Patent ID: 6587186
Filing Date: 2003-07-01
Classification: G01C,G01S

Abstract:
A method to determine distance z between a pixel detector and a target, the method comprising the following steps:(a) illuminating said target with optical energy having a periodic waveform that includes a high frequency component S1(&ohgr;Â·t); (b) disposing said pixel detector so as to detect an optical energy signal having a high frequency component S2(&ohgr;Â·t)=AÂ·S1(&ohgr;Â·tâˆ’&PHgr;) reflected from said target, where A is a coefficient proportional to brightness of said target, and &PHgr; is phase shift proportional to time-of-flight of light over said distance z; and (c) homodyne signal-processing said signal S2(&ohgr;Â·t) to generate a phase signal &PHgr; proportional to said distance z and to preserve said coefficient A; wherein homodyne signal-processing at step (c) is carried out using an internally generated signal whose frequency is derived from said S1(&ohgr;Â·t) and whose phase is dynamically forced by closed loop feedback to track said high frequency component S2(&ohgr;Â·t).