Expanded beam, single fiber, fiber optic connector

The expanded beam, single fiber, fiber optic connector includes a lens holder, a lens, and a ferrule. The lens holder retains the lens, and the lens holder accommodates the ferrule. The lens is in optical communication with an optical fiber retained in the ferrule. The lens holder has an outside diameter that is substantially the same as the outside diameter of a ferrule of a physical contact, single fiber, fiber optic connector, such as one of an LC, SC, FC, and ST style or standard fiber optic connectors.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention pertains to fiber optic connectors. The invention more particularly concerns a fiber optic connector which enables a user to replace a single fiber, physical contact, fiber optic connector with a single fiber, expanded beam, fiber optic connector.

2. Discussion of the Background

Fiber optic connectors and cables are known in the art. Typically, a fiber optic cable is terminated at each end by a respective fiber optic connector. At least two categories of fiber optic connectors exist and include physical contact connectors and expanded beam connectors. In practice, a fiber optic cable terminated with physical contact connectors will only connect to other fiber optic cables which are also terminated with physical contact connectors. Likewise, in practice, a fiber optic cable terminated with expanded beam connectors will only connect to other fiber optic cables which are also terminated with expanded beam connectors.

Physical contact connectors are characterized as such since one end of a ferrule of a first fiber optic connector physically contacts one end of a ferrule of a second fiber optic connector. Light exiting the core of the optical fiber held within the ferrule of the first fiber optic connector is then immediately introduced into the core of the optical fiber held within the ferrule of the second fiber optic connector. If the two cores are misaligned by more than a whole number of diameters of the core of the optical fiber, then most of the optical power is not exchanged from the core of the first fiber optic connector to the core of the second fiber optic connector. If a piece of debris is caught between the core of the first fiber optic connector and the core of the second fiber optic connector, then it is probable that no optical power will be exchanged from the core of the first fiber optic connector to the core of the second fiber optic connector, assuming that the debris has a size which is approximately the same size or larger than the size of the core of one of the optical fibers. Examples of physical contact connectors are set forth in U.S. Pat. Nos. 5,481,634, and 6,234,683. U.S. Pat. Nos. 5,481,634, and 6,234,683 are hereby incorporated herein by reference. Over time, the industry has utilized many physical contact, single fiber, fiber optic connectors as standards or styles, such as the LC, FC, ST, and SC fiber optic connectors.

FIG. 1is a perspective view of one type of physical contact, single fiber, fiber optic connector10. The fiber optic connector10includes a ferrule12. Also shown is an optical cable16. The fiber optic connector10generally conforms to the LC-style fiber optic connector. The ferrule12conforming to the LC-style has an outside diameter of approximately 1.25 millimeters.FIG. 2is an exploded, perspective view of the fiber optic connector10ofFIG. 1. Further shown inFIG. 2is the optical fiber14of the optical cable16. Also, the ferrule12is more clearly shown.FIG. 3is a partial cross-sectional side view of two fiber optic connectors10,20, and two receptacles18,19. Fiber optic connector10is shown in partial cross-section, but the ferrule12is shown in side view. The other fiber optic connector20and the two receptacles18,19are shown in cross-section. Receptacle18is attached to receptacle19. Each receptacle18,19is adapted to receive of fiber optic connector that conforms to the LC-style. Also shown is the physical contact between the ferrule12of the one fiber optic connector and the ferrule22of the other fiber optic connector20.

FIG. 4is a perspective view of three different types or styles of physical contact, single fiber, fiber optic connectors. A flat panel24contains three openings. The first opening is a receptacle26which accommodates two SC-type fiber optic connectors32,33, the second opening is a receptacle28which accommodates two FC-style fiber optic connectors, and the third opening is a receptacle30which accommodates two ST-style fiber optic connectors36,37. The ferrules of the fiber optic connectors32,33,34,35,36,37have an outside diameter of approximately 2.5 millimeters.FIGS. 1,2,3, and4are illustrations derived from figures found U.S. Pat. No. 5,481,634.

