# US 7,746,531 B2 · Electro-optomechanical beam steering system, and associated methods

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- Number: US 7,746,531 B2
- Document ID: US7746531B2
- Status: Granted
- Kind: B2
- Application number: 11/238,262
- Filed: 2005-09-29
- Published: 2007-03-29
- Granted: 2010-06-29
- Earliest claimed: 2005-09-29
- Assignees: Teledyne Scientific & Imaging, LLC
- Inventors: Milind P. Mahajan; Bruce K Winker
- Web page: https://patentgrep.com/patent/US7746531B2

## CPC

- G02B 26/0883: {the refracting element being a prism}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

An electro-optomechanical beam steering system has: a first deflector for selectively deflecting an optical beam in a first field of regard centered about a boresight; and a rotation stage having a second deflector, the rotation stage selectively positioning the second deflector in azimuth about the boresight, the second deflector selectively deflecting the optical beam of the first field of regard in a second field of regard along a polar axis defined by the second deflector and the azimuth as positioned by the rotation stage. Methods using the beam steering system are also provided, to steer an optical beam or to acquire a target in a field of regard.

## Claims

### Claim 1

An electro-optomechanical beam steering system, comprising:
a first deflector having a first configuration for selectively deflecting an optical beam in a first field of regard centered about a boresight, the first deflector being stationary and non-rotatable;
a rotation stage having a second deflector with a second configuration different from the first configuration, the rotation stage including a motor to selectively rotate the second deflector in azimuth about the boresight, the second deflector selectively deflecting the optical beam of the first field of regard in a second field of regard along a polar angle defined by the second deflector and an azimuthal angle as positioned by the rotation stage.

### Claim 2 (depends on 1)

The system of claim 1 wherein the first deflector includes an electro-optic or an electro-mechanical deflector, and the second deflector includes an electro-optic deflector.

### Claim 3 (depends on 1)

The system of claim 1, wherein the first deflector comprises a multistage x-y electro-optic deflector responsive to electrical signals to deflect the optical beam within the first field of regard.

### Claim 4 (depends on 3)

The system of claim 3, wherein the multi-stage x-y electro-optic deflector is configured to deflect the optical beam from the boresight to within the first field of regard up to about 10 degrees from the boresight.

### Claim 5 (depends on 3)

The system of claim 3, wherein each stage of the multi-stage x-y deflector is operable to deflect the optical beam in one dimension in response to the electrical signals.

### Claim 6 (depends on 5)

The system of claim 5, wherein each stage of multi-stage deflector comprises a birefringent prism and a tunable liquid crystal polarization rotator.

### Claim 7 (depends on 1)

The system of claim 1, wherein the first deflector includes two liquid crystal optical phased arrays.

### Claim 8 (depends on 7)

The system of claim 7, wherein the optical phased arrays are operable for continuous deflection of the optical beam of up to about ±2 degrees from the boresight.

### Claim 9 (depends on 7)

The system of claim 7, wherein the first deflector comprises a multistage x-y electro-optic deflector responsive to electrical signals to deflect the optical beam within the first field of regard, the optical phased arrays and the multi-stage x-y deflector cooperating to deflect the optical beam up to about +/−4.5 degrees from the boresight.

### Claim 10 (depends on 1)

The system of claim 1, wherein the first deflector includes a voice coil or piezoelectric fine steering mirror.

### Claim 11 (depends on 10)

The system of claim 10, wherein the fine steering mirror is operable for continuous deflection of the optical beam of up to about +/−2 degrees from the boresight.

### Claim 12 (depends on 10)

The system of claim 10, wherein the first deflector comprises a multistage x-y electro-optic deflector responsive to electrical signals to deflect the optical beam within the first field of regard, the fine steering mirror and the multi-stage x-y deflector cooperating to deflect the optical beam up to about +I-4.5 degrees from the boresight.

### Claim 13 (depends on 1)

The system of claim 1, wherein the second electro-optical deflector comprises a multi-stage polar angle deflector responsive to electrical signals to deflect the optical beam within the second field of regard.

### Claim 14 (depends on 13)

The system of claim 13, wherein the multi-stage polar angle deflector includes a two-stage polar angle deflector configured to deflect the optical beam from the polar axis by approximately 0, 9, 18, or 27 degrees.

### Claim 15 (depends on 13)

The system of claim 13, wherein each stage of the multi-stage polar angle deflector is operable to deflect the optical beam in one dimension in response to the electrical signals.

