Abstract:
A method for mechanically stripping the protective coating from a silica or glass optical fiber using a polymeric or soft metal blade having a hardness less than that of the glass optical fiber but greater than the protective coating. The blade is preferably selected from a group of polymeric materials, or alternately a soft metal, which is selected or treated so as to not detrimentally oxidize in conventional operating environments. For a silica-containing optical fiber, the blade has a hardness of less than approximately 125 on the Knoop hardness scale, and preferably less than approximately 60 on the Knoop hardness scale. A method of inhibiting damage to the exposed region of the silica-containing optical fiber comprises applying a substance that forms a protective layer to provide a barrier to particulates and moisture, and which does not inhibit subsequent processing of the optical fiber, selected from a group of silane-containing compounds.

Description:
This application claims the benefit of priority under 35 USC § 120 from the U.S. Provisional Application Ser. No. 60/091,259, filed on Jun. 30, 1998. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to methods and apparatuses for removing a protective coating from an optical fiber, and in particular to a method and apparatus for removing the protective coating from a silica or glass optical fiber without scoring or abrading the optical fiber, and further a method for inhibiting damage to the optical fiber. 
     2. Technical Background 
     Optical fiber manufacturers typically cover an optical fiber with one or more protective polymer coatings. Technicians routinely remove the outer protective coating from the optical fiber to make splices, attach connectors, pigtail the fiber to an optical component, or use the exposed portion of the optical fiber in fabricating an optical component. Removing or “stripping” the outer protective layer can be accomplished in a variety of ways, including contact stripping (such as mechanical or chemical processes) and non-contact stripping (such as a hot gas jet). 
     In many situations, mechanical stripping processes are generally preferred, particularly when the optical fiber must be stripped manually or in the field. 
     Concurrent with the advent of optical fiber, mechanical stripping tools similar in form and function to conventional wire-strippers were developed. In one example, a stripping tool having a deformable polymer or soft metal blade was suggested for use both with copper wire and acrylic optical fiber. Mechanical stripping tools generally provided a grooved or notched blade, with an adjustable diameter corresponding to that of the wire or optical fiber. 
     Glass or silica optical fibers quickly became the standard for fiber-optic communications, due to the exceedingly low attenuation or loss in the 1.3 nm and 1.55 nm wavelength transmission windows. 
     However, silica or glass optical fibers could be easily scored or abraded by mechanical stripping blades, resulting in weakening and breaking of fibers. Nicked or scored fibers could break due to tension or flexion well after connections were made, requiring significant time to track and repair the fault. Conventional stripping blades often damaged the optical fiber and reduced its tensile strength. For example, a coated optical fiber typically has a tensile strength of 600 to 800 Kpsi. Removing the polymer coating with a conventional fiber-stripping tool may cause the strength of the optical fiber to drop to 100 Kpsi or lower. Optical fibers having a tensile strength below 100 Kpsi are often considered unsuitable for use. 
     As such, significant emphasis has been devoted to increasing the precision and reliability of mechanical stripping equipment and processes. 
     One approach is to maintain strict tolerances for the alignment and position of the guides, gripping elements, stripping blades, and mandrels used in strippers. However, these tolerances can be difficult to monitor or adjust, and the blades must be maintained in optimal condition. Sharpening a blade perturbs the operational tolerances, as does using a dulled blade. In additional, accurate mechanical strippers do not conform easily to a variety of fiber diameters or coating types. 
     Consequently, other approaches have been employed in combination with mechanical stripping tools or equipment in order to lessen the required tolerances, as well as mitigate against damaging the glass optical fiber. 
     In particular, chemical-, thermal-, or radiation-softening processes have been developed to lower the hardness or modulus of the protective coating and permit it to be stripped more easily (thus allowing the blade of the stripping tool to remain displaced slightly from the surface of the glass optical fiber). 
     While functional, these processes suffer from several drawbacks, such as requiring additional equipment and supplies to operate, being more time consuming and labor intensive, allowing less portability and therefore less applicability for use in the field or outside a controlled manufacturing environment, and being more susceptible to variability in the softening process itself. 
     Similar techniques have also been employed to completely remove the protective coating from the optical fiber, but apart from non-contact stripping processes these chemical and thermal contact stripping processes can adversely affect the optical fiber, leave residues that degrade transmission, adhesion, or splicing, and have other undesirable side-effects. These adverse results similarly occur when the processes are used in combination with a mechanical stripping blade. 
