WO2002056507A2 - A free-space redundant optical communications infrastructre, and appurtenances for use therewith - Google Patents

Abstract

A free-space redundant optical communications infrastructure and appurtenances for use therewith are presented wherein 'partial aperture' functions such as beam splitting into a plurality of sub-beams and dividing an aperture into substantially segmented areas for respectively transferring such sub-beam are disclosed. These partial aperture functions are taught for transceivers, transmitter apparatus, receiver apparatus, and for hybrid combinations thereof. Furthermore, optical communications grating components presented for use therewith and for use in fiber transmitted optic beams are discussed.

Description

  



   A FREE-SPACE REDUNDANT OPTICAL COMMUNICATIONS
INFRASTRUCTURE, AND APPURTENANCES FOR USE THEREWITH
FIELD OF THE INVENTION
The present invention generally relates to multi-user optical communication infrastructures, systems, and appurtenances used therewith. More specifically, the present invention relates to cost effective improvements for free-space optical path communication networks.



  BACKGROUND OF THE INVENTION
Present telecommunication systems are useful for providing traditional telecommunication services which are generally limited to relatively low-speed, low-capacity applications. While standard telephone lines have data rate limits of approximately 60   kilobits    per second (Kbps), other more rapid systems have been developed over the last decade. These include Integrated Services Digital
Network   (ISDN)    systems which provide data rates up to 128 Kbps,
Asymmetrical Digital Subscriber Line (ADSL) systems having data rate capacities up to eight megabits per second (Mbps), conventional satellite networks which deliver data at up to 30 Mbps and Local Multi-Distribution (LMD) systems providing data at rates of about four to eight gigabits per second (Gbps) per two km cell.



   While these systems provide data at rates significantly higher than traditional systems, they are still inadequate for modern needs, such as video teleconferencing, multi-media presentations and computer applications. Typical personal computers can transmit and receive data at rates in excess of 100 Mbps.



  There is therefore a need for reasonably priced telecommunication systems that can transmit data at even higher rates. 



   Present telecommunication systems use optical lasers and photodiodes to attain high data transmission rates. The short optical wavelengths used maximize bandwidth resulting in high transmission rates. Modern wired optical communication systems allow for high rates of data transmission by feeding laser energy into an optical fiber, and transmitting that energy to a receiving photodiode. The presence or absence of a pulse of laser energy represents a data bit. Optical fiber wired communication systems might be used to transmit data over more than 1000 km and at rates of 6 Gbps or higher.



   Wireless optical communication systems are also available. They use lasers to transmit focused laser energy through space (rather than through optical fibers) to a receiving photodiode. The transmitting laser and receiving photodiode are aligned so that the transmitting laser has a direct line-of-sight with the receiver.



  These systems are often known as free-space or fiber-less optical systems.



  Typical transmission distances for wireless communication systems are 50 meters to 20 km; such systems may support data transmission rates as high as 150 Mbps.



  Wireless optical systems are often used for relatively short distances and as the link between a generally wired system and the system's transmitter or receiver.



  For this reason, in the telecommunications industry wireless optical systems are often referred to as"last mile"systems.



   There are many advantages for using optically wire-less rather than conventionally or optically wired technologies. Wireless systems are free of substantial up-front installation costs and require less maintenance. Wireless networks can be deployed relatively quickly and they respond rapidly to changes, both qualitative and quantitative, in consumer demand. Wireless communication is free of fiber cable outage, a problem that continually plagues the telecommunication industry. Finally, free-space networks easily and relatively cheaply incorporate component redundancies, thereby improving their reliability.



   Free-space optical networks however are not problem-free. Free-space laser communication systems have generally not been used more widely because of the interference produced by common atmospheric conditions, such as rain, fog and snow. Most existing laser communication systems operate at a wavelength of 750-900 nanometers   (min).    Occasionally, lasers operating at wavelengths in the near IR region (1000-1600 nm) are used. At these wavelengths, transmission distance is restricted by the aforementioned atmospheric conditions.



  Transmission distance is also limited by the stability of the platforms on which the optical network's transmitting and receiving elements are mounted.



   However, an equally important problem is physical line-of-sight obstruction between the transmitter and receiver. The transceivers-each including a transmitter and a receiver-used at the ends of a free-space transmission line must have a clear line-of-sight of each other at all times, so that there is no signal interruption. However, birds and other airborne objects regularly obscure the line-of-sight between transmitters/receivers in wireless communications.



   Reference is now made to Fig.   1A,    1B and 1C where three prior art solutions to the physical line-of-sight obstruction problem in free-space communication networks are illustrated. Fig.   1A    represents two systems 103A and 104A containing two transceivers 105A and 106A at site A transmitting to two receiving transceivers 108A and 107A respectively at site B. The two systems transmit two generally parallel but identical signals   101 A    and 102A. If a bird or object obstructs the line-of-sight of one system, for example 103A, the second system 104A still operates, ensuring uninterrupted data transmission.



   Fig. 1B illustrates another prior art solution to the problem of the physical obstruction of the line-of-sight in optically wireless communication systems. The network 100B illustrated can be described as a"mesh"or nodal system. While similar to the first solution in that redundancy is created, the"mesh"system presents a multiplicity of transceivers, each transmitting to different receiving sites or nodes. The signal transmissions are generally in non-parallel directions.



  Transceivers 109B and HOB at site (node) A transmit identical data signals   111B    and 113B to transceiver 114B at site (node) B and transceiver 116B at site (node) 
C respectively. Subsequent to the reception of signal   111B    at site (node) B, transceiver   114B    transmits signal   112B    to transceiver   115B    located at site (node)
C. If one of the signals   111B    or 113B is obstructed at any point in its transmission path (s), the other signal acts as a backup ensuring that at least one data signal is always received at site (node) C. It should readily be understood that there could, and usually will, be more than three sites (nodes) involved in   "meshed"or    nodal systems.

   The larger the number of sites (nodes) used, the larger the number of identical, but non-parallel paths, used to transmit data and the greater the likelihood that there is no obstruction and interruption of data.



  Systems that transmit data in a manner like signal 25A are called multi-hop systems.



   The systems shown in Figs.   1A    and 1B have drawbacks. The system in Fig.



     1A    and the"mesh"/nodal system of Fig. 1B are expensive since they are redundant systems. The"mesh"/nodal system is also very complicated. Because of the different path lengths involved, signals most be stored and matched with identical signals received later from other transmitters sending the same signals over longer transmission paths. Furthermore, a"mesh"system usually requires confirmation that an identical signal has been transmitted from each and every transmitter.