### Claim 16 (depends on 13)

The system of claim 13, wherein each stage of the multi-stage polar angle deflector comprises a birefringent prism and a tunable liquid crystal polarization rotator.

### Claim 17 (depends on 1)

The system of claim 1, further comprising two quarter wave plates configured to couple appropriate polarization of the optical beam from the first electro-optical deflector to the rotation stage.

### Claim 18 (depends on 1)

The system of claim 1, further comprising a tunable liquid crystal polarization rotator configured at an output of the rotation stage, for maintaining constant exit polarizations.

### Claim 19

An electro-optomechanical beam steering system comprising:
a first deflector comprising a tunable component responsive to an electrical signal for selectively deflecting an optical beam in a first field of regard centered about a boresight; and
a rotation stage having a second deflector, the rotation stage selectively positioning the second deflector in azimuth about the boresight, the second deflector selectively deflecting the optical beam of the first field of regard in a second field of regard along a polar angle defined by the second deflector and the azimuthal angle as positioned by the rotation stage, the rotation stage comprising a motor for rotating the second deflector in azimuth, and the motor comprising a ring motor operable to rotate polar angle deflectors of the second deflector.

### Claim 20 (depends on 1)

The system of claim 1, wherein the first and second deflectors and the rotational stage cooperate to provide a total field of regard up to about 90 degrees.

### Claim 21 (depends on 1)

The system of claim 1, further comprising an exit tunable liquid crystal polarization rotator that maintains constant exit polarization for all deflection states.

### Claim 22 (depends on 1)

The system of claim 1, further comprising a polarizer for suppressing cross-talk.

### Claim 23

A method for steering an optical beam, comprising:
applying first control signals to a tunable component of a first deflector, the tunable component being responsive to the first control signals to selectively deflect an optical beam within a first field of regard centered about a boresight;
commanding a motor to rotate a second deflector about the boresight; and
applying second control signals to the second deflector to selectively deflect the optical beam of the first field of regard within a second field of regard in a direction, away from the boresight, defined by polar deflection of the second deflector and azimuthal direction defined by the rotation of the motor.

### Claim 24 (depends on 23)

The method of claim 23, wherein the applying first control signals includes applying signals to at least one optical phased array.

### Claim 25 (depends on 23)

The method of claim 23, wherein the applying first control signals includes applying signals to at least one fine steering mirror.

### Claim 26 (depends on 23)

The method of claim 23, wherein the applying first control signals includes applying signals to at least one stage having a birefringent prism and a tunable liquid crystal polarization rotator.

### Claim 27 (depends on 26)

The method of claim 26, wherein the applying first control signals includes applying signals to at least two stages, each stage deflecting the optical beam in one dimension.

### Claim 28 (depends on 24)

The method of claim 24, wherein the commanding the motor includes rotating the second deflector in azimuth about the boresight.

### Claim 29 (depends on 23)

The method of claim 23, wherein the applying second control signals includes applying signals to at least one stage having a birefringent prism and a tunable liquid crystal polarization rotator.

### Claim 30 (depends on 29)

The method of claim 29, wherein the applying second control signals includes applying signals to at least two stages, each stage deflecting the optical beam in one dimension.

### Claim 31 (depends on 23)

The method of claim 23, further comprising modifying polarization of electro-magnetic energy between the first deflector and the second deflector.

### Claim 32 (depends on 31)

The method of claim 31, wherein the modifying includes utilizing at least one quarter wave plate.

### Claim 33 (depends on 23)

The method of claim 23, further comprising modifying polarization exiting the second deflector with a tunable liquid crystal polarization rotator, to maintain a constant polarization of electro-magnetic energy exiting the second deflector.

### Claim 34 (depends on 23)

The method of claim 23, further comprising suppressing cross-talk using a polarizer.

### Claim 35

A software product comprising instructions, stored on computer-readable media, wherein the instructions, when executed by a computer, perform steps comprising:
applying first control signals to a tunable component of a first deflector, the tunable component being responsive to the first control signals, thereby deflecting the optical beam within a first field of regard centered about a boresight;
commanding a motor to rotate a second deflector, thereby selectively repositioning the deflected optical beam of the first field of regard in azimuth; and
applying second control signals to the second deflector, thereby selectively deflecting the optical beam of the first field of regard away from boresight and within a second field of regard centered about boresight.