Telescope with floating secondary mirror

Abstract

A telescope system comprising a primary mirror and / or a secondary mirror assembly including a secondary mirror including a reflective surface positioned to receive light reflected from the primary mirror and which may be configured to concentrate the light into a beam and which may have a magnetic component which may be fixed relative to the secondary mirror's periphery; and / or a magnetic member which may be peripheral to the magnetic component, which may stabilize the secondary mirror assembly relative to the primary mirror, even absent any physical support for the secondary mirror.

Description

[0001] Telescope With Floating Secondary Mirror

[0002] FIELD OF THIS DISCLOSURE

[0003] The present invention relates generally to telescopes, and more particularly to secondary mirrors in telescope systems.

[0004] BACKGROUND

[0005] Processes for manufacturing light-weight mirrors are known, such as described, by way of example, in US patent 7145739.

[0006] Patent document CN102185540 describes a magnetic suspension supporting system for a main reflecting mirror.

[0007] Patent document US4943147 describes a chopping secondary mirror system.

[0008] The following online publication: ntrs.nasa.gov / api / citations / 20120015763 / downloads / 20120015763. pdf describes alternating magnetic field forces for satellite formation flying.

[0009] Patent document US3761158 describes a telescope having an immersed mirror stabilizer.

[0010] Patent document US7880964 describes a space telescope with free-flying secondary and receiver elements.

[0011] The disclosures of all publications and patent documents mentioned in the specification, and of the publications and patent documents cited therein directly or indirectly, are hereby incorporated by reference, other than subject matter disclaimers or disavowals. If the incorporated material is inconsistent with the express disclosure herein, the interpretation is that the express disclosure herein describes certain embodiments, whereas the incorporated material describes other embodiments. Definition / s within the incorporated material may be regarded as one possible definition for the term / s in question. SUMMARY OF CERTAIN EMBODIMENTS

[0012] Certain embodiments herein seek to provide a telescope with an easily adjustable (typically even in orbit) secondary mirror which prevents undesirable diffraction phenomena.

[0013] Certain embodiments herein seek to provide a telescope with a floating secondary mirror which prevents undesirable diffraction phenomena by eliminating elements such as "spiders" which physically support conventional secondary mirrors. No spiders are required, given that their secondary mirror stabilizing functionality is performed by a pair of interacting magnetic elements, one of which may be fixed to the secondary mirror, and another of which may be peripheral to the secondary mirror.

[0014] Certain embodiments herein seek to provide a secondary mirror assembly which may be stabilized electromagnetically, relative to the primary mirror, even absent any physical support for the secondary mirror. Telescope performance may be improved, since magnets which achieve electromagnetic stabilization of the secondary mirror assembly relative to the primary mirror, may be deployed outside the field of view of the camera, as opposed to prior art spiders which are deployed within the field of view of the camera.

[0015] Certain embodiments seek to conveniently install a secondary mirror in (typically reflecting) telescopes of various types, such as but not limited to Cassegrain, Anastigmatic Three Mirrors Telescope, and Newtonian telescopes. The mirror may be held in place by an assembly of magnets (e.g. electro-magnets), which will allow the mirror to be realigned in orbit and / or by remote control. This will enable the performance of the camera to be enhanced, even when the platform bearing the camera is already in orbit, optimizing performance. Embodiments herein enable diffraction phenomena, as seen in the images of the Hubble camera and the James Webb Space Telescope (JWST), to be prevented, since diffraction phenomena often result from the presence of spiders and other elements in the light path, or non-circular primary mirrors in telescopes.

[0016] Certain embodiments enable a camera's performance to be corrected, even once the camera is in space or in orbit.

[0017] The method typically positions a secondary mirror, without resorting to use of gripping arms (spiders) which, when used, partially obscure incoming light, causing undesirable effects / artifacts in the resulting image. Instead, the secondary mirror assembly is held in position by an assembly of magnets (permanent or electromagnets, or any combination thereof).

[0018] Certain embodiments of the present invention seek to provide circuitry typically comprising at least one processor in communication with at least one memory, with instructions stored in such memory executed by the processor to provide functionalities which are described herein in detail. Any functionality described herein may be firmware- implemented or processor-implemented, as appropriate.

[0019] It is appreciated that any reference herein to, or recitation of, an operation being performed is, e.g. if the operation is performed at least partly in software, intended to include both an embodiment where the operation is performed in its entirety by a server A, and also to include any type of "outsourcing" or "cloud" embodiments in which the operation, or portions thereof, is or are performed by a remote processor P (or several such), which may be deployed off-shore or "on a cloud", and an output of the operation is then communicated to, e.g. over a suitable computer network, and used by, server A. Analogously, the remote processor P may not, itself, perform all of the operations, and, instead, the remote processor P itself may receive output / s of portion / s of the operation from yet another processor / s P’, may be deployed off-shore relative to P, or "on a cloud", and so forth.

[0020] The present invention typically includes at least the following embodiments:

[0021] Embodiment 1. A telescope system comprising a primary mirror and / or a secondary mirror assembly including a secondary mirror including a reflective surface positioned to receive light reflected from the primary mirror and configured to concentrate the light into a beam and having a magnetic component fixed relative to the secondary mirror's periphery; and / or a magnetic member peripheral to the magnetic component, e.g. to stabilize the secondary mirror assembly relative to the primary mirror, even absent any physical support for the secondary mirror.

[0022] It is appreciated that the term "magnetic" is intended to include any material responsive to a magnetic field, which may be provided by either permanent magnets and / or electromagnets.

[0023] Embodiment 2. A system according to any of the preceding embodiments wherein the magnetic component comprises an assembly of magnets at least partly surrounding the secondary mirror assembly and wherein the magnetic member comprises at least a portion of an electromagnetic annulus.

[0024] If the secondary mirror is itself electromagnetic, the electromagnetic component may comprise the secondary mirror itself; thus the secondary mirror may be fixed in an assembly at least partly formed of a magnetic material.

[0025] Embodiment 3. A system according to any of the preceding embodiments wherein the magnetic member comprises an assembly of magnets at least partly surrounding the secondary mirror assembly and wherein the magnetic component comprises at least a portion of the electromagnetic annulus.

[0026] Embodiment 4. A system according to any of the preceding embodiments wherein the secondary mirror is convex.

[0027] It is appreciated that (e.g. if the system is based on Newtonian type telescope) the secondary mirror may alternatively be flat.

[0028] Embodiment 5. A system according to any of the preceding embodiments wherein at least a portion of the electromagnetic annulus is formed of a magnetic material such as metal.

[0029] Embodiment 6. A system according to any of the preceding embodiments wherein the magnetic member or magnetic component comprises an assembly of magnets which comprises a ring of magnets surrounding the secondary mirror.

[0030] Embodiment 7. A telescoping method comprising: providing a reflective telescope comprising a structure; and in the structure, providing accurate positioning to a primary mirror assembly and a secondary mirror assembly stabilized electromagnetically, relative to the primary mirror, even absent any physical support for the secondary mirror.