   Fig. 1C indicates a third method,   100C    and 101C, which has been used to prevent obstruction of line-of-sight in free-space communication systems. The solution requires enlarging the transmitting laser beam by using larger lenses in both transmitters and receivers. The increase in lens size increases the size of the virtual cylinder connecting the transmitter and receiver in which the transmitted signal is carried. The enlarged cross-sectional area of the cylinder makes it more difficult for a bird or object to obstruct the entire area of the cross-section. By using larger lenses, there is an increase in the probability that a sufficient percentage of the transmitted optical signal always reaches the receiver and that the signal will not be interrupted.

   The larger lenses have, in effect, introduced "redundant"cross-sectional area of the transmission path.



   As mentioned above, this last solution requires larger lenses. Since larger lenses are used, the focal point is further from the lens and therefore the entire apparatus is larger, more complicated and more expensive.



   Examples of typical prior art free-space optical communication systems can be found in the following patents.



   PCT 99/45665 assigned to Air Fiber Inc. describes a multi-hop architecture with an interconnection pattern consisting of a recursive grid or a quasi-rectangular mesh. While the patent deals with optically wired networks, the principles it elucidates are also applicable to free-space systems.



   PCT 00/04660 assigned to Terabeam Corporation describes a communication system, which includes an interconnection of networks. Each network is a node of the complete system and all the networks are interconnected. Data is exchanged between the networks point-to-point, point-to-multipoint, multipoint-to-point and multipoint-to-multipoint. Using diffraction gratings, lenses, holographic optical elements or other standard beam-shaping optics can generate the light cones and collimated light beams.



   PCT 00/25454 and PCT 00/25456 both assigned to Air Fiber Inc. illustrates inter alia a communications network wherein the nodes of the network are capable of sending to, and receiving from, a multiplicity of other nodes in the network.



   As discussed above, prior art solutions to the line-of-sight transient-obstruction problem in free-space communications networks have often used redundancy as a solution. However, these redundancies have been radically implemented using gross duplication of numerous key components, making such implementations viable albeit expensive."Key components"in the current context relate to using multiple optical sources, independently modulating them, independently directing their propagation at the transmitter side and at the receiver side, and independently detecting them.



   There is a longstanding need in the are for viable implementations of the essential redundancy solution without using gross duplication of the key components. Specifically, there is a need in the art to implement the benefits of optical communications path redundancy using more cost efficient methods of aperture management. One central aspect of efficient aperture management includes the using of beam splitting methods.



   To the best of the Applicant's knowledge beam splitting methods have not heretofore been employed to create optical path redundant communications infrastructures. In the context of this startling observation, and for the benefit of readers whose background is biased toward issues in communications infrastructures and away from optical components per se, a brief review of beam splitting methods is forthcoming.



   More particularly, there is a need in the art for improved beam splitting components which facilitates division into sub-beams, and these sub-beams either that respectively use an aperture substantially like that of the original beam, or preferably that use an aperture smaller than that, or that can be integrated together for shared use of a segmented aperture. Each of these needs in the art relates to a potentially less expensive implementation of current practices in optical communications.



   Furthermore, disregarding the price advantages of their use, there are other uses for such beam splitting components. These needs occur when the optical density cross-section of the resultant sub-beams would preferably be substantially like that of the original beam. Furthermore, there is a need in the art for such components in low-resolution interferometer apparatus, where lowering the optical flux of sub-beams (such as by using partially silvered mirrors) produces threshold events that require more sensitive detectors. 



   Beam splitters are optical devices that permit some incident light to pass through while reflecting the remainder. Usually splitters consist of a partially reflecting mirror or prism, which divides a light beam into two or more paths.



   Present conventionally available beam splitters include:
Plate beam splitters, which separate a beam into two paths   90  apart.    Both surfaces are generally coated with light-absorbing, partially reflective dielectric coatings.



   Cube beam splitters consist of matched pairs of right angle prisms cemented together. One prism face generally has a partially reflective coating.



   Pellicle beam splitters are formed from high tensile strength elastic membranes stretched over drumhead-like frames. The membranes are typically comprised of nitrocellulose. One surface of the splitter may be coated.



   While the above are all commercially available, other beam splitter configurations have been suggested.



   US Patent 5,418,769 describes a beam splitter using three prism members, each of which has a vertex end. The first member is cemented to the second and the second to the third. The vertex end of at least one of the three prisms is truncated.



   US Patent 5,657,155 describes an optical filter which incorporates a series of birefringent elements, each element splitting an input beam into two beams having planes of light polarized perpendicular to each other.



   According to methods embodied in above beam splitter examples, every ray of the incident beam is split into reflected and transmitted portions with a concomitant reduction in energy per unit area. Therefore were a split beam to be used in creating a redundant signal system for free-space communication networks, the entire transmitted laser beam would be split, reducing the energy per unit area received at receivers.



   Hence, there remains a need in the art for beam splitting components which produce sub-beams having energy per unit area like that of the original pre-split beam. Specifically, in free-space optical communication systems attempts are usually made so that the signal beam is focussed to minimize spot size, especially since increasing distance increases spot size. If beam splitters were to be used to create redundancy in free-space networks, it would be desirable to use a method wherein the energy per unit area received at a receiver remains undiminished from that of the incident beam.



   Combining all of the heretofore-mentioned prior arts, it is relevant to observe that optical communication systems are widely used for information transfer for a number of reasons, not the least of which is speed and convenience.



  In the field of optical communications, high bandwidth communication systems use optical lasers and photodiodes. With these components, maximum bandwidth can be achieved. This is due to the fact that optical wavelengths are short wavelengths and, therefore, this enables high transmission rate of data. To a man of the art, this high transmission rate technique is known as Broadband
Information Transfer.



   Most commonly, to transmit optical communications, fiber optic cables are used as a transfer medium. Fiber Optics technology involves converting electronically transferred data into transferred pulses of light data. Such light data is transferred through fiber optic cables, specially created and laid for this purpose. Over relatively short distances and, particularly over short distances within a city, such transfer ranges are defined as the"last mile"in the telecommunications industry. Over"last mile"distances, wireless optical or wireless radio frequency and cable-free solutions are also available. Other wireless solutions have come to be known as"fiber-less optics"or"free-space" optical communications using air as a transfer medium instead of fiber optic cables.



   There are many advantages to transmitting data using a wireless technique rather than through conventional electrical or optical cable technologies.



  Installation of electrical or optical cable systems is costly, invasive and very disruptive, especially within relatively densely populated areas such as cities and within building complexes. Much time is required for local governmental approval for implementing new types of communications infrastructures and their component systems.



