Patent ID: 7359057
Filing Date: 2008-04-15
Classification: G01P,G01S,Y02A

Abstract:
1. A method for determining a shift in optical wavelength, comprising: generating light having a first wavelength at a first location; directing said generated light towards an area of interest; receiving light reflected from said area of interest at about said first location, wherein at least some of said reflected light comprises at least a portion of said generated light; directing a first portion of said received reflected light along a first optical path to form a first beam; directing a second portion of said received reflected light along a second optical path to form a second beam: delaying a first portion of said received light directed along said first optical path by a first delay interval at time t, wherein said delaying a first portion of said received light includes reflecting said first portion of said received light off a first portion of a first mirror assembly; delaying a second portion of said received light directed along said first optical path by a second delay interval at time t, wherein said delaying a second portion of said received light includes reflecting said second portion of said received light off a second portion of said first mirror assembly; delaying a third portion of said received light directed along said first optical path by a third delay interval at time t, wherein said delaying a third portion of said received light includes reflecting said third portion of said received light off a third portion of said first mirror assembly, wherein at time t a position of said first mirror assembly is fixed, and wherein time t is about equal to a travel time of light to and from said area of interest; combining at least some of said first beam with said delayed first portion of said second beam to obtain a first interference signal; combining at least some of said first beam with said delayed second portion of said second beam to obtain a second interference signal; combining at least some of said first beam with said delayed third portion of said second beam to obtain a third interference signal; determining at a common instant in time an intensity of said received interference signals at each of said three different delay intervals, wherein said delays are spaced at known intervals of said first wavelength from one another, wherein time t comprises one instant in time, and wherein said determining an intensity of said received reflected light at three different delay intervals at time t includes measuring an intensity of each of said first, second and third interference signals at time t; and determining from a ratio of said first, second and third interference signal intensities a change in wavelength between said generated light and said reflected light.