Optical system, in particular telephoto device

Abstract

The optical system includes an optical device, the optical device being a spherical body or having a spherical shape, and the optical device including: a first spherical surface; a plurality of block bodies which are adjacent in pairs, wherein the plurality of block bodies which are adjacent in pairs cover the first spherical surface; and at least one optically transparent filling substance accommodated in the spherical cavity of the optical device. The optical system includes: a curved focal plane surrounding an optical device and on which an image generated by the optical device is focused; and a receiving device including a plurality of chambers arranged at a curved focal plane. Each chamber includes a field lens and a diaphragm disposed downstream of the field lens with respect to a center of the optical device. A center of the diaphragm is located on an optical axis of the field lens such that an optical projection of the diaphragm on the optical device through the field lens defines a virtual diaphragm extending into the optical device.

Description

Technical Field

[0001] The invention relates to an optical system, in particular to a telescopic device. Background Art

[0002] The invention has preferred (but not exclusive) application in the technical field relating to devices or instruments for observing objects at great distances, and in particular in the technical field relating to optical instruments for observing celestial bodies used in astronomy, wherein a continuous search of the visible sky from a single point on the surface of the Earth or of a planet is usually required.

[0003] The invention can also be applied to optical instruments where half of the total available field of view is of particular interest, such as for example in observations of the sea bed from the keel of a ship or observations of the Earth's surface from a satellite in low orbit.

[0004] In the case of night applications, from a single point on the Earth's surface, this type of search consists of patrolling for transient phenomena (e.g. changes in brightness, color, shape or position) of natural or artificial objects in the wavelength range of visible radiation and in the ranges adjacent to it (infrared and ultraviolet). A non-exhaustive list of these transient phenomena in the field of natural phenomena may include, for example, novae and supernovae, variable stars, eclipsing binaries, stars with transiting exoplanets, asteroids, asteroids in close Earth orbit, meteorites, atmospheric phenomena (lightning flashes, cloud formations, etc.), gamma flashes, and currently unknown phenomena. A similar non-exhaustive list of visible artificial phenomena, for which the search system is capable of simultaneous observation of half of the entire field of view, not necessarily but usually preferably under night conditions, includes, for example, transits of artificial satellites, orbital debris (commonly referred to as "space junk"), missiles and rockets (including upper stages of suborbital or orbital launches), releases of gases at high altitudes, aircraft, contrails, and drones.

[0005] The ability to detect these phenomena depends critically on the ability of the observing system to simultaneously collect light from the entire sky with as many equivalent openings as possible. The equivalent opening represents the geometric surface size of the collection of light emitted by the phenomenon of interest, such as, for example, those listed above.

[0006] Typically, large aperture optics are not compatible with a large field of view unless a large number of large aperture optics are added.

[0007] For example, taking as a reference an aperture equivalent to that of a circular aperture of one meter in diameter, a conventional telescope is capable of covering a field of view of the order of one square degree. Even current optical systems with a field of view of one meter in diameter and an aperture of more than ten square degrees would require the replication of thousands or tens of thousands of such telescopes to simultaneously cover the entire sky at a single location on Earth or, equivalently, at the same time, at the entire sky.

[0008] Therefore, in the case of small apertures (up to a maximum equivalent diameter of several tens of centimeters), the problem of searching the entire sky with a small aperture is usually solved by large-scale replication of the telescope.

[0009] By way of example, consider the article by LAW NICHOLAS M.ET AL: “Low-cost Access to the Deep, High-cadence Sky: the Argus Optical Array”, PUBLICATIONS OF THEASTRONOMICAL SOCIETY OF THE PACIFIC, vol. 134, no. 1033, 1 March 2022 (2022-03-01), page 035003, XP093001948, US, ISSN: 0004-6280, D01: 10.1088 / 1538-3873 / ac4811. The article relates to the “ARGUS” array, which comprises a group of about a thousand telescopes with a diameter of about 20 cm, each of which is arranged on a sphere with a diameter of about 15 m. Regardless of the overall size of the artifact, its equivalent opening is still comparable to the diameter of a single telescope, which happens to be equal to 20 cm in diameter.

[0010] This technical solution is particularly inefficient from a volumetric point of view while maintaining a moderately equivalent opening.

[0011] On the other hand, for openings of the order of meters or more, Schmidt-type or "FlyEye"-type telescopes are known. An example of a "FlyEye"-type telescope is described in European patent EP 2901198 B1.

[0012] Another example of a telescope is described in the following article by AARON M BROWN ET AL: “Panoramic SETI: overall mechanical system design”, ARXIV.ORG, CORNELL UNIVERSITY LIBRARY, 201OLIN LIBRARY CORNELL UNIVERSITY ITHACA, NY 14853, 24 November 2021 (2021-11-24), XP091102807.

[0013] The Applicant has observed that the known optical solutions are extremely inefficient (in fact they require thousands or tens of thousands of times more collector area than is actually used simultaneously over the entire field of view) or in any case they require a continuous scan of the sky with a noticeably and proportionally limited search time continuity.

