Tool for optically finishing multiple mounted optical fibers

The axial positions of two or more fibers are simultaneously controlled in three grinding or polishing stages. The fibers (72) are first ground flush with the guide (120) in which they are housed. The fiber ends and faces of the guides are then ground flat and square. The fibers are thereafter polished to their optical quality and required length. The tool for accomplishing these steps includes a retainer (74) which holds the assembly (73) of fiber optic ferrules (70) and their optical fibers (72) therein at a tool surface (16). This tool surface is protected by a guard (18) from being too rapidly ground away while the fibers and fiber/guide combinations are ground flush with the surface. The surface and its retained guides and fibers are then axially moved to an unprotected position (FIG. 3) so that the surfaces and the fibers within their ferrules may be polished on a suitable polishing wheel or similar device.

TECHNICAL FIELD 
The present invention relates to a tool which is useful in simultaneously 
producing optically finished transmitting/receiving end faces on a 
plurality of optical waveguides. 
CROSS-REFERENCE TO RELATED APPLICATIONS 
The present invention has particular use for simultaneously optically 
finishing the end faces of a plurality of optical waveguides mounted in 
the fiber optic connector of copending patent application, Ser. No. 
65,032, and constitutes an improvement over U.S. Pat. No. 4,330,965 issued 
May 25, 1982. 
BACKGROUND OF THE INVENTION 
It is essential that, when optical fibers are to be optically coupled in a 
connect-disconnect mechanism, the mating ends of the fibers be optically 
finished to preclude or, at least, to minimize losses in transmission 
through reflection or scattering of the transmitted signals at their end 
faces. There are many well known methods for providing an adequately 
finished fiber optic end, including proper cleavage of glass fiber, and 
polishing of the fiber ends when encapsulated or otherwise held within an 
optical fiber ferrule. While successful to a greater or lesser extent, 
improvements are still needed, especially where it is necessary to mass 
produce optically polished fiber ends by use of relatively unskilled 
labor. When, more than one optical fiber is to be mounted in a connector, 
further problems arise if the fibers are not to be twisted or broken as 
would occur in the threaded construction of above-identified U.S. Pat. No. 
4,330,965 issued May 25, 1982. 
SUMMARY OF THE INVENTION 
The present invention accomplishes these and other objectives and overcomes 
the breakage problems by simultaneously controlling the axial position of 
two or more fibers in three grinding or polishing stages while the fibers, 
as retained in individual contacts or ferrules, are mounted together in an 
assembly mount, to position and hold their end faces even in a common 
plane. The glass fibers in their contacts, as a unit, are first ground 
flush with their contacts. The fiber ends and face of the contacts are 
then ground flat and square. The fibers are thereafter polished to their 
optical quality and required lengths. 
The tool for accomplishing these steps, in its preferred embodiment, 
includes a retainer which holds the assembly mount and, therefore, the 
fiber optic contacts or ferrules and their optical fibers therein at a 
tool surface. This tool surface is protected by a guard from being too 
rapidly ground away while the fibers and fiber contacts are ground flush 
with the surface. The surface and its retained contacts and fibers are 
then axially moved, but not rotated, to an unprotected position so that 
the surface and the fibers within their contacts may be positioned on a 
suitable polishing wheel or similar device. 
One advantage of the present invention provides a means by which optical 
finishes can be applied simultaneously to the end faces of optical fibers 
mounted in their optical fiber ferrules or contacts, without subjecting 
the fibers to twisting or torsion. 
Other aims and advantages as well as a complete understanding of the 
present invention will appear from the following explanation of an 
exemplary embodiment and the accompanying drawings thereof.

DETAILED DESCRIPTION OF THE INVENTION 
As illustrated in the drawings, a hand-held fiber optic ferrule grinding 
and polishing tool 10 includes a body 12 of generally cylindrical 
configuration which is concentrically placed within a spring housing 14. 
For convenience, these as well as most other parts are all made of 
aluminum, except as otherwise indicated. For example, it is preferred that 
body 12 be provided with an end surface which is of a relatively softer 
material than the end surface of housing 14. Accordingly, the end surface 
of body 12 comprises a plate 16 of brass while the end surface of spring 
housing 14 comprises an annular limiting ring plate 18 of stainless steel. 
Two or more centrally located holes 20 in plate 16 support the ends of as 
many fiber optic contracts as are to be ground and polished. For purposes 
of example, four holes 20 for four optical fibers and ferrules are 
depicted. 
