(12) United States Patent
`Bishop et al.
`
`(10) Patent N0.:
`(45) Date of Patent:
`
`US 6,798,992 B1
`*Sep. 28, 2004
`
`US006798992B1
`
`(54) METHOD AND DEVICE FOR OPTICALLY
`CROSSCONNECTING OPTICAL SIGNALS
`USING TILTING MIRROR MEMS WITH
`DRIFT MONITORING FEATURE
`
`_
`(75) Inventors: David John Bishop, Summit, NJ (US);
`Randy Clinton Giles, Whippany, NJ
`
`(Us)
`
`-
`_
`(73) Asslgnees'
`
`’
`Murray Hill, NJ (US)
`
`PA
`
`"
`
`(58) Field of Search ............................ .. 398/45, 46, 49,
`398/48, 50, 52, 55, 56, 12, 19; 356/731;
`385/16, 17, 18, 19, 20—24, 33, 119
`
`(56)
`
`References Cited
`
`US. PATENT DOCUMENTS
`
`6,198,856 B1 * 3/2001 Schroeder et al. .......... .. 385/17
`
`6,301,402 B1 * 10/2001 Bhalla et al. . . . . . . . . .
`6,411,751 B1 * 6/2002 Giles et al. . . . . . . .
`
`. . . .. 385/16
`. . . .. 385/16
`
`l. ............... .. 385 16
`6424 757 B1 * 72002 S k t
`’
`’
`/
`P“ S e a
`/
`
`OTHER PUBLICATIONS
`
`US. application No. 09/512174 (Aksyuk et al) ?led on Feb.
`24, 2000*
`
`( * ) Notice:
`
`_
`
`_
`
`_
`
`_
`
`_
`
`SubJect to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 0 days.
`
`This patent is subject to a terminal dis-
`
`* Cited by examiner
`
`Clalmer'
`
`Primary Examiner—Hanh Phan
`
`(21) Appl. N0.: 09/518,070
`(22) Filed:
`Mar. 2, 2000
`
`Related U-S- Application Data
`(60) Provisional application N°~ 60/164,459, ?led 0n NOV- 10,
`1999'
`(51) Int. Cl.7 ............................................... .. H04J 14/00
`(52) US. Cl. ........................... .. 398/45; 398/50; 398/52;
`398/55; 398/56; 398/12; 398/19; 398/47;
`398/48; 398/46; 385/16; 385/17; 385/18;
`385/19; 385/20; 385/21; 385/22; 385/23;
`385/24; 385/33; 385/119; 356/731
`
`ABSTRACT
`(57)
`A device and method for detecting rotational drift of mirror
`elements in a MEMS tilt mirror array used in an optical
`crossconnect. The optical crossconnect directs optical sig
`nals from an input ?ber to an output ?ber along an optical
`path by rotatably positioning mirror elements in desired
`POSitiOHS- A monitoring device disposed Outside Of the
`Optical Path is used to Obtain images of the MEMS may of
`to transmit and receive a test signal through the crossconnect
`for detecting the presence of mirror element drift.
`
`16 Claims, 2 Drawing Sheets
`
`Petitioner Ciena Corp. et al.
`Exhibit 1006-1
`
`

`

`U.S. Patent
`
`Sep. 28,2004
`
`Sheet 1 0f 2
`
`US 6,798,992 B1
`
`FIG. 7
`
`12“ 00636
`
`0000
`
`r16
`\14
`
`009$
`
`FIG. 2
`
`4——108
`
`129
`
`Petitioner Ciena Corp. et al.
`Exhibit 1006-2
`
`

`

`U.S. Patent
`US. Patent
`
`Sep. 28,2004
`Sep. 28, 2004
`
`Sheet 2 0f 2
`Sheet 2 of2
`
`US 6,798,992 B1
`US 6,798,992 B1
`
`FIG. 3
`FIG. 3
`
`350
`
`
`
`Petitioner Ciena Corp. et 21].
`Exhibit 1006-3
`
`Petitioner Ciena Corp. et al.
`Exhibit 1006-3
`
`

