Optical systems, especially telescopes

Abstract

The optical system includes an optical device having a spherical or spherical shape. The optical device includes a first spherical surface, a plurality of adjacent 2×2 blocks covering the first spherical surface, and at least one optically transparent filler material contained in a spherical cavity of the optical device. The optical system includes a curved focal plane surrounding the optical device on which an image generated by the optical device is focused when illuminated, and a receiving device including a plurality of chambers disposed in the curved focal plane. Each chamber includes a field lens and an aperture disposed downstream of the field lens relative to a center of the optical device. The center of the aperture is on the optical axis of the field lens, and an optical projection of the aperture through the field lens onto the optical device defines a virtual aperture centered on the center of the optical device that extends into the optical device.

Description

[Technical field]

[0001] The present invention relates to optical systems, and more particularly to telescopes.

[0002] The invention finds preferred application in the technical field relating to devices or instruments for observing objects at great distances, in particular, but not exclusively, in optical instruments used in astronomy for observing celestial bodies, which generally require a continuous search of the visible sky from a point on the Earth's surface or from a planetary surface.

[0003] The invention is also applicable to optical instruments that cover half of the total available field of view, such as observations of the ocean floor from the keel of a ship, or of the Earth's surface by a satellite in low earth orbit. [Background technology]

[0004] For nighttime applications from a point on the Earth's surface, this type of search involves patrolling for transients (e.g., changes in brightness, color, shape, or location) of natural or man-made objects in the wavelength range of visible light radiation and adjacent ranges (infrared and ultraviolet). A non-exhaustive list of these transients in the realm of natural phenomena may include, for example, novae and supernovae, variable stars, eclipsing binaries, stars passing exoplanets, asteroids, asteroids orbiting close to Earth, meteorites, atmospheric phenomena (electrical flashes, cloud formations, etc.), gamma ray flashes, and currently unknown phenomena. Similarly, a non-exhaustive list of visible man-made phenomena, often but not necessarily at night, for a search system capable of observing half of the full field of view simultaneously, includes, for example, passing satellites, orbital debris (often known as "space junk"), missiles and rockets (including those that do not reach orbit or upper stages for orbital launches), high-altitude gas emissions, aircraft, contrails, drones, etc.

[0005] The ability to detect these phenomena depends critically on the observation system's ability to simultaneously collect light from the entire sky with as much equivalent aperture as possible, which represents the geometric surface dimensions of the collection of light emitted by the phenomenon under study, e.g. as mentioned above.

[0006] Typically, large aperture optical systems cannot accommodate large fields of view unless multiple large aperture optical systems are multiplied together.

[0007] For example, a conventional telescope can cover a field of view of about 1 square degree, based on an aperture equivalent to a circle with a diameter of 1 m. Even existing optical systems in the region of apertures of 1 m diameter and 10 square degrees or more would require thousands or tens of thousands of copies of these telescopes to simultaneously cover the entire sky available at a single location on Earth or in a comparable situation.

[0008] Therefore, when searching the entire sky with a small aperture (up to an equivalent diameter of a few tens of centimeters), the usual solution is to replicate the telescope in large numbers.

[0009] For example, the paper "Low-cost Access to the Deep, High-cadence Sky: the Argus Optical Array" by LAW NICHOLAS M. et al. (PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC, vol. 134, no. 1033, March 1, 2022, p. 035003, XP093001948, US, ISSN: 0004-6280, D01: 10.1088 / 1538-3873 / ac4811) describes the "ARGUS" array, which consists of about 1000 20 cm diameter telescopes arranged on a sphere about 15 m in diameter. Despite the overall size of the artifacts, the equivalent aperture remains that of a single 20 cm diameter telescope.

[0010] This technical solution is particularly inefficient on a volumetric basis while maintaining a reasonable equivalent aperture.

[0011] On the other hand, for apertures of 1 m or more, Schmidt or "fly's eye" telescopes are known. An example of a "fly's eye" telescope is described in EP 2 901 198 B1.

[0012] Further examples of telescopes are described in the paper "Panoramic SETI: overall mechanical system design" by AARON M BROWN et al., ARXIV.ORG, CORNELL UNIVERSITY LIBRARY, 201 OLIN LIBRARY CORNELL UNIVERSITY, ITHACA, NY, 14853 (24 November 2021), XP091102807.

[0013] The applicant has observed that known optical solutions are either extremely inefficient (indeed, such solutions require collector areas thousands or tens of thousands of times larger than those used simultaneously over the corresponding field of view) or they require continuous surveys of the sky with an obvious and proportionately limited temporal continuity of the search.

