Patent ID: 7619744
Filing Date: 2009-11-17
Classification: G01B,G01P,G01S

Abstract:
1. A relative movement sensor for measuring movement of an object and said sensor relative to each other, the sensor comprising: at least one laser, having a laser cavity, for generating a measuring beam and illuminating an object therewith, wherein at least some of the measuring beam radiation reflected by said object re-enters said laser cavity; measuring means for measuring changes in operation of said laser cavity caused by interference of reflected measuring beam radiation re-entering said laser cavity and the optical wave in said laser cavity; means for providing a first electric signal representative of said changes; band pass filter means for filtering said first electric signal so as to at least reduce the contribution thereto by low and high frequency noise to produce a second electric signal representative of said changes for use in determining relative movement of said object and said sensor; and a motor configured to effect said relative movement, wherein a pass band of the band pass filter means is set and dynamically changed and controlled in accordance with a speed of said motor.