Ranging system which compares an object-reflected component of a light beam to a reference component of the light beam

US4533242A · kind A · utility

Assignee

• The United States of America as represented by the Administrator of the National Aeronautics and Space Administration · US

Inventors

• John McLauchlan · Pasadena, US
• John AuYeung · Alhambra, US
• Eldred F. Tubbs · Claremont, US
• Willis C. Goss · Altadena, US
• Demetri Psaltis · Altadena, US

Key dates

• Filing date: Sep 28, 1982
• Grant date: Aug 6, 1985
• Expiry date: Sep 28, 2002

Classification

• Technology area (CPC G): Physics
• CPC primary: G01S17/10
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A system is described for measuring the distance to an object by comparing a first component (18) of a light pulse that is reflected off the object (14), with a second component (20) of the light pulse that passes along a reference path (26) of known length, which provides great accuracy with a relatively simple and rugged design. The reference path (26) can be changed in precise steps so that is has an equivalent length approximately equal to the path length of the light pulse component that is reflected from the object. The resulting small difference in path lengths can be precisely determined by directing the light pulse components into opposite ends of a detector (70) formed of a material that emits a second harmonic light output at the locations where the opposite-going pulses pass simultaneously across one another.