Patent ID: 7414704

Claim:
A laser light receiver system, comprising: (a) a laser light receiver, having: (i) a housing that has at least two predetermined mounting locations; (ii) a first laser light photosensor, which generates a first signal if receiving a beam of laser light energy from an external laser light source; (iii) a visible readout to indicate if said laser light receiver is substantially on-grade with respect to said received beam of laser light energy; (b) a mounting apparatus having: (i) at least one mating area to receive said housing at one of said at least two predetermined mounting locations of the housing; and (ii) a physical feature that is positioned at a predetermined location with respect to said at least one mating area; and (c) said laser light receiver further comprising: (iv) a sensor that detects said physical feature of the mounting apparatus, and produces a second signal having a first logic state if said laser light receiver detects a first state of said physical feature of the mounting apparatus, and produces said second signal having a second logic state if said laser light receiver detects a second state of said physical feature of the mounting apparatus; and (v) a processing circuit that receives said first signal and said second signal, wherein said processing circuit is configured: (A) to automatically select a zero-reference point from at least two possible states; (B) to enable a first state of the zero-reference point if said processing circuit receives said first logic state of said second signal; (C) to enable a second state of the zero-reference point that is different than said first state of the zero-reference point if said processing circuit receives said second logic state of said second signal; and (D) to determine whether said received beam of laser light energy has impacted said first laser light photosensor at an on-grade position, with respect to said enabled zero-reference point.