     For example, chemical stripping involves using chemicals such as methylene chloride or hot concentrated sulfuric acid. This approach does not provide sufficiently precise control over the amount or depth of coating stripped from the optical fiber, or the affect of the chemical on the optical fiber itself. The chemical often removes the coating outside the desired stripping area because it cannot be prevented from flowing along the optical fiber underneath the coating. Once the coating has been stripped, chemical residue remaining on the optical fiber prevents the optical fiber from being coated again. Further, this chemical process cannot be used in the field because the chemicals are dangerous and hard to handle, technicians in the field lack adequate training or qualifications, and the chemicals require a significant amount of time (on the order of thirty minutes) to remove the coating from a typical optical fiber. 
     Another approach to improving mechanical stripping of glass optical fibers has been to use a blade fabricated from a “softer” non-metallic material such as graphite. However, it is difficult to characterize the relative “softness” of graphite and reproduce blades of uniform quality, since graphite is a general term covering a large range of carbon structures having various physical properties, including hardness. If a graphite composition of requisite softness is selected, it may be difficult to maintain an accurate edge on the blade without frequent sharpening and adjustment. The edge of the blade itself may be subject to damage which might not be visible to the technician, but which would increase the potential risk of damaging the fiber. In addition, while graphite may be considered “soft” at a macroscopic level, it is relatively “hard” at the microscopic level, having a crystalline-like structure that cleaves to form very sharp, acute hard edges which can micro-score or abrade the optical fiber, again resulting in the same weakening and breakage potential as a conventional hard metal blade. 
     Conventional mechanical fiber-stripping tools thereby create an unacceptable reliability problem, since they periodically produce optical fibers having a reduced tensile strength that is unsuitable for use. Though testing the tensile strength of the stripped optical fibers could diminish the reliability problem, technicians often cannot perform such testing. And even if unsuitable optical fibers could be reliably identified, the conventional fiber-stripping tool remains disadvantageous because it wastes the time needed to test and restrip the fiber (as well as the fiber itself). 
     Furthermore, in addition to the disadvantages discussed above regarding chemical and thermal stripping techniques, the conventional fiber-stripping tools and processes do not accommodate for preventing damage to the optical fiber after the protective coating layer has been removed. The bare optical fiber can be damaged by incidental contact, or even airborne particulates that lodge on its surface and create flaws. The optical fiber can also be damaged if moisture is allowed to contact the surface of the optical fiber. 
     SUMMARY OF THE INVENTION 
     In one aspect, the present invention provides for a mechanical stripping process or apparatus in which the hardness of the blade is less than that of the silica or glass optical fiber (to prevent scoring or abrading the optical fiber upon incidental contact), but is also harder than the protective coating to be removed. Various polymeric and soft metal materials are discussed as being suitable alternatives for practicing the present invention. 
     In another aspect, the present invention utilizes the discovery that certain soft metals otherwise suitable for fabricating blades for mechanically stripping silica or glass optical fiber oxidize upon exposure to normal operating environments, and this layer of oxidation increases the hardness of the blade to a degree where it is no longer suitable for stripping glass optical fiber without the risk of damage and unsuitable tensile strengths. As such, certain polymeric materials are deemed preferable for practicing the method or fabricating the apparatus of the present invention in some applications, or alternatively soft metals, which are selected or treated so as to not detrimentally oxidize in conventional operating environments. 
     A further aspect of the present invention includes a method for preventing or minimizing damage to the exposed glass optical fiber subsequent to stripping the protective coating layer. 
     As embodied and broadly described herein, the invention comprises a method of removing a protective coating from a glass optical fiber a ambient temperatures and without applying a chemical softening agent including the steps of providing a tool having a blade with a lower hardness than the glass optical fiber but higher than the protective coating, engaging the protective coating with the portion of the blade, and applying force to the blade relative to the coating so as to cause the protective coating to be removed from the glass optical fiber. 
     The invention further comprises an apparatus for removing a protective coating from a silica-containing optical fiber, the apparatus including a blade and a tool configured to grip the optical fiber and engage the blade against the optical fiber when removing the protective coating, a portion of the blade having a hardness less than 125 on the Knoop hardness scale. 
     The invention further comprises a method for preventing or inhibiting damage to the exposed portion of a stripped optical fiber including the step of applying a substance to at least the exposed portion of the optical fiber to form a protective layer that provides a barrier to at least one of either particulates or moisture, and that does not inhibit subsequent processing of the optical fiber. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are hereby incorporated by reference, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. 
     FIG. 1 shows a plan view of a first embodiment of an apparatus for removing a coating according the present invention; 
     FIG. 2 shows a side view of the first embodiment shown in FIG. 1; 
