U.S. patent application number 11/026698 was filed with the patent office on 2006-07-06 for method of optically aligning a workholder for connector geometry control and in-line measurement capability and apparatus used therefor.
Invention is credited to Alfred J. Cheswick, Cuneyt Erdogan, Terrance J. Schmidt.
Application Number | 20060147160 11/026698 |
Document ID | / |
Family ID | 36613622 |
Filed Date | 2006-07-06 |
United States Patent
Application |
20060147160 |
Kind Code |
A1 |
Schmidt; Terrance J. ; et
al. |
July 6, 2006 |
METHOD OF OPTICALLY ALIGNING A WORKHOLDER FOR CONNECTOR GEOMETRY
CONTROL AND IN-LINE MEASUREMENT CAPABILITY AND APPARATUS USED
THEREFOR
Abstract
An apparatus, integral to a polishing fixture, that enables a
plurality of fiber optic connectors to be independently aligned to
a polishing surface. Once inserted into the apparatus, a reference
connector is positioned over an optical interferometer, whose focal
plane is parallel with that of the polishing surface plane. The
apparatus is then adjusted to the known interferometric geometry of
the reference connector. This procedure is performed for each
integral apparatus insuring that all consecutive connectors
inserted into said apparatus are polished to the same
interferometric geometry as that of the reference connector. The
same apparatus also permits connector geometries to be measured by
the interferometer while the connectors are mounted in the
polishing fixture.
Inventors: |
Schmidt; Terrance J.;
(Ocean, NJ) ; Erdogan; Cuneyt; (Franklin Park,
NJ) ; Cheswick; Alfred J.; (Loch Arbour, NJ) |
Correspondence
Address: |
Alfred J. Cheswick
104 Ocean Avenue
Loch Arbour
NJ
07711
US
|
Family ID: |
36613622 |
Appl. No.: |
11/026698 |
Filed: |
December 31, 2004 |
Current U.S.
Class: |
385/85 |
Current CPC
Class: |
G02B 6/385 20130101;
G02B 6/381 20130101 |
Class at
Publication: |
385/085 |
International
Class: |
G02B 6/36 20060101
G02B006/36 |
Claims
1. An apparatus, integral to a polishing fixture, enabling an
alignment of an optical component to a polishing means and a focal
plane of an optical measurement device, comprising: a positioning
means; a leveling means disposed upon said positioning means;
2. The apparatus of claim 1 wherein said positioning means is
disposed upon said polishing fixture.
3. The apparatus of claim 2 wherein said positioning means enables
a freedom of movement of said leveling means perpendicular to said
polishing means and said focal plane.
4. The apparatus of claim 3 wherein said leveling means is formed
to accept the insertion of said optical component.
5. The apparatus of claim 4 wherein an adjustment of said leveling
means orients said optical component relative to said polishing
means and said measurement device.
6. The apparatus of claim 1 wherein said positioning means enables
contact between said optical component and said polishing
means.
7. The apparatus of claim 1 wherein said positioning means locates
said optical component into said focal plane of said measurement
device.
8. The apparatus of claim 7 wherein said measurement device is an
interferometer.
9. An apparatus enabling an independent orientation of an optical
component mounted in a polishing workholder, relative to a
polishing media and an optical measurement device, comprising: a
gimbal means; a translation means;
10. The apparatus of claim 9 wherein an adjustment of said gimbal
means alters said orientation of said component with respect to
said polishing media and said measurement device.
11. The apparatus of claim 10 wherein said orientation enables a
geometrical alignment between a longitudinal axis of said component
and said polishing media.
12. The apparatus of claim 10 wherein said orientation enables a
geometrical alignment between said longitudinal axis of said
component and a focal plane of said measurement device.
13. The apparatus of claim 9 wherein said gimbal means is disposed
upon said translation means.
14. The apparatus of claim 13 wherein said translation means
enables a linear positioning of said component with reference to
said polishing media and said measurement device.
15. The apparatus of claim 14 wherein said linear positioning
enables contact between said component and said polishing
media.
16. The apparatus of claim 15 wherein said linear positioning
results in a development of pressure between said component and
said polishing media.
17. The apparatus of claim 14 wherein said linear positioning
locates said component within said focal plane of said measurement
device.
18. The apparatus of claim 9 wherein said gimbal means consists of
a sphere captured between two surfaces, said surfaces secured by a
plurality of screws.
19. The apparatus of claim 9 wherein said translation means is a
linear slide.
Description
FIELD OF THE INVENTION
[0001] The present invention generally relates to a method and to
devices enabling the alignment of optical connectors to a desired
orientation with reference to a polishing surface and the focal
plane of an optical measurement device.
