Optics: measuring and testing – For optical fiber or waveguide inspection
Reexamination Certificate
2003-01-16
2004-05-25
Nguyen, Tu T. (Department: 2877)
Optics: measuring and testing
For optical fiber or waveguide inspection
Reexamination Certificate
active
06741337
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an end face polishing apparatus for polishing an end of an optical fiber used for optical connection and a method of polishing an end face.
2. Description of the Related Art
To connect optical fibers to each other in a face-to-face relationship, the pair of optical fibers has been optically connected using an apparatus having a semiconductor laser provided at an end of either of the optical fibers for emitting light from the optical fiber and a pair of optical systems for collimating the light from the semiconductor laser and converging it into the other optical fiber.
Such an apparatus has a problem in that the semiconductor laser and the optical systems must be provided with high accuracy relative to a pair of optical fibers and in that a great insertion loss occurs when they are provided with low positional accuracy.
For this reason, a method has been proposed in which an end of one of optical fibers is polished into a wedge-like configuration instead of providing a semiconductor laser at the end of the optical fiber and in which light similar to that emitted by a semiconductor laser is emitted from that end.
An optical fiber having a wedge-shaped end will now be described.
FIG. 7A
is a perspective view of the optical fiber, and
FIG. 7B
is a plan view of the optical fiber taken in the direction of the wedge-shaped end face thereof.
As illustrated, an optical fiber
1
has a clad
2
and a core
3
provided in the middle of the same, and the clad
2
is formed in a wedge-like configuration. The end face where the core
3
is provided is formed such that it protrudes in the form of the character R.
When such an optical fiber
1
having a wedge-shaped end is used, there is no need for positioning required for providing a semiconductor laser, which allows steps for assembling the same to be simplified.
However, in the case of such an optical fiber that has been polished by measuring the outer diameter thereof first and by using the center of the outer diameter as the center of the core to be used as a reference, a problem has arisen in that the polishing process has poor processing accuracy even when the center of the outer diameter is used as a reference for polishing because the center of the core is offset from the outer diameter because of the accuracy of formation of the optical fiber.
In a case in which a member welded to an end of an optical fiber is polished, a problem arises in that processing accuracy is further adversely affected by an error that occurs during welding when the polishing is performed using the outer diameter of the welded member as a reference for processing.
Taking such situations into consideration, the invention is aimed at providing an end face polishing apparatus and a method of polishing an end face with which an optical fiber can be processed with improved accuracy.
SUMMARY OF THE INVENTION
In a first mode of the invention for solving the above-described problems, there is provided an end face polishing apparatus which has a polishing member rotatably provided on a main body of the apparatus and a jig for holding an optical fiber and in which an end of the optical fiber held by the jig is polished with the polishing member, characterized in that it has an inspection unit for introducing inspection light into the optical fiber and detecting return light from an end face of the optical fiber or light transmitted by the optical fiber coming from the end face, a moving unit for moving relative positions of the polishing member and the optical fiber in the direction of a Z-axis that is the axial direction of the optical fiber, in the directions of X and Y axes orthogonal to the direction of the Z-axis, and in a rotating direction about the Z-axis, and a coordinate acquiring unit for acquiring a moving position of the polishing member as a coordinate by substantially moving the polishing member with the moving unit while detecting the return light or transmitted light from the optical fiber with the inspection unit, in that the position of a boundary between a clad and a core of the optical fiber is detected with the inspection unit in at least three directions from the outer circumference of an end face of the optical fiber while moving the polishing member toward the axial center of the same, the boundary position being acquired as a coordinate with the coordinate acquiring unit, and in that the position of the center of the core is acquired as a coordinate and the end of the optical fiber is polished using the center position of the core as a reference.
In a second mode of the invention, there is provided an end face polishing apparatus in accordance with the first mode, further characterized in that the moving unit moves the optical fiber in the directions of the X-, Y-, and Z-axes and moves the polishing member in the rotating direction about the Z-axis.
In a third mode of the invention, there is provided an end face polishing apparatus in accordance with the first or second mode, further characterized in that the moving unit moves the polishing member such that a polishing surface thereof is at a predetermined angle relative to the end face of the optical fiber.
In a fourth mode of the invention, there is provided an end face polishing apparatus in accordance with any of the first through third modes, further characterized in that the acquiring unit acquires the position of the center of the polishing member as a coordinate.
In a fifth mode of the invention, there is provided an end face polishing apparatus in accordance with any of the first through fourth modes, further characterized in that the acquiring unit acquires the coordinate of the center position of the core by calculating the same from the coordinate of the position of the boundary between the clad and the core.
In a sixth mode of the invention, there is provided an end face polishing apparatus in accordance with any of the first through fifth modes, further characterized in that the polishing member polishes the end of the optical fiber along with a holding member that holds the same.
In a seventh mode of the invention, there is provided an end face polishing apparatus in accordance with any of the first through sixth modes, further characterized in that the polishing member polishes the end of the optical fiber into a wedge-like configuration or convex spherical configuration.
In an eighth mode of the invention, there is provided a method of polishing an end face of an optical fiber held by a jig with a polishing member rotatably provided on a main body of an apparatus, characterized in that it has the steps of obtaining an end face orthogonal to the axial direction of the optical fiber by polishing the end face of the optical fiber with the polishing member, acquiring the position of the center of the core as a coordinate by performing a step of polishing the optical fiber by substantially moving the polishing member toward the axial center thereof from the outer circumference in the radial direction thereof with an inspection light introduced in the optical fiber and acquiring the position of a boundary between a clad and a core of the optical fiber as a coordinate by detecting return light from the end face of the optical fiber or transmitted light from the end face of the optical fiber, the step being performed in at least three directions from different positions of rotation about the axis, and polishing the end of the optical fiber using the position of the center of the core as a reference.
In a ninth mode of the invention, there is provided a method of polishing an end face in accordance with the eighth mode, further characterized in that at the step of acquiring the position of the boundary between the clad and the core of the optical fiber as a coordinate, the coordinate is acquired from the coordinate of the center of rotation of the polishing member.
In a tenth mode of the invention, there is provided a method of polishing an end face in accordance with the eighth or ninth mode
Katakura Kazumasa
Minami Kouji
Adams & Wilks
Nguyen Tu T.
Seiko Instruments Inc.
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