[0031] The structure may comprise a housing e.g. a solid tube and may comprise a truss. It is appreciated that the structure defines a main axis which may but does not necessarily coincide with the telescope's optical axis (e.g. defined by the primary mirror's center and the secondary mirror's center).

[0032] Embodiment 8. The method of any of the preceding embodiments wherein the secondary mirror assembly, at least on occasion, floats within a ring of electromagnets, without any mechanical support.

[0033] Embodiment 9. The method of any of the preceding embodiments wherein the reflective telescope is deployed on a moving platform whose motion is initially (e.g., during launch) rough (highly turbulent) and then (e.g., in orbit) becomes smoother (less turbulent), and wherein the secondary mirror assembly is supported mechanically while the platform's motion is initially rough and then floats within the ring of electromagnets, without any physical support, once the motion becomes smoother and current is applied to each electromagnet.

[0034] Embodiment 10. The method of any of the preceding embodiments wherein the primary mirror and secondary mirror define an optical path for light reaching the telescope system and wherein the secondary mirror is supported mechanically by and / or engaged by a retractable physical support member which, when the motion becomes smoother, is retracted and / or is withdrawn from engagement with the secondary mirror and / or is removed from the optical path.

[0035] Embodiment 11. The method of any of the preceding embodiments wherein the moving platform comprises a satellite whose motion becomes smoother (e.g. less turbulent) once the satellite is in orbit, relative to the satellite's motion before the satellite goes into orbit. It is appreciated that initial motion (e.g. during launch) may be rough (e.g. characterized by high turbulence, relative to motion once the satellite goes into orbit) due to platform maneuvers and / or platform separation phases occurring before the satellite goes into orbit. Typically, during this initial rough motion, the system does not conduct any imaging.

[0036] Embodiment 12. The system of any of the preceding embodiments wherein the assembly of magnets comprises electromagnets defining axes, and wherein, for a first subset of the electromagnets, the axes have a component parallel to a main axis.

[0037] Embodiment 13. The system of any of the preceding embodiments wherein, for a second subset of the electromagnets, the axes have a component perpendicular to the main axis.

[0038] Embodiment 14. The system of any of the preceding embodiments wherein the first subset of electromagnets' axes are parallel to the main axis, and the second subset of electromagnets' axes are perpendicular to the main axis.

[0039] Embodiment 15. The system of any of the preceding embodiments wherein a controller determines a current at which each electromagnet is to operate.

[0040] Embodiment 16. The system of any of the preceding embodiments wherein the magnets comprise permanent magnets.

[0041] Embodiment 17. The system of any of the preceding embodiments wherein the magnets comprise electromagnets.

[0042] Embodiment 18. A system according to any of the preceding embodiments and also comprising a structural member encasing the primary mirror, and wherein the magnetic member, peripheral to the magnetic component, is fixed to the structural member.

[0043] Embodiment 19. A system according to any of the preceding embodiments wherein the structural member is cylindrical, thereby to define a tube having a main axis perpendicular to a main plane of the primary mirror, and wherein the magnetic member is fixed to, e.g., attached to, an external surface of the tube. Embodiment 20. A system according to any of the preceding embodiments wherein the primary mirror is apertured, definingan aperture, and wherein the secondary mirror assembly's reflective surface is positioned to receive light reflected from the primary mirror and to concentrate the light into a beam which travels back toward the primary mirror and then through the aperture.

[0044] Embodiment 21. A system according to any of the preceding embodiments which forms an off-axis telescope.

[0045] Embodiment 22. The system of any of the preceding embodiments wherein the ring of magnets is fixed to, e.g., mounted on, the structural member's external surface.

[0046] Embodiment 23. The system of any of the preceding embodiments wherein the ring of magnets is mounted on the structural member's internal surface.

[0047] Embodiment 24. The system of any of the preceding embodiments wherein the ring of magnets is deployed interiorly to a volume defined by the structural member's typically cylindrical walls.

[0048] Also provided, excluding signals, is a computer program comprising computer program code means for performing any of the methods shown and described herein when the program is run on at least one computer; and a computer program product, comprising a typically non-transitory computer-usable or -readable medium e.g. non- transitory computer -usable or -readable storage medium, typically tangible, having a computer readable program code embodied therein, the computer readable program code adapted to be executed to implement any or all of the methods shown and described herein. The operations in accordance with the teachings herein may be performed by at least one computer specially constructed for the desired purposes, or a general-purpose computer specially configured for the desired purpose by at least one computer program stored in a typically non-transitory computer readable storage medium. The term "non-transitory" is used herein to exclude transitory, propagating signals or waves, but to otherwise include any volatile or non-volatile computer memory technology suitable to the application. Any suitable processor / s, display and input means may be used to process, display, e.g., on a computer screen or other computer output device, store, and accept information such as information used by or generated by any of the methods and apparatus shown and described herein; the above processor / s, display and input means including computer programs, in accordance with all or any subset of the embodiments of the present invention. Any or all functionalities of the invention shown and described herein, such as but not limited to operations within flowcharts, may be performed by any one or more of: at least one conventional personal computer processor, workstation or other programmable device or computer or electronic computing device or processor, either general-purpose or specifically constructed, used for processing; a computer display screen and / or printer and / or speaker for displaying; machine-readable memory such as flash drives, optical disks, CDROMs, DVDs, BluRays, magnetic-optical discs or other discs; RAMs, ROMs, EPROMs, EEPROMs, magnetic or optical or other cards, for storing, and keyboard or mouse for accepting. Modules illustrated and described herein may include any one or combination or plurality of: a server, a data processor, a memory / computer storage, a communication interface (wireless (e.g. BLE) or wired (e.g. USB)), a computer program stored in memory / computer storage.

[0049] The term "process" as used above is intended to include any type of computation or manipulation or transformation of data represented as physical, e.g., electronic, phenomena which may occur or reside, e.g., within registers and / or memories of at least one computer or processor. Use of nouns in singular form is not intended to be limiting; thus, the term processor is intended to include a plurality of processing units which may be distributed or remote, the term server is intended to include plural typically interconnected modules running on plural respective servers, and so forth.

[0050] The above devices may communicate via any conventional wired or wireless digital communication means, e.g., via a wired or cellular telephone network or a computer network such as the Internet.

[0051] The apparatus of the present invention may include, according to certain embodiments of the invention, machine readable memory containing or otherwise storing a program of instructions which, when executed by the machine, implements all or any subset of the apparatus, methods, features, and functionalities of the invention shown and described herein. Alternatively, or in addition, the apparatus of the present invention may include, according to certain embodiments of the invention, a program as above which may be written in any conventional programming language, and optionally a machine for executing the program, such as but not limited to a general-purpose computer which may optionally be configured or activated in accordance with the teachings of the present invention. Any of the teachings incorporated herein may, wherever suitable, operate on signals representative of physical objects or substances.

[0052] The embodiments referred to above, and other embodiments, are described in detail in the next section.

[0053] Any trademark occurring in the text or drawings is the property of its owner and occurs herein merely to explain or illustrate one example of how an embodiment of the invention may be implemented.

