CA1220958A - Piezoelectric apparatus for positioning optical fibers - Google Patents
Piezoelectric apparatus for positioning optical fibersInfo
- Publication number
- CA1220958A CA1220958A CA000488934A CA488934A CA1220958A CA 1220958 A CA1220958 A CA 1220958A CA 000488934 A CA000488934 A CA 000488934A CA 488934 A CA488934 A CA 488934A CA 1220958 A CA1220958 A CA 1220958A
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- Prior art keywords
- optical fiber
- bender
- radiation
- bender assembly
- free end
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Mechanical Light Control Or Optical Switches (AREA)
- Optical Communication System (AREA)
Abstract
ABSTRACT OF THE DISCLSOURE
Apparatus for selectably positioning an optical fiber end along a range of positions comprising a bender assembly including at least one piezoelectric bender element and having a first end thereof arranged for association with one or more optical fiber ends and a second end thereof located at a reference position. Suitable application of electrical energy to the piezo-electric bender element causes it to assume a selected position along the range of positions. Various embodiments of bender assemblies and applications thereof in communication are also described.
Apparatus for selectably positioning an optical fiber end along a range of positions comprising a bender assembly including at least one piezoelectric bender element and having a first end thereof arranged for association with one or more optical fiber ends and a second end thereof located at a reference position. Suitable application of electrical energy to the piezo-electric bender element causes it to assume a selected position along the range of positions. Various embodiments of bender assemblies and applications thereof in communication are also described.
Description
~2~1~9~
1 This appli.cation is a di~vision of co-pendi.n~ applicat~on serîal number 369,0.87 Eiled on January 22, 1981.
The present ~nvention relates to optical f:iber commun-icati.on, and more particularly to optical fiber switching and i.nte~connections.
BACKGROU~I) OF THE INVENTION
In recent years optical fibers have come into wide-spread use in a wide variety of applications and particularly in communications. The efficient utilization of optical fibers in many applicat~.ons is dependent on the ability of associated apparatus to accurately and repeatably position optical fiber ends. Presently various mechanical devices such as x-y-z trans-lators, concentric tubing and V - groove assemblies are employed for posit~oning o~ the opt;cal fiber ends.
It has been proposed to employ a single piezoelectric bender element as a two position switch. for an optical fiber.
See Y. Ohmor~ and Ho Ogiwara, Applied optics, Vol. 17 No. 22 P,3531. This ~L2~9~
reference does no-t eonta-n any sugc;estion of using such a bender element Eor selectable positioning along a range of positions.
Switching employing directable liyht heams has also been proposed in U.S. Patents 3,985,975 and 4,065,64~, using holograms and CRT tubes for direeting the light heam.
The mecilanieal apparatus presently used for pos~tioning of optieal fibers involves signifiea~t disadvantayes in terms of eost, deslgn limltations and reliability. The inadequacies of preselltly known optieal fiber positioning apparatus are believed to limit the introduetion of optieal - fiber teehnology into many other possible applieations.
SU~ARY OF THE INVENTIO~
The present invention seeks to overeome the disadvantages of the prior art apparatus for positioning optieal fibers and to provide apparatus for positioning optical fibers which is characterized by greatly improved performance charaeterlsties, design flexibility and economy and significantly smaller size.
There is thus provided in aeeordanee with the present inven-tion apparatus for selectably positioning an optieal fiber end along a range of positions eomprising a bender assembly comprising at least one piezoe]ectric bender element and having a first end thereof arranged for association with one~ or more optieal fiber ends and a seeond end the~reof loeated at a referenee position. Suitable appliea-tion of electrical energy to the piezoelectric bender element ca~lses it to assllme a selectecl position alorlg tihe range of positions.
L Further in accordance with an embod.irnent of the presellt invent.ion tllere is provi.ded apparatus for selectably posit.ioning an optical fiber end cornprlsin a bendex assembly comprising a plurality of piezoelectric bender elements arranged in series and SUC}I that the motion of the bender elements have mutually perpendicular components.
The present invention also seeks to provide a switching exchange for telephone or other communicatlons apparatus which is simple and which is easy to construct, economieal and modular in the sense that it can be accommodated changeably to the growing needs of a customer.
There is thus provid^d in accor~ance wlth an embodiment o~ the invention a communications exchange comprising a first array of transmitters employing piezoelectrlc bender elements, each of which provides a beam of information bearing electromagnetic radiation in a selectable direction; a second array ~0 of electromagnetie radiation receivers arranged in radiation receiving relationship with the first array whereby the radlation output of any of the transmitters may be directed for receipt thereof by any selected one of the receivers. In accor~ance with the invention, instructions are provided to the transmitters for establishing communications between subscribers connected to respective transmitters and subscribers connected to respective receivers impinged upon by radiation from respecti~e transmitters.
l;'urther in accor~lance with an embodi3i~el~t o F the invention eacn subscriber is connected to one ~2~gs~ (~
transmitt~r and to one recei.v~x such that two-way communi.ca-tion is establlsiled by the way of modulated radiation beams. PreEerably, every transmitter can communicate w:ith eve~ry recelver.
Additionally in accordance with an embodiment of the present invention there is provided a communications exchange comprising a first array o~
transmitters, each of which provides a bealn of information bearing electromagnetic radiation and at lU least one directable electromagnetic radiation receiver arranged for selectable radiation receiving relationship with one or more transmit-ters of the first array.
It is a particular feature of the present invention that substantially no cross talk is encountered since the intersection of electromagnetlc radiation produces substantially no interference.
BRIEF DESCRIPTION OF THE DRAWING~
The present invention will be more fully understood and appreciated from the following detailed description ta~en in conjunction with the drawings in which:
Fig. 1 illustrates a one-dimensional optical fiber end positioning device constructed and operative in accordance with an embodiment of the present invention;
Fig.s. 2 and 3 illustrate respective two- and three-dimensional counterparts o the device illustrated in Fig. l;
Fig. ~ is a schematic illustration of a directable t:ransmi.t~.er;
~22~
1 Fig. 5 is a sche~matic illu.s~ration of a transmitter constructed and operative in accordarlce wi-th an alternative embodimen-t of the invention;
Fig. 6 illus-trates display apparatus ernploying positioning devices of the presen-t invention;
Fig. 7 illustrates detecting apparatus employing positioning devices of the present invention;
Fig. ~ illustrates a one-dimensional optical fiber end positioning device associated with a single array of optical fibers;
Fig. 9 illustrates a one-dimensional optical fiber end positioning device associated with a plurality of arrays of optical fibers;
Fig. 1~ illustrates optical fiber positioning a~paratus employing rod lenses;
Fig. llA illustrates a multi-position selector for coupling one optical fiber to a selected one of a plurality of optical fibers;
Fig. llB is a sectlonal view taken along lines
1 This appli.cation is a di~vision of co-pendi.n~ applicat~on serîal number 369,0.87 Eiled on January 22, 1981.
The present ~nvention relates to optical f:iber commun-icati.on, and more particularly to optical fiber switching and i.nte~connections.
BACKGROU~I) OF THE INVENTION
In recent years optical fibers have come into wide-spread use in a wide variety of applications and particularly in communications. The efficient utilization of optical fibers in many applicat~.ons is dependent on the ability of associated apparatus to accurately and repeatably position optical fiber ends. Presently various mechanical devices such as x-y-z trans-lators, concentric tubing and V - groove assemblies are employed for posit~oning o~ the opt;cal fiber ends.
It has been proposed to employ a single piezoelectric bender element as a two position switch. for an optical fiber.
See Y. Ohmor~ and Ho Ogiwara, Applied optics, Vol. 17 No. 22 P,3531. This ~L2~9~
reference does no-t eonta-n any sugc;estion of using such a bender element Eor selectable positioning along a range of positions.
Switching employing directable liyht heams has also been proposed in U.S. Patents 3,985,975 and 4,065,64~, using holograms and CRT tubes for direeting the light heam.
The mecilanieal apparatus presently used for pos~tioning of optieal fibers involves signifiea~t disadvantayes in terms of eost, deslgn limltations and reliability. The inadequacies of preselltly known optieal fiber positioning apparatus are believed to limit the introduetion of optieal - fiber teehnology into many other possible applieations.
SU~ARY OF THE INVENTIO~
The present invention seeks to overeome the disadvantages of the prior art apparatus for positioning optieal fibers and to provide apparatus for positioning optical fibers which is characterized by greatly improved performance charaeterlsties, design flexibility and economy and significantly smaller size.
There is thus provided in aeeordanee with the present inven-tion apparatus for selectably positioning an optieal fiber end along a range of positions eomprising a bender assembly comprising at least one piezoe]ectric bender element and having a first end thereof arranged for association with one~ or more optieal fiber ends and a seeond end the~reof loeated at a referenee position. Suitable appliea-tion of electrical energy to the piezoelectric bender element ca~lses it to assllme a selectecl position alorlg tihe range of positions.
