Patent ID: 7012237
Filing Date: 2006-03-14
Classification: G01C,H03F

Abstract:
1. A modulated laser light detector, comprising: (a) at least one laser light photosensor, which generates at least one first electrical signal when receiving modulated laser light energy having at least one predetermined range of wavelengths and at least one predetermined range of modulation frequencies; (b) at least one amplifier stage that receives said at least one first electrical signal and outputs at least one second electrical signal having a first waveform that exhibits voltage components of both positive-going and negative-going regions; (c) a phase and frequency detector that receives said at least one second electrical signal and generates a lock signal that corresponds to a zero crossing of said first waveform; (d) at least one synchronous rectifier stage that receives said lock signal and receives said at least one second electrical signal, and generates at least one third electrical signal of a second waveform that comprises a substantially rectified version of said first waveform; (e) at least one low pass filter that receives said at least one said third electrical signal and outputs at least one fourth electrical signal that comprises a substantially DC voltage; and (f) at least one signal strength detector that inspects the substantially DC voltage of said at least one fourth electrical signal, and determines a relative strength of said received modulated laser light energy.