Missile for use in a laser beam riding missile guidance system

1. A method for aligning a missile with a target in a laser beam riding missile guidance system, the system including a laser transmitter for generating and projecting a laser information field towards the target and an optical sight for aiming the laser information field towards the target, the missile comprising a light sensor, a target sensor, a guidance processor unit and a guidance control for controlling the flight of the missile, the method comprising:

detecting, using the light sensor onboard the missile, light in the laser information field;

determining, using the guidance processor unit onboard the missile, and based on the detected light, a point in the laser information field with which the missile is currently aligned;

determining, using the guidance processor unit onboard the missile, a distance of the target from the missile;

detecting, using the target sensor onboard the missile, a position of the target;

determining, using the target sensor onboard the missile, and based on the detected position of the target, an angular displacement between the missile's current direction of travel and the direction in which the target lies from the missile;

determining, using the guidance processor unit onboard the missile, and based on said distance and angular displacement, a new point in the laser information field with which the missile should be aligned to reach the target; and

using the guidance control onboard the missile to bring the missile into alignment with the new point in the laser information field.

2. A method according to claim 1 , wherein

the laser information field is generated by scanning a pulsed laser beam across a region of space, the intervals between successive laser pulses being varied as the laser scans across the region of space, and

the point in the laser information field with which the missile is currently aligned is determined based on the time interval between receiving successive laser pulses.

3. A method according to claim 2 , wherein determining the new point in the laser information field comprises identifying the inter-pulse interval that corresponds to the new point in the laser information field.

4. A method according to claim 1 , wherein determining the new point in the laser information field comprises determining the spatial resolution of the laser information field at the missile's present distance from the laser source, the spatial resolution defining the lateral distance between points in the field having different inter-pulse intervals.

5. A method according to claim 1 , wherein the distance of the target from the missile is determined by comparing the distance of the target from the optical sight with the distance of the missile from the laser transmitter.

6. A method according to claim 5 , wherein the distance of the missile from the laser transmitter is determined by use of an inertial navigation system onboard the missile.

7. A method according to claim 5 , wherein data conveying the distance of the target from the optical sight is received by the missile via the laser information field.

8. A method according to claim 6 , wherein the laser transmitter is co-located with the missile launcher from which the missile is launched.

9. A missile for use in a laser beam riding missile guidance system, the missile comprising:

a light sensor configured to detect light in a laser information field generated by a laser transmitter and projected by the laser transmitter towards a target;

a target sensor configured to detect a position of the target, and configured to determine, based on the position of the target an angular displacement between the missile's current direction of travel and the direction in which the target lies from the missile;

a guidance processor unit configured to determine a distance of the target from the missile, the guidance processor being configured to determine, based on the detected light, a point in the laser information field with which the missile is currently aligned and to determine, based on said distance and angular displacement, a new point in the laser information field with which the missile should be aligned to reach the target;

the missile further comprising a guidance control configured to control the flight of the missile, the guidance control being configured to bring the missile into alignment with the new point in the laser information field.

10. A missile according to claim 9 , wherein

the laser information field is generated by scanning a pulsed laser beam across a region of space, the intervals between successive laser pulses being varied as the laser scans across the region of space, and

the guidance processor unit is configured to determine the point in the laser information field with which the missile is currently aligned based on the time interval that occurs between detecting successive laser pulses at the light sensor.

11. A missile according to claim 10 , wherein in determining the new point in the laser information field, the guidance processor unit is configured to identify the inter-pulse interval that corresponds to the new point in the laser information field.

12. A missile according to claim 9 , wherein in determining the new point in the laser information field, the guidance processor unit is configured to determine the spatial resolution of the laser information field at the missile's present distance from the laser transmitter, the spatial resolution defining the lateral distance between points in the field having different inter-pulse intervals.

13. A missile according to claim 9 , wherein:

the detected light encodes data conveying the distance of the target from an optical sight of the laser transmitter; and

the guidance processor unit comprises a range calculator that is configured to determine the distance of the target from the missile by comparing the distance of the target from the optical sight of the laser transmitter with the distance of the missile from the laser transmitter.

14. A missile according to claim 13 , wherein the missile comprises an inertial navigation system for determining the distance of the missile from the laser transmitter.

15. A missile according to claim 13 , wherein the laser transmitter is co-located with the missile launcher from which the missile is launched.

16. A missile according to claim 9 , wherein the missile comprises one or more guidance fins and the guidance control is configured to control the flight of the missile by adjusting the fin(s).

17. A system comprising:

a laser transmitter for generating a laser information field and projecting the laser information field towards a target; and

a missile according to claim 9 .