[0014] A further drawback is that such a solution requires massive duplication of telescopes in order to simultaneously cover the entire sky available at one location on the ground or in an equivalent situation. Summary of the Invention [Problem to be solved by the invention]

[0015] SUMMARY OF THE PRESENT EMBODIMENT It is an object of the present invention to make available an optical system that is structurally and functionally designed to overcome at least one of the limitations of the prior art mentioned above. [Means for solving the problem]

[0016] The above mentioned object is achieved by an optical system made in accordance with the attached independent claims.

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

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

[0019] The term "spherical" in reference to an element, e.g., a body, surface, cavity, etc., means that the element is shaped substantially like a sphere.

[0020] The expression "solid sphere" refers to a mass that is substantially shaped like a sphere and has no voids.

[0021] The expression "light-transmitting" in relation to an element / substance / material means the ability of such element / substance / material not to significantly attenuate the light passing through it, i.e. it means that such element / substance / material is characterized by an attenuation length (the distance over which the attenuation of light is less than the relative value of 1 / e) of at least 0.5 m.

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

[0023] The expression "highly transparent filling material" means a filling material characterized by an attenuation length (the distance over which the light attenuation falls below the relative value of 1 / e) greater than 1 m and preferably at least equal to 10 m.

[0024] The expression "field lens" refers to a single lens or a lens system that replaces it, located in the focal plane of an optical system.

[0025] The term "outline" of a field lens refers to the edge of the field lens.

[0026] The expression "optical projection" refers to the image of a particular object, for example a stop, as seen by an observer at a location other than where the object is located.

[0027] The expression "light" preferably means electromagnetic radiation having a wavelength between 90 nm and 5000 nm, more preferably between 300 nm and 1000 nm.

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

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

[0030] The optical device is a solid, light-transmitting sphere, or the optical device has a spherical shape and includes a first spherical surface centered at a center of the optical device, a plurality of adjacent 2×2 blocks covering the first spherical surface, and at least a filler material contained within a spherical cavity defined by the first spherical surface within the optical device.

[0031] The block is a light-transmitting lens, preferably a meniscus lens.

[0032] The block defines an outer surface of the optical device.

[0033] The filling material is transparent to light.

[0034] Additionally, the optical system includes a curved focal surface onto which the image produced by the optical device is focused when illuminated.

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

[0036] The optical system includes a receiving device that includes a plurality of chambers disposed in a curved focal plane.

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

[0038] The field lens is positioned in the curved focal plane with its optical axis passing through the center of the optical system.

[0039] The stop is disposed downstream of the field lens relative to the center of the optical system and extends within a solid angle subtended by a half line having its origin at the center of the optical system and passing through the outline of the field lens.

[0040] The center of the aperture is on the optical axis of the field lens, and the optical projection of the aperture through the field lens onto the optical device defines a virtual aperture extending into the optical device and centered on the center of the optical device.

[0041] These features advantageously avoid the need for a (physical) aperture in the optical system and avoid the preference for certain directions over others.

[0042] Also, due to the fact that the above-mentioned multiple chambers are arranged in a curved focal plane on which the image generated by the optical device is focused when illuminated, the optical system according to the invention can be 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, in the optical system according to the invention, the ratio between the amount of light collected by the respective optical device and its diameter is particularly favorable.

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

[0045] This results in an optical system with a relatively large equivalent aperture that can simultaneously collect light from the entire sky.

[0046] This result cannot be obtained with the optical solutions described in the above-mentioned publications "Low-cost Access to the Deep, High-cadence Sky: the Argus Optical Array" and "Panoramic SETI: overall mechanical system design", because such solutions envisage mounting telescopes with a relatively narrow field of view on a spherical (or hemispherical) surface that serves exclusively as a mechanical support. The amount of light collected by the optical solutions described in such publications therefore does not depend on the size of the corresponding sphere (or hemisphere), but only on the aperture of the individual telescope mounted thereon. The size of the aperture of such a telescope is more than ten times smaller than the aperture of the corresponding sphere.

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

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

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

[0050] Preferably, the diameter of the optical device is between 20 cm and 2 m, and more preferably, the diameter of the optical device is 1 m.

[0051] As mentioned above, the optical device may correspond to a solid, light-transmitting sphere, preferably when its size is less than 1 m.

[0052] In this case, the above-mentioned sphere is preferably made of glass, more preferably made of optical glass.