[0014] A further disadvantage is that this solution requires a large number of duplications of the telescope in order to simultaneously cover the entire available sky at a single location on Earth or, equivalently, at a single location on Earth. Summary of the invention

[0015] An object of the present invention is to provide an optical system that is structurally and functionally designed to overcome at least one of the above-mentioned limitations of the prior art.

[0016] This object is achieved by an optical system made according to the independent claims attached to this description.

[0017] Further preferred features of the invention are defined in the dependent claims.

[0018] The meanings of certain terms and / or expressions used in this disclosure are set forth below.

[0019] The term "spherical" in connection with an element, such as, for example, a body, a surface or a cavity, means that the element is generally shaped like a sphere.

[0020] The expression "solid spherical body" means a huge object, ie without empty spaces, which is roughly shaped like a sphere.

[0021] The expression "light-transparent" in connection with an element / substance / material means the capability of such element / substance / material not to significantly attenuate light passing through it, i.e., means that such element / substance / material is characterized by an attenuation length (the distance over which the light attenuation falls below a relative value of 1 / e) of at least half a meter.

[0022] The expression "filling substance having a low refractive index" means a filling substance having a refractive index less than 1.33.

[0023] The expression "filling substance with high transparency" means a filling substance characterized by an attenuation length (the distance over which the light attenuation falls below the relative value of 1 / e) greater than 1 meter, preferably at least equal to 10 meters.

[0024] The expression "field lens" means a single lens or a lens system which acts as a replacement for a lens placed on the focal plane of an optical system.

[0025] The expression "profile" of a field lens means the edge of the field lens.

[0026] The expression "optical projection" means the image of a given object (eg a stop) as seen by an observer located at a position other than where the object is located.

[0027] The expression "light" is intended to mean electromagnetic radiation having a wavelength preferably comprised between 90 nm and 5000 nm, more preferably between 300 nm and 1000 nm.

[0028] In a first aspect, the present invention relates to an optical system.

[0029] The optical system includes an optical device having a center.

[0030] The optical device is a solid and light-transparent sphere, or the optical device has a spherical shape and includes: a first spherical surface, which is centered on the center of the optical device; a plurality of blocks adjacent to each other, which cover the first spherical surface; and at least a filling substance, which is contained in a spherical cavity defined by the first spherical surface in the optical device.

[0031] The block is an optically transparent lens, preferably the block is a meniscus lens.

[0032] These blocks define the exterior surfaces of the optical device.

[0033] The filling material is transparent to light.

[0034] The optical system also includes a curved focal plane on which an image produced by the optical device is focused when the optical device is illuminated.

[0035] The curved focal plane extends on a second spherical surface centered at the center of the optical device and surrounding the optical device.

[0036] The optical system comprises a receiving device comprising a plurality of chambers arranged at a curved focal plane.

[0037] Each chamber includes a field lens and an aperture.

[0038] The field lens is placed on the curved focal plane such that the field lens has an optical axis passing through the center of the optical arrangement.

[0039] The aperture stop is placed downstream of the field lens relative to the center of the optical device and extends within a solid angle defined by a half-line starting from the center of the optical device and passing through the contour of the field lens.

[0040] The center of the aperture is located on the optical axis of the field lens, so that the aperture defines a virtual aperture by an optical projection of the field lens onto the optical device, which extends into the optical device and has its center at the center of the optical device.

[0041] These features advantageously allow avoiding the placement of (physical) apertures inside the optical device, which would favor one direction over others.

[0042] Furthermore, the fact that the above-mentioned multiple chambers are placed at a curved focal plane (on which the image produced by the optical device when the optical device is illuminated is focused) makes the optical system according to the invention particularly advantageous in terms of the ratio between the amount of light it collects and the size of the optical system itself.

[0043] In particular, for the optical system according to the invention, the ratio between the amount of light collected by the respective optical device and the diameter size of the optical device is particularly advantageous.

[0044] In fact, the amount of light collected by an optical system according to the invention depends on the size of the optics of this optical system.

[0045] This makes it possible to obtain an optical system with a relatively large equivalent opening, so as to be able to collect light from the entire sky simultaneously.

[0046] This result cannot be obtained from the optical solutions described in the publications “Low-cost Access to the Deep, High-cadence Sky: the Argus Optical Array” and “Panoramic SETI: overall mechanical system design” mentioned above, because in these solutions it is envisaged that telescopes with a relatively limited field of view are mounted on a spherical (or hemispherical) surface that serves only as a mechanical support. Therefore, the amount of light collected by the optical solutions described in these publications does not depend at all on the size of the corresponding sphere (or hemisphere), but only on the opening of each individual telescope mounted thereon, the size of the opening of such telescopes being more than one tenth smaller than the size of the opening of the corresponding sphere.

[0047] Preferably, the optical system is a telescope.

[0048] In at least one embodiment of the present solution, the optical device is a spherically symmetric monocentric device.

[0049] Preferably, the optical device has a diameter equal to or greater than 20 cm.

[0050] Preferably, the optical device has a diameter comprised between 20 cm and 2 meters. More preferably, the optical device has a diameter of 1 meter.

