Optics: measuring and testing – For optical fiber or waveguide inspection
Reexamination Certificate
1997-06-27
2001-01-23
Font, Frank G. (Department: 2877)
Optics: measuring and testing
For optical fiber or waveguide inspection
Reexamination Certificate
active
06177985
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to switching assemblies, and more specifically, to switching assemblies, and/or optical switches used for testing optical fibers, devices, and/or fiber optic devices, such as fiber optic couplers. The present completely, accurately, and reliably tests a fiber optic device for some, many and/or all relevant optical characteristics.
2. Background of the Related Art
Fiber optic devices are typically tested after manufacture to determine their optical characteristics. For example, attenuators may be tested to determine the actual attenuation of the device, and fiber optic couplers may be tested to determine the coupling ratio at selected wavelengths and polarizations.
Currently, various techniques and/or switching assemblies are available for testing of fiber optic devices. For example, FIGS.
1
A-
1
B illustrate one testing assembly disclosed in United Kingdom Patent Application 2235043A to Philip C. Longhurst, incorporated herein by reference. In
FIG. 1A
, an optical measurement system measures insertion loss of each fibre in sequence of a multi-fibre connector
15
connected to an optical fibre ribbon
16
to be obtained using light source
17
,
18
and detector
22
of the system. A multi-channel optical switch
1
is connected to a light source
17
,
18
. A 1×2 bi-directional splitter
2
is optically coupled between each of the switch channels
4
and a respective fibre
8
of a standard multi-fibre connector
3
mating with the connector
15
to be tested. Optical fiber
5
is fusion spliced at
6
to the channel
4
and to one of the fibers
8
of an optical fiber ribbon
7
connected to the connector
3
by an optical fiber
9
which is fusion spliced at
10
.
FIG. 1B
is an illustration when the optical measurement system is used to monitor and record the return loss between the pair of optical fibers interconnected by the mating of the standard multi-fibre connector
3
and the multi-fibre connector
15
under test. To perform the return loss test, the adaptor
21
and large area detector
22
(shown in
FIG. 1A
) are disconnected and removed from the end of the optical fibre ribbon
16
. The free end of the optical fibre ribbon
16
is immersed in an index matching gel
23
from which no light will be reflected. The testing for the return loss is then conducted using light source
17
,
18
and additional detectors
19
,
20
.
Thus, in the Longhurst reference, the testing procedure is complex and cumbersome. Further, all desired properties of the fiber optic device cannot be tested without additional connections being made, and/or operations being conducted and/or additional testing equipment being required, between different test procedures. Thus, the testing system in the Longhurst reference is inefficient and not sufficiently and/or adequately automated.
FIG. 2
is an illustration of another prior art switching assembly; that is, the transmission measurement facility described in Bellcore Generic Requirements for Fiber Optic Branching Components, Bellcore GR-1209-CORE, Issue 1, November 1994, incorporated herein by reference. The source switch
112
is used to launch light from one of sources
104
selected via switch
106
into any of the devices under test
108
in environmental chamber
110
. The detector switch
114
connects any DUT
108
to the power meter
118
, measuring transmitted power and reflected power. The coupler
116
directs the optical power reflected by the DUT
108
to port (r) on Switch
114
for detection. A reference fiber
120
, located at port (m) of Switches
112
,
114
is used to correct for variations in source power over time. A reflectance reference
122
is located at port (r) of Switch
112
, and is used to calculate reflectance from the measured optical power.
Insertion loss is calculated by subtracting the power transmitted through the reference fiber
120
from the power transmitted through the DUT
108
. Reflectance is calculated by subtracting the power reflected by the reflectance reference
122
from the power reflected by the DUT
108
. The Switches, Power Meter and Environmental Chambers are computer controlled via GPIB interface. However, I have realized that this switching assembly (suggested for use for environmental testing of fiber optic devices) cannot be used to collect and/or capture sufficient data to define a full transfer matrix needed to calculate/determine the prescribed device characteristics for adequate and/or sufficient fiber optic device testing. For example, this switching assembly cannot obtain or collect directivity and/or near end crosstalk measurements of a fiber optic device.
It is therefore desirable to provide a testing assembly capable of completely, accurately, and reliably testing a fiber optic device for some, most, and/or all relevant optical characteristics.
It is also desirable to provide a testing assembly capable of completely, accurately, and reliably testing a fiber optic device, such as an optical fiber biconical taper (FBT) coupler.
It is also desirable to provide a testing assembly capable of completely, accurately, rapidly, and reliably testing a fiber optic device without altering or changing the test configuration and/or testing equipment.
It is also desirable to provide a testing assembly capable of completely, accurately, rapidly, and reliably testing a fiber optic device without requiring the connections between the testing device and the device under test (DUT) to be altered or changed during the testing operation.
It is also desirable to provide a testing assembly capable of completely, accurately, rapidly, and reliably testing a fiber optic device without altering or changing the test configuration and/or testing equipment, while also connecting to, and/or disconnecting from, and/or simultaneously testing, another device under test.
SUMMARY OF THE INVENTION
It is a feature and advantage of the present invention in providing a testing assembly capable of completely, accurately, and reliably testing a fiber optic device for all relevant optical characteristics.
It is another feature and advantage of the present invention in providing a testing assembly capable of completely, accurately, and reliably testing a fiber optic device such as an optical fiber biconical taper (FBT) coupler.
It is another feature and advantage of the present invention in providing a testing assembly capable of completely, accurately, and reliably testing a fiber optic device without altering or changing the test configuration and/or testing equipment.
It is another feature and advantage of the present invention in providing a testing assembly capable of completely, accurately, and reliably testing a fiber optic device without requiring the connections between the testing device and the device under test (DUT) to be altered or changed during the testing operation.
It is another feature and advantage of the present invention in providing a testing assembly capable of completely, accurately, rapidly, and reliably testing a fiber optic device without altering or changing the test configuration and/or testing equipment, while also connecting to, and/or disconnecting from, and/or simultaneously testing, another device under test.
The present invention is based, in part, on the realization or identification of the problem that during testing of fiber optic devices, the testing equipment and/or the fiber optic devices require manual intervention during the testing program before the fiber optic device can be completely and adequately tested. This requires much effort to be expended by personnel running or implementing the testing program, thereby creating many inefficiencies in the entire process of testing a fiber optic device.
Advantageously, I have discovered that it is possible to fully test a fiber optic device in accordance with a predetermined testing program without requiring changes in testing equipment, and/or connections between the testing equipment and the device under test. Further, I have discovered that
Donner Irah H.
Font Frank G.
Hale & Dorr LLP
Nguyen Tu T.
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