of the satellite,
wherein:
the first laser communication transmitter and the second laser communication transmitter do not include a gimbal or mechanical actuator to transmit the first steered laser beam over the first hemisphere or the second steered laser beam over the second hemisphere;
the first laser communication transmitter comprises a first plurality of liquid lenses to provide two-axis steering of the first steered laser beam over the first hemisphere;
the second laser communication transmitter comprises a second plurality of liquid lenses to provide two-axis steering of the second steered laser beam over the second hemisphere;
the first plurality of liquid lenses steer a first source laser beam propagating along a first optical axis to provide the first steered laser beam, the first plurality of liquid lenses comprising:
a first liquid lens offset in a first direction perpendicular to the first optical axis, wherein a first focal length of the first liquid lens is controlled via a first applied voltage to deflect the first source laser beam along a first axis perpendicular to the first optical axis; and
a second liquid lens offset in a second direction perpendicular to the first direction and to the first optical axis, wherein a second focal length of the second liquid lens is controlled via a second applied voltage to deflect the first source laser beam along a second axis perpendicular to the first axis and the first optical axis; and

the second plurality of liquid lenses steer a second source laser beam propagating along a second optical axis to provide the second steered laser beam, the second plurality of liquid lenses comprising:
a third liquid lens offset in a third direction perpendicular to the second optical axis, wherein a third focal length of the third liquid lens is controlled via a third applied voltage to deflect the second source laser beam along a third axis perpendicular to the second optical axis; and
a fourth liquid lens offset in a fourth direction perpendicular to the third direction and to the second optical axis, wherein a fourth focal length of the fourth liquid lens is controlled via a fourth applied voltage to deflect the second source laser beam along a fourth axis perpendicular to the third axis and the second optical axis.

9. The satellite of claim 8 , wherein:
the first laser communication transmitter further comprises a first fisheye lens to amplify a first angular deflection of the deflected first source laser beam to provide the first steered laser beam from the satellite; and
the second laser communication transmitter further comprises a second fisheye lens to amplify a second angular deflection of the deflected second source laser beam to provide the second steered laser beam from the satellite.

10. The satellite of claim 9 , wherein:
the first laser communication transmitter further comprises first folded optics in a first beam path of the deflected first source laser beam; and
the second laser communication transmitter further comprises second folded optics in a second beam path of the deflected second source laser beam.

11. The satellite of claim 10 , wherein the satellite is a 3U CubeSat.

12. The satellite of claim 9 , wherein:
at least one of the first liquid lens or the second liquid lens is controlled so as to vary a first beam divergence of the first steered laser beam; and
at least one of the third liquid lens or the fourth liquid lens is controlled so as to vary a second beam divergence of the second steered laser beam.

13. The satellite of claim 9 , wherein:
the first laser communication transmitter further comprises at least one first beam splitter to facilitate monitoring and adjusting of the first angular deflection of the deflected first source laser beam; and
the second laser communication transmitter further comprises at least one second beam splitter to facilitate monitoring and adjusting of the second angular deflection of the deflected second source laser beam.

14. The satellite of claim 9 , wherein:
the first laser communication transmitter is a first laser communication transceiver to receive, over the first hemisphere and via the first fisheye lens, a third steered laser beam from a first other satellite, the first laser communication transceiver further comprising a first MEMS shutter array adjustable iris to reduce a first field of view over the first hemisphere to substantially block first noise beyond the received third steered laser beam from the first other satellite; and
the second laser communication tr

Assignees

• Massachusetts Inst Technology

Inventors

• Cahoy Kerri
• Haughwout Christian
• Clark James
• Do Vale Pereira Paula

Classifications

• B64G1/2221

  characterised by the manner of deployment · CPC title

• G02F1/294

  Variable focal length devices · CPC title

• G02F2203/24

  beam steering · CPC title

• G02F1/29 Primary

  for the control of the position or the direction of light beams, i.e. deflection · CPC title

• B64G1/1007

  Communications satellites · CPC title