   Conversely, fiber-less optical systems are substantially free of the high installation and maintenance costs of cabled systems. Furthermore, in contrast to cable systems, a fiber-less optic system is quickly deployed without disruption, inconvenience or intrusiveness. In addition, fiber-less optical systems are able to respond rapidly and dynamically to developing demand for increasing and expanding service needs and for advanced telecommunications. Another advantage of fiber-less optic systems is the freedom from, so-called, fiber cable outages and cuts that plague the telecommunication industry. Also, architecture of such a wireless network allows service providers to install their facilities in a manner closely conforming to product demand; specifically at the locations of users are easily accommodated using line of sight implementations.



  Consequently, fiber-less optic installations avoid high initial investment that cable systems necessitate. Another advantage of fiber-less optic or free-space systems is that installation redundancy is easily prevented. All these advantages are well appreciated by engineers implementing optical communication systems.



   However, a major issue in free-space optics is a need to deal with obstruction in the line-of-sight between transmitters and receivers. This issue of obstructions in a line-of-sight may affect reliability of free-space optic systems and remains a most pressing issue related to fiber-less optic transmission. In free-space optic transmission systems, at each extremity of each installation are transceivers. Each transceiver unit consists of a transmitter and a receiver unit. It is imperative that there exists a continuous clear line-of-site between transceivers at each extremity of a fiber-less free-space optic transmission system to ensure continuity and to avoid interruption of signal transfer. 



   Flying or airborne objects commonly cause temporary signal interruptions.



  Birds, especially relatively large birds such as pigeons, insects, bats, leaves, aircraft and even moderately dense puffs of smoke and a variety of other moving objects, by obscuring a line-of-site between transceivers, cause momentary signal disruption. This is a most common problem causing system interruptions.



   Generally, a solution for improving reliability of a fiber-less optic system and, there, for avoiding signal disruption by flying objects is to set up a pair of individual transceiver systems relatively adjacent to each other. A flying or airborne object may obstruct one signal while the other system compensates for loss of signal and continues to transmit data.



   More specifically, alternative to having two adjacent systems, a solution for preventing obstructions from interrupting a line-of-sight is to broaden a transmitting laser beam by using large lenses. However, a large lens would be required at both transmitter and receiver extremity. A beam would have to be widened so that any airborne object interfering with a signal would only obstruct a part of this signal and data would still be continuously and successfully transmitted. Signal systems such as this have been utilized in telecommunication systems. However, large lenses or apertures are costly, intrusive and require relatively sophisticated maintenance and protection from damage. Moreover, the larger the redundant area or the more the number of redundant optical paths in free space optical communication, the lower the probability that all will be simultaneously obstructed.



   Operationally, known systems assume that using such large lenses in a fiber-less optic transmitting and receiving system are a viable solution, however there are a number of associated technical problems apart from those already mentioned. When large lenses are used to transmit data, it is significant to note that a plurality of large aperture lenses is necessary. One large lens to widen the signal at transmitter end and another large lens at a respective linked receiver end, for example a customer's premises to a receiver hub. The receiving end may also require a large reflective receiving dish to capture optical data.



   Since large aperture optical components, such as lenses and mirrors, are more expensive than smaller aperture components of like type, there remains an economically motivated need in the art for optical communications solutions wherein the smaller aperture components are used.



   Notices
The present invention will forthwith be described with a certain degree of particularity, however those versed in the art will readily appreciate that various modifications and alterations may be carried out without departing from either the spirit or scope, as hereinafter claimed.



   In the context of the present invention"spatially separated"relates to a spatial separation substantially larger than the aperture diameter. Furthermore, "interference phenomenon"relates to spatial frequency being substantially larger than the wavelength
Furthermore, in the context of the present invention,"partial aperture" relates to part of the area of a whole aperture. Particularly, according to the present invention, a partial aperture beam splitting performs two operations.



  Firstly it divides the beam into sub-beams. Secondly, it divides the aperture into sub-apertures, each transferring its respective sub-beam.



   SUMMARY OF THE INVENTION
The present invention relates to a free-space redundant optical communications infrastructure including a plurality of respectively linked pairs of signal-transferring systems wherein the linked pairs form a single contiguous data-communications topology and at least one of the linked pairs is using a free-space redundant optical communications system. This infrastructure has benefits for inter-user communications applications and also for intra-system multi-processor data applications (such as in optical data-bussing networks, etc.), wherever the parties to the applications are physically separated and that separation can be bridged at least one of topology transfer link using a modulated line-of-sight optical beam connection.



   The present invention also relates to a free-space redundant optical communications system including a pair of respectively linked transceivers and each of the transceivers has: a) a free-space redundant optical communication transmitter apparatus; and b) a free-space redundant optical communication receiver apparatus.



   According to the preferred embodiment of the system of the present invention, the transmitter apparatus and likewise the receiver apparatus of at least one of the transceivers share at least one common optical or electro-optical component, such as a common light source, a common detector, lens, beam splitter, mirror, etc. Thus one of the economic advantages of the present invention is instantly realized.



   Furthermore, according to the preferred embodiments of the present invention, both with respect to the transmitter apparatus and likewise with respect to the receiver apparatus, at least one path selected from the incoming or outgoing optical paths can be independently directed differently from other optical paths in the same transceiver, transmitter apparatus or receiver apparatus.



   Additionally, according to the preferred embodiment of the present invention, on the side of at least one of the transceivers there is a sharing of a common aperture wherein the area of the aperture is divided into regions and each region is assigned a predetermined function selected from receiving or transmitting.



   The present invention further relates to a free-space redundant optical communication transmitter apparatus including: a light source emitting an optical signal beam; a divider dividing the optical signal beam into at least two partial-aperture beams; and transmitter-directors respectively directing each of the at least two partial-aperture beams to respective predetermined spatially separated targets.



   In the context of the present invention,"a light source emitting an optical signal beam"includes a modulated light source or a light source whose resultant beam is modulated thereafter.



   According to the preferred embodiment of the free-space redundant optical communication transmitter apparatus, at least one of the partial-aperture beams can be independently"pointed"by its respective directing transmitter-directors.



   The present invention additionally refers to a free-space redundant optical communication receiver apparatus wherein the apparatus includes: a) multiple spatially separated receiver-directors each directing a respective received optical signal partial-aperture beam to a combiner; and b) the combiner for combining the partial-aperture beams.



   According to the preferred embodiment of the free-space redundant optical communication receiver apparatus, at least one of the partial-aperture beams can be   independently"pointed"by    its respective directing receiver-directors.