[0051] As indicated above, the optical device may correspond to a solid and light-transparent spherical body, preferably, the optical device may correspond to a solid and light-transparent spherical body when the size of the spherical body is less than one meter.

[0052] In this case, preferably, the spherical body is made of glass, and more preferably, the spherical body is made of optical glass.

[0053] Compared to a solid spherical body made of glass (even glass with a low refractive index, such as, for example, quartz), an optical device including a spherical cavity filled with a filling substance may also achieve one or more of the following advantages:

[0054] The spherical cavity contains a filling substance with a refractive index lower than that of any glassy substance (e.g., quartz), thereby allowing for a longer focal ratio and thus reducing spherical aberration affecting the image produced by the optical device,

[0055] A solid glass sphere with a thickness on the order of a meter may more easily exhibit attenuation and / or inclusions greater than that of the filler material,

[0056] The melting and processing of a solid glass sphere of the order of a meter in diameter is generally relatively costly compared to making a block covering the first spherical surface, and

[0057] - Glass, with a density of about two and a half times that of a fill material similar to water, has a proportionally higher overall mass, which has significant structural effects on the supports of the optical device and possibly also on the internal stresses of the glass structure itself.

[0058] In at least one embodiment of the present solution, the aperture is arranged perpendicular to the optical axis of the respective field lens.

[0059] Preferably, the aperture is made in the form of a disk with a central hole.

[0060] The aperture of an optical system defines the respective equivalent opening of the optical system.

[0061] In other words, each stop allows collecting downstream of the field lens relative to the center of the optical device only the light that passes through a virtual stop placed at the center of the optical device and each stop characterizes a relative equivalent opening of the optical device relative to the diameter of the optical device.

[0062] Preferably, the equivalent opening has a circular shape, the diameter of the equivalent opening being at least equal to 60% of the diameter of the optical device, more preferably the diameter of the equivalent opening being equal to 80% or more than 80% of the diameter of the optical device.

[0063] In at least one embodiment of the present solution, the optical device is made of a tessellated pattern of a first spherical surface, wherein the blocks cover the first spherical surface but do not overlap two by two.

[0064] In other words, the optical device comprises a spherical core containing a filling substance and a spherical cap surrounding the core and made with the aid of the block described above.

[0065] In at least one embodiment of the solution, the block has a first face and a second face opposite the first face, wherein the first face of the block forms an inner surface of the optical device and the second face of the block forms an outer surface of the optical device.

[0066] Essentially, the interior and exterior surfaces of the optical device have a single common center of curvature.

[0067] Preferably, the block is made of glass, more preferably, the block is made of optical glass.

[0068] Preferably, the block has a refractive index greater than 1.4.

[0069] In at least one embodiment of the present solution, the block comprises a spherical portion having a polygonal outline.

[0070] Preferably, the block has a pentagonal shape.

[0071] Alternatively, the blocks may be square or triangular.

[0072] Alternatively, the plurality of blocks correspond to two spherical caps.

[0073] Preferably, the blocks are of the same shape and size as each other.

[0074] Alternatively, the blocks may have different shapes and / or sizes from each other.

[0075] In at least one embodiment of the present solution, the outline of the block is represented by the central projection of a dodecahedron.

[0076] In this case, the block comprises spherical parts having a pentagonal outline, all of the spherical parts being identical in size to one another.

[0077] In this case, therefore, the number of blocks is equal to twelve, but the present solution does not exclude different types of tessellation of the first spherical surface.

[0078] It is noteworthy that if the individual blocks are made by successive cutting of a block with a circular profile, the case of the dodecahedron exposed above (i.e. the case of twelve blocks with pentagons) is the case that allows for maximum efficiency between the (glass) material used to construct the optical device and the final result.

[0079] In at least one embodiment of the present solution, a tessellation with a number of blocks greater than twelve can be used, such as, for example, a tessellation with a total of 32 blocks consisting of 12 spherical blocks with pentagonal outlines and 20 spherical blocks with hexagonal outlines.

[0080] In the case of large spherical devices, for example with a diameter greater than one meter, a mosaic with a greater number of blocks is obviously preferred so that the individual blocks can be of an economically advantageous and materially manageable size.

[0081] In at least one embodiment of the present solution, the outer surface of the optical device has a radius greater than or equal to 20 cm and / or less than or equal to 2 meters. Preferably, the outer surface of the optical device has a radius of 1 meter. This radius is referred to as the outer radius of the optical device.

[0082] Thus, the optical device comprises an inner radius characterizing the spherical cavity (ie the first spherical surface) and an outer radius characterizing the outer surface of the optical device.

[0083] Preferably, the difference between the outer radius and the inner radius of the optical device is comprised between 2 cm and 10 cm.

[0084] In at least one embodiment of the solution, this difference substantially corresponds to the thickness of the block.

[0085] In particular, for optical devices having a relatively small diameter (i.e., less than 0.5 m), it is preferred to use a block with a thickness of approximately 2 cm, while for optical devices having a relatively large diameter (i.e., greater than or equal to 1 m), it is preferred to use a block with a thickness of at least 5 cm.