L Further in accordance with an embod.irnent of the presellt invent.ion tllere is provi.ded apparatus for selectably posit.ioning an optical fiber end cornprlsin a bendex assembly comprising a plurality of piezoelectric bender elements arranged in series and SUC}I that the motion of the bender elements have mutually perpendicular components.
The present invention also seeks to provide a switching exchange for telephone or other communicatlons apparatus which is simple and which is easy to construct, economieal and modular in the sense that it can be accommodated changeably to the growing needs of a customer.
There is thus provid^d in accor~ance wlth an embodiment o~ the invention a communications exchange comprising a first array of transmitters employing piezoelectrlc bender elements, each of which provides a beam of information bearing electromagnetic radiation in a selectable direction; a second array ~0 of electromagnetie radiation receivers arranged in radiation receiving relationship with the first array whereby the radlation output of any of the transmitters may be directed for receipt thereof by any selected one of the receivers. In accor~ance with the invention, instructions are provided to the transmitters for establishing communications between subscribers connected to respective transmitters and subscribers connected to respective receivers impinged upon by radiation from respecti~e transmitters.
l;'urther in accor~lance with an embodi3i~el~t o F the invention eacn subscriber is connected to one ~2~gs~ (~
transmitt~r and to one recei.v~x such that two-way communi.ca-tion is establlsiled by the way of modulated radiation beams. PreEerably, every transmitter can communicate w:ith eve~ry recelver.
Additionally in accordance with an embodiment of the present invention there is provided a communications exchange comprising a first array o~
transmitters, each of which provides a bealn of information bearing electromagnetic radiation and at lU least one directable electromagnetic radiation receiver arranged for selectable radiation receiving relationship with one or more transmit-ters of the first array.
It is a particular feature of the present invention that substantially no cross talk is encountered since the intersection of electromagnetlc radiation produces substantially no interference.
BRIEF DESCRIPTION OF THE DRAWING~
The present invention will be more fully understood and appreciated from the following detailed description ta~en in conjunction with the drawings in which:
Fig. 1 illustrates a one-dimensional optical fiber end positioning device constructed and operative in accordance with an embodiment of the present invention;
Fig.s. 2 and 3 illustrate respective two- and three-dimensional counterparts o the device illustrated in Fig. l;
Fig. ~ is a schematic illustration of a directable t:ransmi.t~.er;
~22~
1 Fig. 5 is a sche~matic illu.s~ration of a transmitter constructed and operative in accordarlce wi-th an alternative embodimen-t of the invention;
Fig. 6 illus-trates display apparatus ernploying positioning devices of the presen-t invention;
Fig. 7 illustrates detecting apparatus employing positioning devices of the present invention;
Fig. ~ illustrates a one-dimensional optical fiber end positioning device associated with a single array of optical fibers;
Fig. 9 illustrates a one-dimensional optical fiber end positioning device associated with a plurality of arrays of optical fibers;
Fig. 1~ illustrates optical fiber positioning a~paratus employing rod lenses;
Fig. llA illustrates a multi-position selector for coupling one optical fiber to a selected one of a plurality of optical fibers;
Fig. llB is a sectlonal view taken along lines
2~ A - A of Fig. llA;
Fig. 12 illustrates coupling of an optical fi~er to a radiation transmitter;
Fig. 13A illustrates coupling of an optical fiber to a selected one of a plurality of radiation transmitters;
Fig~ 13B is a sectional view taken along lines A - A of Fig. 13A;
Fig. 14 is a schematlc illustration of a portion of a communications exchange constructed and operative in accordance with an embodiment of the presetlt invent-ion;
- ~Z2~g~
1 Fig. 15 is a schemat:lc iLlustration oE
transmitter ~nd receiver arrays use~ul in the exchanqe of Fig. 14;
Fig. 16 shows alternative arrangements of transmitter and receiver arrays useful in the exchange of Fig. 14;
Fig. 17 is a schematic illustration of a switching exchange comprising a pair of faClng arrays each having in-terspersed receivers and transmitters;
Fig. 18 is a schematic illustration of a switching exchange cornprising an array of inter-spersed receivers and transmitters and a reflecting element;
Fig. 19 is a block diagram illustration of transmission and receiving apparatus associated with a single subscriber in the exchange of Fig. 14;
Fig. 20 illustrates, in block diagram form, apparatus for calibrating the transmission apparatus illustrated in Fig. 19;
Fig. 21 is a schematic il-.ustration of a swltching exchange useful for cable television and similar transmissions;
Fig. 22 is a bloc~ diagram 1llustration of apparatus for high accuracy feedbac}c control of a directional transmitter;
Figs. 23 and 24 are pictorial illustrations of arrangements of optical fibers associated with piezoelectric bender assemblies in accordance with the present invention.
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.. DETAILED DESCRIPTION OF T~IE INVENTION
The pre~erred embo~iment of the invention will now be described with reference to Figs. 1 - 2~
which illustrate a variety of constructions thereof suitable for different applications.
Referring now to Fig. 1 there is seen apparatus for positioning an optical fiber end constructed and operative in accordance with a preferred embodiment of the present invention and comprising a generally elongate piezoelectric bender element 20 which is mounted at a first end thereof onto a base 22.
The piezoelectric bender element 20 may be of conventional construction and manufacture such as a G-1278 Lead Zinconate-Titanate Thin Sheet piezoceramic manufactured by Gulton Industries of Metuchen, New Jersey, U.S.A. Leads 24 associated with the piezoelectric bender element may be connected to any suitable source of electrical volta~e for controlling the position of the free end 26 of the bender alement.
In accordance with the present invention, the free end 28 of an optical fiber 18 is attached as by ~lueing, clamping or by any other suitable means onto the free end 26 of the bender element ~0 or adjacent thereto for motion together ~herewith.
Fig. 1 illustrates bender element 20 in a straight orientation at rest when the bender element is de-energized and curved to one side when a voltage of a first polarity is applied to leads 24 by means of a selectable voltage source 16. It may be appreciated that normally the bender element may also be bent in an opposite~ e~c~o~ by application of a voltage of an opposite polarity to leads 24.
Furthexrllore any desired position intermediate the two extreme bent positions may be realized by the application of a suitable voltage to the leads 24.
It is a particular feature of the present invention that piezoelectric bendex elements 20 of the type employed herein display a generaLly linear and repeatable position in response to voltage inputs within part of their operative xange. The position-voltage characteristics can be calibrated and an open loop control may thus be employed.
Relatively complex control circuitry employing microprocessor technology may be employed to take into account the hysteresis behaviour of the position voltage curve of the bender elements.
Conventional technology is available for this purpose.
Referring now to Fig. 2, th~re is seen apparatus for positioning an optical fiber end along two dimensions~ The apparatus comprises the apparatus of ~ig. 1 to which is attached at the free end of bender element 20 a second bender element 3 which is oriented such that its plane of bending lies perpendicular to the plane of bendlng of bender element 20. In the illustration, the apparatus of Fig. 1 is shown rotated 90 degrees from the illustration of Fig. 1 and bender element 30 is attached to the free end of bender element 20 by means of a mounting element 32 formed of metal or any other suitable material. Bender element 30 is ~9~
provided with leads 34 which are coupled to position control circuitry (not shown). The free end 28 of the optical fiber is mounted on the free end of bender element 30.
Fig. 3 shows apparatus for posltioning an optical fiber end along three dimensions and comprises the apparatus of Fig. 2 to which is attached by means of a second mounting element 36 a third bender element 38 at the free end of second lU bender element 30. Leads 40 are associated with the third bender element 38 and are coupled to position con*rol circuitry (not shown). In practice third bender element 38 is oriented such that its bending plane is perpen~icular to the bending planes of bender elements 20 and 30 and serves to position the free end 28 of the optical fiber whic]~
is attached to its free end for focussing purposes, Bender elements 20 and 30 may be movea through the:ir position ranges to prQvide a scanning function.
It is appreciated that the bender elements forming a multi-element bender assembly need not necessarily be arranged in perpendicular planes.
Instead it may be sufficient that their directions of motion have respective perpendicular components.
Fig. 4 shows a simplified version of a transmitter useful in the present invention and comprising a selectable position modulatable light source 42 which is substantially similar to those lllustrated in Fiys, 1, 2 and ~. The free end 28 of the op^ical fiber provides a beam of electromagnetic radiation ~4 which implnges on a lens 46 which focusses the beam at a location which i5 selected to correspond _g_ - ~2~
J to a receiver ~. The L~osition of ~ne optL(aL fi~er end ~8 determin~s the Local:ioll of the impingincJ Eoc!lsed Ijearn.
Reference is now made -to Fig. 5 which illustrates a transmitter substantially similar to that illus-trated in Figs. 1, 2 and ~ with the difference being that here the lens 50 is mounted on the free end of the bender element 52 in front of the end of the fiheroptlc conduit 54 and thu~
moves together with the free end of the bencler element. Beam directing i5 achieved by changing the direction of the free end of the bender element.
