Production method for objects with radially-varying properties

• US 6,267,915 B1
• Filed: 09/12/1997
• Issued: 07/31/2001
• Est. Priority Date: 09/12/1996
• Status: Expired due to Fees

• Current Assignee: University of Florida Research Foundation, Incorporated (State University System of Florida)
• Original Assignee: University of Florida (State University System of Florida)
• Inventors: Park, Chang-Won, Walker, James K.
• Primary Examiner(s): Vargot, Mathieu D.
• Application Number:
  US08/929,160
• Time in Patent Office: 1,418 Days
• Field of Search: 264/1.1, 264/1.24, 264/1.28, 264/1.29, 264/1.7, 264/40.1, 425/131.1, 425/204, 425/205, 425/382.3, 425/382.4, 425/377, 425/461
• US Class Current: 264/1.24
• CPC Class Codes: B29C 48/05 Filamentary, e.g. strands
• CPC Class Codes: B29C 48/33 with parts rotatable relative to each other
• CPC Class Codes: B29D 11/00682 with a refractive index gradient

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.

Claims

1. A process for producing a graded-index plastic optical fiber with a radially-varying index of refraction, wherein said process transforms an axial variation of said index of refraction into said radial variation of said index of refraction, wherein said transformation to said radial variation is achieved by applying polymeric material having said axial variation of said index of refraction to a rotating cone which converts said axial variation to said radial variation, wherein said process comprises combining at least two polymers having different indices of refraction so as to create a combination having an axial variation of index of refraction, said process 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 a polymeric cylindrical form from the tip of said cone, wherein said polymeric cylindrical form has said radial variation of index of refraction.

10. The process, according to claim 1, 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.

2. A device for producing a polymeric 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;

a combining means for combining at least two optical polymeric materials having a material property of different indices of refraction so as to create a combination having an axial variation of index of refraction;

a mixing chamber, wherein a blend of said polymeric materials is created;

an introducing means for introducing said optical polymeric materials into said device;

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;

a feed chamber;

a second channeling means for channeling said axially varying blend into said feed chamber which houses a rotating cone; and

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 a radial variation of index of refraction,

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.

3. The device, according to claim 2, 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.

4. The device, according to claim 2, 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.

5. The device, according to claim 4, wherein said plurality of flow restrictors are bolts.

6. The device, according to claim 2, 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.

7. The device, according to claim 2, wherein said mixing chamber has a plurality of elliptical mixer blades.

8. The device, according to claim 2, 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.

9. The device, according to claim 2, 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.