Expanded beam connectors are characterized as such since the optical fiber of the fiber optic cable is mated with a lens, typically a ball lens. The expanded beam fiber optic connector hold the terminated end of the optical fiber adjacent to the lens. When optical power exits the core of the optical fiber, the optical power then enters the lens, and then eventually exits the lens. The lens causes the optical power, or light, to diverge or expand before the optical power exits the fiber optic connector. If a second expanded beam fiber optic connector is attached to the first expanded beam fiber optic connector, then, after the optical power exits the first expanded beam fiber optic connector in the expanded state, the optical power will enter the second expanded beam fiber optic connector. The optical power will enter the lens of the second expanded beam fiber optic connector and then exit the lens. The lens of the second expanded beam fiber optic connector causes the optical power to converge. The focal point of the lens of the second expanded beam fiber optic connector is centered at the core of the optical fiber of the second fiber optic cable so that substantially all of the optical power exiting the lens enters the optical fiber. If the two cores are misaligned by less than a whole number of diameters of the core of the optical fiber, then most of the optical power is exchanged from the core of the first fiber optic connector to the core of the second fiber optic connector. If a piece of debris is caught between the lens of the first fiber optic connector and the lens of the second fiber optic connector, then it is probable that some of the optical power will be exchanged from the core of the first fiber optic connector to the core of the second fiber optic connector, assuming that the debris has a size which is approximately the same size or larger than the size of the core of one of the optical fibers but is smaller than the diameter of the expanded beam. Examples of expanded beam connectors are set forth in U.S. Pat. No. 5,247,595. U.S. Pat. No. 5,247,595 is hereby incorporated herein by reference.

FIG. 5is a cross-sectional side view of an expanded beam connector40that includes an optical fiber41and a lens42.FIG. 5is a cross-section side view of two expanded beam connectors10,43which are readied for optical communication with one another.FIGS. 5, and6are illustrations derived from figures found U.S. Pat. No. 5,247,595.

Accordingly, there is a need for a device which incorporates the advantages of the expanded beam fiber optic connector into the well received package size of the known single fiber, physical contact, fiber optic connectors.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a device that includes expanded beam technology and which is mountable to an industrial standard or existing receptacle or adapter where the receptacle or adapter was originally designed to accommodate a physical contact, single fiber, fiber optic connector.

It is another object of the invention to provide a device that includes expanded beam technology and is mountable or intermateable with a receptacle where the receptacle was originally designed to accommodate a LC-style fiber optic connector.

It is another object of the invention to provide a device that includes expanded beam technology and is mountable or intermateable with a receptacle where the receptacle was originally designed to accommodate a SC-style fiber optic connector.

It is another object of the invention to provide a device that includes expanded beam technology and is mountable or intermateable with a receptacle where the receptacle was originally designed to accommodate a FC-style fiber optic connector.

It is another object of the invention to provide a device that includes expanded beam technology and is mountable or intermateable with a receptacle where the receptacle was originally designed to accommodate a ST-style fiber optic connector.

In one form of the invention the device includes a lens holder, a lens, and a ferrule. The lens holder retains the lens, and the lens holder accommodates the ferrule. The lens is in optical communication with an optical fiber retained in the ferrule. The lens holder has an outside diameter that is substantially the same as the outside diameter of a ferrule of a physical contact, single fiber, fiber optic connector, such as one of an LC, SC, FC, and ST style or standard fiber optic connectors.

In a second form of the invention the device includes a lens holder, a lens, a ferrule holder, a ferrule, a body, an optical cable holder, a spring, and a snap ring. The lens holder retains the lens, and the lens holder accommodates the ferrule. The ferrule holder retains the ferrule. The lens holder is mounted to the ferrule holder. The spring is retained between the ferrule holder and the optical cable holder. A portion of the ferrule holder, a portion of the optical cable holder, and the spring are mounted within the body. The optical cable holder is retained, essentially in an unmovable manner, to the body by a snap ring. The lens is in optical communication with an optical fiber retained in the ferrule. When the lens holder makes physical contact with a lens holder of another fiber optic connector, the lens holder, and ferrule holder translate, thus compressing the spring against the optical cable holder. In turn the optical cable holder reacts the force into the body. Once the spring is compressed to some degree, the lens holder and the ferrule holder can accommodate some amount of misalignment. The lens holder has an outside diameter that is substantially the same as the outside diameter of a ferrule of a physical contact, single fiber, fiber optic connector, such as one of an LC, SC, FC, and ST style or standard fiber optic connectors.