A rod lens may be used instead of the lens 50.
Alternatively, the elements described in Figs. 4 and 5 may be utilized as directable radiation detectors.
Fig. 6 illustrates one of the applications of the positioning apparatus illustrated in Figs. 1, 2 and 3. In Fig. 6, two dimensional positloning apparatus 56, such as that illustrated in Fig. 2, is associated with a lens 5~ which images ligh~
emerging from the free end 6~ o~ the optical flber OlltO a screen 62. A light source 64 which communicates with the opposite end of the optical fiber 6~ supplies desired radiation which may be positioned on the screen or scanned thereover as desired, simllar to the raster scan of a televlsion ~ut slower.
q'he apparatus of Flg. 6 is particularly suitable for use in slow scan applications in which cathode ray tubes are presently employed such as l.ect.rocar~ioyraptls.
3L;~2~
1 ~ racliation cletector may he constructecl USinCJ
~he pos:itioner o the presellt invention as illustrated in Fig. 7. A lerls 70 provides an image 72 of an object 7~. Po~itionlng apparatus 7~;
such as that illustrated in any of Figs. 1, 2 and 3 positions the end 77 of the optical flber 78 to the image loca-tion so as to enable ligh-t from the image to be transmitted along the optical fiber 7 to a detector 76.
In accordance with a pre~erred embodiment of the present invention, a plurality of images of radiation sources may be provided by lens 70. The positioning apparatus 75 is then operative to selectably and changeably position the optical fiber end at a selec~able image, thus providing a directable receiver.
A multi-fiber end one dimensional scanner is illustrated in Fig. ~ and comprlses a relatively wide piezoelectric bender element 80 mounted on a base 82 and having associated ~7ith the free end ~4 thereof a one~dimensional array of optical fiber ends 86. Oscillation of bender element 80 along one dimenslon provides a raster scan of a scene imaged by a lens 88. A relatively fast scan may be provided in this manner. The optical fibers may be connected at their opposite ends 89 to a linear detector array ~7.
~s seen in Fic3. 9, a plurality of arrays of optical fiber ends may be assoclated ~i-th a single bender element 80. In such a way a color -television type cclmera ma~ be cGnstruccecl by ~mploylng detectors 91 having different spec'ral ~c~
i responses. Similarly a color television type camera may be cons-truc-ted on the basis of the apparatus illustrated in Fig. 8 by employing optical fiber ends transmitting spectrally different light or detectors of different spectral response in array a7.
It may be appreciated that by replacing the detectors in the apparatus of Figs. 8 and 9 with li~ht sources, a raster scanned display may he provided.
Referring now to Fig. 10 which illustrates selec~able switchlng and coupling apparatus employing optical fiber ends, rod lenses 90 and 92 are connected to the free ends 94 and 9~ of respective optical flbers 98 and 100. Rod lenses 90 and 92 are mounted on the free ends of respec~ e piezoele~tric bender elements 102 and 1~4 which are arranged to have perpendicular bending planes and are mounted onto a frame 106. It is noted that the bender elements are employed to selectably vary the direction of the rod lenses. In the illus~rated embodiment, when the rod lenses are directed parallel, radiation transmission there-between is permitted and when they are directed in different directions, little or no such transmission occurs.
It is noted with respect to the embodiments illustrated in Fig. 10 that a plurality of bender elements arranged in series in the sense o~ Figs. 1, 2 and 3 may ~e employed. Also a plurality of optical fiber ends may be mounted on each bender element.
1 Reference is now made to Figs. llA and 11~
which illustrate an optical fiber switch 110 which is operative to selectably place an optical fiber end 111 in a desired alignment with a selectable one of an array 11~ of optical fiber ends. In the illustrated construction a one-dimensional positioning device similar to that illustrated in Fig. 1 lS employed for positioning of opticaL fiber end 111 and the array 112 of optical fiber ends are arranged in the bending plane of fiber end 111 in a radial orientation. It may be appreciated that control apparatus 114 may be provided for applying a desirèd voltage to the bender element 1]6 of the positioning device to effect alignment of fiber end 111 with a desired fiber end in array 112 or radiation transmission therewith.
A17 optical fiber ends 111 and 112 lie on flat surface 1~6 of the base 1~8 which produces the needed alignment of fibers in the plane parallel to surface 126. Again, two dimensional benders can b~ utilized to eliminate the need for surface 126 and a third bender element may be used to adjust the fiber end-to-end distances. T~e s~lrface 126 may be grooved in order to define discreet positions for the fiber ends 112 for precise alignment thereof with fiber end 111.
Some of the fiber ends 112 may be used for calibration purposes. Suppose that fibers 118, 120, 1~2 and 124 are connected to a light source 125 havin~ different light characteristics which can be distinguished from light emerging from the other ~2~g~ ( 1 fiber ends 112, and having part of the light entering fiber end 111 de-tected by detector 1~3.
By scanning the fiber end 111 from a position facing fiber 118 to a position facing the end of fiber 120, the different voltages applied to the piezoelectric element 116 may be recorded while the light of source 125 is reaching peak value on detector 123. By extrapolation, the voltage needed to reach a position facing any of the fiber ends 112 may be calculated. Fibers 122 and 124 may serve to increase the accuracy of extrapolation.
The hysteresis behavior of the position-voltage characteristics of the piezoelectric element 116 will be covercome by letting the element trave:l a sufficient distance to have element 116 reach it~;
llnear characteristics before fiber end 111 comes to a position facing fiber 118.
Similar calibration can be achieved by replac:ng detector 123 with a light source and light source 125 with a detector.
Control circuitry 114 may conveniently comprise a microprocessor of conventional construction which is programmed to carry out the desired functions.
Reference is now made to Fig. 1~ which illustrates the selectable coupling of an optical fiber end 130 to a light source 1~2 such as a laser diode. The optical f1ber end 130 may be conveniently mounted at the free end of a positioning device 134, typically a three dimensional positioning device of the type illustrated in Fig. 3 and is positioned to face the light source 132 at a desired position relative thereto.
9S~
~ further refinement of the apparatus of Fig. 12 is illustrated in Flgs. 13A and 13B
whicll iLlustrate apparatus fo~ selectable coupling an optical fiber end 140 to a selected one of a plurality of light sources 144. Such an arrangement is particularly useful with laser diodes which are known to have limited lifetimes which are sometimes shorter than a desired servicing cycle. In such applications the operation of a bender element 142 of the type illustrated in any of Figs. 1, 2 and 3 can be controlled to shift the fiber end to a new light source when the brightness of the old light source falls below a predetermined threshold~
Control of element 142 may be simply achieved by adjusting for maximum light to enter the fiber.
Platorm 146 is used together with a curved arrangement of lasers 144 to establish a minimum distance between the output area of the lasers and the center o~ the fiber end~ The need for platforln 146 and the arrangement of lasers 144 can be eliminated by having a two or three dimensional positioner instead of one dimensional positioner 142.
The laser array 144 and platform 146 may b~
constructed from a unitary plece of material for production cost savings.
Reference is now made to Fig. 14 which illustrates a portion of a communications exchange constructed and operative in accordance with an embodiment of the present invention. The exchange is suitable for use in telephone, telegraph, radio or any other mode of communication in which information can be transmitted via e1ectromagnetic radiation ~.~2~9~ ~
The apparatus of Fig. 14 com~rises an array oE transmitters 150 disposed in spaced facing relationshlp to an array of receivers 152. Each subscriber, indicated by reference numeral 154, is interconnected with a single transmitter 150 and a single receiver 152 via circuitry 156, an exemplary embodiment of which will be described hereinafter in detail. In the illustrated embodirnent, three subscribers U, V and W are shown connected to respective transmitters and receivers. Two way communication between subscribers U and W is illustrated, with a radiated beam of electromagnet1c radiation being beamed by the transmitter of subscriber U so as to impinge on the receiver of subscriber W~ and a radiated beam of electromagnetlc radiation being beamed by the transmitter of Subscriber W to impinge on the receiver of subscriber U.
It is appreciated that there may be cases in which each subscriber may be associated with more than one transmitter and more than one receiver, a~i in conference call facilities, for example.
Any suitable form of electromagnetic radiation may be employed. In accordance with a preferred embodiment of the invention infra-red radiation is preferred.
Referring now to Fig. 15 there is seen, in schematic illustration, an array arrangement for a communications exchange constructed and operative ~ in accordance with a preferred embodiment of the invention. There is provided a first array 160 of ~2~ g5~ ( transmitters 162, disposed in selectable radiation communication relationship with a second array 164 of receivers 166. As seen in the illustrated example, arrays 160 and 164 are generally flat arrays disposed in spaced facing orientation such that a beam of radiation provided by any one of the transmitters 162 may selectively impinge on any individual one of the receivers 166 for the establishment of communication therebetween.