BACKGROUND OF THE INVENTION
[0002] Fiber optic connectors are used to link various optical
components, cable assemblies, transmission devices and testing
equipment. To insure low loss and low reflective performance, a
connector's precision ferrule, in which the fiber is mounted, must
be polished to a scratch-free finish with demanding geometric
criteria.
[0003] The ferrule tip of most high performance connectors is
polished to a convex geometry. Ideally, the apex of the convex
surface should coincide with the center axis of the fiber. The
deviation from this ideal geometry is referred to as the
connector's apex offset. Apex offset is created when the ferrule
endface is not held perpendicular to the abrasive surface used
during the polishing process. An interferometer is a commonly used
test instrument that can measure apex offset through the analysis
of interference patterns created by light reflected off of the
ferrule and fiber endface.
[0004] Prior art has demonstrated that equipment has been developed
to automatically polish connectors. These polishers utilize
precisely machined workholders in which connectors are inserted.
The workholder is then engaged with a support bracket and
positioned so that the connector's ferrules are placed in contact
with a rotating polishing surface. The degree of perpendicularity
maintained between the ferrule axis and the polishing surface is
highly dependent upon the polisher's mechanical assembly, machined
parts' tolerances, and workholder/polisher engagement mechanism.
These variables compound upon each other resulting in increased
apex offset error.
[0005] Prior art also has a significant shortcoming regarding the
control of apex offset. Most automated polishers are designed to
support the simultaneous processing of a plurality of connectors.
Hence the workholder is machined with a multitude of connector
ports. There always exists a machining tolerance from port to port,
a variable that will be reflected in differing apex offsets. These
ports are fixed and cannot be adjusted for individual
connectors.
[0006] An additional shortcoming of prior art is the method in
which connectors are secured within the workholder. Connectors are
slip fitted into bushings or sleeves and locked into position.
Because of dimensional tolerance differences between the outer
diameter of the connector ferrule and the inner diameter of the
bushing/sleeve, the locking means tilts the ferrule creating
additional apex offset.
[0007] A further shortcoming of prior art is that polisher
workholders are machined and mechanically assembled. The connector
orientation cannot be adjusted with an interferometric reference.
Therefore the workholder cannot be utilized for in-line
interferometric inspection of connectors that are secured in the
workholder.
SUMMARY OF THE INVENTION
[0008] Therefore, it is the objective of the invention to provide a
means of minimizing the apex offset of a plurality of connectors
residing in a workholder, by independently aligning the connectors
so they all will be perpendicular to an abrasive surface during a
polishing process.
[0009] An advantage of the present invention is that it provides a
workholder fixture that permits the optical alignment of an
individual connector port with an interferometric reference. Such
alignment guarantees that any ferrule inserted in the connector
port will be held perpendicular to a polishing surface for minimal
apex offset.
[0010] Still another advantage of the present invention is that the
said optical alignment is performed after the workholder is secured
in the polishing machine. This compensates for any compounding of
machining tolerances and assembly misalignment throughout the
polisher's mechanical structure.
[0011] A further advantage of the present invention is that the
said optical alignment is performed after a reference connector is
secured and locked in the workholder. This compensates for ferrule
tilting due to dimensional tolerance variability between the
ferrule's outer diameter and the bushing/sleeve inner diameter,
thus eliminating potential contribution to apex offset.
[0012] An additional advantage of the present invention is that a
plurality of connector ports contained in a single workholder can
be optically aligned independent of each other. This permits mass
polishing of multiple connectors while controlling geometric
criteria at every connector port.
[0013] Another advantage of the present invention is that an apex
offset for each connector can be intentionally induced for
experimental and process development applications.
[0014] Since the present invention results in polishing ports that
have been optically aligned by an interferometer, polished
connectors can be inspected for interferometric compliance while
they are still secured in the workholder. This eliminates the need
to remove a polished connector from the workholder and transfer it
to a separate interferometric testing station for analysis.
[0015] Other advantages of the invention will become apparent upon
reading the following detailed description and upon reference to
the accompanying drawings.
DESCRIPTION OF FIGURES
[0016] For a more complete understanding of this invention,
reference should now be had to the embodiments illustrated in
greater detail in the accompanying drawings and described below by
way of examples of the invention.
[0017] FIG. 1 is an exploded view of a connector port.
[0018] FIG. 2 is the view of an assembled connector port.
[0019] FIG. 3 is a workholder blank capable of supporting a
plurality of connector ports.
