Brix, Peter (Stadthausstrasse 17 Mainz, 55116, DE)
Gerstner, Klaus (Otto-Hahn-Strasse 17 Mainz, 55192, DE)
Schlatterbeck, Dirk (Leibnitzstrasse 2 Mainz, 55118, DE)
Weisser, Michael (Vogelsbergstrasse 67 Mainz, 55129, DE)
Sommer, Martin (Am Sportfeld 12b Ockenheim, 55437, DE)
Rubino Jr., Robert A. (296 Weigold Road Tolland, CT, 06084, US)
Bonja, Jeffrey A. (180 Fiske Hill Road Sturbridge, MA, 01566, US)
Strack, Richard (34 Wells Park Road Sturbridge, MA, 01566, US)
Henze, Inka (Osterstrasse 22a Udenheim, 55288, DE)
CARL-ZEISS-STIFTUNG trading as SCHOTT GLAS (Hattenbergstrasse 10 Mainz, 55122, DE)
Carl-zeiss-stiftung (Heidenheim, 89518, DE)
Plichta, Armin (Graf-Eberhard-Strasse 19 Sponheim, 55595, DE)
Brix, Peter (Stadthausstrasse 17 Mainz, 55116, DE)
Gerstner, Klaus (Otto-Hahn-Strasse 17 Mainz, 55192, DE)
Schlatterbeck, Dirk (Leibnitzstrasse 2 Mainz, 55118, DE)
Weisser, Michael (Vogelsbergstrasse 67 Mainz, 55129, DE)
Sommer, Martin (Am Sportfeld 12b Ockenheim, 55437, DE)
Rubino Jr., Robert A. (296 Weigold Road Tolland, CT, 06084, US)
Bonja, Jeffrey A. (180 Fiske Hill Road Sturbridge, MA, 01566, US)
Strack, Richard (34 Wells Park Road Sturbridge, MA, 01566, US)
Henze, Inka (Osterstrasse 22a Udenheim, 55288, DE)
| 1. | A method for forming a waveguide having a desired MxN array of optical fibers extending between first and second surfaces, including: (a) providing a plurality of fibers arranged in a 1xN array to form a first ribbon of optical fibers; (b) bending the first ribbon of optical fibers through a desired path to form one nonlinear segment; (c) providing another plurality of fibers arranged in a IxN array to form a in' ribbon of optical fibers; (d) bending the in'ribbon of optical fibers through the desired path to form a tA'nonlinear segment; (e) placing the ribbon of optical fibers on top of the one ribbon of optical fibers such that the first nonlinear segment and the mth nonlinear segment are generally nested to form a two dimensional array of optical fibers at the first and second surfaces; and (f) repeating steps (c), (d), and (e) for m = 2 through M ribbons of optical fibers to form the desired MxN array. |
| 2. | The method of claim 1, wherein the bending of the first ribbon of optical fibers includes bending the first ribbon of optical fibers through a desired angle to form one bent end. |
| 3. | The method of claim 1, further includes adding an adhesive as a potting material to secure the optical fibers in position. |
| 4. | The method of claim 1, further including adhesively securing the in' ribbon of optical fibers to one of the first ribbon of optical fibers or a previous one of the in'ribbons of optical fibers when nesting the ribbon of optical fibers thereover. |
| 5. | A method of forming a fiber bundle, including : arranging a plurality of optic fiber preforms and leachable spacers to form a fiber bundle preform having an initial crosssectional area and having, within an initial tolerance value, an initial distance between centers of the plurality of optic fiber preforms; and heating and drawing the fiber bundle preform to obtain a drawn fiber bundle formed of a plurality of drawn optic fibers, the drawn fiber bundle having a cross sectional area reduced in size from the initial crosssectional area by a determined value, the drawn fiber bundle having, within a second tolerance value, a desired distance between centers of the plurality of drawn optical fibers, and the desired distance between centers of the plurality of drawn optical fibers being equal to the initial distance divided by the determined value. |
| 6. | The method of 5, further including: coating ends of the drawn fiber bundle with a leaching agent resistant material; and leaching some material from the spacers from a middle portion of the drawn fiber bundle to form a flexible region. |
| 7. | The method of 5, further includes installing a ferrule on at least one end of the drawn fiber bundle. |
| 8. | The method of claim 5, further measuring the determined value prior to completing the heating and drawing of the plurality of optic fiber preforms. |
| 9. | The method of claim 5, further including measuring the drawn fiber bundle to measure the determined value during the heating and drawing, and controlling the drawing process utilizing a feedback system to attain the determined value. |