[0053] Compared to a solid sphere made of glass, even one with a low refractive index, such as quartz, an optical device including a spherical cavity filled with a filling material can achieve one or more of the following advantages: The refractive index of the filling material contained within the spherical cavity is smaller than that of a glassy material (such as quartz), which allows for a longer focal length and reduces the spherical surface aberrations that affect the images produced by optical devices. Solid glass spheres with thicknesses of the order of 1m may more readily exhibit greater attenuation and / or inclusions than filled materials. Melting and machining a solid glass sphere of around 1m diameter is generally relatively expensive compared to manufacturing a block covering the first spherical surface. Glass, with a density approximately 2.5 times that of water-like fillers, has a proportionately larger overall mass, with obvious structural effects on the supports for optical devices and possibly even on the internal stresses of the glass structure itself.

[0054] In at least one embodiment of the solution, the apertures are arranged perpendicular to the optical axis of the opposing field lenses.

[0055] Preferably, the aperture is made in the form of a circular disk with a central hole.

[0056] The stops of an optical system define the respective equivalent aperture of the optical system.

[0057] In other words, each aperture allows only light to be collected that passes through a virtual aperture located at the center of the optical device, downstream of the field lens relative to the center of the optical device, characterizing the relative equivalent aperture of the optical device with respect to the diameter of the latter.

[0058] Preferably, the equivalent aperture has a circular shape with a diameter that is at least 60% of the diameter of the optical device, more preferably 80% or more.

[0059] In at least one embodiment of the solution, the optical device is made by tessellation of a first spherical surface, where the blocks cover the first spherical surface without two-by-two overlapping.

[0060] In other words, the optical device includes a spherical core containing a filling material and a spherical crown surrounding the core and made from the blocks described above.

[0061] In at least one embodiment of the present solution, the block has a first side and a second side opposite the first side, where the first side of the block forms an inner surface of the optical device and the second side of the block forms an outer surface of the optical device.

[0062] Essentially, the inner and outer surfaces of the optical device have a single common center of curvature.

[0063] Preferably, the block is made of glass, more preferably optical glass.

[0064] Preferably, the refractive index of the blocks is greater than 1.4.

[0065] In at least one embodiment of the present solution, the block consists of a spherical portion having a polygonal outline.

[0066] Preferably, the blocks have a pentagonal shape.

[0067] Alternatively, the blocks may be square or triangular.

[0068] Alternatively, the blocks correspond to two spherical caps.

[0069] Preferably, the blocks have the same shape and size as each other.

[0070] Alternatively, the blocks may have different shapes and / or sizes from one another.

[0071] In at least one embodiment of the present solution, the outline of the block is represented by a central projection of a dodecahedron.

[0072] In this case, the blocks are made up of spherical sections with a pentagonal outline, all the same size.

[0073] Therefore, in this situation the number of blocks is equal to 12, although different types of tessellations of the first spherical surface are not excluded from the solution.

[0074] It should be noted that when the individual blocks are produced by successive cutting of a block having a circular outline, the dodecahedral case described above (i.e. the case of 12 blocks having a pentagonal shape) is the one that offers the greatest efficiency between the (vitreous) material used to construct the optical device and the final result.

[0075] At least one embodiment of the present solution may use a tessellation with more than 12 blocks, such as, for example, a tessellation consisting of 12 spherical blocks with pentagonal contours and 20 spherical blocks with hexagonal contours for a total of 32 blocks.

[0076] For large spherical devices (e.g., greater than 1m in diameter), it is clear that a tessellation with a large number of blocks is preferred, so that the individual blocks are of an economically advantageous size and are materially manageable.

[0077] In at least one embodiment of the solution, the radius of the outer surface of the optical device is greater than or equal to 20 cm and / or less than or equal to 2 m. Preferably, the radius of the outer surface of the optical device is 1 m. This radius is called the outer radius of the optical device.

[0078] Thus, the optical device includes an inner radius that characterizes the spherical cavity, i.e., the first spherical surface, and an outer radius that characterizes the outer surface of the optical device.

[0079] Preferably, the difference between the outer radius and the inner radius of the optical device is between 2 cm and 10 cm.

[0080] In at least one embodiment of the present solution, this difference substantially corresponds to the thickness of the block.

[0081] In particular, for optical devices having a relatively small diameter, i.e., less than 0.5 m, it is preferable to use a block having a thickness of about 2 cm, and for optical devices having a relatively large diameter, i.e., 1 m or more, it is preferable to use a block having a thickness of at least 5 cm.

[0082] In at least one embodiment of the present solution, the second spherical surface is sized to extend at a focal position of the optical system.

[0083] Thus, the radius of the second spherical surface may be determined based on the refractive index of a fill material included in the optical device.