`

`US 6,798,992 B1
`
`1
`METHOD AND DEVICE FOR OPTICALLY
`CROSSCONNECTING OPTICAL SIGNALS
`USING TILTING MIRROR MEMS WITH
`DRIFT MONITORING FEATURE
`
`This application is based on US. Provisional Application
`Ser. No. 60/164,459 ?led on Nov. 10, 1999.
`
`BACKGROUND OF THE INVENTION
`
`1. Field of the Invention
`The present invention pertains to ?ber optic communica
`tions systems and, more particularly, to monitoring devices
`and methods for monitoring shifts in optical crossconnect
`con?gurations utilizing micro electromechanical systems
`(MEMS) tilting mirror arrays.
`2. Description of the Related Art
`In ?ber optic communication systems, signal routing is
`essential for directing an optical signal carrying data to an
`intended location. Existing routing techniques typically
`experience optical poWer loss due to inef?cient coupling of
`optic signals betWeen input and output ?bers. This increases
`the dependence on optical poWer sources (e.g., pump lasers)
`Which are used to compensate for poWer losses by injecting
`optical poWer back into the optical system. The need for
`optical poWer sources increases the overall cost of the
`optical system.
`Another criteria for signal routing is the ability to direct
`a signal received from one of a plurality of input ?bers or
`ports to any of a plurality of output ?bers or ports Without
`regard to the frequency of the optical signal.
`Free-space optical crossconnects alloW interconnecting
`among input and output ports in a recon?gurable sWitch
`fabric. An example of such an optical crossconnect utiliZing
`mirco-electromechanical systems (MEMS) tilting mirror
`devices is disclosed in commonly oWned and copending
`US. patent application Ser. No. 09/410,586, ?led Oct. 1,
`1999. By adjusting the tilt angles of the MEMS mirror
`devices, optical signals can be directed to various
`destinations, ie to numerous output ?bers.
`MEMS devices and, in particular, tilting mirror devices
`are susceptible to unWanted movement or drift due to
`external factors such as temperature changes and mechanical
`fatigue experienced by actuator elements used to deploy and
`control the individual mirror elements. As a result, optical
`signal poWer may be lost due to misalignment of the
`re?ected optical signal With its intended target (eg an
`output ?ber). Accordingly, a system is desired to monitor
`MEMS optical crossconnect con?guration to provide for
`displacement adjustment.
`
`SUMMARY OF THE INVENTION
`An optical crossconnect device having a monitoring fea
`ture for detecting optical signal drift is provided. The device
`provides optical connection of optic signals betWeen input
`?bers and output ?bers by using a MEMS tilt mirror array.
`The MEMS array includes a plurality of tiltable mirror
`elements Which are positionable in an intended orientation
`for directing optical signals, but Which are susceptible to
`drift that causes degradation in the optical coupling of the
`signals to the output ?bers. A monitoring device positioned
`outside of the optical path dynamically monitors the position
`of one or more of the mirror elements to detect drift.
`In a preferred embodiment, the monitoring device is a
`camera for obtaining an image of one or more mirror
`elements.
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`2
`In another embodiment, the monitoring device comprises
`an optical transmitter and an optical receiver for transmitting
`a test signal through the optical crossconnect to monitor
`mirror position drift.
`In yet another embodiment, a pattern is formed on one or
`more of the mirror elements and an image or re?ection of the
`pattern is obtained for determining the presence of mirror
`drift.
`A method is also described for monitoring mirror element
`positions of mirror elements in a MEMS tilt mirror array
`used in an optical crossconnect. The method is used With a
`MEMS mirror array having mirror elements disposed at
`desired tilt positions for crossconnecting an optic signal
`betWeen an input ?ber and an output ?ber along an optical
`path. A monitoring device disposed outside of the optical
`path monitors the positions of the mirror elements to detect
`When position drift occurs. The mirror positions are then
`adjusted by forming control signals based on the detected
`drift and applying the control signals to the drifted mirror
`elements.
`Other objects and features of the present invention Will
`become apparent from the folloWing detailed description
`considered in conjunction With the accompanying draWings.
`It is to be understood, hoWever, that the draWings are
`designed solely for purposes of illustration and not as a
`de?nition of the limits of the invention, for Which reference
`should be made to the appended claims. It should be further
`understood that the draWings are not necessarily draWn to
`scale and that, unless otherWise indicated, they are merely
`intended to conceptually illustrate and explain the structures
`and procedures described herein.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`In the draWings, Wherein like reference numerals denote
`similar elements throughout the several vieWs.
`FIG. 1 is a planar vieW of an example of a MEMS mirror
`array used in connection With the present invention;
`FIG. 2 is a schematic representation of an optical cross
`connect monitoring device in accordance With one embodi
`ment of the present invention; and
`FIG. 3 is a schematic representation of a monitoring
`device for a “folded” optical crossconnect in accordance
`With another embodiment of the present invention.
`
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENTS
`Arrays of tWo-axis tilt mirrors implemented using micro
`electromechanical systems (MEMS) technology in accor
`dance With the invention alloW for the construction of large
`scale optical crossconnects for use in optical systems. Opti
`cal crossconnects are commonly employed to connect a
`number of input optical paths to a number of output optical
`paths. Atypical requirements of optical crossconnects is that
`any input be capable of being connected to any output. One
`example of a MEMS mirror array 10 is depicted in FIG. 1.
`The mirror array 10 includes a plurality of tilt mirrors 12
`formed on a substrate 11, mounted to actuation members or
`springs 14 and controlled by electrodes (not shoWn). Each
`mirror 12 is approximately 100—500 Microns across, may be
`shaped as square, circular or elliptical, and is capable of
`operatively rotating or tilting about orthogonal X-Y axes,
`With the tilt angle being selectively determined by the
`amount of voltage applied to the control electrodes. Further
`details of the operation of the MEMS mirror array 10 are
`found in copending US. patent application Ser. No. 09/415,
`
`Petitioner Ciena Corp. et al.
`Exhibit 1006-4
`
`

