An improved laser light receiver is provided that senses a laser light beam and determines positional elevation of the laser receiver based on the position where the laser light beam impacts the light sensors of the laser receiver. The laser receiver automatically adjusts its zero-reference point when...http://www.google.com/patents/US7414704?utm_source=gb-gplus-sharePatent US7414704 - Laser light receiver apparatus with automatically adjustable zero-reference point
