Tracking laser interferometer

US4790651A · kind A · utility

Assignee

• Chesapeake Laser Systems, Inc. · US

Inventors

• Lawrence B. Brown · Cochranville, US
• David N. Wells · Silver Spring, US
• J. Bradford Merry · Annapolis, US

Key dates

• Filing date: Sep 30, 1987
• Grant date: Dec 13, 1988
• Expiry date: Sep 30, 2007

Classification

• Technology area (CPC G): Physics
• CPC primary: G01S2013/466
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A system for tracking a randomly moving object using a laser beam and first and second beam steering assemblies. The steering assemblies pivot, respectively, about substantially perpendicular and intersecting X and Y axes and direct the laser beam along an R axis, which is perpendicular to the X axis and intersects the X and Y axes. Along the R axis, the laser beam is intercepted by a retroreflector, which is coupled to the moving object and which returns the laser beam to a quadrant detector via the steering assemblies. The quadrant detector generates an error signal representative of the object's movement relative to the X and Y axes, and this signal is transmitted to two motors which pivot the steering assemblies about the X and Y axes to reduce the error to zero. The system includes an interferometer to determine the distance of the object from a reference location. The first beam steering assembly includes two prisms which redirect the laser beam through three 90.degree. reflections from an initial direction parallel to the Y axis and towards the X axis to an intermediate direction along the X axis and towards the Y axis. The second beam steering assembly includes a third pris…