`

`US 6,798,992 B1
`
`10
`
`15
`
`20
`
`25
`
`3
`178, ?led Oct. 8, 1999, the entire contents of Which are
`incorporated herein by reference. The general concept of
`utilizing tWo or more such tilt mirror arrays 10 to form an
`optical crossconnect is disclosed in copending US. patent
`application Ser. No. 09/410,586, ?led Oct. 1, 1999, the entire
`contents of Which are also incorporated herein by reference.
`The use of one or more MEMS tilt mirror arrays in
`conjunction With a lens array is disclosed in co-pending US.
`patent application Ser. No. 09/512,174, ?led Feb. 24, 2000,
`the entire content of Which is also incorporated herein by
`reference. As disclosed in that application, various optical
`crossconnect con?gurations of compact siZe (i.e. minimal
`spacing betWeen crossconnect components) and exhibiting
`minimal optical poWer loss can be realiZed. One such optical
`crossconnect 100 discussed in the aforementioned applica
`tion is depicted in FIG. 2. Crossconnect 100 receives input
`optic signals 108 through a plurality of optic ?bers 112,
`preferably formed in an array as is Well knoWn in the art. For
`ease of illustration ?ber array 110 is shoWn as a one
`dimensional array having four ?bers 112a, 112b, 1126, 112d.
`It is in any event to be understood that ?ber array 112 as Well
`as other ?ber arrays discussed herein are preferably tWo
`dimensional arrays such as, for example, N><N arrays.
`Fiber array 112 transmits the optical signals 108 to an
`array of lenses 114 that function as collimating lenses. The
`lens array 114 is positioned relative to ?ber array 112 so that
`each lens communicates With a corresponding ?ber for
`producing pencil beams 116 from the optic signals 118.
`Thus, beam 116a is produced from a signal carried by ?ber
`112a, beam 116d is produced from a signal carried by ?ber
`112d, etc.
`A?rst MEMS tilt mirror array 118, also referred to as the
`input array, is positioned in alignment With lens array 114 so
`that each mirror element 12 Will receive a corresponding
`beam 116. The mirror elements are operatively tilted, in a
`manner discussed in application Ser. No. 09/415,178, to
`re?ect the respective beams 116 to a second or output
`MEMS mirror array 122 positioned in optical communica
`tion With MEMS array 118. Depending on the tilt angle of
`each mirror element in input MEMS array 118, the re?ected
`signals can be selectively directed to speci?c mirror ele
`ments in output MEMS array 122. To illustrate this
`principle, beam 116a is shoWn in FIG. 2 generating re?ec
`tion beams 120a and 120a‘ and beam 116d is shoWn in the
`?gure generating re?ection beams 120a' and 120d‘. These
`beams are received by mirror elements in the output MEMS
`45
`array 122 and are directed as beams 124 to an output lens
`array 126. An output ?ber array 128 is aligned With lens
`array 126 to receive and output optical signals 129. Thus,
`lens array 126 couples beams 124 into the output ?ber array
`128.
`The rotatable positions or orientations of the individual
`mirror elements 12 of arrays 118 and 122 are, hoWever,
`affected by environmental conditions such as temperature
`changes. As a result, once the positions of the mirror
`elements 12 are set, those intended positions may drift or
`change due (for example) to temperature variations, thereby
`adversely causing inef?cient or unintended signal routing
`and associated poWer losses. A similar problem may be
`caused by mechanical fatigue and stress on the actuators
`used to control mirror position, and by electric charging
`effects on the actuators. These variations can result in
`conditions referred to as macro-drift, Wherein all of the
`mirror elements in an array drift by an equal amount, and
`micro-drift, in Which only some of the mirror element
`positions unintendedly change.
`To detect such unWanted mirror drift in optical crosscon
`nects in accordance With the present invention to compen
`
`30
`
`35
`
`40
`
`50
`