Each transmitter 162 is associated with a giv~n subscriber and coupled thereto by apparatus prividing a modulated radiation beam containin~
information to be communicated. This modulation ,.. .
may take any suitable form depending on the cornmunication requirements of the system, Each transmitter 162 may be constructed similarly i:o the directable transmitter described in Fig. 4, an~ the optlcal fiber may be coupled to a light emitting diode or laser diode.
Since modulation of light beams for communications applications is widely known in the literature it will not be described here/ and reference will only be made here to the employment of such modulated li~ht information transmission.
A general description of light communication is provided in:
Optical Communication Research and Technology;
Fiber Optics, by T. G. Giallorenzi, Proc. of the IEEE, Vol. 66, No. 7, July, 1978, p. 744.
The receiving elements may typically comprise photo detectors each of which is coupled via suitable amplification means to a given subscriber.
-1?-~221~
Fig. 16 illustrates an alternative ~orm ofarrangement of transmitters and receivers employing a reflecting element Eor communication. Here arrays 170 and 172, comprising transmltters 174 and receivers 176 respectively, are disposed in adjacent an~led relationship facing a reflecting element 178 and arranged so that beams of radlation from any of the transmitters 174 can selectably impinge on any of the receivers 176.
According to an alternative embodlment of the invention illustrated in Fig. 17 first and second arrays 180 and 182 are provided in respectlve facing arrangement. ~ach of the arrays comprises an in~erspersed arrangement of transmitters and receivers 184 and 186. It is appreciated that the transmitters and receivers 184 and 186 on the same array cannot communicate. Nevertheless, such a construction would be suitable for use with a xubmarine cable, where such local communication would not be required.
Pig~ 18 shows an alternative embodiment of the invention in which a single array 192 is arranged facing a reflecting element 194. Array 192 comprises an interspersed arrangement of transmitters 196 and receivers 198. It is appreciated that in this arrangement any o~ the transmitters 196 can communicate with any of the receivers 198.
Reference is now made to Fig. lg which illustrates transmission and receiving apparatus associated with a single subscriber in the exchange of Fig, 14. A sub~criber, 236 which may 1 represent an~ des:Lred type oE communications terminal is coupled to transmitter and receiver circuits 240 and 242, respectlvely. Transmltter circuit 240 comprises a line receiver 244 which separates the dialing information ~in the case of a telephone link) or alternatively the address instructions from the voice or data information.
The dialing information passes to a dialing information decoder 246 while the voice or data information passes to a modulator 248.
The voice or data information causes the modula~or 248 to operate a source of radiation, for example a LED with a selectable modulation representative of the voice or data signal received thereby. This radiation is transmitted along an optical fiber link 2~0 and from an end thereof through a lens 252 which beams the radiation at a desired receiver.
The dialing or aadress instructions are employed to determine the angular o~ientation of the radiation beam, typically by suitable energizat:ion of a piezoelectric bender element, as shown in Fig. 2.
The dialing decoder 246 employs a conven~ional microprocessor ~54, such as an Intel 8080 and memories 256 for decoding received address or diali.ng inputs into X and Y position co-ordinates.
Decoder 24~ provides X and Y position outputs along a data bus to first and second latches 257 and 258, each of which is coupled to a respective Digital to Analog converter ~60 and 262. Digital to Analog converte~ 260 is coupled to the electrodes of a piezoelectric bender element 261 arranged to bend along an X-axis and converter 262 is coupled to the electrodes of a piezoelect~ic bender element 263 arranged to bend along a Y-axis.
The receiver circuit 24~ cornprises a wlde field of view detector 264 which is arranged to receive an incident beam of light from a transmitter and which provides an output to an amplifier 26~.
Amplifier 266 provldes an output to a call detector 268 which may be of conventional constructlon and which interfaces with the dialing information decoder 246 for producing dialing ar address information on the basis of information given by the incoming beam.
~nplifier 266 also provides an output to a demodulator 270 which provides a decoded voice or data output to a line transmitter ~72 which also receives an address or dialing input from call detector 268 and which is coupled to the subscriber terminal.
Signalling can be accomplished using a common electrical bus shared among all of the subscribers and a time ordered usage of this bus by subscribers.
~n alternative control arrangement may be utili~ed using a central processor unit shared among several subscribers.
According to a preferred embodiment of the invention, a switching exchange may be constructed having a 10,000 subscriber capacity and comprising transmit-ter and receiver arrays arranged in a 100 x 100 grid. In such an example, each array would have to be of area lm , each transmitter and receiver being separated by 10 ~n from each 3L~Z~ 8 adjacent transmitter and receiver in their respective arrays. Assuming tha~ the arrays are arranged in facing relationship a~ shown schematlcally ln Fig. 15, the separation between the arrays would be approximately 5 meters.
If a transmitter of the general type illustrate~
in Fig. 2 were employed, the diameter of the fiber optic core would be 5 microns and the focal length of the lens 5 mm. The diameter of the spot of radia~ion impinging on the opposite array would be 8 mm. The f number of the lens would be between 1 and 2. The field of motion of the free end of the fiber optic would be 1 x 1 mm~
The preferred piezoelectric bender element is catalog number G-1~78 manufactured by Gulton Industries, Inc., of New Jersey and is made of Zirconate Titanate. It has a pie~oelectric -12m constant as follows: d = -270 x 10 v .
The thickness of the piezoelectric bender element is selected to be 0.125 mm and its length is selected to be 25 mm. Its voltage requirement is 50 volts for producing a 1 mm movement. The light source is preferably a LED and the detector is P.I.N. Silicon.
Fig. 20 illustrates calibration apparatus for a beam directing system such as that employed for directing the transmitter beams in accordance with dialing or address informatlon. A plurality of detectors 210 are arranged facing a transmitter 212. The detectors 210 may conveniently be arranged in a grid 200 and are individually connected to a selector circuit 214. The selector ~ 2C~35~ ( `. i5 coupl,ed to an analo~ to digital converter 216 which :in turn is couplecl to a microprocessor 21f1, WiliCh may be of conventional construction ancl interfaces with one or moLe EP~OM memories ~20.
The microprocessor 2l8 provides direction signals -to the transmit-ter 2l2 ancl selection signals to selector 214.
Calibration is efEected as follows:
~ beam is trans1nitted in sequence to the individual L0 detectors 210 disposed on grid 200, which defines 'che detection surface. The signal received by each detector will be maximized by adjustment of the beam direction. The instructlons producing the best direction for each detector are writtel~ on the EPROM and this data may be used to interpolate for any other detectors intermediately positioned between detectors 210. The microprocessor 218 may be employed as microprocessor 154 (Fic3. l9).
ReEerence is now macle to Fig, 21 which illustrates another type o~ switching exchange.
~1e~re, as opposecl to the conEigurations describecl hereinabove, a plurality of transmitters 222 provides a wide beam that impinges on substantially all of the receivers ~2~ arranged in a facing grid 226. Each rece:iver 224 is coupled to a subscriber and is selectabLy directable so as to receive the radia-tion from only a single transmitter 222 at any given timc-~. It is noted that this type of exchancJe is particular:Ly useful ln cable -televis,ion systems.
~2Z~
I It may be a~preciated that the s~"itching exchange operates by providing to each selectabL~
direc-table receiver 224 con-trol inputs which causes it to aim its detector at a desired single transmitter, thus coupling a subscriber associated with that receiver to the inforrnation channel associated with that transmitter. In a cable television system, each television receiver receives a broadcast channel by controlling the directable receiver 224. The optical fiber that emerges from receiver 224 may be extended towards the television receiver and carry T.V. channel information directly to the receiver.
Reference is now made to Fig. 22 which is a block diagram illustration of apparatus for high accuracy feed~ack control of a directional transmitter. The transmi-tter 280, which may be a transmitter of the type illustrated in any of E`igs~ 1, 2 and 3, receives a siynal input from a da~a source 2~2 and from a con-trol signal source 284.
A detector 286 receives the combined data and control signals which may be differentiated from each other by conventional frequency filters or equivalent techniques. The da~a outputs from detector 286 are supplied to a data destination 288 and the control outp~lts from detector 286 are supplied to a control signal utilization circuit 290. A microprocessor control 292 senses the received control signal at circuit 290 and aims the transmitter accordingly.
~;~Z~9S~ ( 1 Fig. 23 illustrates an arrangement of a pair oE opti.cal fibers 29~ ancl 294 arranye(i on -the :Eree end of l)ender e:Lement 296. Preferably one of the optical ibers ls a data carryiny fiber while the other carries control information for assisting in accurate aiming.
Fi.g. 24 shows a plurality of optical Eibers arranged on the free end of bender element 298.
center fiber 300 carries data while the remaining fibers 302 carry control signals for providing a very hiyh level of aiming accuracy.
Bender assemblies having a plurality of optical fibers assoc3ated therewith an including both data and contro.l information carrying fibers may be incorporated in any of the switching exchanges illustra~ed in Figs.
