Novel production method for objects with radially-varying properties

Abstract

The present invention is a continuous process of producing an object with radially-varying material properties. These objects can be cylindrical forms made from polymeric materials. This process requires a novel device. The device can be used to produce high bandwidth gradient-index plastic optical fiber (GRIN-POF). This fiber is highly advantageous for use in high speed local area networks (LANs) as well as other short-range optical communication applications. The device can also be used to produce GRIN lenses which can be used in the focusing and transmission of images.

1 . A process for producing a cylindrical form with at least one radially-varying material property, wherein said process transforms an axial variation of said material property into said radial variation of said material property.  
     
     
         2 . The process, according to  claim 1 , wherein said transformation to said radial variation is achieved by applying polymeric material having said axial variation of said material property to a rotating cone which converts said axial variation to said radial variation.  
     
     
         3 . The process, according to  claim 2 , wherein said property is an optical property.  
     
     
         4 . The process, according to  claim 3 , wherein said property is index of refraction.  
     
     
         5 . The process, according to  claim 4 , wherein said process produces a plastic optical fiber.  
     
     
         6 . The process, according to  claim 5 , wherein said process comprises combining at least two optical materials having different indices of refraction so as to create a combination having an axial variation of index of refraction.  
     
     
         7 . The process, according to  claim 6 , wherein said optical materials are polymers.  
     
     
         8 . The process, according to  claim 5 , wherein said process comprises combining at least one optical polymeric material with a least one low molecular weight additive having a different index of refraction than said optical polymeric material so as to create a combination having an axial variation of index of refraction.  
     
     
         9 . The process, according to  claim 7 , wherein said plastic optical fiber is a graded-index plastic optical fiber.  
     
     
         10 . The process, according to  claim 9 , further comprising the steps of: 
 (a) introducing said optical polymeric materials into a die block;    (b) channeling each optical polymeric material into a mixing chamber, which houses a mixing means, such that the ratio of said optical polymeric materials varies within said mixing chamber along a first axis;    (c) mixing said optical polymeric materials within said mixing chamber such that said blend has said axial variation of index of refraction along said first axis;    (d) channeling said axially varying blend into a feed chamber which houses said cone; and    (e) after applying said blend to said rotating cone, pulling said polymeric cylindrical form from the tip of said cone, wherein said polymeric cylindrical form has said radial variation of index of refraction.    
     
     
         11 . The process, according to  claim 7 , wherein said plastic optical fiber is a step-index plastic optical fiber.  
     
     
         12 . The process, according to  claim 11 , further comprising the steps of: 
 (a) introducing said optical polymeric materials with different indices of refraction into a die block;    (b) channeling said optical polymeric materials into adjacent positions to produce said combination having axial variation of index of refraction wherein said axial variation is perpendicular to the direction of flow; and    (c) after applying said combination to said rotating cone, pulling said polymeric cylindrical form from the tip of said cone, wherein said polymeric cylindrical form has said radial variation of index of refraction.    
     
     
         13 . The process, according to  claim 7 , wherein at least one of said optical polymeric materials is an amorphous homo-, co-, or ter-polymer.  
     
     
         14 . The process, according to  claim 7 , wherein at least one of said optical polymeric materials comprises a dissolved additive, wherein said additive raises or lowers the index of refraction.  
     
     
         15 . The process, according to  claim 7 , wherein at least one of said optical polymeric materials is a polymethacrylate, or a derivative thereof.  
     
     
         16 . The process, according to  claim 2 , wherein said rotating cone has a monotonically decreasing radius from the base of said cone to the tip of said cone.  
     
     
         17 . The process, according to  claim 16 , wherein said rotating cone has a straight-line, concave, or convex side profile.  
     
     
         18 . A device for producing a cylindrical form with at least one radially-varying material property comprising: a transforming means for transforming an axial variation of said material property into said radial variation of said material property.  
     
     
         19 . The device, according to  claim 18 , wherein said transforming means is a cone which converts said axial variation to said radial variation, wherein said transformation to said radial variation is achieved by applying polymeric material having said axial variation of said material property to said cone while said cone is rotating.  
     
