Optical waveguides – Accessories
Reexamination Certificate
1999-11-01
2001-11-27
Lee, John D. (Department: 2874)
Optical waveguides
Accessories
C385S135000
Reexamination Certificate
active
06324331
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to improvements to systems and methods for manufacturing devices containing optical components, and more particularly to a system and methods for holding optical components in position in a device and splicing their leads together.
BACKGROUND OF THE INVENTION
Devices and systems employing fiber optics typically include a number of optical components that must be interconnected to form an optical path for the transmission of data. In one approach, optical components are mounted onto a printed circuit motherboard, and their optical fiber leads are then spliced together. The splicing process, however, is complicated by the relative fragility of optical fiber, which can be damaged by bending, excessive tension, or other stresses. Excessive signal attenuation due to bending of the fiber is also an issue. Further, the splicing process may require more than one attempt, if it is determined that the splice was not successfully made. In such a case, the improper splice must be broken out, the leads trimmed back, and a new splice performed. Finally, the continuous loop of fiber that results from a splice must be properly stowed away to prevent damage to the fiber.
FIG. 1
is a perspective view of one approach for mounting an optical component
10
onto a motherboard. The optical component
10
includes optical fiber leads
12
, extending from either end. A cable tie
14
, or spring clip, is used to attach the optical component
10
to a holder
16
, which is fabricated from a glass-filled polymer or other suitable material that has coefficient of thermal expansion is close to that of optical fiber, is moldable and machinable yet stiff, and has other useful properties. Finally, the holder
16
is affixed to a motherboard by means of a pair of plastic rivets
18
. This process is performed for all of the optical components used in the device being manufactured. Once all of the optical components have been securely mounted to the motherboard, their fiber leads must then be spliced together to create an optical path for the transmission of data. However, the task of splicing optical fiber leads together is far more complex than the splicing of electrical component leads.
The splicing task is typically a precise one. If the cores of two spliced fiber leads are not properly aligned, the optical path may be interrupted. In that event, the improper splice must be broken out and another splice performed. Thus, optical fiber leads tend to be quite long compared to electrical component leads, in order to provide a worker with an adequate amount of fiber to make numerous attempts at a proper splice.
However, this in turn means that the splicing together of two optical component leads results in a continuous loop of fiber, the length of which depends upon the amount of fiber required to achieve a proper splice. Because optical fiber is easily damaged, it is generally undesirable to have long loops of fiber freely floating within an optical device. Rather, the loops of fiber resulting from splices must be stowed away in a manner that will not result in damage to the fiber arising from bending, tension, or other mechanical stresses.
FIG. 2
is a partial perspective view of a system for managing the continuous loops of optical fiber resulting from the splicing of optical leads. The system provides a matrix of curved guides
20
,
22
a-d
, made from a glass filled polymer or another suitable material, that are mounted to a motherboard
24
. As described below, loops of optical fiber resulting from splices are protected from damage by winding them around the curved guides in a predetermined pattern. The length of these loops is precisely measured using grids
28
a
and
28
b
so that an optimal level of slack is maintained in the loops after they are wound over the curved guides, the tension in the loops being sufficient to hold them in place on the guides without causing damage to the fiber or degrading the optical characteristics of the fiber.
The matrix of curved guides includes a set of six central coil guides
20
that are arranged to form a central coil. These central coil guides
20
are shaped, and are positioned relative to each other, such that optical fiber can be wound around them without causing damage to the fiber. In addition, the matrix of curved guides includes pairs of auxiliary guides
22
a-b
,
22
c-d
that are mounted onto the motherboard
24
on either side of each optical component,
10
a
,
10
b
. Each of these pairs of auxiliary curved guides
22
a-b
,
22
c-d
is shaped, and positioned relative to the central coil and to the optical components, such that the auxiliary curved guides
22
a-b
,
22
c-d
provide safe winding paths for the optical fiber leads
12
from their respective optical components to
10
a
,
10
b
the central coil.
The functions of the central coil guides
20
can better be understood with reference to a specific example.
FIG. 2
shows first and second optical components
10
a
,
10
b
, which are mounted to the motherboard
24
. (For clarity of illustration, only one holder
16
a
is shown, although in an actual device, each optical component is held by its own holder). Each of these two optical components
10
a
,
10
b
has a pair of optical fiber leads
12
a-b
,
12
c-d
, extending from either end. In this example, a first lead
12
a
, that extends from the left end of the first optical component
10
a
, is spliced to a second lead
12
d
, that extends from the right end of the second optical component
10
b.
Prior to the actual splicing of the two leads together, each lead must first be precisely measured and then trimmed, so that the continuous loop of fiber resulting from the splice will be the correct length. Measuring grids
28
a
,
28
b
are provided on the motherboard
24
to allow the worker to precisely determine the point at which the two leads
12
a
,
12
d
are to be spliced. Of course, the point chosen for the splice
30
must provide clearance for a splicing sleeve
26
between the center coil guides
20
. Once a splicing point has been determined, using a measuring grid, the first lead
12
a
and the second lead
12
d
are marked for length along the measuring grid.
The leads
12
a
,
12
d
are then stripped, cleaned, and cleaved at the marked splicing point so that the leads will meet at the proper spot and the splicing sleeve
26
is on a straight run. If that operation is successfully accomplished, the splicing sleeve
26
is then acrylated in place over the splice
30
, forming a long, continuous loop of fiber
32
extending from the left end of the first component
10
a
to the right end of the second component
10
b
. If the splice
30
has been properly measured and executed, the length of the continuous loop of
32
is such that it will just fit over the center coil guides
20
, with the splicing sleeve
26
coming to rest in its predetermined position.
The motherboard includes rows of optical components
10
, with leads
12
extending out of either end. Because the position of each optical component is fixed, and because the splicing point for each pair of leads must be carefully measured and executed within a narrow tolerance, this method of splicing optical fiber leads is called a “deterministic” fiber wrapping process. As the complexity and quantity of optical communication systems modules increases, a number of disadvantages of the deterministic process have become apparent.
First, the above-described method for wrapping fiber requires a high degree of skill on the part of the worker performing the splicing process. The process of splicing optical fiber is a difficult, painstaking task, which is complicated by trying to achieve sufficient slack in the fiber after it is wrapped back onto the center coil guides. If the fiber is too tight, light loss may occur, and the fiber may even snap. If the fiber is too loose, the fiber may slide up and off the guides and wander within the device, which can cause it to get pinched or otherwise damaged by other components.
Second
DeMeritt Jeffrey A.
Kubissa Cynthia A.
Corning Incorporated
Kim Ellen E.
Lee John D.
Smith Eric
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