Laser spot tracking with off-axis angle detection

Method of locating at least one object being illuminated by a laser designator comprising:

• providing a tracker having a quadrant detector in a field of view;
• receiving laser light scattered by the at least one object being illuminated;
• causing the received laser light to impinge as a corresponding at least one spot on the quadrant detector;
• for each of the spots of received laser light impinging on the detector, determining an angle of the spot of the received laser light relative to a center of the field of view;
• calculating azimuth and elevation angular co-ordinates for centroids of the spots by measuring energy of the received laser light in each quadrant of the detector;
• and
• adding signals from the quadrants on each side of an axis of interest, and deriving a ratio of these quadrants such that that the ratio varies as the spot traverses the quadrants across the axis of interest.

Method of locating multiple objects being illuminated by at least one laser designator comprising:

• providing a tracker having a quadrant detector in a field of view;
• receiving laser light scattered by the multiple objects being illuminated;
• causing the received laser light to impinge as corresponding multiple spots on the quadrant detector;
• for each of the spots of received laser light impinging on the detector, determining an angle of the spot of the received laser light relative to a center of the field of view;
• and
• wherein the quadrant detector comprises two quadrant detectors, and further comprising:
• disposing a first of the two detectors effectively in front of a focal plane;
• disposing a second of the two detectors effectively behind the focal plane;
• and
• combining outputs of the two detectors to reduce inconsistencies of amplitude within the spots.