[0054] Unless stated otherwise, terms such as, "processing", "computing", "estimating", "selecting", "ranking", "grading", "calculating", "determining", "generating", "reassessing", "classifying", "generating", "producing", "stereo-matching", "registering", "detecting", "associating", "superimposing", "obtaining", "providing", "accessing", "setting" or the like, refer to the action and / or processes of at least one computer / s or computing system / s, or processor / s or similar electronic computing device / s or circuitry, that manipulate and / or transform data which may be represented as physical, such as electronic, quantities e.g. within the computing system's registers and / or memories, and / or may be provided on-the-fly, into other data which may be similarly represented as physical quantities within the computing system's memories, registers or other such information storage, transmission or display devices or may be provided to external factors, e.g., via a suitable data network. The term "computer" should be broadly construed to cover any kind of electronic device with data processing capabilities, including, by way of non-limiting example, personal computers, servers, embedded cores, computing system, communication devices, processors (e.g. digital signal processor (DSP), microcontrollers, field programmable gate array (FPGA), application specific integrated circuit (ASIC), etc.) and other electronic computing devices. Any reference to a computer, controller or processor is intended to include one or more hardware devices, e.g., chips, which may be co-located or remote from one another. Any controller or processor may for example comprise at least one CPU, DSP, FPGA or ASIC, suitably configured in accordance with the logic and functionalities described herein.

[0055] Elements separately listed herein need not be distinct components, and, alternatively, may be the same structure. A statement that an element or feature may exist is intended to include (a) embodiments in which the element or feature exists; (b) embodiments in which the element or feature does not exist; and (c) embodiments in which the element or feature exist selectably, e.g., a user may configure or select whether the element or feature does or does not exist.

[0056] Functionalities shown and described herein may be divided between a server computer and a plurality of client computers. These or any other computerized components shown and described herein may communicate between themselves via a suitable computer network.

[0057] The system shown and described herein may include a user interface which may, for example, include all or any subset of: an interactive voice response interface, automated response tool, speech-to-text transcription system, automated digital or electronic interface having interactive visual components, web portal, visual interface loaded as web page / s or screen / s from server / s via communication network / s to a web browser or other application downloaded onto a user's device, automated speech-to-text conversion tool, including a front-end interface portion thereof and back-end logic interacting therewith. Thus, the term user interface or "Ul" as used herein, includes also the underlying logic which controls the data presented to the user, e.g., by the system display and receives and processes data entered by a user, e.g., using her or his workstation / device.

[0058] BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a simplified optical diagram of a telescope according to an embodiment of the invention.

[0059] Fig. 2 is a perspective drawing of the telescope of Fig. 1.

[0060] Fig. 3 is a simplified block diagram illustration of a telescope system, where the telescope with EM assembly may comprise the apparatus of Figs. 1, 2, or 4.

[0061] Fig. 4 is a variation on the embodiment of Fig. 1 which includes a truss tube telescope rather than a solid tube. In this figure the traditional spiders are shown, however these can be replaced as described herein.

[0062] Fig. 5a illustrates an electromagnetic assembly whose electromagnets are not, contrary to previous embodiments, arranged all along a circle.

[0063] Fig. 5b illustrates another electromagnetic assembly whose electromagnets are not, contrary to previous embodiments, arranged all along a circle.

[0064] Figs. 6a - 6d illustrate a variation, in which the secondary mirror assembly includes a reflective surface (which may be concave or convex) with a diameter D and a support member with a diameter d < D.

[0065] Fig. 7 is a variation on the embodiment of Fig. 2.

[0066] Fig. 8 illustrates prior art telescope apparatus.

[0067] DETAILED DESCRIPTION

[0068] In conventional telescope systems, the secondary mirror's position vis-a-vis the primary mirror is maintained by a mechanical element which engages with and supports the secondary mirror.

[0069] The position of the secondary mirror assembly vis a vis the primary mirror is, conventionally, maintained by mechanical element / s such as "spider / s" (e.g. as shown in Fig. 8); a spider typically falls along the optical path, hence is detrimental to the telescope's performance .

[0070] Many conventional telescopes by NASA, Airbus, Elop, and others use these "spiders" to support their telescopes' secondary mirrors. These "spiders" block at least some light from reaching the camera (or the telescope's primary mirror), thereby diminishing the light / signal-to-noise ratio. This tends to cause diffraction phenomena (e.g. as are prominent in the JWT camera) which are caused by the spiders. Also, these installation methods make performance correction cumbersome (e.g. may require plural high-precision mechanical motors to be operated in space), once the camera is in orbit.

[0071] In contrast, reference is now made to Figs. 1 - 4 which illustrate a telescope system comprising an apertured primary mirror defining an aperture, and a secondary mirror having a typically convex reflective surface positioned to receive light reflected from the primary mirror and configured to concentrate the light into a beam which travels back toward the primary mirror and then through the aperture.

[0072] According to certain embodiments, the secondary mirror's reflective surface comprises a reflective central region, aka reflective area, and the secondary mirror assembly is typically at least partly formed of a magnetic material and / or also comprises at least a portion of an electromagnetic, e.g., metal peripheral annulus. This portion typically comprises an arc which surrounds at least a portion of the secondary mirror's reflective central region, e.g., running along at least a portion of the reflective area's outer perimeter.

[0073] The telescope may be aboard an airborne platform or satellite, or may be a ground or astronomical telescope.

[0074] Typically, the mirrors are both generally circular, and are typically lightweight, and the primary mirror's center and the secondary mirror's center define the main axis.

[0075] Location 10, marked with an x, represents the focal point of the primary mirror.

[0076] Typically, the primary mirror receives light from an object to be imaged; in space this light arrives from infinitely far, hence the light beams are collimated. This light is reflected to the secondary mirror and may travel via an aperture in the primary mirror and typically via a lens assembly and / or via additional (flat and / or non-flat) mirrors to a detector which generates an image of the object to be imaged accordingly.

[0077] Typically, a secondary mirror assembly is provided which includes the secondary mirror itself and a metal (e.g.) annulus or portion thereof, typically peripheral to the secondary mirror. The assembly may also include a baffle, e.g., baffle 405 and a member configured to support the mirror.

[0078] Alternatively, the secondary mirror assembly may, rather than including the metal (e.g.) annulus or portion thereof, include a magnet array as described herein in which case the metal (e.g.) annulus or portion thereof, may be deployed on the telescope tube or truss.

[0079] Typically, e.g. as shown in Fig 7, no baffle is provided; instead, the electromagnets may directly surround the secondary ring.

[0080] In either embodiment, the secondary mirror's position vis-a-vis the primary mirror is maintained, at least at certain times, e.g., post-launch, electromagnetically rather than having to rely on a mechanical element being, disadvantageously, in terms of the telescope's mission, present in the optical field of view to engage with and support the secondary mirror.

[0081] Typically, the annulus is thin compared to the secondary mirror's radius e.g. the secondary mirror's diameter may be, say, 200 mm (order of magnitude) whereas the annulus' width (the radial dimension of the annulus) may be, say, 1-3 degrees of magnitude less than the diameter, e.g., the radial dimension of the annulus may be only a mm wide, order of magnitude (which is 2 degrees of magnitude less than the diameter). The metal peripheral annulus may be glued or otherwise attached to the outer perimeter of the secondary mirror. The annulus is typically not on the (typically convex or concave rather than planar) reflective surface (annulus is typically not in the secondary mirror's main surface), thus the annulus does not adversely affect or block the telescope's optical path.