     FIG. 3 shows a plan view of a second embodiment of an apparatus for removing a coating according the present invention; 
     FIG. 4 shows a side view of a third embodiment of an apparatus for removing a coating according the present invention; 
     FIG. 5 shows a plan view of a fourth embodiment of an apparatus for removing a coating according the present invention; 
     FIG. 6 shows a side view of the fourth embodiment shown in FIG. 5; 
     FIG. 7 shows a front view of the fourth embodiment shown in FIG. 5; 
     FIG. 8 shows a plan view of a fifth embodiment of an apparatus for removing a coating according the present invention; 
     FIG. 9 shows a plan view of a sixth embodiment of an apparatus for removing a coating according to the present invention; 
     FIG. 10 shows a plan view of a seventh embodiment of an apparatus for removing a coating according to the present invention; 
     FIG. 11 shows a plan view of an eighth embodiment of an apparatus for removing a coating according to the present invention; 
     FIG. 12 shows a side view of a ninth embodiment of an apparatus for removing a coating according to the present invention; 
     FIG. 13 shows a cross-sectional view of the ninth embodiment taken along line  13 — 13  of FIG. 12; 
     FIG. 14 shows a view of the ninth embodiment taken along line  14 — 14  of FIG. 12; 
     FIG. 15 shows a view of the ninth embodiment taken along line  15 — 15  of FIG. 12; 
     FIG. 16 shows a side view of a tenth embodiment of an apparatus for removing a coating according to the present invention; 
     FIG. 17 shows a cross-sectional view of the tenth embodiment taken along line  17 — 17  of FIG. 16; 
     FIG. 18 plots the results of tensile-strength tests of coated optical fibers and optical fibers from which the protective coatings were removed by an apparatus according to the present invention and by a conventional fiber-stripping tool; 
     FIG. 19 is a copy of a photograph of optical fibers from which the protective coatings were removed by an apparatus according to the present invention and by a conventional fiber-stripping tool; and 
     FIG. 20 is a copy of a photograph of an optical fiber from which the protective coating was removed by an apparatus according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference will now be made in detail to the presently preferred embodiments of the invention. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
     FIGS. 1 and 2 show a first embodiment of an apparatus  30  for removing a coating  32  from an object  34  according to the present invention. While the present invention is believed to be useful for removing a coating from a variety of objects, it is known to be particularly useful for removing a coating from a silica-containing optical fiber. Thus, to illustrate the invention, an optical fiber is shown as the object in the drawings. 
     The apparatus  30  includes a first tool  36 , which is configured to remove the coating  32  from the object  34 . In the embodiment shown in FIGS. 1 and 2, the first tool  36  has a substantially planar first surface  37  extending between substantially parallel and planar second and third surfaces  38  and  39  at oblique angles relative to the second and third surfaces  38  and  39 . 
     As shown in FIG. 2, the first tool  36  preferably includes a notch  40  in the first and third surfaces  37  and  39  configured to receive the object  34 . The notch  40  assists in maintaining the object  34  on the first tool  36 . 
     The first tool  36  also preferably includes a cutting portion  42  configured to cut into the coating  32 . In this embodiment, the cutting portion  42  is disposed within the notch  40 . A beveled surface  44  can be provided to improve the cutting efficiency of the cutting portion  42 . 
     Applying sufficient forces to the first tool  36  and the object  34  in the directions indicated by the arrows in FIG. 1 results in removal of the coating  32  from the object  34 . For ease of reference, the terms vertical and horizontal, based on the orientation of the drawings, will be used to describe the directions of the forces. Sufficient forces applied in the directions indicated by the horizontally extending arrows will cause the cutting portion  42  of the first tool  36  to engage and cut into the coating  32 . Sufficient forces applied in the directions indicated by the vertically extending arrows will cause relative movement between the object  34  and the first tool  36 . The combined forces will result in removal of the coating  32  from the object  34 . 
     To reduce the possibility of damage to the object  34 , at least a portion of the first tool  36  that engages the object  34  has a lower hardness than the object  34 . Preferably, the portion of the first tool  36  has a hardness that is less than approximately twenty percent of the hardness of the object  34  and, more preferably, is less than approximately twelve percent of the hardness of the object  34 . 
     If the object  34  is a silica-containing optical fiber, which typically has a hardness of about five hundred and eighty on the Knoop hardness scale, and a coating  32 , which typically has a hardness of less than twelve on the Knoop hardness scale, the portion of the first tool  36  preferably has a hardness of less than one hundred and twenty five on the Knoop hardness scale and, more preferably, has a hardness of less than sixty on the Knoop hardness scale. 
     Table 1 shows the results of tests conducted to determine the affect on optical fibers of materials of different hardness. The materials listed in Table 1 were each used to strip a protective coating from an optical fiber formed of fused quartz. The tensile strength of the stripped optical fiber was then measured using a device calibrated to NIST standards and, based on the tensile strength, it was determined whether the optical fiber had been damaged during the removal of the protective coating. 
     