     
         20 . The device, according to  claim 19 , further comprising a combining means for combining at least two optical polymeric materials having different indices of refraction so as to create a combination having an axial variation of index of refraction.  
     
     
         21 . The device, according to  claim 20 , further comprising a mixing chamber, wherein a blend of said polymeric materials is created.  
     
     
         22 . The device, according to  claim 21 , further comprising: 
 (a) an introducing means for introducing said optical polymeric materials into said device;    (b) a first channeling means for channeling each optical polymeric material into said mixing chamber such that the ratio of said optical polymeric materials varies within said mixing chamber along a first axis;    (c) a feed chamber;    (d) a second channeling means for channeling said axially varying blend into said feed chamber which houses said cone; and    (e) a pulling means for, after applying said blend to said rotating cone, pulling said polymeric cylindrical form from the tip of said cone, wherein said polymeric cylindrical form has said radial variation of index of refraction.    
     
     
         23 . The device, according to  claim 22 , wherein said first channeling means has a gap profile which varies along said first axis in such a way as to determine the radial variation of refractive index of said graded-index plastic optical fiber.  
     
     
         24 . The device, according to  claim 22 , wherein said second channeling means comprises a plurality of flow restrictors such that adjustment of said flow restrictors can fine-tune the radial variation of refractive index of said polymeric materials.  
     
     
         25 . The device, according to  claim 24 , wherein said plurality of flow restrictors are bolts.  
     
     
         26 . The device, according to  claim 22 , wherein said second channeling means comprises a flexible surface which defines the gap profile of said second channeling means and a set of external adjusters wherein said set of external adjusters can adjust the position of said flexible surface and therefore change the gap profile of said second channeling means, thus fine-tuning the radial variation of refractive index of said polymeric materials.  
     
     
         27 . The device, according to  claim 22 , wherein said mixing means is a plurality of elliptical mixer blades.  
     
     
         28 . The device, according to  claim 22 , wherein said first channeling means comprises a plurality of flow restrictors such that adjustment of said flow restrictors can alter the radial variation of refractive index of said fiber.  
     
     
         29 . The device, according to  claim 22 , wherein said first channeling means comprises a plurality of flexible surfaces which define the gap profile of said first channeling means and a set of external adjusters wherein said sets of external adjusters can adjust the position of said flexible surfaces and therefore change the gap profile of said first channeling means, thus altering the radial variation of refractive index of said fiber.  
     
     
         30 . The device, according to  claim 20 , further comprising: 
 (a) an introducing means for introducing said optical polymeric materials with different indices of refraction into said device;    (b) a channeling means for channeling said optical polymeric materials into adjacent positions to produce said combination having axial variation of index of refraction wherein said axial variation is perpendicular to the direction of flow; and    (c) a pulling means for, after applying said combination to said rotating cone, pulling said polymeric cylindrical form from the tip of said cone, wherein said polymeric cylindrical form has said radial variation of index of refraction.    
     
     
         31 . The device, according to  claim 21 , wherein said device is made of stainless steel, or hastelloy, or ceramic.  
     
     
         32 . The device, according to  claim 21 , wherein said cone can rotate at between about 20 to about 100 RPM.  
     
     
         33 . The device, according to  claim 21 , wherein said rotating cone has a monotonically decreasing radius from the base of said cone to the tip of said cone.  
     
     
         34 . The device, according to  claim 21 , wherein said rotating cone has a straight-line, concave, or convex side profile.  
     
     
         35 . A graded-index polymeric cylindrical form having an index of refraction profile controlled by rigid surfaces of a die wherein said index of refraction profile is uniform throughout the full length of the fiber over arbitrary lengths.  
     
     
         36 . A graded-index polymeric cylindrical form, according to  claim 35 , wherein said form is a graded-index plastic optical fiber.  
     
     
         37 . A graded-index plastic optical fiber, according to  claim 36 , having a power-law index of refraction profile.  
     
