Claims
- 1. A control system for an optical switching fabric, comprising:
a first position sensitive detector positioned to receive a first control beam reflected from individual mirrors of a first mirror array; a first processor coupled to receive signals from the first position sensitive detector and calculate a voltage correction values from a comparison between the position of the first control beam on cells of the first position sensitive detector and assigned positions for the first control beams on cells of the first position sensitive detector; and a first actuator driver that receives the voltage correction values from the first processor and generates actuator voltages which alter the orientation of the individual mirrors on the first mirror array.
- 2. The system of claim 1, further including:
a second position sensitive detector positioned to receive a second control beam reflected from individual mirrors of a second mirror array; a second processor coupled to receive signals from the second position sensitive detector and calculate voltage correction values from a comparison between the position of the second control beam on cells of the second position sensitive detector and assigned positions for the second control beams on cells of the second position sensitive detector; and a second actuator driver that receives the voltage correction values from the second processor and generates actuator voltages which alter the orientation of the individual mirrors on the second mirror array.
- 3. The system of claim 2, further including
a third position sensitive detector positioned to receive a third control beam reflected from individual mirrors on the first mirror array and from individual mirrors on the second mirror array.
- 4. The system of claim 3, wherein the second processor receives data from the third position sensitive detector and calculates a fine voltage control signal for the second actuator driver.
- 5. The system of claim 3, wherein the first processor receives data from the third position sensitive detector and calculates a fine voltage control signal from the first actuator driver.
- 6. The system of claim 3, wherein the first control beam is time multiplexed with a first calibration beam, the first calibration beam being incident on cells of the first position sensitive detector, and the first processor receiving calibration data accumulated when the first calibration beam is on and receiving control data accumulated when the first control beam is on.
- 7. The system of claim 6, wherein the second control beam is time multiplexed with a second calibration beam, the second calibration beam being incident on cells of the second position sensitive detector, and the second processor receiving calibration data accumulated when the second calibration beam is on and receiving control data accumulated when the second control beam is on.
- 8. The system of claim 7, wherein the third control beam is time multiplexed with a third calibration beam, the third calibration beam being incident on cells of the third position sensitive detector.
- 9. The system of claim 8, wherein the second processor receives calibration data accumulated the third calibration bean is on and receiving control data accumulated when the third control beam is on.
- 10. The system of claim 9, wherein the first processor provides a first voltage correction to the first actuator driver to adjust the orientation of an individual mirror of the first mirror array in response to a difference between the position of the first control beam adjusted by the position of the first calibration beam and a specified position on a first corresponding cell of the first position sensitive detector.
- 11. The system of claim 10, wherein the second processor provides a second voltage correction to the second actuator driver to adjust the orientation of an individual mirror of the second mirror array in response to a difference between the position of the second control beam adjusted by the position of the second calibration beam and a second specified position on a second corresponding cell of the second position sensitive detector.
- 12. The system of claim 11, wherein the second voltage correction also is responsive to the position of the third control beam adjusted according to the position of the third calibration beam.
- 13. A method of controlling an optical switching fabric, comprising:
receiving port assignment for a first mirror on a first mirror array; calculating a target position of a first control beam reflected from the first mirror on a corresponding cell of a first position sensitive detector; measuring an actual position of the first control beam on the cell; adjusting the orientation of the first mirror so that the measured position matches the target position; and maintaining the orientation of the first mirror so that the measured position matches the target position.
- 14. The method of claim 13, wherein calculating the target position includes determining the target position from a look-up table based on the port assignment.
- 15. The method of claim 13, wherein maintaining the orientation of the first mirror includes
measuring the position of the first control beam in a first time interval; measuring the position of a first calibration beam in a second time interval; correcting the position of the first control beam in response to the position of the first calibration beam in order to obtain a measured position; comparing the measured position with the target position; calculating a voltage correction from the comparison of the measured position with the target position; applying the voltage correction to actuators of the first mirror in order to alter the orientation of the first mirror.
- 16. The method of claim 15, further including calculating an estimated state of the first mirror.
- 17. The method of claim 16, wherein the state includes an estimate of an angular position of the first mirror.
- 18. The method of claim 17, wherein calculating the voltage correction includes
calculating a desired torque to apply to the first mirror to achieve the desired position; and converting the desired torque to the voltage correction.
- 19. The method of claim 18, wherein calculating the desired torque includes adding the desired position times a first factor, the error signal times a second factor, and an estimated state of the mirror times a matrix multiplier.
- 20. The method of claim 18, wherein converting the desired torque to the voltage correction includes calculating the voltage based on an estimate of the angular orientation of the first mirror and a model of the response of the first mirror.
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is related to the following co-filed, commonly assigned, U.S. patent applications: Attorney Docket No. M-10967, application Ser. No. 09/839,848, Attorney Docket No. M-11418 U.S., Attorney Docket No. M-11419 U.S., Attorney Docket No. M-11502 U.S., and Attorney Docket No. M-11745 U.S., all of which are incorporated herein by reference in their entirety. This application is also related to U.S. patent application Ser. No. 09/779,189 entitled “A Microelectromechanical Mirror,” filed Feb. 7, 2001, assigned to the assignee of the present invention, and incorporated herein by reference in their entirety.