   Moreover, the present invention relates to a method for segmenting an aperture for use in a free-space redundant optical communications system, the method including the steps: a) accepting an optical signal beam; b) dividing the optical beam into at least two partial-aperture beams using at least one optical communication-grating component; and c) respectively directing each of the at least two partial-aperture beams. 



   It should also be appreciated that the preferred embodiments of receiver apparatus, transmitter apparatus, and the above method as associated therewith preferable maintain substantially same length optic paths for phase"of the information modulation on the optical beams and sub-beams" (NOT of the wavelength of the optical source), thereby improving the unambiguous information decoding capacity of signals being processed from any associated detectors.



   Simply stated, the optical carrier beam is modulated and then divided into at least two redundant paths, from a transmitter to a receiver. Since the receiver preferably combines the at least two redundant path beams back together before directing them to a detector, a path difference of more than about an inter modulated bit length interval on the carrier beam would cause a"smearing"of the carried signals when combined back into a single beam. In the smeared beam, there would be no discrete boundaries between optical bits, especially in environments where there is a high probability that one of the redundant beams is interrupted for durations of more than about half a bit length.



   This is also an important consideration when implementing the present invention in dense wavelength dividing multiplexing   (DWDM)    transceiver applications, or when using the highest available transmission and detection speeds and trying to electronically resolve smeared signals; which would be a technical liability.



   Furthermore, it should likewise be appreciated that the preferred embodiments of receiver apparatus, transmitter apparatus, and the above method as associated therewith preferable, each incorporate beam splitting elements which respectively divide a single aperture beam into multiple sub-aperture beams (or conversely combine sub-aperture beams into a single aperture beam).



  The simple and straightforward way to accomplish this is using a plurality of full reflective mirrors, each of which respectively operates on a segment original converging beam or diverging beam of the source or detector ; E. g. knife edge reflectors and pyramidal element reflectors, or crystallographic elements used as substrates for reflectors, etc.



   It is furthermore an aspect of the present invention that fiber energy splitting or fiber couplers may substantially be accomplished using a construction similar to a transmitter apparatus of the present invention or similar to a receiver apparatus of the present invention, or substantially using an optical grating component of the present invention therein.



   Furthermore, the present invention relates to an optical communications grating component including at least one optical substrate having an optical film selectively arranged thereon in a deterministic (non-random) fashion.



   BRIEF DESCRIPTION OF THE FIGURES
In order to understand the invention and to see how it may be carried out in practice, embodiments including the preferred embodiment will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:
Figure   1A    illustrates a schematic view of two parallel optical systems two transceivers;
Figure 1B illustrates a schematic view of a"mesh"or nodal optic network system ;
Figure 1C illustrates a schematic view of a fiber-less optic system for preventing obstruction of line-of-sight in free-space communication systems by using larger lenses in both transmitter and receiver;
Figure 1 illustrates a schematic view of a fiber-less optical transmitter system;
Figure 2 illustrates a schematic view of a two-segment split beam transmitter system;

  
Figure 3 illustrates a schematic view of a two-segment split beam transmitter system using concave reflector segments; 
Figure 4 illustrates a schematic view of a split-apertures transmitter/receiver (transceiver);
Figure 5 illustrates a schematic view of an alternative fiber-less optic transmitter system;
Figure 6 illustrates a schematic view of a free-space redundant optical communications infrastructure;
Figure 7 illustrates a schematic view of a free-space redundant optical communications infrastructure including an optical bussing network;
Figure 8 illustrates a schematic view of a free-space redundant optical communications infrastructure including a repeater;
Figure 9 illustrates a schematic view of a free-space redundant optical communications system including a pair of respectively linked transceivers;

  
Figure 10 illustrates a schematic view of a free-space redundant optical communications system with at least one of the respectively linked pairs of signal transceivers includes a repeater;
Figure 11 illustrates a schematic view of a free-space redundant optical communications system with a repeater or a transceiver is located on an orbital platform;
Figure 12 illustrates a schematic view of a free-space redundant optical communications transmitter;
Figure 13 illustrates a schematic view of a free-space redundant optical communications receiver;
Figure 14 illustrates a block diagram view of a method for segmenting an aperture for use in a free-space redundant optical communications system;
Figure 15 illustrates a schematic view of an optical substrate (perforated) having an optical film selectively arranged thereon;

  
Figure 16 illustrates a schematic view of a an optical substrate (deflective) having an optical film selectively arranged thereon; 
Figure 17 illustrates a schematic view of a an optical substrate having an optical film selectively arranged thereon so that deflecting portions are respectively targeting two spatially separated targets ;
Figure 18 illustrates a schematic view of a reflective/perforated pellicle substrate;
Figure 19 illustrates a schematic view of a substrate, which are the two interior faces of a beam splitter cube;
Figure 20 illustrates a schematic view of a current state of the art beam splitter system;
Figure 21 illustrates a schematic view of a two-part beam splitter system; and
Figure 22 illustrates a schematic view of a multiple-part beam splitter system.



   DETAILED DESCRIPTION OF THE PRESENT INVENTION
The preferred embodiment of the present invention incorporates the best features and advantages of a large aperture fiber-less optic transmission-and-receiving system as well as the best features and advantages of a multi-redundant system; all of which generally share the disadvantages of large apertures are associated large costs. In order to prevent transmission interruptions to a fiber-less optic transmission data link, consider an existing large aperture, that is, a large lens, of a transmitter and divide it into two, or more, segments.



  Segments so created are then positioned at a predetermined distance from each other. In the same way, a receiver aperture is similarly divided into two, or more, segments and similarly positioned at a predetermined distance from each other.



   An implication of this arrangement is that both transmitter and receiver are using a Multiple Aperture Splitting, which in effect represents a separation of each large transmitter and receiver aperture, into several segments located at a predetermined distance apart. Segments are situated far enough apart so that, in the event of an airborne object or any other moving object, obscuring a line of sight between a transmission and a receiver segment, there remain other aperture segment pairs that continue to project portions of the originally transmitted beam.



   In effect, the predetermined distance between segments increases the redundant cross-sectional area to a size, considerably larger than the original large lens. The present invention, by this technique, allows a flow of optical communication data to continue with substantially reduced probability of signal interruption as a result of the dramatic increase in the redundant cross-sectional area relative to the individual segmented beams as well as a result of the multiplicity of beams. Furthermore, instead of requiring large, expensive lenses, the present invention enables the use of much smaller and significantly less expensive lenses and associated equipment.