       
         
               
               
               
               
             
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                   
                 Knopp 
                   
               
               
                   
                   
                 Hard- 
               
               
                   
                   
                 ness 
               
               
                   
                   
                 KgF/ 
               
               
                   
                 Material 
                 mm 2 ) 
                 Fiber Strength, Comments 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 1) 
                 Fused silica 
                 578-587 
                 &lt;100 Kpsi, damages fiber 
               
               
                 2) 
                 Soda Lime Glass 
                 510-540 
                 &lt;100 Kpsi, damages fiber 
               
               
                   
                 (microscope slide) 
               
               
                 3) 
                 Tool Steel 
                 420-460 
                 &lt;100 Kpsi damages fiber 
               
               
                   
                 (conventional fiber- 
               
               
                   
                 stripping tool) 
               
               
                 4) 
                 304 stainless steel 
                 280-300 
                 &lt;100 Kpsi, damages fiber 
               
               
                 5) 
                 Brass 
                 200-230 
                 &lt;100 Kpsi, damages fiber 
               
               
                 6) 
                 Copper 
                 136-155 
                 &lt;100 Kpsi, damages fiber 
               
               
                 7) 
                 Aluminum alloy 6061-T6 
                 113-125 
                 &lt;100 to &gt;200 Kpsi, 
               
               
                   
                   
                   
                 marginal 
               
               
                 8) 
                 Zinc (commercially pure) 
                 62-70 
                 &lt;100 to &gt;200 Kpsi, 
               
               
                   
                   
                   
                 marginal 
               
               
                 9) 
                 Aluminum alloy 4043 
                 58-60 
                 &lt;100 to &gt;200 Kpsi, 
               
               
                   
                   
                   
                 marginal 
               
               
                 10) 
                 Aluminum (commercially 
                 28-30 
                 &gt;200 Kpsi, no fiber damage 
               
               
                   
                 pure - not oxidized) 
               
               
                 11) 
                 polystyrene 
                 20-24 
                 &gt;200 Kpsi, no fiber damage 
               
               
                 12) 
                 polymethylmethacrylate 
                 19-21 
                 &gt;200 Kpsi, no fiber damage 
               
               
                   
                 (acrylic) 
               
               
                 13) 
                 polycarbonate 
                 13-15 
                 &gt;200 Kpsi, no fiber damage 
               
               
                 14) 
                 Sn/Cu/Ag 
                 14-15 
                 &gt;200 Kpsi, no fiber damage 
               
               
                   
                 (95.4%/4%/.5%) 
               
               
                   
                 solder 
               
               
                 15) 
                 Sn/Sb (95%/5%) solder 
                 13-18 
                 &gt;200 Kpsi, no fiber damage 
               
               
                 16) 
                 Lead (commercially pure) 
                 &lt;12 
                 &gt;200 Kpsi, no fiber damage 
               
               
                   
               
             
          
         
       
     
