Eldred F Tubbs

US Patent:

45332428, Aug 6, 1985

Filed:

Sep 28, 1982

Appl. No.:

6/425202

Inventors:

John M. McLauchlan - Pasadena CA
John AuYeung - Alhambra CA
Eldred F. Tubbs - Claremont CA
Willis C. Goss - Altadena CA
Demetri Psaltis - Altadena CA

Assignee:

The United States of America as represented by the Administrator of the
National Aeronautics and Space Administration - Washington DC

International Classification:

G01C 308

US Classification:

356 5

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.