Abstract:
A method of processing a plurality of optical components simultaneously includes providing a plate structure with first and second opposed plate faces and a plurality of the optical components retained within a sacrificial matrix material. Each optical component includes first and second component faces coinciding with, respectively, the first and second plate faces The matrix and optical-component materials are selected such that the former is soluble in a solvent in which the latter is relatively insoluble. A portion of the matrix material is dissolved is order to recess the matrix relative to at least the first component faces. With a remainder of the matrix retaining the components in their initial spatial relationships, a single, continuous substrate is adhered to a plurality of the first component faces protruding relative to the matrix. The remainder of the matrix material is then dissolved such that the substrate to which the first component faces are adhered retains the optical components.

Description:
PROVISIONAL PRIORITY CLAIM 
     Priority based on Provisional Application, Ser. No. 61/194,781 filed Sep. 30, 2008, and entitled “METHOD OF COATING AND HANDLING MULTIPLE OPTICAL RODS SIMULTANEOUSLY” is claimed. The entirety of the disclosure of the previous provisional application, including the drawings, is incorporated herein by reference as if set forth fully in the present application. 
    
    
     BACKGROUND 
     Various industries incorporate into light-transmissive—including image-transmissive—optical-assembly products small, difficult to handle optical rods, rod segments, and fused fiber bundles, which are hereinafter alternatively included within the term “optical components.” Currently, during processes such as polishing and coating, for example, these optical components are processed individually, frequently by the thousands. It will be readily appreciated that individual process handling of such components contributes significantly to their cost. Moreover, production losses attributable to lost and damaged components are also incurred. 
     Accordingly, there exists a need for methods of processing (e.g., coating) multiple “rod-like” optical components simultaneously. 
     SUMMARY 
     Implementations of the present invention are directed to methods of simultaneously processing (i.e., fabricating, cleaning, coating and handling) multiple rod-like optical components that have heretofore been cleaned, coated and handled individually and, in various embodiments, to optical components made in accordance with the methods. 
     Various aspects employ techniques analogous to those applied in the fabrication of optical fiber faceplates. For instance, various implementations include the formation of a fused fiber bundle including a plurality of mutually fused optical fibers extending generally along a longitudinal axis between first and second ends. Each fiber includes a core fabricated from a first material exhibiting a first refractive index and a cladding fabricated from a second material fusedly disposed about the core and exhibiting a second refractive index, lower in magnitude than the first refractive index, such that light entering either of first and second ends of the fiber can propagate therethrough by internal reflection. In various aspects, each of the core and the cladding comprises glass. When individual fibers (i.e., monofibers) are bound, heated and drawn, the claddings of adjacent fibers become fused to one another resulting in a unitary structure (i.e., a “fused bundle”) in which the cores are fusedly supported in a matrix of the second material from which the claddings of the monofibers were fabricated. The formation of such structures is generally known among fabricators of fused optical fiber components. 
     The fused fiber bundle is cut along, but not necessarily parallel to, a plane that extends perpendicularly to its longitudinal axis to form a plurality of fused fiber plates, each of which fused fiber plates includes first and second plate faces. In various implementations, the first and second plate faces of a fused fiber plate are ground and polished to create smooth plate faces and, if desired, a fused plate of uniform thickness or alternative profile. Each plate includes a plurality of rod-like, light-transmissive optical components (i.e., fiber segments) retained within a matrix of the aforementioned second material. Each optical component includes first and second component faces coinciding with, and forming a part of, respectively, the first and second plate faces. At least one component side extends between the first and second component faces of each optical component. 
