Abstract:
The fiber optic hinge can mechanically connect a first fiber optic tray and a second fiber optic tray of a fiber optic device, while providing an optical fiber path extending continuously through the first and second hinge members.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority of U.S. provisional application no. 61/351,094, filed Jun. 8, 2010 by applicant. 
     
    
     BACKGROUND 
       [0002]    Several types of fiber optic systems can have fiber optic components on more than one fiber optic tray. This is especially the case especially in systems designed for occupying a limited volume. It was known for instance in the field of lasers or amplifiers using fiber optics to mount the fiber optics on several superposed trays in a fixed structure. However, such designs had maintenance limitations including the fact that when a component of the system broke, a relatively large portion of the stack required disassembly to allow replacing the component, which led to undesirably high maintenance-associated costs. 
         [0003]    Optical fibers have particular handling characteristics. One of these is the fact that during use, they can be curved to a certain extent, but bending past a critical radius will likely affect the light transmission ability. The critical radius is a specification of optical fibers which are typically made available to designers, so that fiber optic systems can be designed with optical fiber paths which avoid having areas of curvature which are inferior to the critical radius of the given fiber it is intended to receive. Another of these is that optical fibers have a limited tolerance to mechanical stress and are relatively fragile. It was therefore known, for instance, to design an optical fiber path in a fixed stack fiber optic laser which transited from one tray to the next in a progressive fashion. 
       SUMMARY 
       [0004]    In accordance with one aspect, there is provided a fiber optic hinge which is both mechanically interconnected to fiber optic trays foldable with respect to one another, and allows transition of at least one optical fiber between the trays through the hinge. In this manner, the trays can be made openable to access the components with little or no disassembly required, and potentially even while the device is being operated. 
         [0005]    In accordance with one aspect, there is provided a fiber optic hinge mechanically connectable to a first fiber optic tray and a second fiber optic tray of a fiber optic device, the fiber optic hinge comprising a first hinge member securable to the first fiber optic tray, a second hinge member securable to the second fiber optic tray, the first hinge member being pivotally connected to the second hinge member about a hinge axis of the first and second fiber optic trays, each of the first and second fiber optic trays having a corresponding optical fiber port oriented toward the corresponding tray, away from the hinge axis, and an optical fiber path extending continuously through the first and second hinge members between the port in the first hinge member and the port in the second hinge member and passing by the hinge axis. 
         [0006]    In accordance with another aspect, there is provided a fiber optic device such as a laser or amplifier using fiber optics, in which two or more trays are hingedly interconnected, and where an optical fiber path between at least two of the trays passes through the hinge. 
     
    
     
       DESCRIPTION OF THE FIGURES 
         [0007]      FIG. 1  is an elevation view of an example of a fiber optic device; 
           [0008]      FIG. 2  is an oblique view of the fiber optic device with trays hingedly opened relative to one another; 
           [0009]      FIG. 3  is an oblique view showing a fiber optic hinge of the fiber optic device; 
           [0010]      FIG. 4  is an exploded view of the fiber optic hinge; 
           [0011]      FIG. 5  is another oblique view of the fiber optic hinge, showing it in a folded state; 
           [0012]      FIG. 6  is an oblique view, enlarged, of a hinge member of the fiber optic hinge; 
           [0013]      FIG. 7  is an oblique view of an alternate embodiment of a fiber optic hinge, having three hinge members. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]      FIG. 1  shows an example of a fiber optic device  10  having hingedly interconnected fiber optic trays  12 ,  14 ,  16 . In this particular example, the fiber optic device  10  illustrated is a fiber optic laser  10   a  which includes three hinged fiber optic trays  12 ,  14 ,  16 . More or fewer fiber optic trays can be used in alternate embodiments. In this particular example, all three of the hinged fiber optic trays  12 ,  14 ,  16  are pivotally hinged about a common hinge axis  18 . In alternate embodiments, the fiber optic trays can be hinged about distinct axes, such as in an accordion configuration for instance. In  FIG. 2 , the fiber optic trays  12 ,  14 ,  16  are shown deployed. Providing a device  10  using fiber optics with hinged trays can significantly ease maintenance compared to fixed stacks, by allowing easier access to malfunctioning fiber optic components on the hinged trays for replacement. 