| 10. | A method of forming an ordered optic fiber array, including: providing at plurality of fiber optic preforms; providing a guide plate having a plurality of bores therethrough; heating and drawing the plurality of fiber optic preforms to form a plurality of drawn optic fibers; guiding each of the plurality of drawn optic fibers through a separate one of the plurality of bores; stopping the drawing process; applying an adhesive or a potting material over a portion of each of the plurality of drawn optic fibers adjacent to the guide plate to form a plug; and separating at least a portion of the plug to form an end of an ordered optic fiber array. |
| 11. | The method of claim 10, further comprising separating the plug into at least two portions such that ends of two ordered fiber arrays are formed. |
| 12. | The method of claim 10, further characterized by the positioning of the adhesive or the potting material includes forming the plug on a side of the guide plate opposite from an initial position of the plurality of fiber optic preforms. |
[0004] It has been previously known to produce image conductors or guides for transmitting optical signals in the form of ordered optical fiber arrays. Such fiber arrays typically include a large number of optical fibers arranged in an ordered manner, with each fiber having a small diameter, for example 10-100 microns. The fiber bundles may be formed by drawing a fiber bundle preform having a number of pre-arranged optic fiber preforms, in the form of glass rods and/or tubes, together with at least some leachable glass spacers located between or encapsulating each of the desired optic fiber preforms. The fiber bundle preform is drawn down to the desired size for the optical fibers, which are fused together with the leachable glass spacers as they are drawn. Individual fibers can also be drawn and bundled together in a separate operation.
[0005] Precise spacing with extremely small tolerances between the ends of the fibers must be obtained to form an ordered array that can be used, for example, in a connector to mate with an array of opto-electronic emitters and/or detectors. It has been very inefficient and costly to produce an ordered fiber array according to such predetermined specifications within a small tolerance, especially as the number of individual fibers increases. These difficulties are further compounded when the finished fiber bundle must be shaped as a bent waveguide.
[0006] It would be advantageous to increase the efficiency with which ordered fiber arrays having precise spacing with small tolerances between the fibers can be produced. It would also be advantageous to simplify the bending of a fiber bundle and to simplify the securing of optical fibers as an ordered array.
[0007] SUMMARY [0008] Briefly stated, one aspect of the present invention provides a method of forming a fiber bundle. The method includes: arranging a plurality of optic fiber preforms and leachable spacers to form a fiber bundle preform having an initial cross- sectional area and having, within an initial tolerance value, an initial distance between centers of the plurality of optic fiber preforms; and heating and drawing the fiber bundle preform to obtain a drawn fiber bundle formed of a plurality of drawn optic fibers, the drawn fiber bundle having a cross-sectional area reduced in size from the initial cross-sectional area by a determined value, the drawn fiber bundle having, within a second tolerance value, a desired distance between centers of the plurality of drawn optical fibers, and the desired distance between centers of the plurality of drawn optical fibers being equal to the initial distance divided by the determined value.
[0009] In another aspect, the present invention provides a method for forming a waveguide having a desired MxN array of optical fibers extending between first and second surfaces. The method includes: (a) providing a plurality of fibers arranged in a IxN array to form a first ribbon of optical fibers; (b) bending the first ribbon of optical fibers through a desired path to form one nonlinear segment; (c) providing another plurality of fibers arranged in a 1xN array to form a mth ribbon of optical fibers; (d) bending the ribbon of optical fibers through the desired path to form a mth nonlinear segment; (e) placing the ribbon of optical fibers on top of the first ribbon of optical fibers such that the first nonlinear segment and the mt''nonlinear segment are generally nested to form a two dimensional array of optical fibers at the first and second surfaces; and (f) repeating steps (c), (d), and (e) for m = 2 through M ribbons of optical fibers to form the desired MxN array.