It will be appreciated by persons skilled in the art that the invention is not limited to the particular examples illustrated and discussed herein. Rather the scope of the present invention is defined only by the claims which follow.
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Fig. 12 illustrates coupling of an optical fi~er to a radiation transmitter;
Fig. 13A illustrates coupling of an optical fiber to a selected one of a plurality of radiation transmitters;
Fig~ 13B is a sectional view taken along lines A - A of Fig. 13A;
Fig. 14 is a schematlc illustration of a portion of a communications exchange constructed and operative in accordance with an embodiment of the presetlt invent-ion;
- ~Z2~g~
1 Fig. 15 is a schemat:lc iLlustration oE
transmitter ~nd receiver arrays use~ul in the exchanqe of Fig. 14;
Fig. 16 shows alternative arrangements of transmitter and receiver arrays useful in the exchange of Fig. 14;
Fig. 17 is a schematic illustration of a switching exchange comprising a pair of faClng arrays each having in-terspersed receivers and transmitters;
Fig. 18 is a schematic illustration of a switching exchange cornprising an array of inter-spersed receivers and transmitters and a reflecting element;
Fig. 19 is a block diagram illustration of transmission and receiving apparatus associated with a single subscriber in the exchange of Fig. 14;
Fig. 20 illustrates, in block diagram form, apparatus for calibrating the transmission apparatus illustrated in Fig. 19;
Fig. 21 is a schematic il-.ustration of a swltching exchange useful for cable television and similar transmissions;
Fig. 22 is a bloc~ diagram 1llustration of apparatus for high accuracy feedbac}c control of a directional transmitter;
Figs. 23 and 24 are pictorial illustrations of arrangements of optical fibers associated with piezoelectric bender assemblies in accordance with the present invention.
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.. DETAILED DESCRIPTION OF T~IE INVENTION
The pre~erred embo~iment of the invention will now be described with reference to Figs. 1 - 2~
which illustrate a variety of constructions thereof suitable for different applications.
Referring now to Fig. 1 there is seen apparatus for positioning an optical fiber end constructed and operative in accordance with a preferred embodiment of the present invention and comprising a generally elongate piezoelectric bender element 20 which is mounted at a first end thereof onto a base 22.
The piezoelectric bender element 20 may be of conventional construction and manufacture such as a G-1278 Lead Zinconate-Titanate Thin Sheet piezoceramic manufactured by Gulton Industries of Metuchen, New Jersey, U.S.A. Leads 24 associated with the piezoelectric bender element may be connected to any suitable source of electrical volta~e for controlling the position of the free end 26 of the bender alement.
In accordance with the present invention, the free end 28 of an optical fiber 18 is attached as by ~lueing, clamping or by any other suitable means onto the free end 26 of the bender element ~0 or adjacent thereto for motion together ~herewith.
Fig. 1 illustrates bender element 20 in a straight orientation at rest when the bender element is de-energized and curved to one side when a voltage of a first polarity is applied to leads 24 by means of a selectable voltage source 16. It may be appreciated that normally the bender element may also be bent in an opposite~ e~c~o~ by application of a voltage of an opposite polarity to leads 24.
Furthexrllore any desired position intermediate the two extreme bent positions may be realized by the application of a suitable voltage to the leads 24.
It is a particular feature of the present invention that piezoelectric bendex elements 20 of the type employed herein display a generaLly linear and repeatable position in response to voltage inputs within part of their operative xange. The position-voltage characteristics can be calibrated and an open loop control may thus be employed.
Relatively complex control circuitry employing microprocessor technology may be employed to take into account the hysteresis behaviour of the position voltage curve of the bender elements.
Conventional technology is available for this purpose.
Referring now to Fig. 2, th~re is seen apparatus for positioning an optical fiber end along two dimensions~ The apparatus comprises the apparatus of ~ig. 1 to which is attached at the free end of bender element 20 a second bender element 3 which is oriented such that its plane of bending lies perpendicular to the plane of bendlng of bender element 20. In the illustration, the apparatus of Fig. 1 is shown rotated 90 degrees from the illustration of Fig. 1 and bender element 30 is attached to the free end of bender element 20 by means of a mounting element 32 formed of metal or any other suitable material. Bender element 30 is ~9~
provided with leads 34 which are coupled to position control circuitry (not shown). The free end 28 of the optical fiber is mounted on the free end of bender element 30.
Fig. 3 shows apparatus for posltioning an optical fiber end along three dimensions and comprises the apparatus of Fig. 2 to which is attached by means of a second mounting element 36 a third bender element 38 at the free end of second lU bender element 30. Leads 40 are associated with the third bender element 38 and are coupled to position con*rol circuitry (not shown). In practice third bender element 38 is oriented such that its bending plane is perpen~icular to the bending planes of bender elements 20 and 30 and serves to position the free end 28 of the optical fiber whic]~
is attached to its free end for focussing purposes, Bender elements 20 and 30 may be movea through the:ir position ranges to prQvide a scanning function.
It is appreciated that the bender elements forming a multi-element bender assembly need not necessarily be arranged in perpendicular planes.
Instead it may be sufficient that their directions of motion have respective perpendicular components.
Fig. 4 shows a simplified version of a transmitter useful in the present invention and comprising a selectable position modulatable light source 42 which is substantially similar to those lllustrated in Fiys, 1, 2 and ~. The free end 28 of the op^ical fiber provides a beam of electromagnetic radiation ~4 which implnges on a lens 46 which focusses the beam at a location which i5 selected to correspond _g_ - ~2~
J to a receiver ~. The L~osition of ~ne optL(aL fi~er end ~8 determin~s the Local:ioll of the impingincJ Eoc!lsed Ijearn.
Reference is now made -to Fig. 5 which illustrates a transmitter substantially similar to that illus-trated in Figs. 1, 2 and ~ with the difference being that here the lens 50 is mounted on the free end of the bender element 52 in front of the end of the fiheroptlc conduit 54 and thu~
moves together with the free end of the bencler element. Beam directing i5 achieved by changing the direction of the free end of the bender element.
A rod lens may be used instead of the lens 50.
Alternatively, the elements described in Figs. 4 and 5 may be utilized as directable radiation detectors.
Fig. 6 illustrates one of the applications of the positioning apparatus illustrated in Figs. 1, 2 and 3. In Fig. 6, two dimensional positloning apparatus 56, such as that illustrated in Fig. 2, is associated with a lens 5~ which images ligh~
emerging from the free end 6~ o~ the optical flber OlltO a screen 62. A light source 64 which communicates with the opposite end of the optical fiber 6~ supplies desired radiation which may be positioned on the screen or scanned thereover as desired, simllar to the raster scan of a televlsion ~ut slower.
q'he apparatus of Flg. 6 is particularly suitable for use in slow scan applications in which cathode ray tubes are presently employed such as l.ect.rocar~ioyraptls.
3L;~2~
1 ~ racliation cletector may he constructecl USinCJ
~he pos:itioner o the presellt invention as illustrated in Fig. 7. A lerls 70 provides an image 72 of an object 7~. Po~itionlng apparatus 7~;
such as that illustrated in any of Figs. 1, 2 and 3 positions the end 77 of the optical flber 78 to the image loca-tion so as to enable ligh-t from the image to be transmitted along the optical fiber 7 to a detector 76.
In accordance with a pre~erred embodiment of the present invention, a plurality of images of radiation sources may be provided by lens 70. The positioning apparatus 75 is then operative to selectably and changeably position the optical fiber end at a selec~able image, thus providing a directable receiver.
A multi-fiber end one dimensional scanner is illustrated in Fig. ~ and comprlses a relatively wide piezoelectric bender element 80 mounted on a base 82 and having associated ~7ith the free end ~4 thereof a one~dimensional array of optical fiber ends 86. Oscillation of bender element 80 along one dimenslon provides a raster scan of a scene imaged by a lens 88. A relatively fast scan may be provided in this manner. The optical fibers may be connected at their opposite ends 89 to a linear detector array ~7.
~s seen in Fic3. 9, a plurality of arrays of optical fiber ends may be assoclated ~i-th a single bender element 80. In such a way a color -television type cclmera ma~ be cGnstruccecl by ~mploylng detectors 91 having different spec'ral ~c~
i responses. Similarly a color television type camera may be cons-truc-ted on the basis of the apparatus illustrated in Fig. 8 by employing optical fiber ends transmitting spectrally different light or detectors of different spectral response in array a7.
It may be appreciated that by replacing the detectors in the apparatus of Figs. 8 and 9 with li~ht sources, a raster scanned display may he provided.
Referring now to Fig. 10 which illustrates selec~able switchlng and coupling apparatus employing optical fiber ends, rod lenses 90 and 92 are connected to the free ends 94 and 9~ of respective optical flbers 98 and 100. Rod lenses 90 and 92 are mounted on the free ends of respec~ e piezoele~tric bender elements 102 and 1~4 which are arranged to have perpendicular bending planes and are mounted onto a frame 106. It is noted that the bender elements are employed to selectably vary the direction of the rod lenses. In the illus~rated embodiment, when the rod lenses are directed parallel, radiation transmission there-between is permitted and when they are directed in different directions, little or no such transmission occurs.