         [0015]    In this particular example, a fiber optic hinge  20  shown in  FIG. 3  is used to provide an optical fiber path  22  between two of the fiber optic trays  12 ,  14 . The fiber optic hinge  20  is designed to protect the functionality of the optical fiber(s) to be received therein, especially during folding and unfolding of the trays  12 ,  14  about the hinge  20 . Further, the hinge  20  can provide the versatility of using the fiber optic device in any one of a folded and unfolded state for instance. Fiber optic devices can include more than one fiber optic hinge. 
         [0016]    In  FIG. 3 , the fiber optic hinge  20  can be seen to include two main components: a first hinge member  24  and a second hinge member  26 . The first hinge member  24  is secured to a first fiber optic tray  12  in a manner that it can pivot collectively with it around the hinge axis  18 . Similarly, the second hinge member  26  is secured to a second fiber optic tray  14  in a manner that it can pivot collectively with it around the hinge axis  18 , relative to the collective first hinge member  24  and the first fiber optic tray  12 . In this particular example, the hinge members  24 ,  26  are secured to corresponding fiber optic trays  12 ,  14  via a corresponding securing flange  28 ,  30 . Further, the first fiber optic tray  12  is hingedly connected to the second fiber optic tray  14  by means other than the fiber optic hinge  20 , though it will be understood that in alternate embodiments, the first fiber optic tray  12  can be connected to the second fiber optic tray  14  solely by means of the fiber optic hinge  20 . 
         [0017]    In this particular example, a supplemental, structural hinged connection  34 ,  36  is provided between the fiber optic trays  12 ,  14  and each one of the hinge portions  24 ,  26  is connected to a corresponding portion of the structural hinged connection  34 ,  36  by a shaft extending along the hinge axis  18 . Each one of the hinge members  24 , has an optical fiber port  38 ,  40  which extends toward the corresponding fiber optic tray  12 ,  14 , away from the hinge axis  18 , into or from which optical fiber enters or exits the corresponding hinge member  24 ,  26 . The hinge members  24 ,  26  each have a channel  42 ,  44  extending from the port  38 ,  40 , and the channels  42 ,  44  communicate at a pivotal connection  50  between the two hinge members  24 ,  26 , defining an optical fiber path  22 . Optical fiber (not shown) extending along the optical fiber path  22  in the channels  42 ,  44  is protected during normal use of the device. In this particular embodiment, the channels  42 ,  44  have an opening  52 ,  54  on a side (face) opposite the corresponding tray  12 ,  14  to allow easier installation of the optical fiber. The openings  52 ,  54  bridge when the fiber optic trays  12 ,  14  are in the open state shown in  FIG. 3 . In this embodiment, it can be understood that the optical fiber path  22  coincides with the hinge axis  18  at the pivotal connection  50 . 
         [0018]      FIG. 4  shows the fiber optic hinge  20  exploded. It will be noted here that the pivotal connection  50  between the first hinge member  24  and the second hinge member  26  can optionally include a male member which is configured to pivotally mate with a female member provided on the other hinge member and act as an extension of a shaft coinciding with the hinge axis  18 . 
         [0019]    In  FIGS. 1 and 2 , it can also be seen that in this particular embodiment, the second fiber optic tray  14  defines a plane which is parallel to and aligned with the hinge axis  18 . The first fiber optic tray  12  defines a plane which is parallel but offset from the hinge axis  18 , to allow for the thickness of fiber optic components between the trays  12 ,  14 . To bridge this gap, the first hinge member  24  ( FIG. 3 ), extends obliquely between the two trays  12 ,  14  when the latter are folded parallel to one another, and is made longer than the second hinge member  26 . 