   Referring now to Figure 1, this illustrates a schematic view of a fiber-less optical transmitter system 100 in which a beam source 101 transmits a beam 102 through a beam splitter 103, giving multiple beam segments 104. These multiple beam segments are further transmitted via small apertures 105 preferably reflector components, positioned at a predetermined distance apart, as multiple beam segments 106 towards a similarly designed receiver system. Making use of a beam split into multiple small segments, gives rise to a beneficial large redundant cross sectional area of free-space, and uses multiple small components   105    rather than a single large aperture component 107.



   Turning now to Figure 2, which illustrates a schematic view of a preferred embodiment of the present invention two-segment split beam transmitter system 200, a transmitting light source 201, either a laser diode or a light emitting diode (LED), is positioned in the focal plane of a projection lens 202. In a conventional fiber-less optical transmission system, a projection lens 202 is placed immediately in the path of a laser source. In accordance with the present invention, namely a Multiple Aperture Splitting system, a transmitter is illustrated as a two-aperture system 200 for simplicity. Instead of using a conventional projection lens 202, a beam cone 203 is divided by mirrors 204 and   205,    into separated beam segments, respectively 206 and 207. Each of these two beam segments is directed in a different direction, respectively to mirrors 208 and 209.

    > From these mirrors, each of the separated beam segments 210 and 211 is directed respectively to segments 212 and 213 of a now divided original projection lens, 202. Each lens segment now projects a respective segment 214 and 215 of the beam cone towards a similar and corresponding segmented receiver lens system. This division into two beam segments is a simplified example of a more complex embodiment of the present invention, wherein a beam signal is divided into more than two segments.



   Figure 3 illustrates a schematic view of a more sophisticated and advanced system 300 in which a further embodiment of the present invention is demonstrated. Compared with the system 200 illustrated in figure 2, the second pair of mirrors 208 and 209 and the pair of refractive lens segments 210 and 211 are replaced by segments 301 and 302 of a concave reflector surface. These direct each respective semi-cylindrically shaped beam segment 303 and 304 towards a receiver system, designed in a similar fashion to transmitter system 300. This embodiment of the present invention represents a further significant advance in the art. The need is eliminated for large and more costly refractive lenses as is utilized in the present state of the art, or for lens segments, as described in the earlier embodiment of the present invention,.

   Instead, simpler, less costly, segmented concave reflectors are utilized.



   The dividing of both transmitting and receiving apertures into two or more segments positioned a predetermined distance apart, prevents signal interruptions that may occur as a result of flying or airborne objects or of any other moving objects. An interruption of any one, or even more than one beam segment, will not prevent data, transmitted by at least one single beam segment, being successfully received.



   Turning now to Figure 4 which illustrates a schematic view of an embodiment of the present invention split-apertures producing partial aperture beams transmitter/receiver (transceiver). This transceiver 400 includes, in this view, four transmitting quarter-segments or apertures 401 of a full transmitting lens or aperture 402 shown schematically and four receiving quarter-segments or apertures 403 of a full receiving lens or aperture 404. All the segments are arranged at a predetermined distance apart to give both optimum optical path cross-sectional area redundancies as well as for reducing the cross-sectional area of each separate path. This substantially reduces the probability of total obstruction of the multiple split beam by any flying, airborne or moving object and, therefore, largely prevents any interruption in data signal flow.

   According to the preferred version of this embodiment, a number of less than full aperture segments are arranged to share a common aperture, thereby participating in a partial aperture propagation system.



   Turning now to Figure 5, which illustrates a schematic view of an alternative fiber-less optic transmitter system 500, This system is a lesser preferred embodiment of the present invention. A laser or LED source 501 emits a beam signal 502, which ordinarily would manifest as an ever-increasing cone beam 503. Directly in the path of this beam signal is a cubical beam-splitter 504 already known to a man of the art. The essential element of a cubical beam-splitter is a partially silvered refractive surface 505 which is so constructed that a portion 506 of the beam striking this partially silvered surface is reflected and a portion 509 passes through the refractive surface. The reflected portion 506 of the emitted beam signal is directed towards a segment of a parabolic reflecting surface 507, from which it is reflected 508 towards a distant receiver system.



   Simultaneously, another portion of the original beam signal passes through the partially silvered reflector surface 505 as a refracted beam signal 509. This refracted beam signal is reflected by a further reflecting surface 510. The reflected beam signal 511 is directed towards another segment of a parabolic reflecting surface 512, from which a beam signal 513 is reflected towards the distant receiver system. Parabolic reflecting segments 507 and 512 are positioned at a predetermined distance apart to produce, in this example, two beams with a significant redundancy of space to reduce the risk of signal interruption by flying, airborne or any other moving objects.

   Multiple beams are produced by addition of further cubical beam splitters, or other beam splitter devices, placed into each partial beam signal path, further increasing redundancy and further reducing a risk of signal interruption. (note: mirror 512 is intentionally places asymmetrically to mirror 507 so that there are same length optic paths for phase of the information modulation on the carrier beam 502-so as not to result in information smearing.)
Furthermore, embodiments of the present invention relate to a free-space redundant optical communications infrastructure that provides a technique for interconnecting electronic communications systems, for example, data-communications, telecommunications, or computer networks.

   This technique facilitates interconnecting computers which are either distant from one another or where provision of conventional electrical or fiber optic interconnecting cables is not financially or pragmatically feasible. Furthermore, in terms of embodiments of the present invention, use of a free-space redundant optical communications infrastructure reduces the risk of signal beam interruption. This is achieved in terms of various embodiments of the present invention, notably by applying, in the context of the present invention, the consideration that spatially separated partial beam signals have a spatial separation substantially larger than the transmitting aperture diameter and hence the transmitted signal beam diameter.



   Turning now to figure 6, the present invention particularly relates to embodiments of a free-space redundant optical communications infrastructure 600. The infrastructure includes a plurality of respectively linked pairs of signal-transferring systems 602,603 and 604 in which the linked pairs form a single contiguous data-communications topology and at least one of the linked pairs 604 is using a free-space redundant optical communications system 601. 



   Turning now to figure 7, an embodiment of the present invention relates to the infrastructure 700, in which the topology includes an optical bussing network 701,702,703,704 and 705. The network is installed, for example, in a building 706. This network represents a distributed embodiment of the system for providing data linkage between a plurality of optically aligned components.



  Other embodiments of the present invention relate to the infrastructure in which the topology includes a ring structure, a backbone or a mesh.



   Furthermore, turning to figure 8, which illustrates a schematic view of a free-space redundant optical communications infrastructure 800, an embodiment of the present invention relates to the infrastructure in which at least one of the respectively linked pairs 801 and 802 of signal transferring systems includes a repeater 803. Such a repeater serves to enable the rerouting of a signal beam, for example, where a change of direction is necessitated by an obstruction. A variation of an embodiment of the present invention relates to the infrastructure in which the repeater is located on an orbital platform, for example on a satellite.