[0082] The secondary mirror assembly may, for example, be at least partly formed of a magnetic material, e.g., metal. In the illustrated embodiment, the secondary mirror assembly comprises a mirror formed, say, of glass (or other material characterized by a low coefficient of thermal expansion, e.g., Zerodure), and surrounded by a metal annulus 240. A metal annulus may be attached to the secondary mirror; the annulus need not be circular as is shown in the illustrated embodiment, and need not be point-symmetrical. The secondary mirror is typically circular, however this is not necessarily the case; the secondary mirror may be, say, oval or rectangular, or a hexagon or octagon or triangle, or any other desired shape.

[0083] An assembly of electromagnets (of which, by way of example, nine are shown) at least partly surrounds the secondary mirror assembly, to stabilize the secondary mirror assembly relative to the primary mirror, even absent any physical support for the secondary mirror. The electromagnets are not shown in Fig. 1, for simplicity.

[0084] In one of the illustrated embodiments, a ring of (by way of example) 18 electromagnets is provided, surrounding the secondary mirror, of which nine are visible in Fig. 2. The electromagnets are equally spaced in the illustrated embodiment, however this need not be the case. The electromagnets may be, but need not be, equidistant from the center of the secondary mirror. The electromagnets may be, but need not be, identical among themselves. Typically, the electromagnets are positioned outside the field of view, e.g., on the tube or on the metering structure.

[0085] It is appreciated that the electromagnets need not be positioned along an imaginary circular ring surrounding the secondary mirror; they may be, instead, positioned along an imaginary square or triangle, or any other closed or concave curve which at least partly surrounds the secondary mirror.

[0086] According to certain embodiments, the secondary mirror assembly floats and is (at least sometimes) not mechanically supported being instead attached to or integrally formed with a metal (e.g. a metal ring surrounding a circular secondary mirror) which enables electromagnets typically distributed along a closed curve, at least partly or completely surrounding the secondary mirror assembly, to cause the secondary mirror assembly to float in place without any mechanical support. The magnets' fields typically have different directions which enable the secondary mirror's orientation, which is determined by the vector sum of the applicable magnetic fields, to be adjusted by simply adjusting the current supplied to all or some of the electromagnets, to yield a vector sum corresponding to the new desired orientation. According to certain embodiments, the secondary mirror assembly floats relative to the telescope, being mechanically separate therefrom.

[0087] Typically, each magnet in the assembly comprises an electromagnet and the direction and / or force of that magnet's magnetic field may be adjusted separately and independently of other magnets. Typically, during launch, the secondary mirror assembly is held in place by a mechanical arrangement which may be retractable to enable the mechanical arrangement to be retracted once the telescope reaches the orbit. The magnet assembly may then be activated, e.g., using a look-up-table of parameters typically, e.g. magnitude of electrical current for each of the magnet in the magnet assembly determined during a calibration and a testing process in the laboratory or factory, using optical feedback (such as Modulation transfer function (MTF) and / or phase-transfer function (PTF) and / or point spread functions (PSF). Typically, at the end of the calibration / testing process, when the currents applied to the magnets are deemed suitable in magnitude and direction, e.g., because the secondary mirror is deemed to be properly positioned, all currents applied to all magnets are recorded and may be stored in the look-up table.

[0088] Referring now to Figs. 1 - 2, according to an embodiment of the invention, the telescope comprises a metering structure or housing or case e.g. solid (as opposed to truss) tube 220 defining a main axis and / or initial distance between the primary and secondary mirrors, and the primary and secondary mirrors are both perpendicular to the main axis.

[0089] The housing, e.g., tube, may protect the internal optics from (physical trauma and also from) outside aka incidental aka stray light (thereby to block light, which, although it does not come from the target, might otherwise undesirably become part of the image of the target generated by the telescope) and / or moisture and / or dust and / or other contaminants. The housing may also reduce temperature variations, which may cause distortion of the image seen through the telescope. The housing may facilitate optical alignment, or collimation, of the apparatus along the optical path, e.g., from the objective (mirror or lens), via the secondary mirrors, and finally to the detector, sensor, or eyepiece. The housing may also support or serve as a mechanical platform for other auxiliary hardware, such as but not limited to a finder scope and / or red dot finder and / or laser holder and / or guide scope and / or camera. All or some optical components may, sometimes or permanently, be attached to the optical bench and / or bezel. The housing may also serve as a platform enabling the optical components to be pointed in a desired direction.

[0090] The tube's cross section may be any suitable shape e.g. circular as shown, square, hexagonal etc. The tube 220 in Fig. 2 is just one example of a metering structure which may be used to maintain the fixed relative positions of the primary and secondary mirrors; alternatively, the "metering structure" may comprise suitable trusses, for example.

[0091] In the embodiment of Fig. 4, the telescope comprises a truss tube telescope. More generally, any type of telescope may be employed.

[0092] Use of a truss tube telescope may be advantageous in that relative to a solid tube, the truss 410 is lightweight which may be critical in space, and / or in terms of thermal stability of the system. The embodiment of Fig. 4 also typically comprises all or any subset of secondary mirror baffle 405, a secondary mirror reference center 422 and a telescope optical bench 425. The spider 415 shown in Fig. 4 may however be obviated or eliminated e.g. by deploying electromagnets in conjunction with a metal annulus, both as described herein, which would then physically stabilize or support the secondary mirror, rather than spider / s. It is appreciated that the electromagnets may be added to the embodiment of Fig. 4 in accordance with the embodiment of Fig. 2, in which the electromagnets are peripheral relative to the annulus, or in accordance with the embodiment of Fig. 7, in which the annulus is peripheral relative to the electromagnets.

[0093] The current at which each electromagnet is to operate may be fixed once the secondary mirror assembly has been calibrated and aligned. The current for each electromagnet may be adjusted in a factory or laboratory or in orbit to increase system performance.

[0094] It is appreciated that currents flowing through or applied to "parallel" magnets, whose magnetic fields are parallel to the tube's optical axis, affect the secondary mirror's Y1 tilt, whereas currents flowing through or applied to "perpendicular" magnets, whose magnetic fields are perpendicular to the optical axes, can translate the secondary mirror assembly within its own main plane, e.g., right or left, or up or down, within the secondary mirror's own main plane or main surface), depending on the angular orientation (e.g. position along the ring) of each "perpendicular" magnet.

[0095] In the illustrated embodiment, magnets 245 include parallel magnets 245a (Figs. 2, 7) presented in bold and perpendicular magnets 245b represented with hatching. For simplicity, the actual shape of the magnets is not necessarily as shown.

[0096] Fig. 3 is a simplified block diagram illustration of a telescope system where the telescope with EM assembly may comprise the apparatus of Figs. 1, 2, or 4. The system typically comprises all or any subset of the telescope itself 310, a camera / spacecraft controller or CCU 320, power distribution / supply unit 330, connector 340, payload or camera 355, satellite 360 or other platform bearing the telescope, and a ground unit 370 which provides controls even after the satellite is in orbit.

