Patent ID: 6133993
Filing Date: 2000-10-17
Classification: G01P,G01S

Abstract:
A measurement apparatus for measuring the distance of a target, the measurement apparatus comprising:means for generating an optical signal;means for modulating said optical signal with an RF microwave signal defining a modulated optical signal;means for generating an RF microwave signal having a first frequency F.sub.1 ;means for transmitting said modulated optical signal to a target of interest by way of a first aperture and receiving reflected optical signals from said target of interest by way of a second aperture;means for demodulating the RF microwave signal from said modulated optical signal reflected from said target defining a detected RF signal;means for summing said detected RF signal with an RF reference signal to generate an RF sum signal;means for demodulating said RF sum signal defining a demodulated sum signal;means for sweeping the frequency of said generating means from said first frequency F.sub.1 to a second frequency F.sub.2 ;means for counting the periods in said demodulated sum signal while said frequency is varied from F.sub.1 to F.sub.2 ; anda movable carriage for carrying said measurement apparatus and enabling the distance between said measurement apparatus and said target of interest to be adjusted toward and away from the target as a function of the periods of said RF sum signal; the movable carriage adapted to being maintained in a stationary position after adjustment and during a measurement.