   Likewise an embodiment of the present invention relates to the infrastructure in which at least one of the respectively linked pairs of signal-transferring systems is located on an orbital platform. In addition, an embodiment of the present invention relates to the infrastructure in which the topology includes at least one interruptible link.



   Turning now to figure 9, the present invention also relates to a free-space redundant optical communications system 900 including a pair of respectively linked transceivers 903 and 904 and each of the transceivers has: a) a free-space redundant optical communication transmitter apparatus respectively 907,908 and 909,910; and b) a free-space redundant optical communication receiver apparatus, respectively   905,    906 and 911,912. 



   Generally, it is necessary, in a computer network for example, for signals to be exchanged. This exchange of signals is facilitated by inter-linking pairs of transmitters and receivers using fiber optic cables.



   Turning now to figure 10, another embodiment of the present invention relates to free-space redundant optical communications system 1000 in which at least one of the respectively linked pairs of signal transceivers 1001 and 1002 includes a repeater 1003. Turning now to figure 11, another variation of an embodiment of the present invention relates to free-space redundant optical communications system 1100 in which repeater 1101 is located on orbital   platform    1102. Signal beams 1103 and 1104 are transmitted between locations on the earth 1105 via the repeater.



   A further embodiment of the present invention relates to the free-space redundant optical communications system in which at least one of the respectively linked pairs of signal transceivers is located on an orbital platform.



  Such a linked pair of signal transceivers could serve as a node in a free-space optical communication system, between two stations located substantially beyond line-of-sight from each other or where the intervening space is interrupted by structures, trees or other fixed or moving obstructions.



   Turning to figure 12, additionally, the present invention relates to a free-space redundant optical communication transmitter apparatus 1200 including: a) a light source 1202 emitting an optical signal beam 1203; b) a divider 1201 dividing 1204,1205 and 1206 the optical signal beam into at least two partial-aperture-type beams 1207,1208 and 1209-which is to say dividing the signal beam into sub-beams that could be directed to share an aperture; and c) transmitter-directors 1210,1211 and 1212 respectively directing each of the at least two partial-aperture beams to respective predetermined spatially separated targets. 



   Another aspect of figure 12 will be appreciated after considering the materials presented in figure 20. Particularly in figure 12 one can easily select the proportion of light density respectively between the sub-beams by selecting appropriate quantified optical grating components according to the present invention. Whereas in apparatus, such as that presented in figure 20, precision of randomly silvered partial reflective surfaces are comparatively difficult to achieve for predetermined quanta of reflectivity. Hence the cost of the optical communications grating components of the present invention should be considerably less than these well known classical type components.



   A significant aspect of the divider, with regard to the present invention, is that there are two distinct types. Beam dividers in current use maintain, for each partial beam, the original beam's cross sectional area while reducing the beam intensity. Such a divider also finds use in the present invention. However, an embodiment of the present invention, relates to a divider that produces a number of partial beams such that the sum of the cross sectional areas is the same as the original beam. This means that each partial beam retains the beam intensity of the original undivided beam.



   Other embodiments of the present invention relates to the free-space redundant optical communication transmitter apparatus in which at least two of the transmitter-directors direct their respective partial-aperture beams on parallel paths or, alternatively, in which at least two of the transmitter-directors direct their respective partial-aperture beams on non-parallel paths.



   An additional embodiment of the present invention relates to the free-space redundant optical communication transmitter apparatus in which the transmitter-directors are symmetrically arranged with respect to the divider.



   In the context of the present invention,   a"polarizer    element"relates to any component that modifies a property of the traversing light beam. For example, a polarizer element is one that polarizes traversing light or one that diffracts passing light or one that filters passing light or one that resolves or introduces an interference aspect, etc.



   Moreover, an embodiment of the present invention relates to the free-space redundant optical communication transmitter apparatus in which the light source includes a beam polarizer element. Likewise, an embodiment of the present invention relates to the free-space redundant optical communication transmitter apparatus in which the divider includes a beam polarizer element.



  Furthermore, an embodiment of the present invention relates to the free-space redundant optical communication transmitter apparatus in which at least one of the transmitter-directors includes a beam polarizer element.



   Also, an embodiment of the present invention relates to the free-space redundant optical communication transmitter apparatus in which the light source includes a fiber optic component. Another embodiment of the present invention relates to the free-space redundant optical communication transmitter apparatus in which at least one of the transmitter-directors includes a fiber optic component.



   These embodiments provide for a continuous optical communications network including both fiber and fiber-less or free-space sections. For example, it may be difficult to install optic fiber cables in an already existing building to inter link parts of a computer network whereas a fiber-less link would easily provide non-invasive solution. Similarly, laying cables across a built-up area of a city is both inconvenient and costly whereas a non-invasive fiber-less optical beam is cheaply and quickly installed.



   One other embodiment of the present invention relates to the free-space redundant optical communication transmitter apparatus in which the divider includes an optical communication-grating component.



   Other, embodiments of the present invention relate to the free-space redundant optical communication transmitter apparatus in which the light source is a monochromatic source or a polychromatic source or a laser source. 



   In addition, turning to figure 13, the present invention relates to a free-space redundant optical communication receiver apparatus 1300 wherein the apparatus includes: a) multiple spatially separated receiver-directors 1301, each directing a respective received optical signal partial-aperture beam 1302 to a combiner 1303; and b) the combiner for combining the partial-aperture beams 1304.



   An embodiment of the present invention relates to the free-space redundant optical communication receiver apparatus in which the combiner includes a fiber optic component.



   Another embodiment of the present invention relates to the free-space redundant optical communication receiver apparatus in which the combiner includes an optical communication-grating component.



   A further embodiment of the present invention relates to the free-space redundant optical communication receiver apparatus in which the receiver-directors are symmetrically arranged with respect to the combiner.



   Furthermore, turning now to figure 14, the present invention relates to a method 1400 for segmenting an aperture for use in a free-space redundant optical communications system, the method including the steps: a) accepting 1401 an optical signal beam; b) dividing 1402 the optical beam into at least two partial-aperture beams using at least one optical communication-grating component; and c) respectively directing 1403 each of the at least two partial-aperture beams.



   Such accepted optical signal beam is emitted by, for example, a laser activated initially by a computer or other electronic communication device.