     As shown by Table 1, certain soft metals can provide marginally acceptable results. Table 1 also shows that some particularly soft metals (e.g., commercially pure aluminum and lead and low melting point solders) and plastic materials (e.g., polystyrene, polymethylmethacrylate, and polycarbonate) provide very good results. Additional materials that it is presently believed will provide good results include polypropylene, a liquid crystal polymer, such as VECTRA, a polymer reinforced with an aramid fiber such as KEVLAR, and a polymer reinforced with a polyethylene fiber such as SPECTRA. These materials can be used alone or in combination. It should be noted that in applications or embodiments where a soft metal is utilized, that metal should be selected to have a hardness within the prescribed range or parameters as discussed throughout this specification, and further inherently possessing the property or being treated so as to not be susceptible to oxidation in the normal operating environment of the apparatus  50  which would otherwise produce a oxidation layer or film of unsuitable hardness or abrasiveness that could damage the optical fiber  34 . 
     FIG. 3 shows a second embodiment of an apparatus  50  according to the present invention. This second embodiment is similar to the first embodiment. In this second embodiment, however, the first tool  52  includes a fourth surface  54  extending between the first surface  37  and the third surface  39  and also has two beveled surfaces  44  that meet to form a cutting portion  42 . This embodiment permits the coating  32  to be stripped from the object  34  in either direction with approximately equal cutting efficiency. 
     FIG. 4 shows a third embodiment of an apparatus  60  according to the present invention. This embodiment is essentially the same as the first embodiment, except the first tool  62  has a plurality of notches  40 . Thus, even after a notch  40  becomes worn beyond its useful life, additional notches  40  on the first tool  62  can be used, thereby increasing the useful life of the first tool  62 . 
     In the previously described first embodiment, as well as the second and third embodiments, a technician likely will directly apply the horizontal force on the object  34  needed to oppose the horizontal force applied by the first tool  36 . As shown by the following fourth through sixth embodiments, however, that horizontal force can be applied by at least one additional tool. 
     FIGS. 5 to  7  show a fourth embodiment of an apparatus  68  according to the present invention. This embodiment includes a first tool  36  that is preferably the same as the first tool  36  of the first embodiment. The first tools  52  and  62  of the second and third embodiments, however, could also be used. 
     This fourth embodiment also includes a second tool  70  that applies a horizontal force to the object  34 . The second tool  70  can engage the object  34  on a substantially opposite side of the object  34  from the first tool  36 . The second tool  70  is offset from the first tool  36  on a downstream side of the first tool  36 . 
     The second tool  70  preferably includes a guiding portion  72  configured to guide the object  34  without causing damage. In this embodiment, the guiding portion  72  includes a rounded edge  73 . 
     Since the second tool  70  engages the object  34 , at least the portion of the second tool  70  that engages the object  34  preferably has a hardness that will not damage the object  34 . Accordingly, the portion of the second tool  70  preferably is made of a material that satisfies the hardness criteria stated above in regard to the first tool  36  of the first embodiment. 
     A support device  74  can be provided to support the first and second tools  36  and  70  and to bring them into engagement with the coating  32  and the object  34 . The support device  74  shown in FIG. 6 includes a first handle portion  75  and a second handle portion  76 . The first and second tools  36  and  70  are mounted to ends of the first and second handle portions  75  and  76  by conventional fasteners, such as bolts  80  and nuts  81 . 
     A pivot connection  77  connects the first and second handle portions  75  and  76  while permitting relative movement there between. Pivoting the first and second handle portions  75  and  76  causes the first and second tools  36  and  70  to move toward and away from each other. The support device  74  preferably includes a restraining device  84  that limits the forces applied to the object  34  by the first and second tools  36  and  70 . As shown in FIG. 6, the restraining device  84  preferably includes a first contact member  85  extending from the first handle portion  75  and a second contact member  86  extending from the second handle portion  76 . When the first contact member  85  contacts the second contact member  86 , the ends of the first and second handle portions  75  and  76 , and thus the first and second tools  36  and  70 , are prevented from moving toward each other. The restraining device  84  can be configured to prevent the first and second tools  36  and  70  from applying forces to the object  34  that would cause damage. 
     FIG. 8 shows an apparatus  88 , which constitutes a fifth embodiment of the present invention. This embodiment is similar to the fourth embodiment, except the second tool  70  is offset from the first tool  36  on an upstream side of the first tool  36 . Since the second tool  70  is upstream from the first tool  36 , the second tool  70  will only contact the coating  32  and, therefore, can have a hardness greater than the object  34 . 