It is noted with respect to the embodiments illustrated in Fig. 10 that a plurality of bender elements arranged in series in the sense o~ Figs. 1, 2 and 3 may ~e employed. Also a plurality of optical fiber ends may be mounted on each bender element.
1 Reference is now made to Figs. llA and 11~
which illustrate an optical fiber switch 110 which is operative to selectably place an optical fiber end 111 in a desired alignment with a selectable one of an array 11~ of optical fiber ends. In the illustrated construction a one-dimensional positioning device similar to that illustrated in Fig. 1 lS employed for positioning of opticaL fiber end 111 and the array 112 of optical fiber ends are arranged in the bending plane of fiber end 111 in a radial orientation. It may be appreciated that control apparatus 114 may be provided for applying a desirèd voltage to the bender element 1]6 of the positioning device to effect alignment of fiber end 111 with a desired fiber end in array 112 or radiation transmission therewith.
A17 optical fiber ends 111 and 112 lie on flat surface 1~6 of the base 1~8 which produces the needed alignment of fibers in the plane parallel to surface 126. Again, two dimensional benders can b~ utilized to eliminate the need for surface 126 and a third bender element may be used to adjust the fiber end-to-end distances. T~e s~lrface 126 may be grooved in order to define discreet positions for the fiber ends 112 for precise alignment thereof with fiber end 111.
Some of the fiber ends 112 may be used for calibration purposes. Suppose that fibers 118, 120, 1~2 and 124 are connected to a light source 125 havin~ different light characteristics which can be distinguished from light emerging from the other ~2~g~ ( 1 fiber ends 112, and having part of the light entering fiber end 111 de-tected by detector 1~3.
By scanning the fiber end 111 from a position facing fiber 118 to a position facing the end of fiber 120, the different voltages applied to the piezoelectric element 116 may be recorded while the light of source 125 is reaching peak value on detector 123. By extrapolation, the voltage needed to reach a position facing any of the fiber ends 112 may be calculated. Fibers 122 and 124 may serve to increase the accuracy of extrapolation.
The hysteresis behavior of the position-voltage characteristics of the piezoelectric element 116 will be covercome by letting the element trave:l a sufficient distance to have element 116 reach it~;
llnear characteristics before fiber end 111 comes to a position facing fiber 118.
Similar calibration can be achieved by replac:ng detector 123 with a light source and light source 125 with a detector.
Control circuitry 114 may conveniently comprise a microprocessor of conventional construction which is programmed to carry out the desired functions.
Reference is now made to Fig. 1~ which illustrates the selectable coupling of an optical fiber end 130 to a light source 1~2 such as a laser diode. The optical f1ber end 130 may be conveniently mounted at the free end of a positioning device 134, typically a three dimensional positioning device of the type illustrated in Fig. 3 and is positioned to face the light source 132 at a desired position relative thereto.
9S~
~ further refinement of the apparatus of Fig. 12 is illustrated in Flgs. 13A and 13B
whicll iLlustrate apparatus fo~ selectable coupling an optical fiber end 140 to a selected one of a plurality of light sources 144. Such an arrangement is particularly useful with laser diodes which are known to have limited lifetimes which are sometimes shorter than a desired servicing cycle. In such applications the operation of a bender element 142 of the type illustrated in any of Figs. 1, 2 and 3 can be controlled to shift the fiber end to a new light source when the brightness of the old light source falls below a predetermined threshold~
Control of element 142 may be simply achieved by adjusting for maximum light to enter the fiber.
Platorm 146 is used together with a curved arrangement of lasers 144 to establish a minimum distance between the output area of the lasers and the center o~ the fiber end~ The need for platforln 146 and the arrangement of lasers 144 can be eliminated by having a two or three dimensional positioner instead of one dimensional positioner 142.
The laser array 144 and platform 146 may b~
constructed from a unitary plece of material for production cost savings.
Reference is now made to Fig. 14 which illustrates a portion of a communications exchange constructed and operative in accordance with an embodiment of the present invention. The exchange is suitable for use in telephone, telegraph, radio or any other mode of communication in which information can be transmitted via e1ectromagnetic radiation ~.~2~9~ ~
The apparatus of Fig. 14 com~rises an array oE transmitters 150 disposed in spaced facing relationshlp to an array of receivers 152. Each subscriber, indicated by reference numeral 154, is interconnected with a single transmitter 150 and a single receiver 152 via circuitry 156, an exemplary embodiment of which will be described hereinafter in detail. In the illustrated embodirnent, three subscribers U, V and W are shown connected to respective transmitters and receivers. Two way communication between subscribers U and W is illustrated, with a radiated beam of electromagnet1c radiation being beamed by the transmitter of subscriber U so as to impinge on the receiver of subscriber W~ and a radiated beam of electromagnetlc radiation being beamed by the transmitter of Subscriber W to impinge on the receiver of subscriber U.
It is appreciated that there may be cases in which each subscriber may be associated with more than one transmitter and more than one receiver, a~i in conference call facilities, for example.
Any suitable form of electromagnetic radiation may be employed. In accordance with a preferred embodiment of the invention infra-red radiation is preferred.
Referring now to Fig. 15 there is seen, in schematic illustration, an array arrangement for a communications exchange constructed and operative ~ in accordance with a preferred embodiment of the invention. There is provided a first array 160 of ~2~ g5~ ( transmitters 162, disposed in selectable radiation communication relationship with a second array 164 of receivers 166. As seen in the illustrated example, arrays 160 and 164 are generally flat arrays disposed in spaced facing orientation such that a beam of radiation provided by any one of the transmitters 162 may selectively impinge on any individual one of the receivers 166 for the establishment of communication therebetween.
Each transmitter 162 is associated with a giv~n subscriber and coupled thereto by apparatus prividing a modulated radiation beam containin~
information to be communicated. This modulation ,.. .
may take any suitable form depending on the cornmunication requirements of the system, Each transmitter 162 may be constructed similarly i:o the directable transmitter described in Fig. 4, an~ the optlcal fiber may be coupled to a light emitting diode or laser diode.
Since modulation of light beams for communications applications is widely known in the literature it will not be described here/ and reference will only be made here to the employment of such modulated li~ht information transmission.
A general description of light communication is provided in:
Optical Communication Research and Technology;
Fiber Optics, by T. G. Giallorenzi, Proc. of the IEEE, Vol. 66, No. 7, July, 1978, p. 744.
The receiving elements may typically comprise photo detectors each of which is coupled via suitable amplification means to a given subscriber.
-1?-~221~
Fig. 16 illustrates an alternative ~orm ofarrangement of transmitters and receivers employing a reflecting element Eor communication. Here arrays 170 and 172, comprising transmltters 174 and receivers 176 respectively, are disposed in adjacent an~led relationship facing a reflecting element 178 and arranged so that beams of radlation from any of the transmitters 174 can selectably impinge on any of the receivers 176.
According to an alternative embodlment of the invention illustrated in Fig. 17 first and second arrays 180 and 182 are provided in respectlve facing arrangement. ~ach of the arrays comprises an in~erspersed arrangement of transmitters and receivers 184 and 186. It is appreciated that the transmitters and receivers 184 and 186 on the same array cannot communicate. Nevertheless, such a construction would be suitable for use with a xubmarine cable, where such local communication would not be required.
Pig~ 18 shows an alternative embodiment of the invention in which a single array 192 is arranged facing a reflecting element 194. Array 192 comprises an interspersed arrangement of transmitters 196 and receivers 198. It is appreciated that in this arrangement any o~ the transmitters 196 can communicate with any of the receivers 198.
Reference is now made to Fig. lg which illustrates transmission and receiving apparatus associated with a single subscriber in the exchange of Fig, 14. A sub~criber, 236 which may 1 represent an~ des:Lred type oE communications terminal is coupled to transmitter and receiver circuits 240 and 242, respectlvely. Transmltter circuit 240 comprises a line receiver 244 which separates the dialing information ~in the case of a telephone link) or alternatively the address instructions from the voice or data information.
The dialing information passes to a dialing information decoder 246 while the voice or data information passes to a modulator 248.
The voice or data information causes the modula~or 248 to operate a source of radiation, for example a LED with a selectable modulation representative of the voice or data signal received thereby. This radiation is transmitted along an optical fiber link 2~0 and from an end thereof through a lens 252 which beams the radiation at a desired receiver.
The dialing or aadress instructions are employed to determine the angular o~ientation of the radiation beam, typically by suitable energizat:ion of a piezoelectric bender element, as shown in Fig. 2.
The dialing decoder 246 employs a conven~ional microprocessor ~54, such as an Intel 8080 and memories 256 for decoding received address or diali.ng inputs into X and Y position co-ordinates.