At its forward end, body 12 has a radially extending flange 22 which is 
adapted to cooperate with a recess 24 in spring housing 14 to limit 
forward movement of the spring housing with respect to the body and, 
thereby, to ensure that the polishing and grinding surfaces of plates 16 
and 18 are flush, one with respect to the other. It is to be understood 
that the surfaces of plates 16 and 18 do not have grinding and polishing 
abrasive materials in them, but are disposed to be placed against such 
materials on grinding and polishing wheels at appropriate times during 
grinding and polishing of the fiber optic contact ends. For convenience of 
describing their use, however, they are termed "grinding" and "polishing" 
surfaces. 
At the opposite end of body 12, an adjustable annulus 26 is secured to the 
body by a set screw 28 which is normally engaged within an annular recess 
30 of the adjustable annulus. A retaining ring 32 residing within a recess 
34 of the body prevents adjustable annulus 26 from slipping off the body 
when set screw 28 temporarily does not secure the body and the annulus 
together. Between the adjustable annulus and housing 14 are a plurality of 
generally symmetrically placed springs 36 which normally bias the spring 
housing and the body together at their contacting recess 24 and flange 22. 
Movement between the body and the spring housing is effected by means of an 
eccentric cam 40 which is, and operates, the same as that disclosed and 
described in U.S. Pat. No. 4,330,965 issued May 25, 1982. Cam 40 is 
rotatable within a cylindrical opening of housing 14 by a handle 50 which 
extends beyond the outer surface of housing 14. Cam 40 is adapted to 
rotate approximately 180.degree. against the bias of springs 36 to 
compress them and to move body 12 and its plate 16 forward of housing 14 
and its plate 18. Rotation of eccentric cam 40 is limited by means of a 
pin 56 (see FIG. 1) which is secured within spring housing 14 and which is 
contacted by stops (one of which is shown by indicium 62) on a plate 58 
having a stepped periphery. The plate has a larger periphery 58a, whose 
radius is the same as that of a hole 60 within housing 14, and a smaller 
periphery 58b whose radius is less than that of hole 60. The points, at 
which peripheries 58a and 58b meet, define a pair of generally radial 
surfaces, such as surface 62. Thus, radial surfaces 62 act as stops which 
contact stationary pin 56 to limit rotation of cam 40. 
As shown in FIG. 4, a plurality of contacts or ferrules 70, which terminate 
optical fibers 72 (for illustration, four are disclosed), are retained as 
a unitary structure within an assembly mount 73. Mount 73 fits into and is 
housed in a split cradle 74 (see also FIG. 1, wherein contacts 70, mount 
73 and fibers 72 are removed). The split cradle is insertable in an 
adjustable carrier 100 (see also FIG. 3). Split cradle 74, which comprises 
a pair of mating halves 74a and 74b, has internal surfaces 76 which are 
configured as the exterior of ferrule assembly mount 73 and its strain 
relief 75. After placement of the mount within the first cradle half, the 
second half is placed over the first half to enclose the mount. The ends 
of ferrules 70 and fibers 72 are positioned to extend through openings 77 
in both halves of cradle 74. A pair of alignment pins, one of which is 
identified by indicum 78a, on opposed cradle halves are receivable within 
holes 78b in their opposed cradle half to maintain alignment between the 
two halves. An annular groove 80 is formed from semicircular grooves on 
the cradle halves. Slots 82 in the cradles halves are disposed to key with 
pins 84 in body 12 to permit axial movement, but prevent rotation, of 
cradle 74 with respect to body 12. 
The assembled cradle is received and held within adjustable carrier 100, 
see also FIGS. 1 and 3, by a clip 102. The clip comprises a pair of 
pivotable halves 102a and 102b which are mounted on the adjustable carrier 
by screws 103, on which they can pivot. The clip halves include U-shaped 
jaws 104 whose inner surfaces 104a are adapted to engage annular groove 80 
of cradle 74. A pair of manipulating legs 105 extend from jaws 104 and are 
biased apart by a spring 106 which, therefore, maintains the jaws normally 
closed. 
