Precision length standard for coherent laser radar
This disclosure presents a version of a coherent laser radar system that is immune to environmental effects on Mach-Zehnder-configured interferometers and reference length standards comprising such systems. The present disclosure also describes methods and materials which alleviate interferometer drift due to vapor absorption using a polyimide coated polarization maintaining fiber to reduce the change in the length of a reference arm.
1 . A substantially hydrophobic and substantially non-outgassing coating for optical fibers, whereby the optical fiber maintains substantial dimensional and refractive stability.
2 . The coating of claim 1 wherein the coating is a polymer.
3 . The coating of claim 1 wherein the coating is selected from the group consisting of: Ultraviolet Cured Acrylate, Teflon, DuPont Tefzel, Hytrel, and Nylon.
4 . The coating of claim 1 wherein the coating comprises a metal.
5 . The coating of claim 2 wherein the polymer is polyimide.
6 . A method of preserving optical path length and polarization maintaining properties of optical fibers comprising coating an optical fiber with a substantially hydrophobic and substantially non-outgassing coating.
7 . The method of claim 6 wherein the coating is a polymer.
8 . The method of claim 6 wherein the coating is selected from the group consisting of: Ultraviolet Cured Acrylate, Teflon, DuPont Tefzel, Hytrel, and Nylon.
9 . The method of claim 6 wherein the coating comprises a metal.
10 . The method of claim 7 wherein the polymer is polyimide.
11 . In a fiber optic interferometer, the improvement comprising at least one optical fiber coated with a substantially hydrophobic and substantially non-outgassing coating, whereby the optical fiber maintains substantial dimensional and refractive stability.
12 . The improvement of claim 11 wherein the fiber optic interferometer is a reference standard in a laser distance measuring apparatus.
13 . The coating of claim 11 wherein the coating is a polymer.
14 . The coating of claim 11 wherein the coating is selected from the group consisting of: Ultraviolet Cured Acrylate, Teflon, DuPont Tefzel, Hytrel, and Nylon.
15 . The coating of claim 11 wherein the coating comprises a metal.
16 . The coating of claim 13 wherein the polymer is polyimide.