[0010] In another aspect, the present invention provides a method of forming an ordered optic fiber array. The method includes: providing a plurality of fiber optic preforms ; providing a guide plate having a plurality of bores therethrough ; heating and drawing the plurality of fiber optic preforms to form a plurality of drawn optic fibers; guiding each of the plurality of drawn optic fibers through a separate one of the plurality of bores; stopping the drawing process; applying an adhesive or a potting material over a portion of each of the plurality of drawn optic fibers adjacent to the guide plate to form a plug; and separating at least a portion of the plug to form an end of an ordered optic fiber array.
[0011] BRIEF DESCRIPTION OF THE DRAWINGS [0012] The foregoing summary, as well as the following detailed description of the preferred embodiments of the present invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there are shown in the drawings embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. In the drawings: [0013] Figure 1 is a schematic elevational view illustrating the drawing of an optical fiber bundle preform in order to form a drawn optical fiber bundle in accordance with a first preferred method of the present invention; [0014] Figure 2 is a cross-sectional view of the optical fiber bundle preform of Figure 1 as taken along the line 2-2 in Figure 1 ; [0015] Figure 3 is a cross-sectional view of the optical fiber bundle preform of Figure 1 as taken along the line 3-3 in Figure 1; [0016] Figure 4 is a partial elevational view of three (3) nested ribbons of optical fibers in accordance with a second preferred method of the present invention ; [0017] Figure 5 is view of the nested ribbons of Figure 4 as viewed along the line 5-5 of Figure 4; and [0018] Figure 6 is a schematic elevational view illustrating the drawing of a plurality of optical fiber preforms to form an ordered array in accordance with a third preferred method of the present invention.
[0019] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0020] Certain terminology is used in the following description for convenience only and is not considered limiting. The terms"a"and"one"are defined as including one or more of the referenced item unless specifically noted.
[0021] The first preferred method of the present invention relates to manufacturing a fiber bundle 10, as shown in Figures 1-3, which is adapted for use as, for example, an image conductor or guide for endoscopes or for transmission of optical signals. The fiber bundle 10 includes a plurality of optic fibers 12 which may be as small as ten microns in diameter or smaller. The fiber bundle 10 may be enclosed in a sheathing of protective material which is preferably a flexible polymeric material. However, the sheathing is not necessary.
[0022] Referring to Figures 4 and 5, a second preferred method of the present invention relates to manufacturing a waveguide 40 having a desired MxN array of optical fibers 42 extending between first and second surfaces 44A, 44B and having a generally nonlinear segment 46 therein. The MxN array is formed by multiple, separately arranged lxN arrays of optical fibers 48 that are formed as ribbons of optical fibers 50.
[0023] Referring to Figure 6, a third preferred method of the present invention relates to a method of forming an ordered optic array with a plurality of drawn optic fibers being secured in a plug 52. This method allows the serial manufacture of segments of multiple optic fibers having ends secured in an adhesive or potting material 54 to maintain the optic fiber ends in precise alignment and simplify interconnection between different segments.
[0024] Referring to Figures 1-3 the first preferred method is as follows. In order to manufacture the fiber bundle 10, a plurality of optic fiber preforms 20 and leachable spacers 22 are arranged to form a fiber bundle preform 24. The fiber bundle preform 24 has an initial cross-sectional area 58 and has, within an initial tolerance value, an initial distance between centers (illustrated as 100R and 100S in Figure 2) of the optic fiber preforms 20. It is preferable, but not necessary, that the fiber bundle preform 34 be arranged in an ordered array and spaced apart using leachable spacers 22 to form a fiber bundle preform 24, as shown in Figure 2.
[0025] The optical fiber preforms 20 are preferably formed from high index glass cores surrounded by a lower index cladding material. The optic fiber preforms 20 are preferably arranged in a rectilinear pattern with the leachable spacers 22 being used to keep the optical fiber preforms 20 spaced apart from one another. The spacers 22 are preferably tubular as shown, with the optic fiber preforms 20 being located within the spacers 22. While the optical fiber preforms 20 and spacers 22 are shown as circular, those skilled in the art will recognize that other shapes could be utilized for the optic fiber preforms 20 and/or the spacers 22. For example, the optic fiber preforms 20 and the spacers 22 could be rectilinear in order to hold the optical fiber preforms 20 in a predetermined spacial relation. Alternatively, the spacers 22 could be in the form of separate rods located in the spaces between the optic fiber preforms 20.
