Metal working – Means to assemble or disassemble – With control means energized in response to activator...
Reexamination Certificate
2000-04-13
2003-09-23
Bryant, David P. (Department: 3726)
Metal working
Means to assemble or disassemble
With control means energized in response to activator...
C065S501000, C385S137000
Reexamination Certificate
active
06622376
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a cylindrically shaped fiber holder that holds a fiber along its primary axis. The holder and associated rotation system allow a conventional motor to precisely rotate a fiber, e.g., an optical fiber, about its longitudinal axis.
2. Discussion of Related Art
Optical fibers are the basis of fiber optical communication systems. While their use is already ubiquitous, it is expected to increase in the future. In order to optimize the use of optical fibers, a number of different type of optical fibers have been developed. One class of optical fibers, referred to as polarization maintaining (PM) optical fibers, is made up of optical fibers that are not rotationally symmetric. PM optical fibers are useful in many applications, such as optical systems, fiber sensors, and coherent optical devices. The cross section of type of PM optical fiber is shown in FIG.
1
(A).
The optical fiber
101
A shown in FIG.
1
(A) is commonly referred to as a “panda” fiber. It has a core
103
A, and two oppositely positioned, cylindrically shaped regions of highly doped glass
105
A. These regions
105
A apply stress on the core
103
A. Because of this stress, the fiber
101
A achieves two orthogonal principal axes with different refractive indexes, causing different light velocities. Linearly polarized light that is injected into the fiber with its polarization direction parallel to one of the different axes of the fiber will remain parallel to the axis along the length of the fiber. Thus, before two polarization maintaining fibers can be spliced together, the polarization axes of the fibers must be aligned to prevent signal loss across the resulting splice. Accordingly, at least one of the fibers must be rotated about its longitudinal axis to match the alignment of the other fiber.
Other types of polarization maintaining fibers are shown in FIGS.
1
(B)-
1
(D). The PM fiber
101
B illustrated in FIG.
1
(B), referred to as a “bowtie” fiber, also has a core
103
B and two oppositely positioned stress-applying portions
105
B. The PM fiber
101
C shown in FIG.
1
(C) has a core
103
C surrounded by an elliptical cladding
105
C, while the PM fiber
101
D shown in FIG.
1
(D) simply has an elliptically shaped core
103
D.
In order to splice a polarization maintaining optical fiber
101
to another with the conventional method, the fiber
101
is first positioned in a fiber holder, such as the fiber holder
201
shown in FIGS.
2
(A) and
2
(B). The fiber holder
201
has a body
203
, which defines a recess
205
for holding the fiber
101
. It also has a hinged cover
207
for securing the fiber
101
in the recess
205
. As seen in FIG.
2
(B), the cover
207
has a number of pads
209
for holding the fiber
101
in place within the recess
205
.
Turning now to
FIG. 3
, when the fiber
101
is to be spliced to another fiber, the holder
201
is mounted on a holder mount
301
. The holder mount
301
is connected to a rotation shaft
303
, which in turn is connected to a gear
305
with teeth
307
. The teeth
307
of gear
305
engage the teeth of another gear
311
. Gear
311
is connected by a drive shaft
313
to a motor
315
. Thus, when the motor
315
turns the gear
311
through the drive shaft
313
, the gear
305
rotates the fiber holder
201
on the fiber mount
301
through the drive shaft
303
. In this manner, the motor
315
rotates the fiber
101
about its longitudinal axis to align it for splicing.
One problem with this prior art arrangement is the precision of the rotation. Even very short operations of the motor
315
can over-rotate the fiber
101
, preventing its proper alignment.
To address this problem, the prior art has employed precision-operated motors, such as stepper motors, to control the rotation of the holder mount
301
. While these precision motors offer some improvement over conventional electrical motors, they still do not provide sufficient precision to accurately rotate the fiber
101
for alignment. Moreover, precision motors can be prohibitively expensive for some applications. Accordingly, there is a need for a relatively inexpensive structure that allows an optical fiber
101
to be precisely rotated about its longitudinal axis for alignment with another fiber.
SUMMARY OF THE INVENTION
The invention provides a rotator and associated system that can precisely rotate a fiber about its longitudinal axis for alignment with another fiber. Moreover, the invention allows the fiber to be precisely rotated with a relatively imprecise, conventional electric motor.
According to one aspect of the invention, a cylindrically shaped rotator is provided that can hold either a fiber or a fiber holder along its central axis. The rotator is driven by a drive roller running parallel to the central axis of the rotator. The diameter of the portion of the drive roller that operates on the rotator is much smaller than the diameter of the rotator, so that even large rotational movement of the drive roller produces only small rotational movement of the rotator. Preferably, the diameter of the rotator is 2 to 6 times larger than the effective diameter of the drive roller.
With one aspect of the invention, the rotator has a friction band wrapped about its circumference. The drive roller then contacts the friction band directly to rotate the rotator. With another aspect of the invention, the drive roller is connected to the rotator by a belt, chain, gear or the like.
According to yet another aspect of the invention, the rotator has markings on its surface, so that the rotational orientation of the rotator and rotational movement of the rotator can be identified. With some embodiments of the invention, the markings are binary markings that can be automatically recognized by, for example, a conventional bar code reader.
REFERENCES:
patent: 4447119 (1984-05-01), Beasley
patent: 5013345 (1991-05-01), Itoh et al.
patent: 5156663 (1992-10-01), Itoh et al.
patent: 5216733 (1993-06-01), Nagase et al.
patent: 5369473 (1994-11-01), Ogawa et al.
patent: 5513295 (1996-04-01), Go
patent: 5766300 (1998-06-01), Hultén et al.
patent: 5999684 (1999-12-01), Bloom
patent: 6035520 (2000-03-01), Yamazaki et al.
patent: 6038361 (2000-03-01), Yoshikawa et al.
patent: 6088503 (2000-07-01), Chandler et al.
patent: 6141861 (2000-11-01), Armenoff et al.
patent: 6151919 (2000-11-01), Hulten et al.
patent: 6400884 (2002-06-01), Matano et al.
Ericsson, brochurePM Splicing with Ericsson, date unknown, but prior to Apr. 4, 2000, 4 pages.
Ericsson, User's ManualFusion Splicer FSU 925 PM-A, date unknown, but prior to Apr. 2000, 28 pages.
Ericsson, advertisement,New Release PM Fusion Splicer, date unknown, but prior to Apr. 2000, 1 sheet (front and back).
Bryant David P.
Capewell Components Company, LLC
DeLio & Peterson LLC
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