  Dividing a signal beam is achieved utilizing essentially two types of devices. One technique provides that the geometry of the divided beam portions resembles that of the original beam but each partial beam has reduced beam intensity, inversely proportional to the number of portions. Alternatively, the partial beams each retains the intensity of the emitted signal beam but have a reduced cross sectional area.



   Turning now to figure 15, additionally, the present invention relates to an optical communication-grating component 1500 including at least one optical substrate 1501 having an optical film 1502 selectively arranged thereon. Portions of the incident signal beam 1504 are reflected 1505 from the selectively arranged optical film whereas other portions pass through perforated areas 1503 of the optical film.



   Also, an embodiment of the present invention relates to the optical communication-grating component in which the optical film is selectively arranged on the substrate forming first spatial frequency significant film portions and leaving second spatial frequency significant substrate portions.



   Additionally, a variation of an embodiment of the present invention relates to the optical communication-grating component in which the first spatial frequency is selected to avoid significant interference interactions for light in a predetermined frequency reflected, refracted or deflected therefrom. Further, interference phenomenon relates to spatial frequency being substantially larger than the wavelength   (X).   



   Another variation of an embodiment of the present invention relates to the optical communication-grating component in which the second spatial frequency is selected to avoid significant interference interactions for light in a predetermined frequency reflected, refracted or deflected therefrom.



   Also, another embodiment of the present invention relates to the optical communication-grating component in which the optical film is reflective.



   Turning now to figure 16, one other embodiment of the present invention relates to the optical communication-grating component 1600 in which the optical film 1601 is deflective 1606 whereas part 1602 of the optical film is reflective 1605. 



   Turning now to figure 17, an additional variation of an embodiment of the present invention 1700 relates to the optical communication-grating component 1701 in which the deflecting portions 1702 and 1703 are respectively targeting 1706 and 1707 at least two spatially separated targets 1704 and 1705.



   Furthermore other embodiments of the present invention relate to the optical communication-grating component in which the substrate is transparent or deflective or is reflective.



   Turning now to figure 18, another embodiment of the present invention relates to the optical communication grating component 1800 in which the substrate 1801 is a pellicle substrate. A pellicle substrate is ultra thin, specifically to avoid image doubling. A Pellicle mirror is one that reflects 1802 a portion 1806 of the light 1805 and passes 1803 the remaining light through 1807. A
Pellicle Mirror is made up from a thin 1804, stretched plastic membrane cemented to a rigid supporting ring. It may be coated to act as a beamsplitter. For example, in a color camera, it is so thin that no perceptible image doubling appears in the reflected beam. Pellicles are, however, very delicate, and liable to resonate to certain vibration frequencies.



   An additional embodiment of the present invention relates to the optical communication-grating component in which the substrate is a physically perforated and, therefore, light passing through the pellicle mirror, will not be deflected.



   Turning now to figure 19, another embodiment of the present invention relates to the optical communication-grating component 1900 in which the substrate 1901 is the two interior faces 1902 and 1903 of a beam splitter cube 1904.



   Likewise, another embodiment of the present invention relates to the optical communication-grating component in which the optical film is a selectively sputtered material. Variations of an embodiment of the present invention relate to the optical communication-grating component in which the selectively sputtered material is reflective or is deflective. A further variation of an embodiment of the present invention relates to the optical communication-grating component in which the selectively sputtered material is a flux, which is thereafter annealedthereby causing the desired optical property to be formed thereat. One other embodiment of the present invention relates to the optical communication-grating component in which the optical film is a selectively sputtered reflector surface of index refractive selective material.



   Fiber-less optic signal beam splitter systems may be applied to fiber transmitted optic beams, both using classical beam splitting methods and also using an optical communication-grating component of the present invention.



   Current fiber optic technology makes use of a fiber-less optic system for splitting input signal beams. However, the techniques currently in use generally result in an attenuation problem relating to each of the split portions. This is caused by utilizing techniques that allow a reduction in the split part-beam's intensity, i. e. fiber energy splitting or fiber couplers.



   Turning now to Figure 20, this illustrates a schematic view of a current state of the art beam splitter system 2000. An incident input optic signal beam, is directed from a fiber optic cable 2001, through a lens aperture 2002 to a plurality of beam splitter cubes 2003,2004,2005, and so on, arranged in series. Note that one of the present complexities of using an arrangement of component beam splitter cubes 2003,2004,2005, is that the deflective percentage must occur in precise carefully calibrated increasing increments so that the deflected optical sub-beams have substantially equal energy cross-sections to each other.



   The series arrangement of beam splitter cubes is such that the partially reflective surface of each successive cube is so coated as to progressively reflect an equal proportion of the original incident beam, allowing the remaining proportion of the beam to pass successively through to the next cube. This process is repeated to give a requisite number of separate beam portions. 



   Each successive split portion of the beam is respectively directed to lens aperture 2006,2007,2008 and so on and thereafter to a plurality of output fiber optic cables, respectively, 2009,2010,2011 and so on.



   This current state of the art beam splitter system has a particular disadvantage. After each repeated splitting procedure, the cross sectional area of each of the reflected beam portions remains the same as that of the original incident input beam. However, the reflected beam portions suffer a reduction of beam intensity in proportion to the number of beam splitter cubes utilized. This results in attenuation of the beam signal.



   Turning now to Figure 21, this illustrates a schematic view of a two-part beam splitter system 2100 in terms of various embodiments of the present invention. An input fiber optic cable 2101 directs an incident input beam signal, either directly or through a lens aperture, not indicated in the figure, to a pair of mirrors 2102. This pair of mirrors is so arranged so as to each reflect a part of or half of the incident beam signal via lens apertures, respectively, 2103 and 2104 to two output fiber optic cables, respectively 2105 and 2106. Using this technique, the two signal beam portions retain signal intensity and avoid attenuation as indicated in the foregoing system 2000.



   A further evolvement according to embodiments of the present invention, is a development of beam splitter system 2100. Beam splitter system 2100 provides for splitting an incident beam signal received from a fiber optic cable into two equal or even unequal portions of equal beam signal intensity.



   Turning now to Figure 22, this is a schematic view of a multiple-part beam splitter system 2200 in terms of embodiments of the present invention. An input fiber optic cable 2201, directs an incident input beam signal, either directly or through a lens aperture, not indicated in the figure, to a pyramidal arrangement of reflecting mirrors 2202. Portions of the incident beam are reflected by each of the pyramidal arranged mirrors via respective lens apertures, 2203A, 2203B, 2203C, 2203D and so on, respectively to output fiber optic cables 2204A, 2204B,   2204C,    2204D and so on. The input signal beam is therefore split into a multiplicity of equal-intensity part beam signals, carried away by the output cables.