     Although the terms “rod,” “rod-like” and similar adjectives are used in describing the optical components, these terms are used in a very broad sense to include, for example, “rod segments.” For instance, rods are commonly thought of as structures having lengths longer than their diameters or widths; the terms “rod” and “rod-like” as used in the current description, and the appended claims, include structures having widths greater than their lengths. More specifically, when plates are formed, the distance between the opposed first and second component faces of each optical component may be shorter than the diameter of that component. The terms “rod” and “rod-like” are also used broadly to refer to optical components of various cross-sectional geometries. Accordingly, to the extent the term “diameter” is associated with an optical component, it should not be assumed that the cross-sectional geometry of that component is circular. More specifically, although “diameter” is frequently thought of narrowly as the longest chord that can be fitted within the curve defining a circle, the more general definition of that term is applicable to this description and the appended claims. For instance, chords within squares, rectangles, hexagons, and even, irregular shapes are also diameters. A radius is a line segment extending from the geometric center of a shape to the boundary of the shape or one half the length of specified diameter. Nothing in the preceding explanation should be construed to attribute to the terms “diameter” and “radius” a meaning more narrow than common usage and a more generalized mathematical usage would attribute to them. 
     While process steps subsequently described are in actuality performed on multiple plates simultaneously or successively, subsequent steps are explained relative to a single plate structure of the general configuration described above, irrespective of whether the plate structure under consideration resulted from a process such as that described above. The first and second materials from which the optical components and the matrix are formed are selected such that the matrix is soluble in a predetermined matrix solvent in which the optical components are relatively insoluble. At least the first plate face is exposed to the matrix solvent in order to dissolve the matrix material to a total depth that is less than the plate thickness such that a remainder of matrix material retains the components, but is recessed relative to at least the first component faces. More specifically, in one implementation, only the first plate face is initially exposed to the matrix solvent in order to dissolve the matrix material from the first plate face toward, but not all the way to, the second plate face. In a second, alternative implementation, both the first and second plate faces are exposed to the matrix solvent in order to partially dissolve the matrix material, leaving a remainder of matrix material that is recessed relative to both the first component faces and the second component faces. In either event, the total depth of dissolution, whether from only the first plate face or from both plate faces, is initially less than the total plate thickness such that a remainder of matrix material retains the components in fixed relative positions. 
     Following the initial dissolution, or “etching,” step described above, the plate is typically cleaned and dried. Irrespective of whether, in any particular implementation, the plate is cleaned and dried after initial etching, a quantity of a predetermined optical coating is applied to at least the first component faces. In processes calling for the production of optical components in which only the first component faces are coated, it will be appreciated that either initial etching process described above may be employed. That is, coating may be equally-well effectuated whether the matrix material is initially etched from both plate faces or from just the first plate face. However, it will also be appreciated that, in a version in which both the first and second component faces are to be coated with a predetermined optical coating, the matrix material is etched below both the first and second component faces. 
     With the optical coating applied to at least the first component faces, the remainder of the matrix material is dissolved by exposure to the matrix solvent, thereby freeing the individual optical components from retention by the matrix material. In various instances, however, it may be desirable to retain the optical components in the same relative positions in which they were retained by the matrix material. Accordingly, in some versions, before the remainder of the matrix material is dissolved, an adhesive substrate is adhered by adhesive to either of the first and second component faces prior to final matrix dissolution. In alternative versions, the adhesive substrate is variously configured and may be, for example, a relatively rigid card or board-like material or a more flexible material such as a tape. However, the substrate of various versions is generally a single-continuous structure that can be adhered to plural component faces simultaneous. The nature of the adhesive may also vary and may be, for example, a pressure-sensitive adhesive and/or a thermally released adhesive, by way of non-limiting example. With the adhesive substrate applied to one side (plate face) of the plate or “wafer,” the remainder of matrix material can be dissolved from the opposite side. With the matrix remainder dissolved, and the adhesive substrate in place, the optical components are retained in an orderly arrangement for subsequent handling, including, where applicable, packaging and shipping to customers. 
     In some cases, only the first component faces are to be coated with the predetermined optical coating. Moreover, there are instances in which the matrix solvent is incompatible with (i.e., will damage) the applied coating. In such instances, the adhesive substrate is applied to the coated first component faces and dissolution of the matrix remainder is performed from the second plate face. In alternative implementations, the substrate also serves to mask the coated first component faces from contact with the matrix solvent. It will be readily appreciated that the designation of first and second plate and component faces is arbitrary. Accordingly, for example, when only one set of component faces is to be coated, that set of faces is by definition “the first component faces,” and the plate side coinciding therewith is the first plate face. 
