Method of directing an optical receiver toward a light source and an apparatus of practicing the method

A method of directing an optical receiver associated with an optical transmitter towards a light source, the method comprising the steps of:

• a) providing the optical receiver with an optical system and a plurality of light detectors positioned around a primary optical axis, the light detectors being configured to receive a first light beam and to detect an intensity thereof relative to the primary optical axis which extends linearly from the light detectors through the optical system, the optical system including a pair of inner lenses movably mounted in the receiver in different x, y and z directions in response to the intensity of the first light beam on the light detectors;
• b) arranging the receiver defocused such that the optical system embraces a largest possible field of view of an area where the first light beam is located, and such that the first light beam is refracted with a largest possible spread angle towards the light detectors;
• c) letting the receiver search for the light source by scanning a surrounding environment until the first tight beam hits at least one of the light detectors;
• d) calculating where the first light beam hits relative to the primary optical axis, and, with the current field of view, adjusting the receiver such that the first light beam is directed towards the primary optical axis;
• e) reducing the field of view of the receiver by moving the pair of inner lenses independently of one another in the x, y and z directions;
• and
• f) repeating the steps d) and e) until a minimum spread angle of the first light beam centers in the smallest possible spot on the light detectors relative to the primary optical axis,
• wherein the secondary optical axis and a spread angle of the second light beam sent out from the transmitter is dependent on the directing of the primary optical axis and the field of view of the receiver.