[0086] In at least one embodiment of the present solution, the second spherical surface is dimensioned such that it extends to the focal position of the optical system.

[0087] Therefore, the determination of the radius of the second spherical surface may be based on the refractive index of the filling substance contained in the optical device.

[0088] Alternatively, the determination of the refractive index of a filling substance contained in the optical arrangement may be based on a (predetermined) radius of the second surface, such that the focus of the optical system is positioned on the second spherical surface.

[0089] Preferably, the filling substance has a low refractive index and / or a high transparency.

[0090] By way of example, the filler material is preferably perfluorohexane (crude molecular formula C6F 14 ), also known as FC-72, or preferably, the filling material is ethoxy nonafluorobutane (crude molecular formula C4F9OC2H5), also known as NOVEC-7200.

[0091] Preferably, the filling substance completely fills the spherical cavity.

[0092] In at least one embodiment of the present solution, the filling substance is a fluid or an aerogel.

[0093] In at least one embodiment of the present solution, the filling substance is a mixture of two or more fluids having respective different refractive indices from each other.

[0094] This feature is particularly useful if the choice of the position of the curved focal plane relative to the center of the optical device is restricted, for example due to the overall size of the optical system, so that the refractive index of the filling substance becomes a free parameter.

[0095] In at least one embodiment of the present solution, each chamber of the plurality of chambers is adjacent to each other. Preferably, each chamber is arranged such that the receiving device seamlessly occupies a portion of the second spherical surface.

[0096] Preferably, the receiving device, in particular the field lens of the receiving device, extends below a horizontal plane passing through the center of the optical device.

[0097] In at least one embodiment of the solution, the receiving device, in particular the field lens of the receiving device, occupies the entire extension of the hemisphere of the second spherical surface.

[0098] This provision therefore makes it possible to obtain precise simultaneous coverage of half of the celestial body (or the equivalent field to be scanned).

[0099] In at least one embodiment of the solution, the receiving device occupies a portion of the second spherical surface obtained by dividing the second spherical surface by two tangent planes containing the center of the optical device.

[0100] Preferably, two tangent planes form an internal angle greater than or equal to 120° and in any case less than 180°.

[0101] This configuration is particularly useful for establishing preferred directions in which the incident beam of light to the optical device does not experience vignetting despite coming from the horizon.

[0102] By way of example, for applications providing for observations of objects situated outside the Earth's atmosphere (such as, for example, for astronomical type observations or for observations of artificial objects in orbit around the Earth), a solution which may be more desirable consists in limiting the observations to objects only above a certain minimum altitude from the horizon, but allowing the field to be collected with vignetted beams and thus with maximum efficiency, thereby facilitating the use of shorter lengths of sight within the Earth's atmosphere.

[0103] For example, observing only objects with an equivalent atmospheric mass equal to 2 (i.e., whose optical path covers a length in the atmosphere at most twice the length of the optical path emitted from the zenith or local vertical direction), the maximum altitude above the horizon is 30 degrees, so the total collected field of view is about ten thousand square degrees.

[0104] In at least one embodiment of the solution, the optical system comprises a frame provided with a plurality of openings adjacent two by two, delimiting respective seats suitable for housing respective blocks of the optical device.

[0105] In this case, the (small) amount of light intercepted by the frame has to be removed from the light collected with the equivalent diameter of the opening of the optical system according to the invention.

[0106] Hence, the blocks are held in place by means of the frame, wherein the individual blocks are preferably mounted to completely cover the first spherical surface together with the extended frame parts between the blocks and allow an undisturbed transmission of light, except for darkening due to the frame.

[0107] It should also be noted that the use of identical blocks allows for a high density of tessellations, ie using the so-called Platonic solids, with minimal interference with the light due to the frame.

[0108] Preferably, the frame is made of metal or composite material and is in any case suitable for retaining the blocks in the respective seats.

[0109] Preferably, the opening of the frame and the block have the same shape.

[0110] Preferably, the frame is in the form of a polyhedron, in particular a regular polyhedron.

[0111] Preferably, the frame forms the edge of a polyhedron.

[0112] Preferably, the opening of the frame is polygonal in shape. Specifically, the opening of the frame may correspond to a face of a polyhedron.

[0113] Alternatively, the opening of the frame may be circular in shape, the circle being inscribed in the corresponding face of the polyhedron.

[0114] Preferably, each opening of the frame is defined by an edge of the frame, the edge of the frame being provided with a recess shaped to receive a peripheral portion of the block.

[0115] Preferably, the optical system comprises a gasket for each seat of the frame, in particular an O-ring gasket, which is arranged between the block and the frame.

[0116] In particular, the gasket extends in a groove that houses a peripheral portion of the block, the gasket abutting against the outer portion of the edge of the frame and against the block itself.

[0117] Furthermore, the optical system may include an elastic preloader for each seat of the frame, the elastic preloader being arranged in a groove of the edge of the frame and opposite to the gasket. The elastic preloader is located on the inner part of the edge of the frame and on the block, the elastic preloader exerting pressure on the block, thereby preventing the filling substance contained in the spherical cavity from leaking through the gasket.