     Depending on the nature of the first and second materials from which the matrix material optical components are fabricated, the matrix solvent may be an acidic or basic solution. In various implementations, the first material from which the optical components are fabricated is a first glass and the second material form which the matrix material is fabricated is a second glass. 
     In still additional versions, the optical components are internally-reflecting clad-rod components. More specifically, in some versions, each optical component includes an optically-transmissive core fabricated from a first material exhibiting a first refractive index and a cladding fabricated from a second material fusedly disposed about the core and exhibiting a second refractive index. The second refractive index is lower in magnitude than the first refractive index, such that light entering either of the first and second component faces can propagate by internal reflection between the opposed faces. In an illustrative implementation in which the optical components are internally-reflecting rods, the first material from which the core is fabricated is a first glass and the second material from which the cladding of each component is fabricated is a second glass. The matrix material is fabricated from a third glass material that, prior to dissolution, fusedly retains the optical components. 
     It is to be understood that, throughout the specification and claims, the identification of the core, cladding and matrix as first, second, and third materials or glasses is entirely arbitrary and merely intended to indicate, in such instances in which the core, cladding and/or matrix material are so identified, that they are made from distinct materials with differing optical, physical or chemical properties. Accordingly, for example, in a case in which a plurality of cores is supported in a matrix, the cores might be identified as fabricated from a first material (e.g., a first glass) whereas the matrix might be identified as being fabricated from a second material (e.g. a second glass). However, as in the preceding paragraph, in instances in which the optical components are internally-reflecting clad-rod components, the cores, the claddings around the cores, and the matrix in which the optical components are retained in fixed positions might be identified as being fabricated from, respectively, first, second and third materials. 
     Representative implementations are more completely described and depicted in the following detailed description and the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  depicts a fused fiber bundle including a plurality of cores surrounded, and retained in position, by fused cladding material; 
         FIG. 1A  shows fused fiber plates cut from the fused fiber bundle of  FIG. 1 ; 
         FIG. 2  is an edgewise depiction of a plate including parallel first and second opposed plate faces and a plurality of rod-like, light-transmissive optical components retained within a matrix material and including first and second component faces coinciding with, and at least partially defining, respectively, the first and second plate faces; 
         FIG. 2A  shows a plate such as that of  FIG. 2  in which a portion of the matrix material, beginning at the first plate face, has been dissolved in a matrix solvent such that portions of the lengths of the optical components, beginning at the first component faces, protrude from the matrix material; 
         FIG. 2B  is an edgewise view of a plate such as the plate of  FIG. 2  in which portions of the matrix material, beginning at both the first and second plate faces, have been chemically etched by a matrix solvent that portions of the lengths of the optical components, beginning at both the first and second component faces, protrude from the matrix material; 
         FIG. 3A  depicts the etched plate of  FIG. 3A  in which the first component faces of the optical components have been coated with a predetermined optical coating; 
         FIG. 3B  depicts the etched plate of  FIG. 3B  in which the first and second component faces of the optical components have been coated with a predetermined optical coating; 
         FIGS. 4A and 4B  show optical-component assemblies comprising the plates of, respectively,  FIGS. 3A and 3B  after application of adhesive substrates; 
         FIGS. 5A and 5B  depict the optical components of, respectively,  FIGS. 4A and 4B  after final dissolution of the matrix material; and 
         FIGS. 6 through 6B  show fiber plates in which the optical components are internally-reflecting clad-rod components. 
     
    
    
     DETAILED DESCRIPTION 
     The following description of methods of coating and handling multiple optical components simultaneous, and of optical components coated in accordance therewith, is demonstrative in nature and is not intended to limit the invention or its application of uses. The various implementations, aspects, versions and embodiments described in the summary and detailed description are in the nature of non-limiting examples falling within the scope of the appended claims and do not serve to define the maximum scope of the claims. 
