Abstract: An optical fiber for use in distributed vibration sensing has perturbations along its length. The perturbations may be applied externally to a mode field diameter of the optical fiber. Alternatively, the perturbations may be applied through the use of fusion splicing of fiber lengths that form the optical fiber.

Abstract: A stream switching valve for alternatively feeding two fluids to an object of interest comprises a housing having first, second and third cavities, first, second and third ball members sealably placeable into said first, second and third cavities, first and second inlet passages being in fluid communication with said first and second cavities, an outlet passage being in fluid communication with said third cavity; said outlet passage connectable to an object of interest; first and second intermediate passages fluidly connecting said first and second cavities to said third cavity, first, second and third vent passages fluidly connecting said into first, second and third cavities to environment. The first and second ball members are configured to connect said first and second intermediate passages to first and second inlet passages and first and second vent passages, respectively, in turn.

Abstract: Elastic compression apparatus for loose tube used in fiber optic cables, comprising compression contacts for gripping the loose tube following extrusion, the loose tube being made of a first material having a predefined post-extrusion shrinkage, and the compression contacts being made of a second material, wherein the compression contacts are modified to provide a coefficient of friction between the two materials such that said compression contacts apply a radial pressure and an axial tension to said tube that cause elastic deformation only and do not cause plastic deformation. The tube may be extruded at a line speed rate that is relatively different from the optical fiber line speed rate, and causes elastic extension of the tube over the distance that would be covered by post-extrusion shrinkage.

Abstract: Elastic compression apparatus for loose tube used in fiber optic cables, comprising compression contacts for gripping the loose tube following extrusion, the loose tube being made of a first material having a predefined post-extrusion shrinkage, and the compression contacts being made of a second material, wherein the compression contacts are modified to provide a coefficient of friction between the two materials such that said compression contacts apply a radial pressure and an axial tension to said tube that cause elastic deformation only and do not cause plastic deformation. The tube may be extruded at a line speed rate that is relatively different from the optical fiber line speed rate, and causes elastic extension of the tube over the distance that would be covered by post-extrusion shrinkage.

Abstract: A stream switching valve for alternatively feeding two fluids to an object of interest comprises a housing having first, second and third cavities, first, second and third ball members sealably placeable into said first, second and third cavities, first and second inlet passages being in fluid communication with said first and second cavities, an outlet passage being in fluid communication with said third cavity; said outlet passage connectable to an object of interest; first and second intermediate passages fluidly connecting said first and second cavities to said third cavity, first, second and third vent passages fluidly connecting said into first, second and third cavities to environment. The first and second ball members are configured to connect said first and second intermediate passages to first and second inlet passages and first and second vent passages, respectively, in turn.

Abstract: A method of coating a silica-silica optical fiber, comprising, in a single pass on a fiber coating machine: applying a primary layer of UV curable acrylate carrying a first color, on said fiber; and applying a second layer of UV curable acrylate carrying a second color different from the first color, on top of the primary layer, the second layer being applied in patterns over the primary layer. The method is used to identify fibers in bundles or loose tubes where there are more fibers than there are basic colors.

Abstract: A method of coating a silica-silica optical fiber, comprising, in a single pass on a fiber coating machine: applying a primary layer of UV curable acrylate carrying a first color, on said fiber; and applying a second layer of UV curable acrylate carrying a second color different from the first color, on top of the primary layer, the second layer being applied in patterns over the primary layer. The method is used to identify fibers in bundles or loose tubes where there are more fibers than there are basic colors.