[0118] It is noteworthy that after filling the spherical cavity with a filling material with a certain density, the block will be subjected to hydraulic pressure, and the hydraulic pressure presents a linear vertical trend with the change of the equivalent column level of the filling material.

[0119] In at least one embodiment of the solution, the optical system comprises a thermal compensator having a coefficient of thermal expansion greater than that of the material constituting the block, the thermal compensator being arranged in the seat between the block and the frame.

[0120] Preferably, the thermal compensator is made of DELRIN or TEFLON.

[0121] This provision is particularly useful for compensating for changes in the relative size between the frame and the block if the frame and the block have different coefficients of thermal expansion with respect to each other.

[0122] In at least one embodiment of the present solution, the optical system comprises one or more arms extending from the frame to the base to keep the frame and the optical device spaced apart from the receiving device.

[0123] In at least one embodiment of the solution, at least one of the above-mentioned chambers, preferably each chamber, further comprises an optical correction unit arranged downstream of the aperture relative to the center of the optical device.

[0124] The optical correction unit is arranged for correcting spherical aberrations present in the image projected onto the field lens of the respective camera.

[0125] In particular, the image projected onto the field lens corresponds to the partial image of the image generated by the optical device affecting the field lens when the optical device is illuminated.

[0126] Preferably, the optical correction unit has the same optical axis as the corresponding field lens.

[0127] Preferably, the field lens, the diaphragm and the optical correction unit belonging to the same chamber are aligned on the optical axis of the field lens.

[0128] Preferably, the optical correction unit is further arranged for correcting chromatic aberrations present in the image projected onto the field lens of the respective camera.

[0129] In at least one embodiment of the present solution, the optical correction unit comprises an appropriately shaped aspherical surface for correcting the above-mentioned aberrations.

[0130] In at least one embodiment of the present solution, the optical correction unit is arranged for straightening the curvature of the curved focal plane.

[0131] Preferably, the optical correction unit comprises a flattening lens shaped to straighten the curvature of the curved focal plane.

[0132] In at least one embodiment of the present solution, at least one of the chambers, preferably each chamber, further comprises an optical detector which is arranged downstream of the optical correction unit with respect to the center of the optical arrangement.

[0133] In particular, the optical detector is suitable for converting the image projected on the field lens into an electrical signal which can be read by a specific electronic data receiving and collecting system.

[0134] In particular, a plurality of optical detectors allow the conversion of a set of images of various parts of the sky into electrical signals that can be read by a specific electronic data reception and collection system.

[0135] Preferably, the field lens, the aperture, the optical correction unit and the optical detector belonging to the same chamber are aligned on the optical axis of the field lens.

[0136] Preferably, the optical detector is a CCD or CMOS detector.

[0137] Preferably, the optical correction unit is arranged for straightening the curvature of the curved focal plane so that light entering the corresponding chamber through the field lens illuminates the optical detector with an optical quality in the order of arc seconds.

[0138] In at least one embodiment of the present solution, the optical correction unit thus compensates for spherical aberrations and preferably chromatic aberrations introduced in the curved focal plane, ie on the surface of the field lens.

[0139] In at least one embodiment of the present solution, the width of the field of view of the optical detector is larger than the nominal field of view covered by the corresponding field lens.

[0140] This feature advantageously allows not to lose any light flux, except that which results from the possible incomplete coincidence between the edges of adjacent field lenses.

[0141] In fact, spherical aberrations that may be introduced by the optical arrangement may cause scattering of light from points close to the edge of the nominal field of view covered by the field lens.

[0142] Thus, the field of view of the optical detector is oversized (e.g., by twice the magnitude of the scattering due to spherical aberration (on each side of the field of view, by twice the magnitude of the scattering due to spherical aberration)) so that light from sources located near the edge of the nominal field of view covered by the field lens is separated between adjacent chambers.

[0143] Thanks to this approach, there are no blind spots even when there are ineffective edges between the field lenses.

[0144] In at least one embodiment of the present solution, the optical system comprises a support on which the chamber is mounted.

[0145] Preferably, the support is rotatable about an axis of rotation parallel to the axis of rotation of the earth.

[0146] This provision is particularly useful for astronomical applications of the optical system according to the present solution.

[0147] In at least one embodiment of the present solution, the optical system comprises a drive operatively connected to a support of the chamber.

[0148] The drive may be an electric drive.

[0149] The drive is arranged to repeat the following steps in a loop:

[0150] · rotating the support member about the rotation axis synchronously with the movement of the earth and by a predetermined angle to move the support member from the rest position to the end position, and then,

[0151] Rotating the support about the axis of rotation so that the support moves from the end position to the rest position.

[0152] Preferably, the drive is arranged such that the movement of the support from the end position to the rest position about its axis of rotation is faster than the movement of the support if it rotates synchronously with the movement of the earth.

[0153] In this way, the apparent rotation of the sky in successive poses can be effectively compensated for without creating a greater number of rooms than will actually be used.