     Referring to  FIGS. 1 and 1A , various implementations include one of (i) fabricating and (ii) providing a fused fiber bundle  10  including a plurality of cores  12  extending through fused cladding material  14  along a longitudinal axis A L  between first and second ends  16  and  18  of the fiber bundle  10 . As is generally known by those of ordinary skill in the art of optical-fiber component fabrication, a fused bundle such as the illustrative bundle  10  of  FIG. 1  is formed by adjacently binding, and then heating and drawing, a plurality of constituent “monofibers,” each of which monofibers includes a core about which is fusedly collapsed a cladding tube. When the bound assembly of monofibers is heated and drawn, each cladding tube fuses to the cladding tubes of adjacent monofibers, resulting in a unitary structure (i.e., a fused bundle  10 ) including a plurality of cores  12  fusedly retained within fused cladding material  14 . 
     Referring to  FIG. 1A , fused fiber plates  20  (or “plate structures”) are formed by cutting the fused bundle  10  perpendicularly to the longitudinal axis A L  thereof. Each plate  20  has opposed first and second plate faces  22  and  24 . In a typical implementation, the first and second plate faces  22  and  24  are ground and polished to create smooth, planar faces. However, cutting, grinding and polishing to create other-than-planar faces and plate profiles that are of other-than-uniform thickness is within the scope and contemplation of the invention. Each plate  20  includes a plurality of rod-like, light-transmissive optical components  30  (i.e., segments of cores  12 ) retained within a matrix  40  of the aforementioned cladding material  14 . Each optical component  30  includes first and second component faces  32  and  34  coinciding with, and forming a part of, respectively, the first and second plate faces  22  and  24 . At least one component side  35  extends between the first and second component faces  32  and  34  to of each optical component  30 . 
     Depicted in  FIG. 2  is edgewise view of a plate  20  including parallel first and second plate faces  22  and  24  defining a predetermined plate thickness T P . The optical components  30  and the matrix  40  are fabricated from disparate first and second materials M 1  and M 2  selected such that the matrix  40  is soluble in a predetermined matrix solvent (not shown) in which the optical components  30  are relatively insoluble. 
     Referring to  FIGS. 2A and 2B , at least the first plate face  22  is exposed to the matrix solvent in order to dissolve the matrix  40  (material M 2 ) to a total dissolution depth D TD  that is less than the plate thickness T P  such that a remainder (undissolved portion) of the matrix  40  retains the optical components  30 .  FIG. 2A  illustrates the result of initially exposing only a portion of the plate thickness T P  beginning at the first plate face  22  to the matrix solvent, while  FIG. 2B  depicts the result of exposing to the matrix solvent portions of the plate thickness T P  beginning at both of plate faces  22  and  24 . In  FIG. 2A , the matrix  40  is dissolved to a first dissolution depth D D1→2  extending from the first plate face  22  toward the second plate face  24  such that the matrix  40  is recessed relative to the first component faces  32 , which faces  32  are, after dissolution, all that remain of first plate face  22 . As indicated in  FIG. 2A , the first dissolution depth D D1→2  is equal to the total dissolution depth D TD . In  FIG. 2B , the matrix  40  has been dissolved from the first plate face  22  to a first dissolution depth D D1→2  extending from the first plate face  22  toward the second plate face  24  and to a second dissolution depth D D2→1  extending from the second plate face  24  toward the first plate face  22  such that the matrix  40  is recessed relative to both the first component faces  32  and the second component faces  34 . In either of the cases shown in  FIGS. 2A and 2B , the total dissolution depth D TD  is less than the total plate thickness T P  such that a remainder of matrix material M 2  retains the optical components  30  in fixed relative positions. 
     With reference to  FIG. 3A , a predetermined optical coating  60  is applied to the protruding first component faces  32  of the plate  20  depicted in  FIG. 2A , while, in  FIG. 3B , optical coating  60  has been applied to both the protruding first and second component faces  32  and  34 . The nature of the optical coating  60  and method(s) of application may vary. The coating  60  may be applied through (i) spraying, (ii) partial immersion in a bath of coating, (iii) chemical vapor deposition (CVD) or (iv) physical vapor deposition (PVD), by way of non-limiting example. The coating  60  may be applied for various purposes, including, for example, (i) to add anti-glare, (ii) to provide mechanical protection, (iii) to impart wave-length responsive scintillation properties and/or (iv) to impart wavelength filtration characteristics to the optical components  30 . 