A key 108 (FIGS. 1 and 3) is pinned to a pivot 110 (FIG.1) on the periphery 
of carrier 100 and is biasable by a spring 112 into contact with a slot or 
keyway 114 formed in a periphery of adjustable annulus 26 in order to lock 
the adjustable annulus and carrier together and, as a consequence, the 
adjustable carrier to body 12. Adjustable carrier 100 further is coupled 
at threads 116 (FIG. 1) with body 12 so that, when key 108 is pivoted out 
of engagement with keyway 114, carrier 100 may be screwed into or out of 
body 12 and, therefore, the carrier both rotates and axially moves with 
respect to body 12. The rotational improvement, however, is not translated 
to cradle 74 because of the engagement of jaws 104 with groove 80 and of 
body pins 84 in cradle slots 82. Therefore, the axial movement of carrier 
100 will be transmitted to cradle 74, which will move axially in the body 
and towards or away from plate 16. Inasmuch as ferrules or contacts 70 
terminate in optical fiber bushings 120 which are received in holes 20, 
the threaded connection at 116 permits bushing 120 to be positioned 
adjacent the surface of brass squaring plate 16. 
An adjustment mechanism is needed for the proper positioning of bushing 120 
with respect to plate 16, and between plates 16 and 18 because the 
surfaces of the plates are of different hardness and subject to 
differential wear through the grinding and polishing operations. 
Specifically, all bushings 120 are generally of the same axial length and 
it is important that, before the initial grinding and polishing 
operations, the surfaces of all bushings 120 be flush with the surface of 
plate 16. The adjustment to make the surfaces flush with one another is 
effected through the intermediary of the attachment between adjustable 
annulus 26 and plate 12. First, set screw 28 is loosened so that 
adjustable carrier 100 and adjustable annulus 26 may be made to rotate 
together through the latching between key 108 and keyway 114. Rotation of 
these latched together parts through the intermediary of screw threads 116 
permits the surfaces of bushings 120 to be moved toward or away from the 
end surface of plate 16. At the point that the end surfaces of bushings 
120 and plate 16 are flush or where the bushing surfaces barely extend 
beyond the plate surface, set screw 28 is tightened. In this position, the 
tool is ready for the initial grinding operation. 
Subsequent to this adjustment, tool 10 is used as follows. Ferrules 70, as 
connected to fibers 72 and their strain relief 75, have already been 
retained in assembly mount 73. The assembly mount is then placed in cradle 
half 74a or 74b. The cradle is closed by adding the second half to enclose 
assembly mount 73 and its contacts and stain relief housing. Jaws 104 are 
opened and the cradle is then inserted into adjustable carrier 100. The 
cradle is turned until body pins 84 engage cradle slots 82. Closing of the 
jaws places jaw surfaces 104a within cradle groove 80 under the action of 
spring 106 to retain the cradle and its fiber optic contact assembly mount 
73 within body 12. 
The tool is then readied for the initial grinding operation, after the 
factory adjustment using set screw 28, as described above. Preferably, a 
3000 grit diamond wheel is utilized. For this grinding operation, 
stainless steel ring plate 18 must be flush with brass plate 16, as 
properly positioned by key device 40 when flange 22 abuts against recess 
24. The tool face is then placed onto the grinding surface of the diamond 
wheel. During grinding, key 108 is unlatched from engagement with keyway 
114 and adjustable carrier 100 is slowly turned clockwise one revolution 
until key 108 again relatches with the keyway. This operation causes 
bushings 120 and their contained ends of fibers 72 to be slightly ground, 
the purpose primarily being to grind the protruding fibers flush with 
guide bushings 120. The tool may be flushed with clean water to remove any 
debris left from the grinding operation. 
Steel limiting ring 18 is then retracted by rotation of eccentric cam 40. 
This movement retracts spring housing 14. Brass plate 16, the bushing 
surface, and the fiber ends are then placed against a phenolic polishing 
wheel wetted preferably with a three micron cerium oxide emulsion. After 
proper polishing, the polished ferrules as contained in assembly mount 73, 
are removed by reversing carrier 100 by one revolution by unlatching and 
relatching key 108 with keyway 114. Cradle assembly 74 is then removed 
from adjustable carrier 100 by releasing jaws 104 from the cradle groove. 
While four fibers 72, contacts or ferrules 70, bushings 120, and holes 20 
have been depicted and illustrated as exemplary of the invention, any 
number may be employed, depending upon the requirements of the ultimate 
interconnection needed. 
Consequently, although the invention has been described with reference to a 
particular embodiment thereof, it should be realized that various changes 
and modifications may be made therein without departing from the spirit 
and scope of the invention.