     
         38 . A graded-index polymeric cylindrical form, according to  claim 35 , wherein said form is a plastic optical rod lens having a power-law index of refraction profile.  
     
     
         39 . A graded-index polymeric cylindrical form, according to  claim 35 , wherein said form is a plastic optical rod lens having a negative gradient index of refraction profile.  
     
     
         40 . A graded-index polymeric cylindrical form, according to  claim 35 , having a radial index of refraction profile with a first derivative which goes from positive to negative and/or negative to positive.  
     
     
         41 . A graded-index polymeric cylindrical form, according to  claim 35 , having a predefined index of refraction profile.  
     
     
         42 . A gradient-index plastic optical fiber, according to  claim 36 , consisting of at least two polymers with different refractive index wherein said fiber has a stable index of refraction profile over temperatures ranging from minus −200° C. to plus +160° C.  
     
     
         43 . A gradient-index plastic optic fiber, according to  claim 36 , wherein the power-law index of refraction profile, as a function of g, of said fiber is controllable such that g is within the range g 0 ±0.05, wherein g 0  is a target value for g.  
     
     
         44 . The process, according to  claim 10 , wherein said die block comprises flow restrictors, wherein the index of refraction profile is measured during the process, thus allowing adjustment of said flow restrictors during the process to fine-tune the profile to achieve the desired profile.  
     
     
         45 . A graded-index polymeric cylindrical form, according to  claim 35 , produced by a device, wherein said device comprises: a mixing chamber wherein a blend of optical polymeric materials is created; a channeling means for channeling a plurality of optical polymeric materials into said mixing chamber such that the ratio of said optical polymeric materials varies within said chamber along an axis; said channeling means having rigid surfaces, said cylindrical form having an index of refraction profile controlled by the rigid surfaces of said channeling means and as such is uniform and reproducible over arbitrary lengths.  
     
     
         46 . An optical fiber having an index of refraction profile which is uniform throughout the length of said fiber.  
     
     
         47 . A plurality of optical fibers wherein the index of refraction profile of each fiber is essentially the same as each other fiber.  
     
     
         48 . The process, according to  claim 7 , wherein a first optical material is a copolymer comprising approximately 50-70% by weight of benzylmethacrylate monomer and approximately 30-50% by weight of methymethacrylate monomer and a second optical material is a copolymer comprising approximately 30-50% by weight of benzylmethacrylate monomer and approximately 50-70% by weight of methylmethacrylate monomer.  
     
     
         49 . The process, according to  claim 48 , wherein a first optical material is a copolymer comprising approximately 60% by weight of benzylmethacrylate monomer and approximately 40% by weight of methymethacrylate monomer and a second optical material is a copolymer comprising approximately 40% by weight of benzylmethacrylate monomer and approximately 60% by weight of methylmethacrylate monomer.  
     
     
         50 . The process, according to  claim 7 , wherein a first optical material is a copolymer comprising approximately 70-80% by weight of styrene monomer and approximately 20-30% by weight of acrylonitrile monomers and a second optical material comprises approximately 100% by weight of polymethylmethacrylate.  
     
     
         51 . The process, according to claim  50 , wherein a first optical material is a copolymer comprising approximately 75% by weight of styrene monomer and approximately 25% by weight of acrylonitrile monomers and a second optical material comprises approximately 100% by weight of polymethylmethacrylate.  
     
     
         52 . The process, according to  claim 7 , wherein a first optical material is a copolymer comprising approximately 30-50% by weight of methylmethacrylate monomer and approximately 50-70% by weight of trifluoroethylmethacrylate and a second optical material is a copolymer comprising approximately 50-70% by weight of methylmethacrylate monomer and approximately 30-50% by weight of trifluoroethylmethacrylate.  
     
     
         53 . The process, according to claim  52 , wherein a first optical material is a copolymer comprising approximately 40% by weight of methylmethacrylate monomer and approximately 60% by weight of trifluoroethylmethacrylate and a second optical material is a copolymer comprising approximately 60% by weight of methylmethacrylate monomer and approximately 40% by weight of trifluoroethylmethacrylate.