[0154] In particular, the drive may include: at least one electric motor; at least one control unit, which is operably connected to the at least one electric motor to drive the electric motor; and at least one motion transmission system, which is operably connected to the at least one electric motor and the support to rotate the support based on at least one signal generated by the control unit.

[0155] These properties are particularly useful for compensating for the apparent shift of the sky dome.

[0156] The characteristics and advantages of the present solution will best be derived from the detailed description of preferred embodiments thereof, which are illustrated by way of non-limiting examples with reference to the accompanying drawings, in which:

[0157] · Figure 1 is a schematic perspective view of an optical system according to an embodiment of the present solution,

[0158] · Figure 2 is a schematic cross-sectional representation of an optical device according to an embodiment of the present solution,

[0159] · Figure 3A is a schematic perspective view of an optical device according to an embodiment of the present solution,

[0160] · Figure 3B is a schematic cross-sectional view of a block and frame portion according to an embodiment of the present solution,

[0161] · Figures 4 to 6 is a partial schematic representation of an optical system according to various embodiments of the present solution,

[0162] · Figure 7 shows the correct overlap of the field of view for each chamber equipped with an optical correction unit according to an embodiment of the present solution,

[0163] · Figures 8 to 10 is a schematic representation of an optical system with a receiving device according to different configurations according to various embodiments of the present solution,

[0164] · Fig.11 is a schematic representation of an optical system according to an embodiment of the present solution, which allows a support for a chamber to be rotatable about an axis of rotation parallel to the axis of rotation of the Earth.

[0165] Referring to the drawings, an optical system manufactured according to the present invention is generally indicated at 100 .

[0166] Special reference Figure 1 and Figure 2 , the device 100 comprises an optical device 1 having a spherical shape and a center 2 .

[0167] The optical device 1 has a first spherical surface 3 centered on the center 2 of the optical device 1 , the first spherical surface 3 delimiting a spherical cavity 4 within the optical device 1 .

[0168] The first spherical surface 3 is covered by a plurality of two-by-two adjacent blocks 5 , which are lenses made of optical glass, are transparent to light and define an outer (spherical) surface 6 of the optical device 1 .

[0169] In detail, the block 5 has a first face 7 and a second face 8 opposite to the first face 7 , wherein the first face 7 forms the inner surface of the optical device 1 , ie the first spherical surface 3 , and the second face 8 forms the aforementioned outer surface 6 .

[0170] In a preferred embodiment of the invention, the first spherical surface 3 and the external surface 6 are concentric and have a radius R1 equal to 0.95 m and a radius R2 equal to 1 m, respectively.

[0171] Special reference Figure 3A , the block 5 comprises a spherical portion having a polygonal (particularly pentagonal) outline.

[0172] The optical system 100 includes at least a filling substance 9 having a low refractive index and high transparency, which is accommodated in a spherical cavity 4 .

[0173] Preferably, the filling substance 9 is a fluid, which may correspond to a mixture of two or more fluids having respective different refractive indices from each other.

[0174] In a preferred embodiment of the present invention, the filling material 9 has a refractive index of 1.25 and a transparency of 0.3 μm. -1 of fluid.

[0175] The optical system 100 comprises a frame 10 provided with a plurality of openings 11 adjacent in pairs, defining respective seats 12 suitable for housing respective blocks 5 .

[0176] Preferably, the frame 10 is made of metal material.

[0177] In a preferred embodiment of the present invention, the frame 10 forms a regular dodecahedron, and the faces of the regular dodecahedron correspond to the corresponding pentagonal openings 11 .

[0178] Special reference Figure 3B Each opening 11 of the frame 10 is defined by an edge 13 of the frame 10 , the edge 13 being provided with a groove 14 shaped for receiving a peripheral portion 15 of the block 5 .

[0179] The optical system 100 also comprises a gasket 16 (O-ring) for each seat 12 of the frame 10. The gasket 16 is arranged between the block 5 and the frame 10, extending in the groove 14 that houses the peripheral portion 15 of the block 5, and it abuts against the outer portion 17 of the edge 13 of the frame 10 and against the block 5 itself.

[0180] Furthermore, the optical system 100 comprises an elastic preloader 18 for each seat of the frame 10, arranged in the groove 14 on the side opposite to the gasket 16. The elastic preloader 18 is located on the inner part 19 of the edge 13 of the frame 10 and on the block 5, the elastic preloader 18 exerting pressure on the block 5, thereby preventing leakage of the filling substance 9 contained in the spherical cavity 4.

[0181] Furthermore, the optical system 100 comprises a thermocompensator 20 (made of DELRIN or TEFLON) having a coefficient of thermal expansion greater than that of the material constituting the block 5 , arranged in the seat 12 between the block 5 and the frame 10 .

[0182] Special reference Figure 4 , the optical system 100 comprises a curved focal plane 21, on which an image generated by the optical device 1 is focused when the optical device 1 is illuminated. The curved focal plane 21 extends on a second spherical surface 22 centered on the center 2 of the optical device 1 and surrounding said optical device 1.

[0183] Special reference Figures 1 to 4 The optical system 100 includes a receiving device 23 , which includes a plurality of chambers 23 a arranged at a curved focal plane 21 .

