US Patent 7947944 Laser transmitter, laser receiver and method

A combination of a laser transmitter and a laser receiver and a method determine the elevation of the receiver with respect to the transmitter. The laser transmitter includes a a laser light source for providing a beam of laser light and an element for directing the beam. The beam diverges vertically and varies in intensity vertically. A laser receiver includes an array of laser beam detectors for detecting the beam and the variations in the beam intensity in a vertical direction. The vertical position of the laser receiver with respect to the laser transmitter can be determined in this manner. The beam varies in intensity vertically in a predetermined vertical pattern, and the laser receiver detects at least a portion of the pattern defined by the beam such that the portion of the beam detected by the laser receiver may be determined.