Decoder 24~ provides X and Y position outputs along a data bus to first and second latches 257 and 258, each of which is coupled to a respective Digital to Analog converter ~60 and 262. Digital to Analog converte~ 260 is coupled to the electrodes of a piezoelectric bender element 261 arranged to bend along an X-axis and converter 262 is coupled to the electrodes of a piezoelect~ic bender element 263 arranged to bend along a Y-axis.
The receiver circuit 24~ cornprises a wlde field of view detector 264 which is arranged to receive an incident beam of light from a transmitter and which provides an output to an amplifier 26~.
Amplifier 266 provldes an output to a call detector 268 which may be of conventional constructlon and which interfaces with the dialing information decoder 246 for producing dialing ar address information on the basis of information given by the incoming beam.
~nplifier 266 also provides an output to a demodulator 270 which provides a decoded voice or data output to a line transmitter ~72 which also receives an address or dialing input from call detector 268 and which is coupled to the subscriber terminal.
Signalling can be accomplished using a common electrical bus shared among all of the subscribers and a time ordered usage of this bus by subscribers.
~n alternative control arrangement may be utili~ed using a central processor unit shared among several subscribers.
According to a preferred embodiment of the invention, a switching exchange may be constructed having a 10,000 subscriber capacity and comprising transmit-ter and receiver arrays arranged in a 100 x 100 grid. In such an example, each array would have to be of area lm , each transmitter and receiver being separated by 10 ~n from each 3L~Z~ 8 adjacent transmitter and receiver in their respective arrays. Assuming tha~ the arrays are arranged in facing relationship a~ shown schematlcally ln Fig. 15, the separation between the arrays would be approximately 5 meters.
If a transmitter of the general type illustrate~
in Fig. 2 were employed, the diameter of the fiber optic core would be 5 microns and the focal length of the lens 5 mm. The diameter of the spot of radia~ion impinging on the opposite array would be 8 mm. The f number of the lens would be between 1 and 2. The field of motion of the free end of the fiber optic would be 1 x 1 mm~
The preferred piezoelectric bender element is catalog number G-1~78 manufactured by Gulton Industries, Inc., of New Jersey and is made of Zirconate Titanate. It has a pie~oelectric -12m constant as follows: d = -270 x 10 v .
The thickness of the piezoelectric bender element is selected to be 0.125 mm and its length is selected to be 25 mm. Its voltage requirement is 50 volts for producing a 1 mm movement. The light source is preferably a LED and the detector is P.I.N. Silicon.
Fig. 20 illustrates calibration apparatus for a beam directing system such as that employed for directing the transmitter beams in accordance with dialing or address informatlon. A plurality of detectors 210 are arranged facing a transmitter 212. The detectors 210 may conveniently be arranged in a grid 200 and are individually connected to a selector circuit 214. The selector ~ 2C~35~ ( `. i5 coupl,ed to an analo~ to digital converter 216 which :in turn is couplecl to a microprocessor 21f1, WiliCh may be of conventional construction ancl interfaces with one or moLe EP~OM memories ~20.
The microprocessor 2l8 provides direction signals -to the transmit-ter 2l2 ancl selection signals to selector 214.
Calibration is efEected as follows:
~ beam is trans1nitted in sequence to the individual L0 detectors 210 disposed on grid 200, which defines 'che detection surface. The signal received by each detector will be maximized by adjustment of the beam direction. The instructlons producing the best direction for each detector are writtel~ on the EPROM and this data may be used to interpolate for any other detectors intermediately positioned between detectors 210. The microprocessor 218 may be employed as microprocessor 154 (Fic3. l9).
ReEerence is now macle to Fig, 21 which illustrates another type o~ switching exchange.
~1e~re, as opposecl to the conEigurations describecl hereinabove, a plurality of transmitters 222 provides a wide beam that impinges on substantially all of the receivers ~2~ arranged in a facing grid 226. Each rece:iver 224 is coupled to a subscriber and is selectabLy directable so as to receive the radia-tion from only a single transmitter 222 at any given timc-~. It is noted that this type of exchancJe is particular:Ly useful ln cable -televis,ion systems.
~2Z~
I It may be a~preciated that the s~"itching exchange operates by providing to each selectabL~
direc-table receiver 224 con-trol inputs which causes it to aim its detector at a desired single transmitter, thus coupling a subscriber associated with that receiver to the inforrnation channel associated with that transmitter. In a cable television system, each television receiver receives a broadcast channel by controlling the directable receiver 224. The optical fiber that emerges from receiver 224 may be extended towards the television receiver and carry T.V. channel information directly to the receiver.
Reference is now made to Fig. 22 which is a block diagram illustration of apparatus for high accuracy feed~ack control of a directional transmitter. The transmi-tter 280, which may be a transmitter of the type illustrated in any of E`igs~ 1, 2 and 3, receives a siynal input from a da~a source 2~2 and from a con-trol signal source 284.
A detector 286 receives the combined data and control signals which may be differentiated from each other by conventional frequency filters or equivalent techniques. The da~a outputs from detector 286 are supplied to a data destination 288 and the control outp~lts from detector 286 are supplied to a control signal utilization circuit 290. A microprocessor control 292 senses the received control signal at circuit 290 and aims the transmitter accordingly.
~;~Z~9S~ ( 1 Fig. 23 illustrates an arrangement of a pair oE opti.cal fibers 29~ ancl 294 arranye(i on -the :Eree end of l)ender e:Lement 296. Preferably one of the optical ibers ls a data carryiny fiber while the other carries control information for assisting in accurate aiming.
Fi.g. 24 shows a plurality of optical Eibers arranged on the free end of bender element 298.
center fiber 300 carries data while the remaining fibers 302 carry control signals for providing a very hiyh level of aiming accuracy.
Bender assemblies having a plurality of optical fibers assoc3ated therewith an including both data and contro.l information carrying fibers may be incorporated in any of the switching exchanges illustra~ed in Figs.
It will be appreciated by persons skilled in the art that the invention is not limited to the particular examples illustrated and discussed herein. Rather the scope of the present invention is defined only by the claims which follow.
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Claims (46)
1. Apparatus for selectably positioning an optical fiber end at a selectable position along a range of positions comprising:
a bender assembly including at least one piezoelectric bender element, said bender assembly having a free end thereof arranged for association with at least one optical fiber end, for selectable positioning thereof along said range of positions, and a mounting end thereof located at a reference position; and beam forming means for association with said at least one optical fiber end.
a bender assembly including at least one piezoelectric bender element, said bender assembly having a free end thereof arranged for association with at least one optical fiber end, for selectable positioning thereof along said range of positions, and a mounting end thereof located at a reference position; and beam forming means for association with said at least one optical fiber end.
2. Apparatus for selectably positioning an optical fiber end comprising:
a bender assembly including at least two series connected piezoelectric bender elements arranged for bending motion in different directions, said bender assembly having a free end thereof arranged for association with at least one optical fiber end and a mounting end thereof located at a reference position.
a bender assembly including at least two series connected piezoelectric bender elements arranged for bending motion in different directions, said bender assembly having a free end thereof arranged for association with at least one optical fiber end and a mounting end thereof located at a reference position.
3. Apparatus according to claim 1 and wherein said bender assembly comprises at least two piezoelectric bender elements.
4. Apparatus according to claim 1 and wherein said range of positions includes at least one position intermediate two extreme positions.
5. Apparatus according to claim 2 and also comprising beam forming means for association with said at least one optical fiber end.
6. Apparatus according to claim 1 and wherein said beam forming means comprises a lens.
7. Apparatus according to claim 6 and wherein said lens comprises a rod lens attached to said at least one optical fiber end.
8. Apparatus according to any of claims 1, 5 and 6 and wherein said beam forming means are arranged to receive radiation from said optical fiber end and to define a beam therefrom.
9. Apparatus according to any of claims 1, 5 and 6 and wherein the position of said optical fiber end relative to said beam forming means determines the direction of a beam produced therefrom.
10. Apparatus according to claim 5 and wherein said beam forming means are arranged to receive light and to produce at least one real image thereof.
11. Apparatus according to claim 10 and wherein said bender assembly is operative to position said at least one optical fiber end at said real image.
12. Apparatus according to claim 10 and wherein said beam forming means provide a plurality of real images corresponding to a plurality of light sources and wherein said bender assembly is operative to selectably position said at least one optical fiber end at a desired one of said plurality of real images.
13. Apparatus according to claim 1 and wherein said at least one piezoelectric bender element comprises a single bender element positionable in a first bending in plane.
14. Apparatus according to any of claims 1, 2 and 7 and wherein said bender assembly comprises first and second bender elements having respective first and second bending planes which are arranged to lie perpendicular to each other.
15. Apparatus according to any of claims 1, 2 and 6 and wherein said bender assembly comprises first, second and third bender elements having respective perpendicular first, second and third bending planes.