[0084] Alternatively, the refractive index of a filler material included in the optical device may be determined based on the (predetermined) radius of the second surface, such that the focal point of the optical system is located on the second spherical surface.

[0085] Preferably, the filling material has a low refractive index and / or high transparency.

[0086] For example, the fill material is preferably perfluorohexane, also known as FC-72 (crude formula C6F 14 ), or preferably ethoxynonafluorobutane (crude formula C4F9OC2H5), also known as NOVEC-7200.

[0087] The filling material preferably completely fills the spherical cavity.

[0088] In at least one embodiment of the present solution, the filling material is a fluid or an aerogel.

[0089] In at least one embodiment of the present solution, the filling substance is a mixture of two or more fluids each having a different refractive index.

[0090] This feature is particularly useful in cases where there are constraints on the choice of the position of the curved focal plane relative to the center of the optical device, for example due to the size of the overall optical system, in order to make the refractive index of the fill material a free parameter.

[0091] In at least one embodiment of the solution, the chambers of the plurality of chambers are adjacent to each other. Preferably, the chambers are arranged such that the receiving device seamlessly covers a portion of the second spherical surface.

[0092] Preferably, the receiving device (and in particular the field lens of the receiving device) extends below a horizontal plane passing through the centre of the optical device.

[0093] In at least one embodiment of the solution, the receiving device (in particular the field lens of the receiving device) occupies the full extension of the hemisphere of the second spherical surface.

[0094] This therefore makes it possible to simultaneously address exactly half of the celestial sphere (or the equivalent of the scanned field).

[0095] In at least one embodiment of this solution, the receiving device occupies a portion of a second spherical surface obtained by dividing the second spherical surface by two cleavage planes that include the central portion of the optical device.

[0096] Preferably, the two cut surfaces form an interior angle greater than or equal to 120° and in any case smaller than 180°.

[0097] This configuration is particularly useful for establishing a privileged direction without vignetting of the incoming light beam of the optical device, even though it is incident from a horizontal plane.

[0098] For example, for applications involving observations of objects located outside the Earth's atmosphere (e.g. astronomical observations or man-made objects in Earth orbit), a solution that only observes objects above a certain minimum elevation above the horizon is preferred, so that the field can be collected without obstructing the beam and makes the most of the short line of sight in the Earth's atmosphere.

[0099] For example, if one were to observe only objects with an equivalent air mass equal to two (i.e., objects whose optical path corresponds at most to twice the length through the atmosphere as for objects coming from the zenith or local vertical direction), then the maximum height placed would be 30 degrees above the horizon, resulting in a total collection field of view of about 10,000 square degrees.

[0100] In at least one embodiment of the present solution, the optical system includes a frame provided with a plurality of adjacent 2x2 openings defining respective seats adapted to accommodate respective blocks of the optical device.

[0101] In this situation, the (small) amount of light blocked by the frame needs to be removed from the light collected with the equivalent diameter of the aperture of the optical system according to the invention.

[0102] The blocks are therefore held in place by a frame, with the individual blocks preferably mounted such that, together with the extended frame portions between the blocks, they completely cover the first spherical surface and allow the undisturbed passage of light, except for obscuration by the frame.

[0103] It should further be noted that the use of identical blocks allows for a dense tessellation, i.e. a tessellation with minimal light obstruction by the frame, using so-called Platonic solids.

[0104] Preferably, the frame is made of a metal or composite material suitable for retaining the blocks in their respective seats.

[0105] Preferably, the openings in the frame and the block have the same shape.

[0106] Preferably, the frame has the form of a polyhedron, in particular a regular polyhedron.

[0107] Preferably, the frame forms an edge of a polyhedron.

[0108] Preferably, the opening in the frame has a polygonal shape. In particular, the opening in the frame may correspond to the faces of a polyhedron.

[0109] Alternatively, the opening in the frame may have a circular shape inscribed on each face of the polyhedron.

[0110] Preferably, each opening in the frame is defined by an edge of the frame that is provided with a groove shaped to receive the peripheral edge of a block.

[0111] Preferably, the optical system includes a gasket, in particular an O-ring gasket, in each seat of the frame, the gasket being arranged between the block and the frame.

[0112] Specifically, the gasket extends into a groove that receives the periphery of the block and abuts the outer portions of the edges of the frame and the block itself.

[0113] The optical system may also include a resilient preloader for each seat of the frame disposed in a groove in the edge of the frame opposite the gasket, the resilient preloader being on the inner portion of the edge of the frame and on the block and exerting pressure on the block to prevent leakage of the fill material contained in the spherical cavity through the gasket.