In a third form of the invention the device includes a lens holder, a lens, and a ferrule. The lens holder retains the lens, and the lens holder accommodates the ferrule. The lens is in optical communication with an optical fiber retained in the ferrule. The lens holder has an outside diameter that is substantially equal to 1.25 millimeters.

In a fourth form of the invention the device includes a lens holder, a lens, and a ferrule. The lens holder retains the lens, and the lens holder accommodates the ferrule. The lens is in optical communication with an optical fiber retained in the ferrule. The lens holder has an outside diameter that is substantially equal to 2.5 millimeters.

Thus, the invention achieves the objectives set forth above. The invention provides a device which includes expanded beam technology, yet is mateable with or connectable to receptacles or adapters where the receptacles or adapter were designed to accommodate physical contact, single fiber, fiber optic connectors such as LC, SC, FC, and ST style fiber optic connectors. Also, the expanded beam connectors of the invention provide a greater resistance to contamination than the physical contact fiber optic connectors.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, and more particularly to FIGS.7-10,12, and14thereof, an embodiment of the present invention is a device or expanded beam, single fiber, fiber optic connector50which is displayed therein.

FIG. 7is a side view of the device or expanded beam, single fiber, fiber optic connector50. The device50includes a body52, an optical cable holder54, a spring64, a lens holder60, a lens (seeFIG. 8), a ferrule holder56, a ferrule58(seeFIG. 8), and a snap ring66.FIG. 8is a cross-sectional side view of the device50taken along section line8-8ofFIG. 7.FIG. 9is a perspective view of the device50.

The lens holder60has an outside diameter identified by alphabetic character B (seeFIG. 12). The lens holder60has a first aperture81, a second aperture82, and a third aperture83. The apertures81,82,83are shown as cross-sectional side views. The first aperture81has an inside diameter, the second aperture82has an inside diameter, and the third aperture83has an inside diameter. The inside diameter of the first aperture81is greater than the inside diameter of the second aperture82. The inside diameter of the first aperture81is greater than the inside diameter of the third aperture83. The inside diameter of the third aperture83is greater than the inside diameter of the second aperture82. The first aperture81is substantially co-linear with the second aperture82, and the second aperture82is substantially co-linear with the third aperture83. The lens holder60can be made of a metallic material, a polymer material, or any other suitable engineering material.

The lens62is a spherical ball lens which can be made of glass, plastic, sapphire, or other suitable engineering material. The lens62has an outside diameter that is less than the inside diameter of the first aperture81of the lens holder60. The lens62can be retained in the lens holder60by way of an optically transparent epoxy, a snap ring, or other suitable retention method. As shown inFIG. 12, the lens62can rest against the ledge formed at the transition between the first aperture81and the second aperture82of the lens holder60. The lens62is separated from the ferrule58by a gap84, as shown inFIG. 12.

The ferrule holder56has an outside diameter and an inside diameter. The outside diameter of the ferrule holder56is less than the inside diameter of the third aperture83of the lens holder60. The inside diameter of the ferrule holder56is greater than the outside diameter of the ferrule58. The ferrule58is retained within the ferrule holder56with an epoxy material or other suitable retaining method or structure. The ferrule holder56is made of a metallic material, a polymer material, or other suitable engineering material. The ferrule58is made of a ceramic material, a polymer material, or other suitable engineering material. The ferrule holder56is mounted to the lens holder60at the interface between the outside diameter of the ferrule holder56and the inside diameter of the third aperture of the lens holder60by way of an epoxy material or other suitable engineering material.

The optical cable holder54includes a multiple slots55, a snap ring groove65(seeFIG. 10), and an aperture. The optical cable holder54is made of a metallic material, a polymer material, or other suitable engineering material. The spring64is a helical compression spring. The spring64and the snap ring66are made of a metallic material or other suitable engineering material based on their respective applications.