[0097] The terms camera and payload may be interchanged herein. The term telescope may be used to include the optics and their mechanical support only, whereas the term camera may be used to include the telescope, detector, and their electronics.

[0098] Any suitable detector may be employed such as, for example, an electronic image sensor, e.g., charge-coupled device (CCD) sensor or CMOS sensor. The Detector and its electronics may be incorporated into a focal plane assembly 350 (Fig. 3) aka FPA which is typically connected to the camera control unit, e.g., via a different connector.

[0099] Typically, the magnets which hold the floating secondary mirror assembly in place are electrically connected, e.g., via a connector as shown, and cable (not shown) to the camera / spacecraft controller, which determines how much current is supplied to which magnet / s, and when.

[0100] Any suitable control scheme may be employed for the controller.

[0101] Typically, a magnetic field is computed, which is related to the current flow in the magnets which may vary over time, and which is able to hold the secondary mirror in place . This field typically depends on the Secondary mirror weight and / or number of balancing electromagnets aka EMs and / or distance between the magnetic ring (aka ring of magnets) and annulus and / or on the electromagnetic characteristics of the magnets, typically on all the above. Accordingly, the amount of current supplied to each magnet, over time, may be determined.

[0102] Typically, the direction of the magnetic field is fixed for each magnet (e.g. each electromagnet). Each electromagnet typically has at least two wires which are respectively connected to at least two assigned pins in the camera / spacecraft controller of Fig. 3 (not shown for simplicity), and current change may then be applied via these pins and wires to the electromagnet connected thereto. A suitable bracket, or other mechanical means (not shown for simplicity) may secure the connectors in place. Typically, although not necessarily, the connector of Fig. 3 includes a pair of pins for each electromagnet. According to certain embodiments, plural ground wires / pins can be replaced by a single wire / pin.

[0103] The connector provides interface between the telescope and the CCU, and the power distribution unit provides power for whatever current is required, via the connector to the electromagnet assembly from the camera / spacecraft (S / C) power distribution unit connected to the solar panels of the camera / spacecraft (S / C). The CCU (Camera control unit) is typically connected to the power supply unit (PSU) to receive power from the camera / spacecraft (S / C).

[0104] According to certain embodiments, a method (method B) for using the apparatus herein (typically "in the field", e.g., in space) including proper positioning of the secondary mirror, may include all or any subset of the following operations: a. Provide a platform, e.g., satellite. b. Provide a telescope including support / tube (solid, trussed, other) and a primary mirror. c. Provide a secondary mirror assembly at least partly formed of a material which can be activated electromagnetically; typically, the secondary mirror is suitably calibrated. d. Position the secondary mirror assembly vis-a-vis the primary mirror. Support in position by removable or retractable or foldable or contractable or compressible mechanical support element, e.g., an arm. It is appreciated that the secondary mirror assembly may be positioned, typically mechanically, only after launch, to enable the assembly to reside in a safe location (not necessarily opposite the primary mirror) during launch, given that turbulence is expected. e. Provide A magnet assembly. f. Turn on assembly's electromagnets, e.g., using current values and directions as stored in a LUT typically generated in a laboratory, as described elsewhere herein. g. Retract mechanical element (or otherwise removed from telescope's field of view or the optical path defined by the telescope, e.g., by translation, retraction, folding, contraction, or compression). Typically, this operation is performed when the platform's motion is smooth enough to ensure that the secondary mirror assembly can be held in place electromagnetically, at which point the mechanical element's presence along the optical path may be terminated.

[0105] According to certain embodiments, each time S / C control detects what appears to be a power drop, the arm / support element which supported the secondary mirror during launch is re-activated, typically including restoring this arm to the position (typically within the telescope's field of view) that the arm occupied during launch, to enable the arm to again support the secondary mirror physically, rather than relying on power-dependent electromagnetic support for the secondary mirror. When suitable logic detects that the risk of a power drop has been averted (power is back up), the arm is again retracted.

[0106] According to other embodiments, once the mechanical element, e.g., arm, has been retracted (typically post-launch), the arm remains outside the telescope's field of view, and does not return under any eventuality. h. During orbit, each time it is desired (e.g. as indicated by ground station) to improve or modify image capture, adjust orientation of secondary mirror by adjusting power to certain of the electromagnets. It is appreciated that various scenarios may be adopted to handle a temporary crisis situation, in which voltage in the batteries temporarily drops below a certain point. For example, the secondary mirror assembly may be held in place using only some but not all of the electromagnets, to prevent the secondary mirror assembly from being so badly mis-positioned during the crisis situation that the mirror cannot be retrieved once the crisis is over; and / or the mechanical element may be restored to its active position e.g., typically, brought back into the telescope's field of view.

[0107] Typically, while these scenarios are playing out, no images are captured; once the crisis has been overcome and the voltage is restored, image capture resumes.

[0108] A method ("method A") for laboratory assembly and calibration of the secondary mirror yielding a LUT of current magnitudes and directions for each of the electromagnets, which LUT may be used in method B, may include all or any subset of the following operations, suitably ordered e.g. as follows:

[0109] 1. Build or provide an optical assembly to secure or align the secondary mirror assembly; for example: interferometer, dedicated target / s e.g. as described below, a flat calibration mirror typically deployed in front of the telescope to reflect interferometer light back onto itself, a computer with wavefront error S / W such as, by way of non-limiting example, https: / / www.vermontphotonics.com / interferometer-software to analyze interferograms during the alignment process (e.g. operations 3 - 7 below).

[0110] 2. Temporarily attach the secondary mirror assembly to mechanical support which is typically deployed in front of the primary mirror, typically as close as possible to the desired location of the secondary mirror.

[0111] 3. Given a nominal design which determines the secondary mirror's desired position, compute current for each of the electromagnets in the magnet assembly, e.g., ring, yielding plural currents which, when all are applied to the plural respective electromagnets in the assembly e.g., ring, retain the secondary mirror assembly in its desired position.

[0112] 4. Evaluate telescope performance (e.g., measure WFE (wavefront error) which is a known metric quantifying one type of telescope distortion, and determine whether required performance (e.g. a predetermined acceptable WFE level) has been achieved. If achieved, store all electromagnets' currents in a lookup table (e.g. in a camera / spacecraft (S / C) control unit) and END.

[0113] 5. If required performance (e.g. a predetermined acceptable WFE level) has not yet been achieved, use software to estimate a displacement / tilt of the secondary mirror assembly which would enhance performance.

[0114] 6. Convert this displacement / tilt to current change in all or a subset of the electromagnets.

[0115] 7. Return to operation 4.

