REFERENCE TO RELATED APPLICATION 0001 This application claims priority to U.S. provisional patent application Serial No. 60/278,226, filed Mar. 23, 2001, the entire contents of which being incorporated herein by reference.

BACKGROUND OF THE INVENTION 0002 There are many situations wherein an optical fiber must interface to a housing or equipment by way of a bulkhead-type connector. In such cases it is important not only to maintain alignment, but also to establish a contaminant-free connection that is easy to use and re-use. 0003 Current optical fiber connector sleeve/housing designs use a metal or ceramic sleeve to locate the ferrule to a tolerance of a micron or so. The accuracy of the location is necessary to either couple the light beam carried by the optical fiber inside the ferrule to another fiber with minimal losses, or to position the light which traverses the fiber in close relation to an external optical system. 0004 The current designs accomplish this through the use of a close-fitting cylinder to surround the ferrule, with perhaps a micron or so of clearance. One problem with the current design is that any contamination, particularly in the form of dust particles, can cause the ferrule to jam in the solid sleeve. 0005 There are a couple of companies, namely Wave Optics of Hillsboro, Oreg. USA and Oz Optics of Ontario, Calif. that make a fiber optic to free space coupler. Again, however, these rely on very tight tolerances between the shrouding around the fiber and the ferrule. A stable material such as zirconia is used to provide a very tight tolerance such that when the male portion is physically aligned to the female portion in a very accurate way. 0006 These and other companies also provide fiber-to-fiber connectors, certain of which use a split-sleeve arrangement. The sleeve, also typically of zirconia and typically a half-inch (0.625) in length, is contained within a body into which the ferrules of the fibers to be joined are inserted. As one example, U.S. Pat. No. 4,892,379 discloses an adaptor for a fiber optic connector of the type which utilizes a split sleeve to align ferrules from oppositely facing connectors. The sleeve has a longitudinal slit and the ferrules receive the optical fiber. A tubular shaped elastic body is installed around the outer periphery of the split sleeve, the body applying a spring force to the periphery of the split sleeve.

SUMMARY OF THE INVENTION 0007 Broadly, this invention makes use of a fixed, split sleeve to accurately and repeatably position a fiber-optic ferrule with respect to a housing. In the preferred embodiment the sleeve is contained within a connector having a land for attachment to the wall of the housing, though the technique is applicable to other configurations including FC, modified FC, and other styles, with and without a land. 0008 The split sleeve, which may be made of metal or ceramic, is attached to the housing in a manner allowing the sleeve to slightly expand. This allows the sleeve to locate the ferrule precisely, while still providing a controlled insertion and extraction force in the presence of a low level of contaminants. 0009 The split sleeve may be accurately located either by bonding it tangentially in a manner that enables the sleeve to expand, or by surrounding the sleeve with a material having a low modulus of elasticity enables the sleeve to expand. As a further option the sleeve may be bonded in a localized area and surrounded with low-modulus material elsewhere to provide a bonded and sealed configuration. 0010 The sleeve may optionally incorporate raised sections on its internal diameter, to better locate the fiber optic ferrule, and to provide increased clearance between the majority of the sleeve's inner diameter and the outer diameter of the ferrule. Such a configuration may further help to minimize the introduction of contaminants. The housing may also incorporate a window to isolate the fiber optic ferrule from the opposite side of the housing.

BRIEF DESCRIPTION OF THE DRAWINGS 0011 FIG. 1A is a drawing which shows a tangentially bonded split sleeve according to the invention; 0012 FIG. 1B is a drawing of the embodiment of FIG. 1A shown from an oblique perspective; 0013 FIG. 1C is a simplified drawing illustrating an alternative location for the location of the bonded outer sleeve, namely, closer to the opening of the split; 0014 FIG. 2A is a perspective-view drawing of a split-sleeve connector according to the invention in a connector body without a land; 0015 FIG. 2B is a perspective-view drawing of the opposing side of the connector of FIG. 2A, showing the way in which the central bore may contain a hermetically sealed window to reduce contamination; 0016 FIG. 3 is a simplified end-view drawing illustrating the way in which a material having a low modulus of elasticity may be disposed between an inner split sleeve and an outer sleeve or bore to provide a connector according to the invention; and 0017 FIG. 4 is an oblique drawing of a split sleeve according to the invention having one or more raised areas to assist with positioning of the ferrule.