     FIG. 9 shows a sixth embodiment of an apparatus  90  according to the present invention. This embodiment is similar to the fifth embodiment. This sixth embodiment, however, also includes a third tool  92 . The third tool  92  applies a horizontal force to the object  34 . The third tool  92  can engage the object  34  on a substantially opposite side of the object  34  from the first tool  36 . The third tool  92  is offset from the first tool  36  on a downstream side of the first tool  36 . The third tool  92  is preferably the same as the second tool  70  of the fourth embodiment, which is shown in FIG.  5 . Thus, it preferably has a guiding portion  72  configured to guide the object  34 , which includes a rounded edge  73 . 
     Since the third tool  92  engages the object  34 , at least the portion of the third tool  92  that engages the object  34  preferably has a hardness that will not damage the object  34 . Accordingly, the portion of the third tool  92  preferably is made of a material that satisfies the hardness criteria stated above in regard to the first tool  36  of the first embodiment. 
     The second and third tools  70  and  92  described in connection with the previously mentioned fourth through sixth embodiments merely apply a force to the object  34 . As shown in the following seventh and eighth embodiments, however, a second tool can also be configured to directly contribute to the removal of the coating  32 . 
     FIG. 10 shows an apparatus  94 , which constitutes a seventh embodiment of the present invention. This embodiment includes a first tool  36  and a second tool  36 ′, which can both be configured the same as the first tool  36  of the first embodiment. The first tools  52  and  62  of the second and third embodiments, however, also could be used. 
     The second tool  36 ′ preferably is disposed on a substantially opposite side of the object  34  from the first tool  36 . The first and second tools  36  and  36 ′ both engage and cut into the coating  32 . Moving the object  34  relative to the apparatus  94  will remove the coating  32 . 
     Since both the first and second tools  36  and  36 ′ engage the object  34 , at least the portions of the first and second tools  36  and  36 ′ that engage the object  34  preferably have a hardness that will not damage the object  34 . Accordingly, the portions of the first and second tools  36  and  36 ′ preferably are each made of a material that satisfies the hardness criteria stated above in regard to the first tool  36  of the first embodiment. 
     Similar to the fourth embodiment, the first and second tools  36  and  36 ′ of this seventh embodiment can be mounted on first and second handle portions  75  and  76  of a support device  74 . 
     FIG. 11 shows an eighth embodiment of an apparatus  96  according to the present invention. This embodiment includes a first tool  98  and a second tool  99  disposed substantially opposite the first tool  98 . In this embodiment, the first tool  98  has cutting portion  42  but does not have a notch. 
     The first and second tools  98  and  99  both engage the coating  32 . Initially, only the cutting portion  42  of the first tool  98  cuts into the coating  32 . When the object  34  is moved relative to the first and second tools  98  and  99 , however, both the first and second tools  98  and  99  engage the coating  32  and remove it from the object  34 . 
     Since both the first and second tools  98  and  99  engage the object  34 , at least the portions of the first and second tools  98  and  99  that engage the object  34  preferably have a hardness that will not damage the object  34 . Accordingly, the portions of the first and second tools  98  and  99  are preferably each made of a material that satisfies the hardness criteria stated above in regard to the first tool  36  of the first embodiment. 
     Similar to the fourth embodiment, the first and second tools  98  and  99  of this eighth embodiment are preferably mounted on first and second handle portions  75  and  76  of a support device  74 . 
     FIGS. 12,  13 ,  14 , and  15  show an apparatus  101 , which constitutes a ninth embodiment of the present invention. This embodiment includes a plurality of first tools  52  and a second tool  102  that are disposed on a first handle portion  103  and a second handle portion  104 , respectively, of a support device  105 . 
     Each of the first tools  52  is preferably configured substantially the same as the first tool  52  of the second embodiment. As shown in FIGS. 13 and 14, the first tools  52  are connected together and slidable within a guide hole  107  of the first handle portion  103 . 
     A knob  108  can be connected to the first tools  52  to permit control over the position of the first tools  52  within the guide hole  107 . The knob  108  preferably has restrainers  109  that extend into guide grooves  110  in the first handle portion. As the first tool  52  in the operative position  111  wears out, the knob  108  can be moved to position a new first tool  52  in the operative position  111 . 
     The second tool  102  is disposed substantially opposite the first tool  52  in the operative position  111 . The second tool  102  can have a substantially V-shaped groove  113  for guiding the object  34 . The second tool  102  can also have a recess for receiving the first tool  52  in the operative position  111 . 
     A flip-over clamp  115  can be provided on the second handle portion  104  to hold the object  34  within the V-shaped groove  113  of the second tool  102 . This clamp  115  is connected to the second handle portion  104  by a bolt  116  and a nut  117  that allow the clamp  115  to pivot between opened and closed positions. A spring  118  biases the clamp  115  toward the closed position. The clamp  115  preferably has a conventional ball and detent mechanism (not shown) to maintain it in either the opened or closed position. 
     Since both the first and second tools  52  and  102  may engage the object  34 , they both preferably have at least a portion with a hardness that will not damage the object  34 . Accordingly, the portions of the first and second tools  52  and  102  preferably are each made of a material that satisfies the hardness criteria stated above in regard to the first tool  36  of the first embodiment. In the case of the second tool  102 , the portion can be provided, for example, by forming the entire second handle portion  76  of a sufficiently soft material or by providing an insert made of a sufficiently soft material. 