[0184] In detail, the chambers 23 a are adjacent to each other in pairs, so that the receiving device 23 seamlessly covers a portion of the second spherical surface 22 .

[0185] In a preferred embodiment of the present invention, the optical system 100 comprises one or more arms 10 a extending as far as possible from the frame 10 to a base 10 b which keeps the frame 10 and the optical device 1 spaced from the receiving device 23 .

[0186] Each chamber 23a comprises: a field lens 24 placed on the curved focal plane 21 so that the field lens 24 has an optical axis 25 passing through the center 2 of the optical device 1; and an aperture 26 arranged downstream of the field lens 24 relative to the center 2 of the optical device 100.

[0187] The aperture 26 extends within a solid angle 27 which is defined by a half-line 28 which has the center 2 of the optical device 1 as its origin and passes through a contour 29 of the field lens 24 .

[0188] The center of the aperture 26 is located on the optical axis 25 of the corresponding field lens 24, so that the aperture 26 defines a virtual aperture 30 through the optical projection of the field lens 24 on the optical device 1, which extends into the optical device 1 and has the center of the optical device 1 as its center.

[0189] It should be noted that the aperture 26 of each chamber 23 a is arranged perpendicular to the optical axis 25 of the corresponding field lens 24 , thereby defining a corresponding equivalent opening of the optical system 100 .

[0190] Special reference Figure 5 Each chamber 23 a further comprises an optical correction unit 31 , which is arranged downstream of the aperture 26 relative to the center 2 of the optical device 1 , and whose optical axis coincides with the optical axis of the corresponding field lens 24 .

[0191] The optical correction unit 31 is arranged to correct spherical aberration and chromatic aberration present in the image projected onto the field lens 24 of the corresponding chamber 23a.

[0192] In a preferred embodiment of the present invention, the optical correction unit 31 comprises a properly shaped aspherical surface 32 for correcting the aforementioned aberrations.

[0193] The optical correction unit 31 is also arranged for straightening the curvature of the curved focal plane 21 .

[0194] In a preferred embodiment of the present invention, the optical correction unit 31 includes a flattening lens 33 shaped to straighten the curvature of the curved focal plane 21 .

[0195] Each chamber 23 a of the optical system 100 also comprises an optical detector 34 (CMOS) which is arranged downstream of the optical correction unit 31 with respect to the center 2 of the optical device 1 .

[0196] In detail, the field lens 24 , the diaphragm 26 , the optical correction unit 31 , and the optical detector 34 belonging to the same chamber 23 a are aligned on the optical axis 25 of the field lens 24 .

[0197] Preferably, the optical correction unit 31 is arranged to straighten the curvature of the curved focal plane 21 so that the light entering the chamber 23a through the field lens 24 illuminates the optical detector 34 with an optical quality in the order of arc seconds.

[0198] Special reference Figure 6 and Figure 7 , the width of the field of view 35 of the optical detector 34 is greater than the width of the nominal field of view 36 covered by the corresponding field lens 24.

[0199] Therefore, the field of view 35 of the optical detector 34 is enlarged by the amount of light scatter caused by the spherical aberration introduced by the optical arrangement.

[0200] Figure 8 A possible configuration of the receiving device 23 is shown in a schematic manner.

[0201] In particular, Figure 8 yes Figure 1Schematic diagram of an optical system 100 , in which the receiving device 23 occupies the entire extension of the hemisphere 22a of the second spherical surface 22, the receiving device 23 extending below a horizontal plane 37 passing through the center 2 of the optical device 1.

[0202] In this case, the optical system 100 allows covering half of the celestial body by accepting vignetting of the light source at the edge of the field of view covered by the plurality of chambers 23a.

[0203] Fig. 9 and Fig.10 Different configurations of the receiving device 23 are shown, wherein the receiving device 23 occupies a portion of the second spherical surface 22 obtained by dividing the second spherical surface 22 by two tangent planes 37a, 37b containing the center 2 of the optical device 1.

[0204] Fig. 9 The tangent planes 37a, 37b correspond one to a horizontal plane and the other to an inclined plane forming an angle equal to 150° with the horizontal plane.

[0205] Fig.10 The tangent planes 37a, 37b correspond to the plane of incidence relative to the horizontal and form an internal angle equal to 150°.

[0206] Fig. 9 and Fig.10 The configuration of the receiving device 23 shown in also allows establishing a preferential direction of the light beam 38 incident on the optical device 1 which is not affected by vignetting phenomena.

[0207] Special reference Fig.11 The optical system 100 comprises a support 39 on which the chamber 23a is mounted, and the support 39 can rotate around an axis of rotation 40 parallel to the axis of rotation of the earth.

[0208] In a preferred embodiment of the present invention, the optical system 100 further comprises an electric drive 41 which is operably connected to the support 39 of the chamber 23a and is arranged to cyclically repeat the following steps:

[0209] Rotating the support 39 about the rotation axis 40 by a predetermined angle in synchronization with the movement of the earth to move the support 39 from the rest position to the end position, and then,

[0210] Rotating the support 39 about the axis of rotation 40 in order to move the support 39 from the end position to the rest position at a higher rotation speed than in the previous step.