         [0020]    Further, in this particular embodiment, a third fiber optic tray  16  similar in configuration to the first fiber optic tray  12  is also provided, opposite the second fiber optic tray  14 , and similarly connected using a fiber optic hinge  60 . There can be even more trays in alternate embodiments. In the particular embodiment of a laser or amplifier using fiber optic components, it can be practical to mount all the trays  12 ,  14 ,  16  about a common pivot  58  located centrally relatively to a base, in a manner that the trays  12 ,  14 ,  16  can be pivoted like pages of a book and have supports on both sides during assembly. 
         [0021]    Referring back to  FIG. 3 , it can be seen that at any point along its length, the optical fiber path  22  in the fiber optic hinge  20  has a radius of curvature which is greater than the critical radius of curvature for the particular optical fiber. In this embodiment, the radius of curvature r in the fiber optic hinge  20  brings the orientation of the optical fiber from normal to the hinge axis  18 , to parallel to the hinge axis  18 , to back to normal to the hinge axis  18 . The entry and exit orientation, i.e. the orientation of the optical fiber which enters or exit the fiber optic hinge, can differ depending of the orientation of the ports  38 ,  40  in alternate embodiments. The optical fiber path  22  being defined in a rigid channel  42 ,  44 , the radius of curvature r is maintained independently of the folding of the fiber optic hinge  20 , such as shown in  FIG. 5 , for instance. When the optical fiber is sufficiently freely held in the fiber optic hinge  20 , and during normal use, torsion stress is the only significant stress to which the optical fiber is subjected. The configuration can allow the fiber optic trays  12 ,  14  to be opened and closed without any significant tension stress being applied by the trays  12 ,  14  or hinge  20  to the optical fibers along the fiber path  22 . 
         [0022]    Most optical fibers can withstand a substantial amount of torsion stress. Further, in this particular embodiment, as long as the optical fiber in the channel  42 ,  44  is substantially free from torsion hindrance, the torsion stresses are spread along a substantial length of optical fiber, which helps avoid occurrences of undesirably high concentrations of torsion stresses. Allowing the optical fiber to have a given freedom of movement when inside the channel contributes to avoid such occurrences. The amount of length of the optical fiber path inside the fiber optic hinge  20 , and extending freely out both ports  38 ,  40 , also contributes to spread out the torsion stress to satisfactorily low concentrations. 
         [0023]    Although the optical fiber can be free from torsion hindrance in the channels, it can be trapped therein. In this particular embodiment, as shown in  FIG. 6 , the optical fiber(s) is trapped in the channel  42  by a plurality of confinement tabs  72 ,  74 ,  76 ,  78 ,  80  which protrude from an edge of the channel  42 , above the optical fiber path  22 . Henceforth, the optical fiber can be manipulated to enter the channel  42  by fitting into the portion of the opening  52  remaining adjacent the corresponding confinement tab, and thereafter trapped therein once freed from manipulation because the optical fiber will thereafter elastically tend to adopt a configuration straighter than the curvature of the opening adjacent the confinement tab and thereby become trapped. A chicane configuration of two opposite confinement tabs such as pair  74  and  76  can also be used to trap the optical fiber with even further certainty. 
         [0024]    To illustrate the looseness the optical fibers can be allowed to have without negatively affecting the concentrations of torsion stress, be it said here that width of the port  38  of the hinge member  24  shown in  FIG. 6  can have 4.5 mm for instance, in which case it can loosely receive up to a dozen of optical fibers having 0.9 mm jackets. The torsion is then spread along about 30 cm of optical fiber. It will be understood that the channel can be sized to receive other equipment, such as wire or the like, in addition to optical fibers. 
         [0025]    Another embodiment of a fiber optic hinge  100  is shown in  FIG. 7 . In this embodiment, the fiber optic hinge  100  still has a first hinge member  124  and a second hinge member  126  defining a fiber optic path  122 , but the second hinge member  126  further defines a second fiber optic path  190  leading to a third hinge member  192 . Other variations are also possible. 
         [0026]    It will be understood that the particular example described above and illustrated is provided for illustrative purposes and that many alternate embodiments are possible. As it can be seen therefore, the examples described above and illustrated are intended to be exemplary only. The scope is indicated by the appended claims.