[0026] The spacers 22 are preferably formed of an acid-soluble material, such as an acid-soluble glass. However, other suitable materials can be utilized. The optic fiber preforms 20 are preferably made of an etch resistant material.
[0027] The first preferred method includes heating and drawing the bundle 24 of optic fiber preforms 20 and spacers 22. Referring to Figures 1 and 6, the bundle 24 is preferably heated and drawn in the usual fashion by heating the bundle 24 locally utilizing heaters 30 and pulling on the bundle 24 in the longitudinal direction to obtain a drawn fiber bundle 32 having a desired size and spacing of the optic fibers 12 within the bundle 32. This is preferably done in a drawing tower.
However, other drawing arrangements may be utilized depending upon the particular circumstances.
[0028] The bundle 24 is reduced in size by drawing to obtain a drawn fiber bundle 32 having a cross-sectional area 60 reduced in size from the initial cross- sectional area 58 by a determined value. While the determined value indicated by the change in spacing in the bundle 24 of Figure 2 (which has a spacing of 100R and 100S) and the drawn fiber bundle 32 of Figure 3 (which has a spacing of R and S) is one hundred (100), those of skill in the art will appreciate that any determined value can be used without departing from the scope of the present invention. When the spacing between the fibers 12 is divided by the determined value, the tolerance in the spacing is also reduced by the same factor. Thus, the first preferred method provides an improved method of manufacturing a fiber bundle 32 having very small tolerances and closely positioned fibers. Accordingly, when the drawn fiber bundle 32 of Figure 3 is reduced in size from the initial cross-sectional area 58, the drawn fiber bundle 32 has, within a second tolerance value, a desired distance (illustrated as R and S in Figure 3) between the centers of the plurality of drawn optical fibers 12.
[0029] This desired distance between centers of the plurality of drawn optical fibers 12 is equal to the initial distance divided by the determined value and the second tolerance value is equal to the initial tolerance value divided by the same value. Those of ordinary skill in the art will appreciate from this disclosure that in the first preferred method, the determined value is preferably determined prior to building the bundle 24 of preforms, and that the drawn fiber bundle 32 is measured and/or monitored during the heating and drawing of the plurality of optic fiber preforms 20 to determine whether the determined value has been obtained.
[0030] The first preferred method preferably includes cutting the drawn fiber bundle 32 to a desired length for further processing and coating ends of the drawn fiber bundle 32 with a leaching agent resistant material. Additionally, end ferrules may be installed on at least one end of the drawn fiber bundle 32. To install a ferrule, the ferrule is typically placed over the fiber end and bonded and/or crimped in position. The end ferrules and bonding agent are preferably made of an acid etch resistant material, or may be coated with an acid etch resistant material, if desired.
Depending upon the particular application, the end ferrules may be omitted or installed after leaching of the spacer material from the drawn fiber bundle 32.
However, this entails higher costs and has a greater probability of damaging the optic fibers 12.
[0031] The first preferred method of the present invention preferably includes leaching some material from the spacers 22 from a middle portion of the drawn fiber bundle 32 to form a flexible region. To accomplish this, the drawn fiber bundle 32 with the protected ends, which may be protected either through coating with an acid etch resistant material or via installation of the etch resistant ferrules, may be placed in a leaching tank (not shown), which may contain, for example hydrochloric acid or any other suitable leachant, depending upon the composition of the leachable spacers 22. Some of the spacer rod material is preferably leached from a middle portion of the drawn fiber bundle 32 so that individual optic fibers 12 are free in the middle portion to form the flexible fiber bundle 10 with an ordered array of fibers at the ends.
[0032] Referring to Figures 4 and 5, the second preferred method will be described in detail. Optic fibers 12 arranged in a 1xN array are provided and form a first ribbon 50'. The first ribbon 50'of optical fibers 12 is bent through a desired path to form one nonlinear segment 46. While the nonlinear segment that is shown is simply a bend, those of ordinary skill in the art will appreciate from this disclosure that the nonlinear segment 46 can be an irregular pattern and can include linear portions therein without departing from the present invention. Preferably, the first ribbon of optical fibers 50'is bent through a desired angle to form one bent end 62.