     The support device  105  can include a restraining device  84  that limits an amount of force that the first and second tools  52  and  102  can apply to the object  34 . As shown in FIG. 12, the restraining device  84  can include a first contact member  85  extending from the first handle portion  103  and a second contact member  86  extending from the second handle portion  104 . The second contact member  86  preferably includes a bolt  150  that extends through a threaded hole  151  in the second handle portion  104 . The bolt  150  can be turned to adjust the amount of its extension from the second handle portion  104 . When the bolt  150  of the second contact member  86  contacts the first contact member  85 , the ends of the first and second handle portions  103  and  104 , and thus the first and second tools  52  and  102 , are prevented from moving toward each other. By adjusting the extension of the bolt  150 , the restraining device  84  can be configured to prevent the first and second tools  52  and  102  from applying forces to the object  34  that would cause damage. 
     A spring  152  can be provided to bias the first and second handle portions  103  and  104  away from each other. Thus, in the non-operative state, the ends of the first and second tools  52  and  102  are spaced from each other. 
     FIGS. 16 and 17 show an apparatus  122 , which constitutes a tenth embodiment of the present invention. This embodiment includes a first tool  124  and a second tool  126  that are disposed on a first handle portion  128  and a second handle portion  129 , respectively, of a support device  130 . 
     The first tool  124  can be in the form of a disk having a plurality of portions for engaging the object  34 . As shown in FIG. 17, the first tool  124  preferably includes a first surface  132  and a second surface  133  that meet to form a cutting portion  134 . 
     The first tool  124  can be rotatably mounted to the first handle portion  128  by a bolt  136  and a nut  137 . A detent mechanism  138  has a plunger  140  that meshes with teeth  139  on the first tool  124  to hold a portion of the first tool  124  in an operative position  111 . The detent mechanism  138  includes a spring  141  for biasing the plunger  140  toward the teeth  139 . After a portion of the first tool  124  in the operative position  111  has worn out, the first tool  124  can be rotated to position a new portion in the operative position  111 . 
     The second tool  126  is disposed substantially opposite the portion of the first tool  124  in the operative position  111 . The second tool  126  can have a substantially V-shaped groove  145  for guiding the object  34 . The second tool  126  can also have a recess  146  for receiving the portion of first tool  124  in the operative position  111 . 
     Since both the first and second tools  124  and  126  engage the object  34 , they both preferably have at least a portion with a hardness that will not damage the object  34 . Accordingly, the portions of the first and second tools  124  and  126  preferably are each made of a material that satisfies the hardness criteria stated above in regard to the first tool  36  of the first embodiment. In the case of the second tool  126 , the portion can be provided, for example, by forming the entire second handle portion  129  of a sufficiently soft material or merely by providing an insert made of a sufficiently soft material. 
     The support device  130  can include a restraining device  84  that limits an amount of force that the first and second tools  124  and  126  can apply to the object  34 . As shown in FIG. 16, the restraining device  84  can include a first contact member  85  extending from the first handle portion  128  and a second contact member  86  extending from the second handle portion  129 . The second contact member  86  preferably includes a bolt  150  that extends through a threaded hole  151  in the second handle portion  129 . The bolt  150  can be turned to adjust the amount of its extension from the second handle portion  129 . When the bolt  150  of the second contact member  86  contacts the first contact member  85 , the ends of the first and second handle portions  128  and  129 , and thus the first and second tools  124  and  126 , are prevented from moving toward each other. By adjusting the extension of the bolt  150 , the restraining device  84  can be configured to prevent the first and second tools  124  and  126  from applying forces to the object  34  that would cause damage. 
     A spring  152  can be provided to bias the ends of the first and second handle portions  128  and  129  away from each other. Thus, in the non-operative state, the first and second tools  124  and  126  are spaced from each other. 
     FIG. 18 shows an advantage of the present invention. FIG. 18 contains Weibull plots of the results of tensile strength tests conducted on (1) coated optical fibers, (2) optical fibers from which the coatings were removed by an apparatus constructed in accordance with the first embodiment of the present invention having a polymethylmethacrylate tool, and (3) optical fibers from which coatings were removed by a conventional fiber-stripping tool having metal blades with a hardness of about 420 to 460 on the Knoop hardness scale. As shown in FIG. 18, coated optical fibers do not have a significant probability of failure until about 800 Kpsi. Optical fibers stripped with the apparatus constructed in accordance with the present invention do not have a significant probability of failure until about 700 Kpsi. In contrast, optical fibers stripped with the conventional fiber-stripping tool have a significant probability of failure as low as about 100 Kpsi. 