`55
`
`60
`
`65
`
`4
`sate for actual mirror positions, one or more monitoring
`devices 130, 132 are included in the crossconnect system
`100 shoWn in FIG. 2. The monitoring devices may be used
`to detect both macro-drift and micro-drift conditions of the
`MEMS mirror arrays 118, 122. For example, each monitor
`ing device may be a camera or other imaging devices Which
`operates independently of other cameras. Each camera is
`shoWn in FIG. 2 positioned outside of the optical path of the
`crossconnect (i.e. the path in Which optical signal 116 travels
`through the crosssconnect to ?ber array 128) and obtains an
`image of its respective MEMS array. Thus, camera 130 is
`focussed on MEMS array 118 and camera 132 is focussed on
`MEMS array 122. The resulting images are then compared
`to reference images of mirror array positions stored, for
`example, in a controller block 500 containing a processor
`and a database (not shoWn) in a manner Well-knoWn to those
`having ordinary skill in the art. In the event that an unac
`ceptable amount of drift is detected for the entire mirror
`array, feedback control signals can be generated by the
`control block 500 for adjusting the tilt angles to compensate
`for drift by applying appropriate voltages to the mirror
`actuators. If on the other hand only certain mirror elements
`need to be adjusted, these mirrors can be identi?ed, through
`the aforementioned image comparison With a reference
`image, and then re-positioned by applying appropriate volt
`ages to the desired actuators.
`The monitoring system of FIG. 2 can also be employed in
`connection With a folded crossconnect con?guration, as for
`example shoWn in FIG. 3, Wherein a single input/output ?ber
`array 312, single MEMS mirror array 318, and re?ective
`surface element 330 comprise the folded con?guration. A
`camera 340 positioned outside of the optical path 316
`obtains an image 342 of the mirror elements in the array 318
`for use in calculating and compensating for detected drift.
`As an alternative or in addition to the use of cameras,
`device 130 (FIG. 2) may comprise one or more illuminators
`(not shoWn) for producing, for example, one or more infra
`red beams 131, 133 directed at mirror arrays 118, 122 and
`devices 130, 132 may comprise an infra-red detector for
`detecting the re?ected infra-red beams. The illumination
`source may produce a test signal having a different Wave
`length from the signal Wavelength or can be modulated to
`discriminate and distinguish it from the signal Wavelength.
`The infrared beams 131, 133 may be pencil beams for
`illuminating a single mirror element Which may be desig
`nated as a reference element, such as element 16 in FIG. 1.
`The re?ected infra-red signal Will pass through the optical
`crossconnect for receipt by its respective infra-red detector.
`For example, for an infra-red test beam directed at a mirror
`element in array 118, the test beam Will be re?ected and
`directed to detector 130, and for an infrared beam directed
`at a mirror element in array 122, the test beam Will be
`received by detector 132. Depending on the characteristics
`of the re?ected and received infra-red beams—such as a
`reduction in beam poWer or intensity and/or a change of
`position on the detector at Which the beam is received,
`etc.—macrodrift can be dynamically detected. For example,
`and as a result of a temperature change, drift may occur
`among all mirror elements in mirror arrays 118, 122. By
`measuring and detecting drift from a reference mirror ele
`ment (e.g. mirror 16), the mirror arrays can be adjusted to
`compensate for drift by generating appropriate feedback
`signals from control blocks 500 to be applied to mirror
`control actuators.
`It Will be appreciated that both devices 130, 132 can
`operate as combined or dual-function source/receiver
`devices Wherein each device produces a signal for receipt by
`
`Petitioner Ciena Corp. et al.
`Exhibit 1006-5
`
`

