Patent ID: 7994460
Filing Date: 2011-08-09
Classification: G02F,G05B,H04B

Abstract:
1. A method for controlling the position of a beam of light, comprising: directing a beam of amplitude modulated (AM) light onto a position sensitive detector (PSD), wherein said AM light is modulated at a modulation frequency, wherein said PSD will produce a first current (I converting said I subtracting said V digitally normalizing said difference signal to produce a normalized signal; controlling, using said normalized signal, said position of said beam of light on said PSD; adding said V filtering said difference signal with a first bandpass filter to produce a filtered difference signal; filtering said sum signal with a second bandpass filter to produce a filtered sum signal; amplifying said filtered difference signal with a first variable gain amplifier system to produce a first amplified difference signal; amplifying said filtered sum signal with a second variable gain amplifier system to produce a first amplified sum signal; detecting said first amplified sum signal with an automatic gain control (AGC) detector to produce a detected sum signal; inputting said detected sum signal to an automatic gain control controller to produce a received signal strength indicator (RSSI); and feeding said RSSI back to said first variable gain amplifier system to produce an amplified difference output signal that is modulated at said modulation frequency.