DETAILED DESCRIPTION OF THE INVENTION 0018 As discussed in the Summary, this invention makes use of a fixed, split sleeve to accurately and repeatably position a fiber-optic ferrule with respect to a housing. Reference is now made to the figures, wherein FIGS. 1A and 1B illustrate a preferred embodiment of the invention configured as an FC-type of connector with a land 100 and mounting holes 101. Central to the structure is a bore 102 designed for flex clearance. Central to the bore 102 and the connector overall, is an aperture 104 through which light is conducted when a fiber-optic ferrule (not shown) of standard design and dimensions is inserted. 0019 The ferrule is received by an inner split sleeve 108 which is surrounded by an outer sleeve 106. The outer sleeve 106 is also preferably split, though in a manner wider than that of the inner split sleeve 108 to allow for expansion. In the preferred embodiment, the inner sleeve is a ceramic such as zirconia, valued for its dimensionally precision, though other materials may be used, including metals and alloys, such as phosphor-bronze, beryllium-copper, and other materials. The outer sleeve 106 is preferably a metal such as brass or stainless steel, though other metals, alloys and perhaps ceramics may be useful for such purpose. Note that the volume 109 between the outer surface of the outer sleeve 106 and the inner surface of the bore 102 may be filled with a low-modulus material such as epoxy or Silastic to adjust for the stiffness of the split sleeve 108, to keep out contaminants, or to create a wiper lip to clean the fiber ferrule. 0020 While the split sleeve 108 may be held within the outer sleeve 106 through the friction of intimate contact, the outer sleeve 106 must be bonded to the inner surface of the bore 102 at some point around its periphery. In the configuration of FIG. 1A, the sleeve 106 is bonded to the inner surface of the bore at point 110, though, as shown in FIG. 1C, the outer sleeve 106 may be bonded at a different point, namely, at a point closer to the opening of the split in the sleeve itself. Any suitable soldering or brazing technique may be used, as appropriate to the materials. 0021 FIGS. 2A and 2B show first that the invention is applicable to other types of connectors 202 which do not use lands, and secondly, to an alternative embodiment wherein central bore 204 is configured to contain a hermetically sealed window. In such a configuration, the window surround 206 is preferably recessed for stress relief on the glass, sapphire or whatever other transparent or semi-transparent material is used. 0022 As an alternative to the inner split sleeve engaging with a very close tolerance frictional fit with the outer sleeve, as shown in FIG. 3, there may be a space between the two sleeves which is preferably filled with a low-modulus material which is stiff enough to spread somewhat while keeping the center of the ferrule aligned relative to the aperture (i.e., 104) through the connector body. Indeed, depending upon the low-modulus material, the inner split sleeve may be disposed with a central bore (i.e., 102) without an outer sleeve, as depicted with the broken lines of FIG. 3. 0023 As yet a further option, as shown in FIG. 4, particularly the inner splits sleeve may include one or more longitudinal raised ribs (402) to better locate the fiber optic ferrule and/or to provide increased clearance between the majority of the inner diameter of the split sleeve and the outer diameter of the ferrule to enhance positioning accuracy despite repeated installation and removal. 0024 What has been shown and described is a precise, self-aligned split sleeve bulkhead-type connector to receive a fiber-optic ferrule, which meets various criteria in terms of positional accuracy and insertion of repeatability. Through the use of the invention, when a ferrule is inserted into the connector, the inner split sleeve begins to flex, and continues to flex slightly as the ferrule is inserted until it bottoms out within the sleeve. The desired insertion pressure depends upon the type of connector. For example, an FC ferrule typically exhibits a spring-loaded preset to 2 pounds, and will stick at that or above. Thus a maximum insertion pressure range of substantially less than value, one the order of a half-pound or less, would be appropriate.