[0211] In detail, the electric drive 41 includes: an electric motor 42; a control unit 43, which is operably connected to the electric motor 43 to drive the electric motor; and a motion transmission system 44, which is operably connected to the electric motor 43 and the support 39 to cause the support 39 to rotate based on at least one signal 45 generated by the control unit 43.

Claims

1. An optical system (100), the optical system (100) comprising: An optical device (1) having a center (2), wherein the optical device is a solid and optically transparent spherical body, or wherein the optical device has a spherical shape and comprises: a first spherical surface (3) centered at the center of the optical device, wherein the first spherical surface defines a spherical cavity (4) within the optical device, a plurality of two-by-two adjacent blocks (5), a plurality of two-by-two adjacent blocks (5) covering the first spherical surface, wherein the blocks are optically transparent lenses and the blocks define the outer surface (6) of the optical device, an at least optically transparent filling substance (9), said filling substance being accommodated in said spherical cavity, a curved focal plane (21) on which an image generated by the optical device is focused when the optical device is illuminated, the curved focal plane extending on a second spherical surface (22) centered at the center of the optical device and surrounding the optical device, A receiving device (23), the receiving device (23) comprising a plurality of chambers (23a), the plurality of chambers (23a) being arranged at the curved focal plane, wherein each chamber comprises: a field lens (24) placed on the curved focal plane such that the field lens (24) has an optical axis (25) passing through the center of the optical device, and an aperture (26) which is placed downstream of the field lens relative to the center of the optical device and which extends within a solid angle (27) defined by a half-line (28) which has the center of the optical device as its starting point and passes through the contour (29) of the field lens, wherein the center of the aperture is located on the optical axis of the field lens, so that the aperture defines a virtual aperture (30) through the optical projection of the field lens on the optical device, the virtual aperture (30) extending into the optical device and having the center of the virtual aperture (30) at the center of the optical device.

2. The optical system according to claim 1, wherein: The filling material (9) has a low refractive index and / or high transparency.

3. The optical system according to claim 1 or 2, wherein: The filling substance (9) is a fluid or an aerogel, wherein preferably, the fluid is a mixture of two or more fluids having different refractive indices from each other.

4. An optical system according to one of the preceding claims, comprising a frame (10) provided with a plurality of openings (11) adjacent to each other, the plurality of openings (11) defining respective seats (12) suitable for accommodating respective blocks (5) of the optical device (1).

5. An optical system according to claim 4, comprising a thermal compensator (20) having a thermal expansion coefficient greater than the thermal expansion coefficient of the material constituting the block (5), the thermal compensator being arranged in the seat (12) and located between the block and the frame (10).

6. The optical system according to claim 1, wherein: The block (5) comprises a spherical portion with a polygonal outline, preferably, the block (5) comprises a spherical portion with a pentagonal outline.

7. The optical system according to claim 1, wherein: At least one of the chambers (23a) further comprises an optical correction unit (31), which is arranged downstream of the aperture (26) relative to the center (2) of the optical device (1), and is arranged to correct spherical aberration present in the image projected onto the field lens (24) of the corresponding chamber (23a).

8. The optical system according to claim 7, wherein: For at least one of the chambers (23a), the corresponding field lens (24) and the corresponding aperture (26) and the optical correction unit (31) are aligned on the optical axis of the field lens (24).

9. The optical system according to claim 7 or 8, wherein: At least one of the chambers (23a) further comprises an optical detector (34) which is arranged downstream of the optical correction unit (31) relative to the center (2) of the optical device (1).

10. The optical system according to claim 9, wherein: For at least one of the chambers (23a), the corresponding field lens (24) and the corresponding aperture (26), the optical correction unit (31) and the optical detector (34) are aligned on the optical axis of the field lens.

11. The optical system according to claim 9 or 10, wherein: The optical correction unit (31) is arranged to straighten the curvature of the curved focal plane (21) so that the light entering the corresponding chamber (23a) through the field lens (24) illuminates the optical detector (34) with an optical quality in the order of arc seconds.

12. The optical system according to claim 9, wherein: The width of the field of view (35) of the optical detector (34) is greater than the nominal field of view (36) covered by the corresponding field lens (24).

13. The optical system according to one of the preceding claims, comprising a support (39) on which the chamber (23a) is mounted, the support (39) being rotatable about an axis of rotation (40) parallel to the axis of rotation of the Earth.

14. An optical system according to claim 13, comprising a drive (41) operatively connected to the support (39), the drive being arranged to cyclically repeat the following steps: The support is rotated about the rotation axis (40) by a predetermined angle in synchronization with the movement of the earth to move the support from a rest position to an end position, and then, Rotating the support about the rotation axis to move the support from the end position to the rest position.

15. The optical system according to claim 14, wherein: The drive is arranged such that movement of the support from the end position to the rest position about the axis of rotation of the support is faster than movement of the support if the support rotates synchronously with the movement of the earth.

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