[0116] Thus, typically, mirror orientation includes changing the current of the corresponding electromagnet. The direction and strength of the change (of the secondary mirror) is computed using dedicated software which decodes the interferogram and the Zernike coefficients computed therefrom. The software, such as, say, vermontphotonics.com / interferometer-software, is configured to predict direction and size, so that the next measurement, after changing the direction of the secondary mirror, yields a better WFE, until a desired level of telescope performance is obtained. At that point, the current supplied to each electromagnet is measured and recorded, e.g., in a LUT (look-up table), which may then be retrieved from satellite controller memory in which it is desired to position the secondary mirror, subsequently, e.g., once the satellite is in orbit.

[0117] The same LUT may also be stored in a ground station (e.g., so ground station can determine that the current applied to electromagnet 12 needs to increase from 1 to 1.03 ampere).

[0118] To help fix aberrations, or when a change in the secondary mirror assembly position is predicted from images taken from space in orbit or during conventional camera tests in the lab, a ground command to change one or more electromagnets' current / s may be sent to the camera / spacecraft (S / C) control unit (where the look-up table as described may be stored) . The term "lab" or "laboratory" as referred to herein refers to any suitable conventional clean room / vacuum chamber / testing area used, e.g., during performance tests of the camera before and / or after integration of the camera into the satellite and / or before launching the satellite.

[0119] Thus, current applied to electromagnet / s can be changed even in orbit, e.g., by the camera / spacecraft computer in accordance with ground command. In orderto ensure that the current change is correct in sign and in value, a ground simulator may be built, and the required change may be tested prior to sending the command.

[0120] Any suitable in-orbit feedback control may be provided. For example, in orbit, camera performance may be measured by analyzing images of dedicated targets (e.g. on- ground target imaging). Targets (which may be located on ground) may comprise point like light source / s and / or knife-edge target / s and / or sharp edges generally. Targets need not be located on ground, e.g., real star / s may be used as point-like light source targets. Analyzing images of such target / s yields an indication of which residual aberration / s and / or mis-alignments and / or gravitation effects, and / or de-focus, in images generated by the telescope, are being produced by the camera. Accordingly, the system may determine that change / s in current are to be applied to one or more electromagnets and the direction and value of the change / s is determined.

[0121] Each such change may be tested in the simulator in the lab and / or each change may be tested using the camera in space, e.g., as per method A above.

[0122] Target image analysis aka image interpretation may include providing the camera PSF / MTF in space environment.

[0123] For example, the following online source: https: / / www.sdstate.edu / image-processing-lab / psfmtf- estimation#:~:text=A%20point%20spread%20function%20(PSF,a%20slight%20amount% 20of%20defocus describes inter alia that: "A point spread function (PSF) or modulation transfer function (MTF) is a measure of how well focused a satellite imaging sensor is. Every type of camera system has a slight amount of defocus. Our work in this category is estimating the amount of defocus based on the satellite's image of specially developed ground targets." by way of example, the above source goes on to say that:

[0124] "Three types of targets are used: edge, pulse and point targets. Edge targets and pulse targets consist of placing a highly reflective material next to a very dark material. These could be tarps spread out on the ground, or level smooth surfaces painted with highly reflective (white) paint and dark (black) paint. Point targets are sets of mirrors that reflect the sunlight to the sensor. This light is seen by the sensor as a point source on the ground and the amount of degradation in the sensor's image of that point source is a direct measure of the PSFfor that system.

[0125] From the image data collected of these targets, calculations are performed to estimate either the PSF or MTF. The MTF is simply the normalized Fourier Transform of the PSF. Therefore, when one function is obtained, so is the other. In general, both the PSF and MTF are functions of two dimensions. However, the full function is difficult to obtain, so typically only the along-track and cross-track components of the PSF and MTF are furnished to the customer.

[0126] Most satellite sensors are specified by meeting certain thresholds on the PSF and / or the MTF such as full width half maximum (FWHM) or MTF at the Nyguist freguency. Thus, our estimates of these functions, along with these specific measures, allow the customer to determine if his or her satellite is meeting specifications in this category of performance" .

[0127] From the image interpretation results, a fine secondary mirror assembly displacement / tilt which will reduce the residual aberration / de-focus, hence increase camera performance, may be computed. Any suitable technology may be employed to compute by how many milliampere the current for a given electromagnet may increase.

[0128] For example, in addition to tests in the laboratory before the launch, e.g. as described herein and / or as is known in the art, a simulator may be designed, with which to test a desired repair. After examination in the simulator, a command detailing which electromagnet / s' current is to be changed and to what value, may be formulated (or, alternatively, the command may stipulate the additional current to be added to or subtracted from the electromagnet in question).

[0129] This may occur repeatedly, which may be advantageous due to possible repeated changes in gravitation and / or pressure and / or temperature differences which may change residual aberration from time to time.

[0130] Example: a need to change a secondary mirror's displacement / tilt is identified. The needed change is transformed to needed change / s in currents applied to certain electromagnet / s, e.g., the ground station determines that the current for a given electromagnet M should increase by, say, 15 milliampere. A ground command to increase M's current accordingly is then conveyed to the camera / spacecraft (S / C) control unit aka controller.

[0131] Typically, the mirrors are both generally circular, and typically undergo a lightweighting process to remove, say, between 50%-70% of the weight the mirror would have, absent light-weighting. For example, Optical Surfaces Ltd. uses light-weighting techniques that reportedly reduce the weight of a mirror by as much as 60%, e.g., by reducing bulk of the mirror's back surface.

[0132] Many variations are possible.

[0133] For example, if the entire secondary mirror is formed of a magnetic material, no separate metal annulus need be provided. Also, electromagnetic elements herein may instead be permanent magnets, and vice versa. Also, metal elements may be magnetic, but non-metal.

[0134] Fig. 5a illustrates an electromagnetic assembly whose electromagnets are not, contrary to previous embodiments, arranged all along a circle. In this embodiment, plural magnets (say, 2, or 4, or 10, or more) are arranged (typically equally distanced) along each of the 4 arcs in the illustration. No magnets are deployed between arcs. The length of each arc may be 1 / 8 of the perimeter of the imaginary circle (e.g. outer surface of the telescope tube) along which all four arcs lie. The arrangement provides 90° rotational symmetry about the origin of the imaginary circle. The distance along the perimeter between each two adjacent arcs may also be 1 / 8 of the perimeter. The magnets may be attached to the outer surface of the telescope tube.

[0135] Fig. 5b illustrates another electromagnetic assembly whose electromagnets are not, contrary to previous embodiments, arranged all along a circle. In this embodiment, plural magnets (say, 2, or 4, or 10, or more) are arranged (typically equally distanced) along each of the three arcs in the illustration. No magnets are deployed between arcs. The length of each arc may be 1 / 6 of the perimeter of the imaginary circle (e.g. outer surface of the telescope tube) along which all three arcs lie. This arrangement provides 60° rotational symmetry about the origin of the imaginary circle. The distance along the perimeter between each two adjacent arcs may also be 1 / 6 of the perimeter. The magnets may be attached to the outer surface of the telescope tube.

[0136] It is appreciated that symmetry about the origin or point-symmetry facilitates easy control of the secondary mirror assembly position. However, optionally, a non- symmetrical configuration may also be provided.