[0020] FIG. 4 illustrates a workholder blank with a plurality of
connector ports mounted thereon.
[0021] FIG. 5 depicts a polishing machine with its polishing disk,
and an interferometer mounted thereon.
[0022] FIG. 6 illustrates the engagement of an assembled workholder
with the polishing machine. It also depicts linear slide transfer
means for the workholder between the interferometer and polishing
disk.
[0023] FIG. 7 depicts a fiber optic connector inserted into a
connector port. It also illustrates the method of adjusting a
connector port so the reference connector is properly aligned
interferometrically.
[0024] FIG. 7A illustrates the interferometric fringe pattern of
the reference connector before connector port alignment.
[0025] FIG. 7B illustrates the true and inherent apex offset of the
reference connector. It also depicts the desired interferometric
pattern after alignment of the reference connector in the connector
port.
DETAIL DESCRIPTION OF THE PREFERRED EMBODIMENT
[0026] While the invention will be described in connection with the
preferred embodiment, it will be understood that it is not intended
to limit the invention to that embodiment. On the contrary, it is
intended to cover all alternatives, modifications and equivalents
as may be included within the spirit scope of the following
description.
[0027] Referring to FIG. 1, apparatus 1 is comprised of a connector
port 2. Connector port 2 is provided with a leveling block 10.
Leveling block 10 is formed with through holes 12, 14, 16, 18, 20,
22 and 24. Suitable materials for leveling block 10 are stainless
steel, aluminum and other metals. Stainless steel is preferred. A
linear slide 26 is provided with a rail 28 and a carriage 30.
Commercially available linear slides are suitable for linear slide
26, including those available from American Linear Manufacturers
(Westbury, N.Y.) with part number LWL5+70. Rail 28 is formed with a
plurality of through holes 32 along its length. Carriage 30 is
formed with threaded holes 34 and 36. Screws 38 and 40 are inserted
into through holes 14 and 12, and engage with threaded holes 36 and
34, respectively.
[0028] A leveling plate 42 is formed into an L-shaped bracket.
Suitable materials for leveling plate 42 are stainless steel,
aluminum and other metals. Stainless steel is preferred. Leveling
plate 42 is formed with a through hole 44. The diameter of through
hole 44 is of sufficient diameter so as to accept the press fitting
of a bushing 46. Bushing 46 is press fit into through hole 44 until
it is flush with the bottom surface of leveling plate 42. Suitable
materials for bushing 46 include carbide, stainless steel, zirconia
and other ceramics. Zirconia is preferred. Commercially available
bushings include those supplied by MicroLap, Inc. (Rolla, N. Dak.)
having part number JA2842000. Suitable bonding means between
bushing 46 and through hole 44 is adhesives and arc welding.
Adhesives are preferred. The inner diameter of bushing 46 is of
sufficient size to accept the slip fitting of commercially
available fiber optic connectors and ferrules.
[0029] Leveling plate 42 is formed with a threaded through hole 48
of sufficient diameter to accept the engagement of a spring plunger
50.
[0030] Leveling plate 42 is formed with a through hole 52. The
diameter of through hole 52 is equivalent to that of through hole
24. A sphere 54 is formed with a diameter of sufficient size to
permit sphere 54 to rest upon through hole 52. Suitable materials
for sphere 54 include carbide, stainless steel, hardened steel and
other metals. Stainless steel is preferred.
[0031] Leveling plate 42 is formed with threaded holes 56, 58, 60
and 62. Relative locations between threaded holes 56, 58, 60 and 62
are identical to the relative locations of through holes 16, 18, 20
and 22. Set screws 64, 66, 68 and 70 are inserted into through
holes 16, 18, 20 and 22, engaging with threaded holes 56, 58, 60
and 62. This engagement confines sphere 54 between through hole 52
and through hole 24 as illustrated in FIG. 2.
[0032] Again referring to FIG. 2, a shaft 72 is press fit into
through hole 24 and bound. Binding means include adhesives and arc
welding. Adhesives are preferred. Suitable materials for shaft 72
include stainless steel and carbide. Carbide is preferred. A lock
collar 74 is secured upon shaft 72. A compression spring 76 is
placed over shaft 72 and rests upon lock collar 74.
[0033] Referring to FIG. 3, a workholder blank 78 is presented.
Blank 78 is fabricated into a T-shape form. Suitable materials for
blank 78 are stainless steel, aluminum and other metals. Aluminum
is preferred. Blank 78 has a vertical component 80 and a horizontal
component 82. Vertical component 80 is formed with a plurality of
threaded holes 84. Threaded holes 84 are aligned into a plurality
of rows 86.