16. Apparatus according to any of claims 1, 2 and 7 and wherein said bender assembly comprises first and second bender elements arranged in a series arrangement.
17. Apparatus according to any of claims 1, 6 and 13 and wherein said at least one piezoelectric bender element comprises first, second and third bender elements arranged in a series arrangement.
18. Apparatus according to any of claims 1, 2 and 6 and also comprising at least one optical fiber, having a free end adjacent said bender assembly and a fixed end.
19. Apparatus according to any of claims 1, 2 and 6 and also comprising at least one optical fiber, having a free end adjacent said bender assembly and a fixed end, and wherein said at least one optical fiber is arranged to be coupled to a source of rad-iation at said fixed end.
20. Apparatus according to any of claims 1, 2 and 6 and also comprising at least one optical fiber, having a free end adjacent said bender assembly and a fixed end, and also comprising a phosphorescent display disposed in light receiving relationship with said free end of said at least one optical fiber.
21. Apparatus according to any of claims 1, 2 and 6 and also comprising at least one optical fiber, having a free end adjacent said bender assembly and a fixed end, and wherein said optical fiber is arranged to be coupled to a radiation detector at said fixed end.
22. Apparatus according to any of claim 1, 2 and 6 and also comprising at least one optical fiber, having a free end adjacent said bender assembly and a fixed end, and also comprising means for governing the operation of said bender assembly in accordance with an information bearing signal.
23. Apparatus according to any of claims 1, 2 and 7 and providing a visually sensible display.
24. Apparatus according to any of claims 1, 2 and 6 and also comprising at least one optical fiber, having a free end adjacent said bender assembly and a fixed end, and wherein said at least one optical fiber is arranged to be coupled to a source of radiation at said fixed end and wherein said radiation source comprises a data source and a source of position control signals.
25. Apparatus according to any of claims 1, 2 and 6 and also comprising at least one optical fiber, having a free end adjacent said bender assembly and a fixed end, and wherein said at least one optical fiber comprises a plurality of optical fibers.
26. Apparatus according to any of claims 1, 2 and 6 and also comprising plurality of fibers, having a free end adjacent said bender assembly and a fixed end, and wherein at least one of said plurality of optical fibers is a data carrying fiber and at least one of said plurality of optical fibers is a position control fiber.
27. Apparatus according to claim 1 and also comprising means for modulating the radiation transmitted along said optical fiber.
28. Apparatus according to claim 27 and wherein said modu-lation is time dependent intensity modulation.
29. Apparatus according to claim 1 and also comprising bender assembly control means for supplying voltage to said bender assembly for governing the orientation of the free end thereof.
30. Apparatus according to claim 29 and wherein said control means is operative for providing a raster scan.
31. Apparatus according to claim 29 and wherein said bender assembly control means is operative for governing the orientation of the free end thereof in a time dependant sequence.
32. Apparatus according to any of claims 1, 2 and 10 and also comprising at least one optical fiber, having a free end adjacent said bender assembly and a fixed end, and wherein said at least one optical fiber comprises a plurality of optical fibers, and wherein free ends of said plurality of optical fibers are arranged in a linear array.
33. Apparatus according to any of claims 1, 2 and 10 and also comprising at least one optical fiber, having a free end adjacent said bender assembly and a fixed end, and wherein said at least one optical fiber comprises a plurality of optical fibers, and wherein free ends of said plurality of optical fibers are arranged in a linear array, and wherein said bender assembly is operative to provide a scanning motion of said linear array per pendicular to the axis thereof.
34. Apparatus according to any of claims 1, 2 and 10 and also comprising at least one optical fiber, having a free end adjacent said bender assembly and a fixed end, and wherein said at least one optical fiber comprises a plurality of optical fibers, and wherein free ends of said plurality of optical fibers are arranged in a linear array, and wherein said bender assembly is
34. Apparatus according to any of claims 1, 2 and 10 and also comprising at least one optical fiber, having a free end adjacent said bender assembly and a fixed end, and wherein said at least one optical fiber comprises a plurality of optical fibers, and wherein free ends of said plurality of optical fibers are arranged in a linear array, and wherein said bender assembly is
Claim 34 cont.
operative to provide a scanning motion of said linear array per-pendicular to the axis thereof and also comprising means for providing a scanned representation of a space whose intensity as a function of time represents the radiation intensity over said space.
operative to provide a scanning motion of said linear array per-pendicular to the axis thereof and also comprising means for providing a scanned representation of a space whose intensity as a function of time represents the radiation intensity over said space.
35, Apparatus according any claims 1, 2 and 10 and also com-prising plurality of fibers having free ends adjacent said bender assembly and fixed ends, and also comprising a phosphorescent display disposed in light receiving relationship with said free ends of said plurality of optical fibers, and wherein said plural-ity of optical fibers is arranged to transmit light or different colors.
36. Apparatus according to claim 1 and also comprising at least one optical fiber, having a free end adjacent said bender assembly and a fixed end f and also comprising at least one radiation source arranged for selectable radiation communication with said at least one optical fiber.
37. Apparatus according claim 36 and wherein said at least one radiation source comprises a plurality of radiation sources.
38. Apparatus according to claim 37 and wherein said plural-ity of radiation sources are arranged for radiation communication with said at least one optical fiber in a desired sequence.
38. Apparatus according to claim 37 and wherein said plural-ity of radiation sources are arranged for radiation communication with said at least one optical fiber in a desired sequence.
38. Apparatus according to claim 1 for selectably positioning an optical fiber end at a selectable position along a range of positions comprising:
a bender assembly including at least one piezoelectric bender element, said bender assembly having a free end thereof
a bender assembly including at least one piezoelectric bender element, said bender assembly having a free end thereof
Claim 39 cont.
arranged for association with at least one first optical fiber end, for selectable positioning thereof along said range of positions, and a mounting end thereof located at a reference position, and also comprising at least one second optical fiber end arranged for selectable radiation communication with at least one first optical fiber end by means of suitable positioning of said at least one first optical fiber end, for providing switching.
arranged for association with at least one first optical fiber end, for selectable positioning thereof along said range of positions, and a mounting end thereof located at a reference position, and also comprising at least one second optical fiber end arranged for selectable radiation communication with at least one first optical fiber end by means of suitable positioning of said at least one first optical fiber end, for providing switching.
40. Apparatus according to claim 39 and also comprising radiation defining means arranged intermediate said first and second optical fiber ends.
41. Apparatus according to claim 40 and wherein said radia-tion defining means comprises beam forming means
42. Apparatus according to claim 40 and wherein said radia-tion defining means comprises a rod lens.
43. Apparatus according to any of claims 39 - 41 and wherein said at least one second optical fiber end comprises a plurality of second optical fiber ends.
44. Apparatus according to claim 39 and also comprising means for measuring the intensity of radiation travelling along optical fibers.
45. Apparatus according to claim 44 and also comprising feed-back means responsive to the intensity of radiation measured by said measuring means for governing the positioning of said at least one optical fiber end.
46. Apparatus according to any of claims 1, 2 and 10 and also comprising microprocessor circuitry for governing the oper-ation of said bender assembly.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000488934A CA1220958A (en) | 1980-02-04 | 1985-08-16 | Piezoelectric apparatus for positioning optical fibers |
Applications Claiming Priority (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| IL59306A IL59306A (en) | 1980-02-04 | 1980-02-04 | Switching exchange exmploying electro-magnetic radiation beams |
| IL59306 | 1980-02-04 | ||
| IL60923A IL60923A (en) | 1980-08-26 | 1980-08-26 | Piezoelectric apparatus for positioning of optical fibres |
| IL60923 | 1980-08-26 | ||
| CA000369087A CA1192646A (en) | 1980-02-04 | 1981-01-22 | Piezoelectric apparatus for positioning optical fibers |
| CA000488934A CA1220958A (en) | 1980-02-04 | 1985-08-16 | Piezoelectric apparatus for positioning optical fibers |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000369087A Division CA1192646A (en) | 1980-02-04 | 1981-01-22 | Piezoelectric apparatus for positioning optical fibers |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1220958A true CA1220958A (en) | 1987-04-28 |
Family
ID=27166948
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000488934A Expired CA1220958A (en) | 1980-02-04 | 1985-08-16 | Piezoelectric apparatus for positioning optical fibers |
| CA000488935A Expired CA1230381A (en) | 1980-02-04 | 1985-08-16 | Piezoelectric apparatus for positioning optical fibers |
Family Applications After (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000488935A Expired CA1230381A (en) | 1980-02-04 | 1985-08-16 | Piezoelectric apparatus for positioning optical fibers |
Country Status (1)
| Country | Link |
|---|---|
| CA (2) | CA1220958A (en) |
-
1985
- 1985-08-16 CA CA000488934A patent/CA1220958A/en not_active Expired
- 1985-08-16 CA CA000488935A patent/CA1230381A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| CA1230381A (en) | 1987-12-15 |
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