`

`US 6,798,992 B1
`
`10
`
`15
`
`40
`
`5
`the other and receives a signal produced by the other.
`Likewise, and in connection With the folded con?guration of
`FIG. 3, device 340 can be implemented by or supplemented
`With a detector/receiver for receiving re?ected test signals
`342, 343 generated by a source such as an infrared source
`350 for illuminating one or more mirror elements 12.
`For micro-drift compensation, the devices 130, 132 in the
`system 100 of FIG. 2 and the device 340 in the system 300
`of FIG. 3 can be connected to a scanning device Which may
`be found in controller block 500 for changing the position of
`the test beam (beam 130 in FIG. 2 and beam 342 in FIG. 3)
`to illuminate multiple mirror elements. For example, the
`scanner can adjust the test beam position to illuminate one
`mirror element 12 at any given time for determining the tilt
`angle of each illuminated mirror.
`As another alternative, the reference mirror element 16
`may be formed With an imaging pattern 14, as for eXample
`by surface etching. This modi?cation alloWs for the use of
`pattern recognition techniques Wherein a generated pattern is
`received or monitored by a detector or camera. Detected
`movement of the pattern indicates mirror drift. Pattern 14
`may be speci?cally oriented to generate a unique pattern that
`is observable in scattered light so as to provide an enhanced
`signature When a light beam is centered on mirror 16. A
`25
`single unique pattern may be used for all mirrors, or each
`mirror can be coated With its oWn unique pattern. Entire
`pathWays through the mirror array may be de?ned by unique
`patterning, thus helping to guide light beams through the
`array during sWitching.
`Thus, While there have shoWn and described and pointed
`out fundamental novel features of the invention as applied to
`preferred embodiments thereof, it Will be understood that
`various omissions and substitutions and changes in the form
`and details of the methods disclosed and devices illustrated,
`and in their operation, may be made by those skilled in the
`art Without departing from the spirit of the invention. For
`eXample, it is eXpressly intended that all combinations of
`those elements and method steps Which perform substan
`tially the same function in substantially the same Way to
`achieve the same results are Within the scope of the inven
`tion. Moreover, it should be recogniZed that structures
`and/or elements and/or method steps shoWn and/or
`described in connection With any disclosed form or embodi
`ment of the invention may be incorporated in any other
`disclosed or described or suggested form or embodiment as
`a general matter of design choice. It is the intention,
`therefore, to be limited only as indicated by the scope of the
`claims appended hereto.
`What is claimed is:
`1. An optical crossconnect monitoring device for directing
`optical signals received from a plurality of input optic ?bers
`along an optical path to a plurality of output optic ?bers, and
`for detecting spatial shifts of the optical signals, comprising:
`a moveable mirror formed on a substrate and positioned
`Within the optical path for receiving optical signals
`from one of the plurality of input optic ?bers and
`directing said received signals along the optical path
`speci?c ones of the plurality of output optic ?bers, said
`mirror being operatively tiltable about a rotational aXis
`to an intended angular orientation relative to said
`substrate for providing desired directional re?ection of
`a one of the optical signals received by said mirror; and
`an optical monitoring device positioned outside of the
`optical path and in optical communication With said
`mirror for optically detecting rotational drift of said
`mirror relative to said intended angular orientation, said
`
`45
`
`55
`
`65
`
`6
`detected rotational drift being indicative of optical
`signal spatial shifts.
`2. The device of claim 1, Wherein said moveable mirror
`comprises a MEMS mirror array having a plurality of
`moveable mirror elements.
`3. The device of claim 2, Wherein said monitoring device
`comprises a camera oriented for obtaining an image of said
`mirror array.
`4. The device of claim 3, Wherein one of said mirror
`elements is formed With a pattern for receipt of an image of
`said pattern by said camera.
`5. The device of claim 2, Wherein said monitoring device
`comprises an illumination device for illuminating a selected
`one of said plural mirror elements With a test optical signal
`and a receiver for receiving the test signal after re?ection of
`the test optical signal from said selected mirror element.
`6. The device of claim 5, Wherein one of said mirror
`elements comprises a pattern for producing a re?ection of
`said pattern for receipt by said receiver When said selected
`mirror element is illuminated by the test signal.
`7. The device of claim 5, Wherein the plurality of input
`optic ?bers and the plurality of output optic ?bers form an
`array of optic ?bers, said device further comprising a
`re?ector element disposed in optical communication With
`said MEMS mirror array for receiving optical signals from
`said MEMS mirror array and for re?ecting the received
`optical signals back to said MEMS mirror array, said
`re?ected optical signals being redirected by said MEMS
`mirror array back to said array of optic ?bers for receipt by
`the output optic ?bers.
`8. The device of claim 7, Wherein said re?ector element
`receives the test signal from said illumination device and
`re?ects the test signal to said receiver.
`9. The device of claim 7, Wherein said illuminating device
`and said receiver are integrally formed.
`10. The device of claim 2, Wherein the plurality of input
`optic ?bers and the plurality of output optic ?bers form an
`array of optic ?bers, said device further comprising a
`re?ector element disposed in optical communication With
`said MEMS mirror array for receiving optical signals from
`said MEMS mirror array and for re?ecting the received
`optical signals back to said MEMS mirror array, said
`re?ected optical signals being redirected by said MEMS
`mirror array back to said array of optic ?bers for receipt by
`the output optic ?bers.
`11. The device of claim 2, further comprising a controller
`connected to said monitoring device and operable for gen
`erating a control signal in response to the detected rotational
`drift.
`12. A method of monitoring a spatial shift of optical
`signals in an optical crossconnect device Which directs
`optical signals received from a plurality of input optic ?bers
`along an optical path to a plurality of output optic ?bers,
`comprising the steps of:
`placing a mirror formed on a substrate Within the optical
`path for receiving optical signals from one of the
`plurality of input optic ?bers and directing said
`received signals along the optical path to speci?c ones
`of the plurality of output optic ?bers, said mirror being
`operatively tiltable about a rotational aXis to an
`intended angular orientation relative to said substrate
`for providing desired directional re?ection of one of the
`optical signals received by said mirror;
`positioning an optical monitoring device outside of the
`optical path and in optical communication With said
`mirror; and
`optically detecting rotational drift of said mirror relative
`to said intended angular orientation using the optical
`
`Petitioner Ciena Corp. et al.
`Exhibit 1006-6
`
`