     As explained in the summary, once at least the first component faces  32  are coated with coating material  60 , the remainder of the matrix material M 2  is dissolved in order to free the individual optical components  30  from retention by the matrix  40 . Further explained in the summary was the desire, in some cases, of retaining the optical components  30 , after final dissolution of the matrix  40 , in the same relative positions that they occupied when retained by the matrix  40 . Accordingly, with reference to  FIGS. 4A and 4B , various implementations include applying an adhesive substrate  80  with an adhesive  82  to one of the first and second component faces  32  and  34  prior to dissolving the remainder of the matrix  40 . In versions associated with each of  FIGS. 4A and 4B , in which the plates  20  of, respectively,  FIGS. 3A and 3B  are depicted, the adhesive substrate  80  is a rigid, card-like structure, although alternatives such as flexible, adhesive strips (e.g., tapes) may be used in different implementations. With the adhesive substrate  80  applied to one side (plate face  22  or  24 ) of the plate  20 , the remainder of matrix  40  is dissolved from the side opposite to which the adhesive substrate  80  is applied.  FIGS. 5A and 5B  show the optical components  30  of, respectively,  FIGS. 4A and 4B  after final dissolution of the matrix  40 . With the remainder of the matrix  40  dissolved, and the adhesive substrate  80  in place, the optical components  30  are retained in the same relative spatial arrangement in which they were retained by the matrix  40 . 
     Although the preceding description is generally demonstrative of the principles of the invention, it was noted in the summary that the optical components of various more particular versions within the scope of the versions previously described are internally-reflecting clad-rod components. Illustratively depicted in each of  FIGS. 6 through 6B  is a fused fiber plate  20  in which, like the plates  20  previously depicted and described, includes a plurality of rod-like, light-transmissive optical components  30 . The plates  20  of  FIGS. 6 ,  6 A and  6 B are in stages of processing analogous to the processing stages depicted in, respectively,  FIGS. 2 ,  2 A, and  2 B. However, each of the optical components  30  of  FIGS. 6 through 6B  includes an optically-transmissive core  36  and a cladding  38  fusedly disposed about the core  36 . With continued reference to  FIGS. 6 through 6B , the core  36  of each optical component  30  is fabricated from a first material M 1  having a first refractive index n 1 , while the cladding  38  is fabricated from a second material M 2  having a second refractive index n 2 , lower in magnitude than the first refractive index n 1 , such that light entering either of the first and second component faces  32  and  34  can propagate by internal reflection between the opposed component faces  32  and  34 . As with versions previously discussed, the matrix  40  fusedly retains the optical components  30  in fixed relative positions. In the versions of  FIGS. 6 through 6B , however, the matrix  40  is indicated as being fabricated from a third material M 3 . The third material M 3 , which may be a glass, is soluble in a predetermined matrix solvent (not shown) in which both the first and second materials M 1  and M 2  of the optical components  30  are relatively insoluble. In other major respects, the processes by which the clad optical components  30  of  FIGS. 6 through 6B  are analogous to the processes previously described in conjunction with  FIGS. 2 through 5B  and, therefore, further description of the processes relative to the versions of  FIGS. 6 through 6B  is unwarranted. 
     The foregoing is considered to be illustrative of the principles of the invention. Furthermore, since modifications and changes to various aspects and implementations will occur to those skilled in the art, it is to be understood that the foregoing does not limit the invention as expressed in the appended claims to the exact constructions, implementations and operations shown and described. It is also to be understood that any sequence of steps presented or implied in the drawings, and discussed above, is illustrative only and not necessarily indicative of the order in which the steps must be performed. Accordingly, nothing in the drawings, the description or the corresponding claims should be construed so as to limit the scope of the invention to a particular sequence of steps unless a particular order is inextricably dictated by context. Moreover, methods within the scope of the claims may include fewer than all steps discussed in the description. Accordingly, all suitable modifications and equivalents may be resorted to that appropriately fall within the scope of the invention as expressed in the appended claims.