FIG. 10is an exploded perspective view of the device50and will be used to illustrate the assembly of the device. The lens62is assembled with the lens holder60. The ferrule58is assembled with the ferrule holder56. The ferrule holder56is then assembled with the lens holder60. The spring64is then assembled over the ferrule holder56so that one end of the spring sets against the spring seat of the ferrule holder56. The chamfered end59of the ferrule holder56is introduced into the split end57of the optical cable holder54so as to cause the split end57to deflect along the multiple slots55. Once the chamfered end59of the ferrule holder56is far enough into the aperture of the optical cable holder54, the split end57and the slots55of the optical cable holder54deflect back to their undeformed positions and surround the chamfered end59of the ferrule holder56, thus retaining the ferrule holder56/lens holder60subassembly, and the spring64is retained between the spring seat of the ferrule holder56and the spring seat of the optical cable holder54. The assembly of the optical cable holder54/spring64/ferrule holder56/lens holder60is then introduced into the body52until the snap ring groove65passes through the other side of the body52. The snap ring66is then placed in the snap ring groove65of the optical cable holder54, thus retaining all of the components to the body52. The snap ring66also helps to prevent the split end57of the optical cable holder54from deflecting.

In use, the sheathing of optical cable (not shown) is terminated in the optical cable holder54, and the optical fiber (not shown) within the optical cable (not shown) is terminated in the ferrule58before the ferrule58is assembled with the ferrule holder56. For reasons of clarity, the optical fiber is not shown.

The device50shown inFIGS. 7,8,9,10,12, and14conforms to the ST industrial standard. The outside diameter B (seeFIG. 12) of the lens holder60is substantially equal to 2.5 millimeters. Thus, the device50is an expanded beam substitute for the physical contact ST connectors36,37disclosed inFIG. 4and is thus capable of plugging into the receptacle30disclose inFIG. 4. Though, the ST style connector is shown inFIGS. 7,8,9,10,12, and14, other connector styles can utilize the concept of this invention such as the SC, FC, and LC style or industrial standards. The SC and FC styles utilize a ferrule having an outside diameter substantially equal of 2.5 millimeters, and the LC style utilizes a ferrule having an outside diameter substantially equal to 1.25 millimeters.

As another comparison between the physical contact connector and the expanded beam connector,FIG. 11is a side cross-sectional view of the physical contact, single fiber, fiber optic connector70. The fiber optic connector70is the same as the ST connectors36,37disclosed inFIG. 4. The fiber optic connector70includes a ferrule71having an outside diameter substantially equal to 2.5 millimeters and is identified by alphabetic character A. The fiber optic connector70includes a cable holder72, a spring74, and a body73. The ferrule71is mounted to the cable holder72and the spring74is interposed between the cable holder72and the body73. The cable holder72is retained to the body73with a snap ring75. When the ferrule71makes physical contact with another ferrule, the ferrule71transmits the force to the cable holder72which in turn deflects the spring74. Thus, both the ferrule71and the cable holder72, to which it is connected, translate. Due to the construction of the device70, the ferrule71can not accommodate angular misalignments, or provide for strain relief of the optical fiber.FIG. 13is an end view of the physical contact, fiber optic connector70taken while looking at the end which contains the ferrule71.

As a comparison,FIG. 12is a cross-sectional side view of the device50ofFIG. 8rotated approximately ninety degrees. The outside diameter B of the lens holder60is substantially equal to 2.5 millimeters, since the device50is to be able to be inserted and accepted by a receptacle designed for a convention physical contact ST connector. The design of the device50does not only provide the advantages of expanded beam technology, the device50provides strain relief or the ability to accept angular misalignment as is explained below. When the device50is inserted into the receptacle30(seeFIG. 4), the lens holder60/ferrule holder56deflects the spring64. However, unlike the physical contact connector70disclosed inFIG. 11, the optical cable holder54does not translate, it essentially remains still. Thus, the chamfered end59of the ferrule holder56moves closer to the snap ring66therefore the chamfered end59of the ferrule holder56lifts off of the surface provided by the split end57of the optical cable holder54. In such a scenario, the lens holder60/ferrule holder56translates and rotates separate from the optical cable holder54and the body52.FIG. 14is an end view of the device50taken while looking at the end which contains the lens holder60.