Applicator for high-speed gel buffering of flextube optical fiber bundles

Abstract

A method for combining a water barrier fluid to a bundle of optical fibers including an entrance die having an orifice which is dimensioned to allow for a bundle of optical fibers to be drawn therethrough. Also, an exit die having an orifice is provided. The entrance die and the exit die, respectively, have inner sides which define a cavity. The cavity is in fluid communication with the orifice of the entrance die and the orifice of the exit die, such that a gap is formed at a meeting point between the cavity and the respective orifices of the entrance and the exit die. The gap is radially surrounded by an extension of the cavity to define a critical flow region. A plurality of baffles are formed in the exit die which are operative to inject fluid into the cavity. Also provided is a main body which supports the entrance die and the exit die. The main body includes a passageway that is in fluid communication with the plurality of baffles. A retaining ring is included which secures the entrance die and the exit die to the main body.

1 . A method of applying a fluid to an optical fiber, the method comprising: 
 drawing an optical fiber through an orifice formed in a die; and    injecting a fluid into a cavity formed in the die, wherein the cavity is in communication with the orifice, and wherein the fluid is pressurized through the cavity and onto the optical fiber.    
   
   
       2 . The method of  claim 1 , wherein the optical fiber is part of a plurality of optical fibers which form a bundle, and the fluid is pressurized onto the bundle.  
   
   
       3 . The method of  claim 2 , wherein a kinetic energy of the fluid as it is extruded onto the bundle is larger than an air boundary layer around the bundle, which eliminates air pockets entrained with the bundle.  
   
   
       4 . The method of  claim 3 , wherein the kinetic energy of the fluid is at least several hundred times a kinetic energy of the air entrained with the bundle.  
   
   
       5 . The method of  claim 2 , wherein the die compresses individual optical fibers of the bundle towards each other such that excess air is removed from the bundle to obtain a predetermined degree of compaction.  
   
   
       6 . The method of  claim 1 , wherein the cavity has a resistance to filling which varies so that a flow-induced shear stress on the fluid is gradually increased toward the optical fiber.  
   
   
       7 . The method of  claim 1 , further comprising providing the fluid with a linear velocity which is sufficient to overcome kinetic energy of an air boundary layer traveling along with the optical fiber.  
   
   
       8 . The method of  claim 1 , further comprising pressurizing the fluid into an injection port before the fluid is pressurized into the cavity.  
   
   
       9 . The method of  claim 2 , further comprising propelling the fluid at a velocity which causes it to reach and be deposited on a central part of the bundle.  
   
   
       10 . The method of  claim 1 , wherein the fluid is applied by controlling its volumetric flow rate.  
   
   
       11 . The method of  claim 1 , wherein the orifice accepts a plurality of optical fibers which are formed in a circular pattern such that when they are passed through the orifice they are radially compressed.  
   
   
       12 . The method of  claim 2 , wherein the fluid is applied in a direction normal to a surface of the optical fibers, as the optical fibers pass between an entrance and an exit of the die.  
   
   
       13 . The method of  claim 1 , wherein the die comprises an entrance part and an exit part, and 
 and a plurality of holes extend through the exit part so as to be radially positioned around the orifice and extend in an axial direction of the orifice, such that the holes are in fluid communication with the cavity.    
   
   
       14 . The method of  claim 13 , further comprising supporting the entrance part and the exit part with a main body which includes a passageway in fluid communication with the plurality of holes, and defining a fluid flow path through the passageway and cavity to an exit gap leading to the optical fiber.  
   
   
       15 . The method of  claim 2 , wherein the fluid passes through an exit gap of the cavity onto the bundle, and wherein a width of the orifice is at least twice as large as a width of the exit gap.  
   
   
       16 . The method of  claim 13 , further comprising spacing the entrance part from the exit part to form an exit gap, such that the fluid flows from the cavity and through the exit gap to contact the optical fiber.  
   
   
       17 . The method of  claim 1 , wherein the fluid is a gel comprising one of a Newtonian liquid, dilute solution containing polymer molecules, and a liquid slurry containing solid particles.  
   
   
       18 . The method of  claim 13 , further comprising forming the entrance part and the exit part from a separate entrance die and an exit die which are brought together to form the cavity.  
   
   
       19 . The method of  claim 18 , wherein the entrance part is formed to angle inwardly toward the exit part.  
   
   
       20 . The method of  claim 13 , wherein the orifice accepts a plurality of optical fibers such that when they are passed through the orifice they are radially compressed.