   By this technique, each of the multiplicity of part beam signals avoids the attenuation resulting from system 2000, using a series of differentially coated beam splitter cube surfaces.

Claims

CLAIMS 1. A free-space redundant optical communications infrastructure including a plurality of respectively linked pairs of signal-transferring systems wherein said linked pairs form a single contiguous data-communications topology and at least one of the linked pairs is using a free-space redundant optical communications system.

2. The infrastructure according to claim 1 wherein said topology includes an optical bussing network for providing data linkage between a plurality of optically aligned components.

3. The infrastructure according to claim 1 wherein said topology includes a ring structure.

4. The infrastructure according to claim 1 wherein said topology includes a backbone 5. The infrastructure according to claim 1 wherein said topology includes a mesh.

6. The infrastructure according to claim 1 wherein at least one of said respectively linked pairs of signal transferring systems includes a repeater.

7. The infrastructure according to claim 6 wherein said repeater is located on an orbital platform.

8. The infrastructure according to claim 1 wherein at least one of said respectively linked pairs of signal-transferring systems is located on an orbital platform.

9. The infrastructure according to claim 1 wherein said topology includes at least one interruptible link.

10. A free-space redundant optical communications system, particularly useful when used in a free-space redundant optical communications infrastructure, the system including a pair of respectively linked transceivers and each of said transceivers has: a) a free-space redundant optical communication transmitter apparatus; and b) a free-space redundant optical communication receiver apparatus.

11. The free-space redundant optical communications system according to claim 10 wherein at least one of said respectively linked pairs of signal transceivers includes a repeater.

12. The free-space redundant optical communications system according to claim 11 wherein said repeater is located on an orbital platform.

13. The free-space redundant optical communications system according to claim 10 wherein at least one of said respectively linked pairs of signal transceivers is located on an orbital platform.

14. A free-space redundant optical communication transmitter apparatus, particularly useful when used in a free-space redundant optical communications system, the transmitter apparatus including: a) a light source emitting an optical signal beam; b) a divider dividing the optical signal beam into at least two partial-aperture beams; and c) transmitter-directors respectively directing each of the at least two partial-aperture beams to respective predetermined spatially separated targets.

15. The free-space redundant optical communication transmitter apparatus according to claim 14 wherein at least two of said transmitter-directors direct their respective partial-aperture beams on parallel paths.

16. The free-space redundant optical communication transmitter apparatus according to claim 14 wherein at least two of said transmitter-directors direct their respective partial-aperture beams on non-parallel paths.

17. The free-space redundant optical communication transmitter apparatus according to claim 14 wherein said transmitter-directors are symmetrically arranged with respect to said divider.

18. The free-space redundant optical communication transmitter apparatus according to claim 14 wherein said light source includes a beam polarizer element.

19. The free-space redundant optical communication transmitter apparatus according to claim 14 wherein said divider includes a beam polarizer element.

20. The free-space redundant optical communication transmitter apparatus according to claim 14 wherein at least one of said transmitter-directors includes a beam polarizer element.

21. The free-space redundant optical communication transmitter apparatus according to claim 14 wherein said light source includes a fiber optic component.

22. The free-space redundant optical communication transmitter apparatus according to claim 14 wherein at least one of said transmitter-directors includes a fiber optic component.

23. The free-space redundant optical communication transmitter apparatus according to claim 14 wherein said divider includes an optical communication-grating component.

24. The free-space redundant optical communication transmitter apparatus according to claim 14 wherein said light source is a monochromatic source.

25. The free-space redundant optical communication transmitter apparatus according to claim 14 wherein said light source is a polychromatic source.

26. The free-space redundant optical communication transmitter apparatus according to claim 14 wherein said light source is a laser source.

27. A free-space redundant optical communication receiver apparatus, particularly useful when used in a free-space redundant optical communications system, wherein said receiver apparatus includes: a) multiple spatially separated receiver-directors each directing a respective received optical signal partial-aperture beam to a combiner; and b) said combiner for combining the partial-aperture beams.

28. The free-space redundant optical communication receiver apparatus according to claim 27 wherein said combiner includes a fiber optic component.

29. The free-space redundant optical communication receiver apparatus according to claim 27 wherein said combiner includes an optical communication-grating component.

30. The free-space redundant optical communication receiver apparatus according to claim 27 wherein said receiver-directors are symmetrically arranged with respect to said combiner.

31. A method for segmenting an aperture for use in a free-space redundant optical communications system, the method including the steps: a) accepting an optical signal beam; b) dividing the optical beam into at least two partial-aperture beams using at least one optical communication-grating component; and c) respectively directing each of the at least two partial-aperture beams.

32. An optical communication-grating component, particularly useful for dividing an optical beam into at least two partial-aperture beams, said component including at least one optical substrate having an optical film selectively arranged thereon.

33. The optical communication-grating component according to claim 32 wherein said optical film is selectively arranged on said substrate forming first spatial frequency significant film portions and leaving second spatial frequency significant substrate portions.

34. The optical communication-grating component according to claim 33 wherein the first spatial frequency is selected to avoid significant interference interactions for light in a predetermined frequency reflected, refracted or deflected therefrom.

35. The optical communication-grating component according to claim 33 wherein the second spatial frequency is selected to avoid significant interference interactions for light in a predetermined frequency reflected, refracted or deflected therefrom.

36. The optical communication-grating component according to claim 32 wherein said optical film is reflective.

37. The optical communication-grating component according to claim 32 wherein said optical film is deflective.

38. The optical communication-grating component according to claim 37 wherein said deflecting portions are respectively targeting at least two spatially separated targets.

39. The optical communication-grating component according to claim 32 wherein said substrate is transparent or deflective.

40. The optical communication-grating component according to claim 32 wherein said substrate is reflective.

41. The optical communication-grating component according to claim 32 wherein said substrate is a pellicle substrate.

42. The optical communication-grating component according to claim 32 wherein said substrate is the two interior faces of a beam splitter cube.

43. The optical communication-grating component according to claim 32 wherein said substrate is a physically perforated.

44. The optical communication-grating component according to claim 32 wherein said optical film is a selectively sputtered material.

45. The optical communication-grating component according to claim 44 wherein said selectively sputtered material is reflective.

46. The optical communication-grating component according to claim 44 wherein said selectively sputtered material is deflective. 47. The optical communication-grating component according to claim 44 wherein said selectively sputtered material is a flux, which is thereafter annealed.

48. The optical communication-grating component according to claim 32 wherein said optical film is a selectively sputtered reflector surface of index refractive selective material.