[0137] The term "metal" (Fe, for example) herein may be replaced with a reference to any material which responds to an electromagnetic field, thereby causing the secondary magnet's orientation and / or position to be affected by the strength of magnetic field applied by each of the electromagnets surrounding the secondary magnet.

[0138] The number of magnets may be defined according to the required degree of freedom and / or the balanced forces required to keep the secondary mirror assembly in its position. Thus, for example, the ring may comprise, say, only three or four electromagnets. Yet if, say, three rotational and three linear degrees of freedom are to be provided to the secondary mirror, more magnets may be provided than if the secondary mirror needs only the linear degrees of freedom. Another design consideration determining the number of electromagnets may be balance between secondary mirror assembly weight and / or stability required and / or orbit conditions, (which, in turn may depend on which camera / spacecraft (S / C) maneuvers must be provided for) and / or the force that is to be applied to the secondary mirror's magnets. Fig. 6a illustrates an alternative embodiment or variation in which the secondary mirror assembly includes a reflective surface (which may be concave or convex) with a diameter D and a support member with a diameter d < D. for example, d may be 185 mm, whereas D may be 200 mm. An annulus or a segment or arc or azimuthal portion thereof then encircles the support member; the width (radial dimension) of the (typically metal) annulus may be a single mm in width, or may be 15 mm in width (200-185 mm) to provide structural stability to the back of the reflective surface. In this configuration, the annulus is typically hidden by the secondary mirror reflective surface, hence does not introduce any additional obscuration of the incoming light. Fig. 6b is a top view of the secondary mirror's reflective surface. Fig. 6c is a top view of the annulus segment of Fig. 6a. Fig. 6d is a bottom view of the secondary mirror.

[0139] Fig. 7 is a variation on the embodiment of Fig. 2 in which the magnets surround the secondary mirror, e.g., are secured to the secondary mirror's periphery, and a magnetic, e.g., metal annulus is mounted peripherally relative to the magnets, e.g., is secured to the tube's outer annular surface, instead of other way as in Fig. 2, in which the magnets are mounted peripherally relative to the annulus, e.g., are secured to the tube's outer annular surface, whereas the magnetic, e.g., metal annulus may be secured to the secondary mirror's peripheral surface. In both cases, current flowing through the magnets affects or governs the orientation of the secondary mirror. However, if the system is regarded as having an electromagnetic component fixed relative to the secondary mirror's periphery, and an electromagnetic member peripheral to the electromagnetic component, then, in Fig. 2, the more peripheral electromagnetic component comprises the magnets, whereas the more central electromagnetic member comprises a magnetic annulus or portion thereof, whereas, in the embodiment of Fig. 7, the less peripheral or more central electromagnetic component comprises the magnets, whereas the more peripheral electromagnetic member comprises a magnetic annulus or portion thereof.

[0140] Any suitable telescope technology may be used to augment the system herein. For example, the primary mirror may be segmented, and may, for example, comprise a honeycomb array of mirrors, which are each hexagonal. Advantages of certain embodiments may include all or any subset of the following: ability to improve camera performance, even once the camera is already in orbit; ability to fine-tune a camera in the laboratory, even in real environmental conditions, e.g., inside a thermal vacuum chamber; images obtained by the camera are free of diffraction phenomena resulting from use of spiders to support a secondary mirror; reduced risk in manufacturing and placing cameras in orbit, since post-launch realignment, e.g., using any technology described herein, can compensate for some residual aberrations from manufacturing such as gravity relief and from the launch campaign.

[0141] Applicability of embodiments herein include cameras based on mirror telescopes, including for use in outer space.

[0142] It is appreciated that terminology such as "mandatory", "required", "need" and "must" refer to implementation choices made within the context of a particular implementation or application described herewithin for clarity, and are not intended to be limiting, since, in an alternative implementation, the same elements might be defined as not mandatory and not required, or might even be eliminated altogether.

[0143] Components described herein as software may, alternatively, be implemented wholly or partly in hardware and / or firmware, if desired, using conventional techniques, and vice-versa. Each module or component or processor may be centralized in a single physical location or physical device or distributed over several physical locations or physical devices.

[0144] Included in the scope of the present disclosure, inter alia, are electromagnetic signals in accordance with the description herein. These may carry computer-readable instructions for performing any or all of the operations of any of the methods shown and described herein, in any suitable order, including simultaneous performance of suitable groups of operations as appropriate. Included in the scope of the present disclosure, inter alia, are machine-readable instructions for performing any or all of the operations of any of the methods shown and described herein, in any suitable order; program storage devices readable by machine, tangibly embodying a program of instructions executable by the machine to perform any or all of the operations of any of the methods shown and described herein, in any suitable order i.e. not necessarily as shown, including performing various operations in parallel or concurrently, rather than sequentially, as shown; a computer program product comprising a computer useable medium having computer readable program code, such as executable code, having embodied therein, and / or including computer readable program code for performing, any or all of the operations of any of the methods shown and described herein, in any suitable order; any technical effects brought about by any or all of the operations of any of the methods shown and described herein, when performed in any suitable order; any suitable apparatus or device or combination of such, programmed to perform, alone or in combination, any or all of the operations of any of the methods shown and described herein, in any suitable order; electronic devices, each including at least one processor and / or cooperating input device and / or output device and operative to perform, e.g., in software, any operations shown and described herein; information storage devices or physical records, such as disks or hard drives, causing at least one computer or other device to be configured so as to carry out any or all of the operations of any of the methods shown and described herein, in any suitable order; at least one program pre-stored, e.g., in memory or on an information network such as the Internet, before or after being downloaded, which embodies any or all of the operations of any of the methods shown and described herein, in any suitable order, and the method of uploading or downloading such, and a system including server / s and / or client / s for using such; at least one processor configured to perform any combination of the described operations or to execute any combination of the described modules; and hardware which performs any or all of the operations of any of the methods shown and described herein, in any suitable order, either alone or in conjunction with software. Any computer-readable or machine-readable media described herein is intended to include non-transitory computer- or machine-readable media.

[0145] Any computations or other forms of analysis described herein may be performed by a suitable computerized method. Any operation or functionality described herein may be wholly or partially computer-implemented, e.g., by one or more processors. The invention shown and described herein may include (a) using a computerized method to identify a solution to any of the problems or for any of the objectives described herein, the solution optionally including at least one of a decision, an action, a product, a service or any other information described herein, that impacts, in a positive manner, a problem or objectives described herein; and (b) outputting the solution.

[0146] The system may, if desired, be implemented as a web-based system employing software, computers, routers, and telecommunications equipment, as appropriate.

[0147] Any suitable deployment may be employed to provide functionalities, e.g., software functionalities shown and described herein. For example, a server may store certain applications, for download to clients, which are executed at the client side, the server side serving only as a storehouse. Any or all functionalities, e.g., software functionalities shown and described herein, may be deployed in a cloud environment. Clients, e.g., mobile communication devices such as smartphones, may be operatively associated with, but external to the cloud.

[0148] The scope of the present invention is not limited to structures and functions specifically described herein, and is also intended to include devices which have the capacity to yield a structure, or perform a function described herein, such that even though users of the device may not use the capacity, they are, if they so desire, able to modify the device to obtain the structure or function.