[0033] Another plurality of fibers is arranged in a IxN array to form a ni' ribbon of optical fibers 502 The notation m is used to designate successive ribbons 50m used to form the desired MxN array 42, where m=2 through M.
[0034] The in'ribbon of optical fibers is bent through the desired path to form a in nonlinear segment. Those of ordinary skill in the art will realize that the precise dimensions of the desired path will change while the ni'ribbon is bent due to the offset caused by the prior ribbon of optical fibers 50. Likewise, the length of individual optical fibers 12 can vary without departing from the scope of the present invention. These changes in the size of the path that the M ribbons 50 are bent through and changes in the length of the optical fibers 12 may be necessary due to the nesting effect, depending on the desired orientation of the first and second surfaces 44A, 44B formed by the ribbons 50. It is preferred that the in'ribbon of optical fibers 50m is adhesively secured to one of the first ribbon of optical fibers 50' or a previous one of the ribbons of optical fibers 50m-'when nesting the in'ribbon of optical fibers 50m thereover.
[0035] The ribbon of optical fibers 50 is placed on top of the one ribbon of optical fibers 50 such that the first nonlinear segment 46 and the in'nonlinear segment 46 are generally nested to form a two dimensional array of optical fibers.
[0036] These steps of providing another m"'ribbon 50m, bending that ribbon 50m, and nesting that ribbon 50m are sequentially repeated for m values of 2 through M (i. e., m=2 through M) to form the desired MxN array 42. The ends 44A and 44B of the array 42 are then preferably cut and polished to provide a smooth, uniform surface for optical signal transmission.
[0037] Referring to Figure 6, the third preferred method of the present invention directed to forming an ordered optic fiber array will be described in detail.
A plurality of fiber optic preforms 20 are provided as well as a guide plate 64 having a plurality of bores 66 therethrough. The bores 66 are positioned in predetermined locations depending on the desired position in which the ends of the optical fibers are to be positioned in order to form the ordered optic fiber array.
[0038] The plurality of fiber optic preforms 20 are heated and drawn to form a plurality of drawn optic fibers 12. The heating and drawing process is preferably similar to that described above in connection with the first preferred method, except that the preforms 20 are drawn so that they are not fused together.
[0039] Each of the drawn optic fibers 12 is guided through a separate one of the plurality of bores 66. After optic fibers 12 extend through the guide plate 64 by a desired length, the drawing process is stopped. An adhesive or a potting material 54 is applied over a portion of each of the plurality of drawn optic fibers adjacent to the guide plate to form a plug 52. By forming the plug 52 adjacent or very close to the guide plate 64, the spacing (denoted as x'in Figure 6) between the drawn fibers 12 is essentially the same as the spacing (denoted as x in Figure 6) between the bores 66. Those of ordinary skill in the art will appreciate that a slight tolerance difference can exist between the distance between the fibers and the distance between the boreswithout departing from the scope of the present invention. It is preferable that the plug 52 be formed on a side of the guide plate 64 opposite from an initial position of the fiber optic preforms 20. At least a portion of the plug 52 is separated to form an end of an ordered optic fiber array. It is preferable, but not necessary, that the plug 52 be separated into at least two portions such that the ends of two ordered arrays are formed. To form two ends of ordered arrays, the plug 52 could be separated along a cut line 56, as shown in Figure 6. This allows for two ends to be formed at the same time that precisely match each other in terms of fiber optic positioning. This method allows for increased efficiency and allows for the serial production of a plurality of segments of ordered optic fiber arrays having ends precisely located and held in position by the adhesive or potting material 54.
[0040] Through the use of the methods in accordance with the present invention, it is possible to provide higher quality fiber bundles 12, waveguides and ordered arrays using a more efficient manufacturing processes. This results in lower component prices and, accordingly, increases the numbers of applications for which these optical components are suitable.
[0041] While the preferred embodiments of the invention have been described in detail, the invention is not limited to the specific embodiments described above, which should be considered as merely exemplary. Further modifications and extensions of the present invention may be developed, and all such modifications are deemed to be within the scope of the present invention as defined by the appended claims.
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