Optics: measuring and testing – Lens or reflective image former testing
Reexamination Certificate
2001-09-18
2003-09-02
Pham, Hoa Q. (Department: 2877)
Optics: measuring and testing
Lens or reflective image former testing
C385S016000, C700S095000
Reexamination Certificate
active
06614517
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention generally relates to techniques for fabricating integrated objects. More particularly, the present invention provides a method and resulting structure for manufacturing a lens array structure onto a fiber array, where the lens array and fiber array are used for interfacing to an optical switching device. Merely by way of example, the present invention is implemented using such lens array and fiber array in a switching system for long haul communications, but it would be recognized that the invention has a much broader range of applicability. The invention can be applied to other types of networks including local area networks, enterprise networks, small switch designs (e.g., two by two) and the like.
As the need for faster communication networks becomes more desirable, digital telephone has progressed. Conventionally, analog voice telephone signals have been converted into digital signals. These signals can be 24,000 bits/second and greater in some applications. Other telephone circuits interleave these bit streams from 24 digitized phone lines into a single sequence of 1.5 Mbit/second, commonly called the T
1
or DS
1
rate. The T
1
rate feeds into higher rates such as T
2
and T
3
. A T
4
may also be used. Single mode fiber optics have also been used at much higher speeds of data transfer. Here, optical switching networks have also been improved. An example of such optical switching standard is called the Synchronous Optical Network (SONET), which is a packet switching standard designed for telecommunications to use transmission capacity more efficiently than the conventional digital telephone hierarchy, which was noted above. SONET organizes data into 810-byte “frames” that include data on signal routing and designation as well as the signal itself. The frames can be switched individually without breaking the signal up into its components, but still require conventional switching devices.
Most of the conventional switching devices require the need to convert optical signals from a first source into electric signals for switching such optical signals over a communication network. Once the electric signals have been switched, they are converted back into optical signals for transmission over the network. There are many examples of such conventional switch systems, such as those made by Sycamore Networks, Inc., Lucent Technologies, Inc. and others. Numerous limitations exist with such conventional electrical switching technique. For example, such electrical switching often requires a lot of complex electronic devices, which make the device difficult to scale. Additionally, such electronic devices become prone to failure, thereby influencing a reliability of the network. The switch is also slow and is only as fast as the electrical devices. Accordingly, techniques for switching optical signals using a purely optical technology have been proposed. Such technology can use a wave guide approach for switching optical signals. Unfortunately, such technology has been difficult to scale for switching a high number of signals from a bundle of optical fibers, which may be desirable today. Other companies have also been attempting to develop technologies for switching such high number of signals, but have generally been limited. Such switches are also difficult to manufacture effectively and reliably, where even connecting the fiber bundle to the system proves to be quite challenging.
As merely an example, some companies have been attempting to form such connection of the fiber bundle to the system using an array of tapered fiber structures. Tapered fibers are often difficult to make with high accuracy and often cannot be scaled up to form large numbered array configurations. U.S. Pat. No. 5,907,650, assigned to Fiber Guide Industries, Inc, describes a conventional way of making a tapered fiber for use of an array. As noted, such tapered fibers are often difficult to make accurately. Additionally, the tapered fibers generally require a substrate structure with accurate sized openings, which are also extremely difficult to make accurately. That is, it is difficult to define center-to-center accuracy between each of the openings to a high degree. Additionally, it is often difficult to form an opening that is controllable and houses the tapered fiber in an accurate manner. These and other limitations limit the practical use of such tapered fibers for large numbered array configurations.
From the above, it is seen that an improved way for fabricating an object for the manufacture of fiber optical devices is highly desirable.
SUMMARY OF THE INVENTION
According to the present invention, a technique including a method and device for manufacturing an integrated object is provided. More particularly, the present invention provides a method and resulting structure for manufacturing a lens array structure onto a fiber array, where the lens array and fiber array are used for interfacing to an optical switching device. Merely by way of example, the present invention is implemented using such lens array and fiber array in a switching system for long haul communications, but it would be recognized that the invention has a much broader range of applicability. The invention can be applied to other types of networks including local area networks, enterprise networks, small switch designs (e.g., two by two) and the like.
In a specific embodiment, the invention provides a method for manufacturing an optical switching device. The method includes forming an array plate comprising at least one hundred sites from a first physical process, where each of the sites is for coupling to an optical fiber. The sites have a first spatial degree of error relative to an ideal mathematical grid of the sites. The first spatial degree of error is derived from at least the first physical process. The method also derives site measurement values from each of the sites and transfers site measurement values for each of the sites into a memory location. The method forms a lens plate comprising a plurality of lenses from a second physical process. Each of the lenses is going to be coupled to at least one of the sites on the array plate. The lenses have a second spatial degree of error relative to a second mathematical grid of lenses. The second spatial degree of error is derived from at least the second physical process. The method then derives lens measurement values from each of the plurality of lenses and transfers the lens measurement values for each of the sites into the memory location. The method compares each of the site measurement values with its respective lens measurement value to determine an error measurement between the lens measurement values and the respective site measurement values at a first reference point. The method then shifts the site measurement values relative to the lens measurement values by a selected increment relative to the first reference point. The selected increment is an x-direction, a y-direction, or a theta direction, or any combination of these. The method repeats the comparing to derive an other error measurement after the site measurement values have been shifted and continuing to perform the comparing and shifting in an iterative manner to reduce and/or possibly minimize the error measurement between the site measurement values with its respective lens measurement values. The method determines a reduced or possibly a minimum error measurement based upon the repeated comparing and shifting. The minimum error measurement is relative to the first reference point. The method couples the array plate with the plurality of lenses by aligning the array plate to the plurality of lenses such that the site measurement values and the lens measurement values are arranged in a manner where the error measurement is at the reduced and/or minimum error measurement.
Many benefits are achieved by way of the present invention over conventional techniques. In a specific embodiment, the invention provides an improved way of aligning a high number lens array (e.g., 2
Aubuchon Christopher
Hallstein Sascha
Davis Willie
Nayna Networks, Inc.
Pham Hoa Q.
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