[0149] Any "if -then" logic described herein is intended to include embodiments in which a processor is programmed to repeatedly determine whether condition x, which is sometimes true and sometimes false, is currently true or false, and to perform y each time x is determined to be true, thereby to yield a processor which performs y at least once, typically on an "if and only if" basis, e.g., triggered only by determinations that x is true, and never by determinations that x is false.

[0150] Any determination of a state or condition described herein, and / or other data generated herein, may be harnessed for any suitable technical effect. For example, the determination may be transmitted or fed to any suitable hardware, firmware, or software module, which is known or which is described herein, to have capabilities to perform a technical operation responsive to the state or condition. The technical operation may, for example, comprise changing the state or condition, or may more generally cause any outcome which is technically advantageous, given the state or condition or data, and / or may prevent at least one outcome which is disadvantageous, given the state or condition or data. Alternatively, or in addition, an alert may be provided to an appropriate human operator or to an appropriate external system.

[0151] Applicability of the subject matter disclosed herein is not limited to embodiments claimed, nor to solutions for specific disadvantages emphasized herein, nor need any element of any system and method described herein, on its own or in combination with other elements described herein, operate only in environments or use-cases or technology areas such as those described herein.

[0152] Features of the present invention, including operations, which are described in the context of separate embodiments, may also be provided in combination in a single embodiment. For example, a system embodiment is intended to include a corresponding process embodiment, and vice versa. Also, each system embodiment is intended to include a server-centered "view" or client centered "view", or "view" from any other node of the system, of the entire functionality of the system, computer-readable medium, apparatus, including only those functionalities performed at that server or client or node. Features may also be combined with features known in the art, and particularly, although not limited to, those described in the Background section or in publications mentioned therein.

[0153] Conversely, features of the invention, including operations, which are described for brevity in the context of a single embodiment or in a certain order, may be provided separately or in any suitable sub-combination, including with features known in the art (particularly although not limited to those described in the Background section or in publications mentioned therein) or in a different order, "e.g." is used herein in the sense of a specific example which is not intended to be limiting. Each method may comprise all or any subset of the operations illustrated or described, suitably ordered, e.g., as illustrated or described herein.

[0154] Devices, apparatus, or systems shown coupled in any of the drawings, may in fact be integrated into a single platform in certain embodiments, or may be coupled via any appropriate wired or wireless coupling, such as but not limited to optical fiber, Ethernet, Wireless LAN, HomePNA, power line communication, cell phone, Smart Phone (e.g. iPhone), Tablet, Laptop, PDA, Blackberry GPRS, Satellite including GPS, or other mobile delivery. It is appreciated that in the description and drawings shown and described herein, functionalities described or illustrated as systems and sub-units thereof, can also be provided as methods and operations therewithin, and functionalities described or illustrated as methods and operations therewithin can also be provided as systems and sub-units thereof. The scale used to illustrate various elements in the drawings is merely exemplary and / or appropriate for clarity of presentation and is not intended to be limiting.

Claims

CLAIMS1. A telescope system comprising: a primary mirror; a secondary mirror assembly including a secondary mirror including a reflective surface positioned to receive light reflected from the primary mirror and configured to concentrate the light into a beam and having a magnetic component fixed relative to the secondary mirror's periphery; and a magnetic member peripheral to the magnetic component, thereby to stabilize the secondary mirror assembly relative to the primary mirror, even absent any physical support for the secondary mirror.

2. A system according to claim 1 wherein the magnetic component comprises an assembly of magnets at least partly surrounding the secondary mirror assembly and wherein the magnetic member comprises at least a portion of an electromagnetic annulus.

3. A system according to claim 2 wherein the magnetic member comprises an assembly of magnets at least partly surrounding the secondary mirror assembly and wherein the magnetic component comprises at least a portion of the electromagnetic annulus.

4. A system according to claim 1 wherein the secondary mirror is convex.

5. A system according to claim 2 or claim 3 wherein at least a portion of the electromagnetic annulus is formed of a magnetic material such as metal.

6. A system according to claim 1 wherein the magnetic member or magnetic component comprises an assembly of magnets which comprises a ring of magnets surrounding the secondary mirror.

7. A telescoping method comprising: providing a reflective telescope comprising a structure; and in the structure, providing accurate positioning to a primary mirror assembly and a secondary mirror assembly stabilized electromagnetically, relative to the primary mirror, even absent any physical support for the secondary mirror.

8. The method of claim 7 wherein the secondary mirror assembly, at least on occasion, floats within a ring of electromagnets, without any mechanical support.

9. The method of claim 7 wherein the reflective telescope is deployed on a moving platform whose motion is initially rough or highly turbulent) and then becomes smoother or less turbulent, and wherein the secondary mirror assembly is supported mechanically while the platform's motion is initially rough and then floats within the ring of electromagnets, without any physical support, once the motion becomes smoother and current is applied to each electromagnet.

10. The method of claim 9 wherein the primary mirror and secondary mirror define an optical path for light reaching the telescope system and wherein the secondary mirror is supported mechanically by and / or engaged by a retractable physical support member which, when the motion becomes smoother, is retracted and / or is withdrawn from engagement with the secondary mirror and / or is removed from the optical path.

11. The method of claim 9 wherein the moving platform comprises a satellite whose motion becomes smoother (e.g. less turbulent) once the satellite is in orbit, relative to the satellite's motion before the satellite goes into orbit.

12. The system of claim 2 or claim 3 wherein the assembly of magnets comprises electromagnets defining axes, and wherein, for a first subset of the electromagnets, the axes have a component parallel to a main axis.

13. The system of claim 12 wherein, for a second subset of the electromagnets, the axes have a component perpendicular to the main axis.

14. The system of claim 12 wherein the first subset of electromagnets' axes are parallel to the main axis, and the second subset of electromagnets' axes are perpendicular to the main axis.

15. The system of claim 1 wherein a controller determines a current at which each electromagnet is to operate.

16. The system of claim 2 wherein the magnets comprise permanent magnets.

17. The system of claim 2 wherein the magnets comprise electromagnets.

18. A system according to claim 1 and also comprising a structural member encasing the primary mirror, and wherein the magnetic member, peripheral to the magnetic component, is fixed to the structural member.

19. A system according to claim 1 wherein the structural member is cylindrical, thereby to define a tube having a main axis perpendicular to a main plane of the primarymirror, and wherein the magnetic member is fixed to, e.g., attached to, an external surface of the tube.

20. A system according to claim 1 wherein the primary mirror is apertured, defining an aperture, and wherein the secondary mirror assembly's reflective surface is positioned to receive light reflected from the primary mirror and to concentrate the light into a beam which travels back toward the primary mirror and then through the aperture.

21. A system according to claim 1 which forms an off-axis telescope.

22. The system of claim 6 wherein the ring of magnets is fixed to, e.g., mounted on, the structural member's external surface.

23. The system of claim 6 wherein the ring of magnets is mounted on the structural member's internal surface.

24. The system of claim 1 wherein the ring of magnets is deployed interiorly to a volume defined by the structural member's typically cylindrical walls.

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