     FIG. 19 is a copy of a photograph of a magnified (20×) view of optical fibers. The coating was removed from the upper optical fiber by the apparatus constructed in accordance with the first embodiment of the present invention. The coating was cleanly stripped from this optical fiber. The coating was removed from the lower optical fiber by the conventional fiber-stripping tool. The conventional fiber-stripping tool left a significant amount of coating residue on the optical fiber. The residue can be removed from the optical fiber with a cloth, but this is believed to cause additional damage to the optical fiber. 
     FIG. 20 is a copy of a photograph of a magnified view (10×) of another optical fiber from which the coating was removed by the apparatus constructed in accordance with the first embodiment of the present invention. The coating  32  was cleanly peeled from the optical fiber. 
     An uncoated portion of an optical fiber, i.e., a portion from which a protective coating  32  was removed or a portion that was never coated, can be damaged by airborne particulates that lodge on the optical fiber and create flaws in the optical fiber, which become break sources. The uncoated portion can also be damaged by moisture deposited on its surface. Thus, it is desirable to have a technique for inhibiting such damage to an uncoated portion of the optical fiber. The present invention provides such a technique. 
     In accordance with the invention, a substance is applied to at least a portion of the optical fiber to form a protective layer. The substance provides a barrier to at least one of particulates and moisture (preferably both) and does not inhibit subsequent processing of the optical fiber. Examples of subsequent processing include writing a grating (e.g., a Bragg grating or a long period grating) using deep ultraviolet light (248 nanometers), splicing, fusing, frit attaching to a substrate, and insertion into a connector. 
     Such subsequent processing can be accommodated by, for example, selecting a substance that is transparent to deep ultraviolet light. Additionally, subsequent processing can be accommodated by selecting a substance that will form a layer having a thickness of less than one hundred nanometers, preferably less than seventy nanometers, and more preferably less than fifty nanometers. 
     The substance preferably will not adversely affect the optical properties of the optical fiber. Also, the substance preferably will form a bond with the optical fiber. The bond can be, for example, a covalent bond, an ionic bond, or a bond due to van der Waal forces. If the optical fiber contains silica, it is presently preferred that the substance establish a covalent bond by forming a self-assembled monolayer on the optical fiber. 
     Preferred substances have a hydrocarbon or fluorocarbon functionality and include silane monomers or oligomers. Examples include hydrocarbon silanes, fluorocarbon silanes, epoxy functional silanes, acrylate functional silanes, amine functional silanes, thiol functional silanes, phenyl functional silanes, and any combination of the above. For example, a small amount of acrylate or thiol silane mixed with a hydrocarbon silane would provide both protection to the optical fiber and permit further bonding of the optical fiber to a conventional acrylate fiber coating. 
     Hydrocarbon silane (C 18 H 37 —Si(OR) 3 ) and fluorocarbon silane (C 3-10 F n —CH 2 CH 2 —Si(OR) 3 ) are specific examples of substances that each meet the preferred requirements stated above. The thickness of a layer of each of these substances is believed to be less than one hundred nanometers because each substance starts as a monomer capable of forming a monolayer (about three nanometers thick). It is possible, however, that the layer is thicker because an oligomer may form. 
     Through testing, it has been determined that an unprotected optical fiber will have a tensile strength of less than fifty Kpsi if placed in an environment where it is exposed to particulates and/or moisture. When an optical fiber is coated with hydrocarbon silane, however, it can maintain a tensile strength of more than several hundred Kpsi after being placed in such an environment. 
     When removing a protective coating from an optical fiber, it is preferable to apply the substance to the optical fiber as quickly as possible to decrease the possibility of damage to the optical fiber. Thus, for example, when removing the coating  32  with the first tool  36 , it is desirable to provide the substance on the first tool  36  such that the substance will be applied to at least a portion of the optical fiber as the coating  32  is removed. 
     The ninth and tenth embodiments of the invention include preferred structures for applying a substance to an optical fiber  34  as the coating  32  is removed. In each of these embodiments, a reservoir  160  and  160 ′ for the substance is provided in the second handle portion  104  and  129 . As shown in FIGS. 13 and 17, the reservoir  160  and  160 ′ of each embodiment includes a sponge  162  and  162 ′, which contains the substance, disposed within a replaceable insert  164  and  164 ′. The substance is applied to the optical fiber  34  as it passes through the reservoir  160  and  160 ′. 
     In both embodiments, a conventional indicator material can be used to indicate when the reservoir  160  and  160 ′ has run dry. Methylene blue, for example, can be added to the substance to give the substance a blue color. The absence of a blue color from the reservoir  160  and  160 ′ indicates that the substance has been drained from the reservoir  160  and  160 ′. 
     It will be apparent to those skilled in the art that various modifications and variations can be made in the above-described embodiments of the present invention without departing from the scope or spirit of the invention. Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.