[0034] Horizontal component 82 is formed with plurality of through
holes 88. The positions of through holes 88 are such that they lay
in the same planes of rows 86. Horizontal component 82 is also
formed with two holes 90 and 92.
[0035] Referring to FIG. 4, a plurality of connector ports 2 is
mounted to workholder blank 78. Shaft 72 is inserted into through
hole 88. Linear slide 26 is secured to workholder blank 78 with a
plurality of screws 94 that engage with threaded holes 84. A lock
collar 96 is slipped over shaft 72 and secured. The locking
position of lock collar 96 can be varied along the length of shaft
72, such as to position leveling plate 42 below or above the bottom
surface of horizontal component 80. FIG. 4 illustrates lock collar
96 secured upon shaft 72 so as to position leveling plate 42 above
the bottom surface of horizontal component 80.
[0036] The operation of apparatus 1 will now be described.
Referring to FIG. 5, a fiber optic connector polisher 98 is
presented. Suitable polishers include the Icon Workcell (part
number IC-3001) manufactured by Krell Technologies, Inc.
(Morganville, N.J.). Polisher 98 consists of a plurality of
polishing disks 100 and an interferometer 102 that is secured upon
a Y-axis linear slide 104. Suitable interferometers include the
SpecMap.TM. supplied by the aforementioned Krell Technologies, Inc.
(part number SMP-IC). A monitor 103 displays images generated by
interferometer 102. An optical focal plane 106 of interferometer
102 is parallel to the plane created by the diameters of polishing
disks 100.
[0037] Polisher 98 also consists of a Z-axis linear slide 110 that
is mounted upon an X-axis linear slide 116. A workholder mount 108
is secured to Z-axis linear slide 110. Two dowel pins 112 and 114
protrude from workholder mount 108. Workholder blank 78 is secured
to workholder mount 108 via the engagement of holes 90 and 92 with
dowels 112 and 114 as illustrated in FIG. 6.
[0038] Again referring to FIG. 6, lock collar 96 is positioned upon
shaft 72 so as to permit the lower surface of leveling plate 42 to
fall below the bottom surface of vertical component 80 upon release
of tension in compression spring 76. FIG. 6 illustrates compression
spring 76 in a compressed state.
[0039] X-axis linear slide 116 and Z-axis linear slide 110 have
ranges of travel that allow the bottom surface of leveling plate 42
to be positioned in focal plane 106 and make physical contact with
polishing disks 100.
[0040] Referring to FIG. 7 and FIG. 7B, a commercially available
reference fiber optic connector 118 with a known interferometric
fringe pattern 122 is inserted into bushing 46 and secured into
position by locking spring plunger 50. Connector 118 consists of a
ferrule 120 that protrudes beneath the bottom surface of leveling
plate 42. A fiber 124 is centered in ferrule 120. For illustrative
clarity, shaft 72 and through hole 24 are not displayed.
[0041] X-axis linear slide 116 and Z-axis linear slide 110 are
manipulated to position the endface of ferrule 120 and fiber 124
into focal plane 106. Referring to FIG. 7A, the resulting initial
fringe pattern 126 and a fiber image 128 of fiber 124 is displayed
on monitor 103. Due to assembly misalignment, the adhesive
interface between bushing 46 and through hole 44, and machining
tolerances of leveling block 10, linear slide 26, workholder blank
78, workholder mount 108, Z-axis linear slide 110 and X-axis linear
slide 116, the vertical center axis of ferrule 120 is not
perpendicular with focal plane 106. This misalignment is
represented by the offset of initial fringe pattern 126 relative to
fiber image 128.
[0042] Using a screwdriver tool 130, set screws 64, 66, 68 and 70
are adjusted to change the pitch and yaw of leveling plate 42 and
therefore ferrule 120 and fiber 124. During this procedure, X-axis
linear slide 116 and Y-axis linear slide 104 are manipulated to
maintain fiber image 128 in the center of the display of monitor
103. Upon attaining known interferometric fringe pattern 122
through the adjustment of set screws 64, 66, 68 and 70, the center
axis of ferrule 120 is now perpendicular with both focal plane 106
and the plane created by the diameters of polishing disks 100. This
procedure is repeated for each leveling plate 42 contained in
apparatus 1.
[0043] All connector ports 2 are now properly aligned for the
polishing of commercially available fiber optic connectors.
Additionally, after a polishing process is completed, the
connectors are properly aligned within their respective connector
ports 2 to focal plane 106 for accurate interferometric
measurements using interferometer 102.
* * * * *