`

`US 6,798,992 B1
`
`7
`monitoring device, said detected rotational drift being
`indicative of optical signal spatial shifts.
`13. The method of claim 12, Wherein said moveable
`mirror comprises a MEMS mirror array having a plurality of
`moveable mirror elements.
`14. The method of claim 13, further comprising the steps
`of determining Which of said plural mirror elements have
`experienced rotational drift, generating control signals from
`said optically detecting step, and using said control signals
`to operatively adjust rotatable positions of said rotationally
`drifted mirror elements.
`15. The method of claim 13, Wherein said positioning step
`further comprises the step of positioning an optical signal
`transmitter outside of the optical path for generating an
`optical test signal directed at said MEMS array for re?ection
`by said MEMS array, and positioning an optical receiver
`
`10
`
`15
`
`8
`outside of said optical path for detecting said re?ected test
`signal after re?ection of the test signal from the MEMS
`array, and Wherein said monitoring step further comprises
`monitoring a poWer level of said test signal received by said
`receiver.
`16. The method of claim 13, Wherein at least one of said
`mirror elements is a pattern mirror element, and Wherein
`said positioning step further comprises positioning an opti
`cal signal transmitter outside of the optical path for gener
`ating an optical test signal directed at said pattern mirror
`element for re?ection by said pattern mirror element to
`thereby generate an image of the pattern, and positioning an
`optical receiver outside of said optical path for receiving and
`detecting said pattern image.
`
`*
`
`*
`
`*
`
`*
`
`*
`
`Petitioner Ciena Corp. et al.
`Exhibit 1006-7
`
`