[0114] It should be noted that after filling the spherical cavity with a packing material having a particular density, the block is subjected to a hydraulic pressure that has a linear vertical trend as a function of the equivalent column level of the packing material.

[0115] In at least one embodiment of the solution, the optical system includes a thermal compensator having a thermal expansion coefficient greater than the thermal expansion coefficient of the material of which the block is made, the thermal compensator being arranged in a seat between the block and the frame.

[0116] Preferably, the thermal compensator is made of DELRIN or TEFLON.

[0117] This is particularly useful for compensating for relative size variations between the frame and the block when the frame and the block have different thermal expansion coefficients.

[0118] In at least one embodiment of the present solution, the optical system includes 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.

[0119] In at least one embodiment of the present solution, at least one, and preferably each, of the above mentioned chambers further comprises an optical correction unit arranged downstream of the diaphragm with respect to a central portion of the optical arrangement.

[0120] The optical correction unit is arranged to correct spherical surface aberrations present in an image projected onto the field lens of the relative camera.

[0121] In particular, the image projected onto the field lens corresponds to that portion of the image that is produced when the optical device is illuminated, which affects the field lens.

[0122] Preferably, the optical correction unit has the same optical axis as the relative field lens.

[0123] 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.

[0124] Preferably, the optical correction unit is arranged to also correct chromatic aberration present in the image projected onto the field lens of the relative camera.

[0125] In at least one embodiment of the present solution, the optical correction unit comprises an aspheric surface of suitable shape for correcting the above-mentioned aberrations.

[0126] In at least one embodiment of the present solution, the optical correction unit is arranged to straighten the curvature of the curved focal surface.

[0127] Preferably, the optical correction unit includes a planarizing lens shaped to straighten out the curvature of the curved focal surface.

[0128] In at least one embodiment of the solution, at least one of the chambers, and preferably each chamber, further comprises an optical detector arranged downstream of the optical correction unit with respect to a central portion of the optical arrangement.

[0129] In particular, the optical detector is adapted to convert the image projected onto the field lens into an electrical signal that can be read through a specific electronic data receiving and collecting system.

[0130] Specifically, a set of images of a portion of the sky can be converted by multiple optical detectors into electrical signals that can be read by a specific electronic data reception and collection system.

[0131] Preferably, the field lens, the diaphragm, the optical correction unit and the optical detector belonging to the same chamber are aligned on the optical axis of the field lens.

[0132] Preferably, the optical detector is a CCD or CMOS detector.

[0133] Preferably, the optical correction unit is arranged to straighten out the curvature of the curved focal plane such that light entering the relative chamber through the field lens illuminates the optical detector with optical quality on the order of arcseconds.

[0134] In at least one embodiment of the present solution, the optical correction unit thus compensates for spherical surface aberrations, preferably chromatic aberrations, which are introduced into the curved focal plane, i.e. the surface of the field lens.

[0135] 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 accommodated by the relative field lens.

[0136] Advantageously, this feature results in no loss of light flux, except due to the possibility of a perfect match between the edges of adjacent field lenses.

[0137] Indeed, spherical surface aberrations that may be introduced by the optical device cause scattering of light coming from points close to the edge of the nominal field of view that the field lens accommodates.

[0138] Therefore, the field of view of the optical detector is enlarged by, for example, twice the magnitude of scattering due to spherical surface aberration (one on each side of the field of view), and light coming from a source located near the edge of the nominal field of view covered by the field lens is split between adjacent chambers.

[0139] With this approach, there are no blind spots even if there are ineffective edges between the field lenses.

[0140] In at least one embodiment of the present solution, the optical system comprises a support on which the chamber is mounted.

[0141] Preferably, the support is rotatable about an axis of rotation parallel to the axis of rotation of the Earth.

[0142] This makes the optical system according to the present solution particularly useful for astronomical applications.

[0143] In at least one embodiment of the present solution, the optical system includes a drive operatively connected to a support of the chamber.

[0144] The drive may be an electric drive.

[0145] The drive unit is - rotating the support around the axis of rotation through a predetermined angle in synchronism with the motion of the earth, moving the support from a rest position to an end position; - rotating the support about an axis of rotation to move the support from an end position to a rest position; are arranged so as to be periodically repeated.

[0146] Preferably, the drive is arranged so that the movement of the support about the axis of rotation from the end position to the rest position is faster than the movement of the support would be if it were rotating synchronously with the motion of the Earth.

[0147] In this way, the apparent rotation of the sky can be efficiently compensated for in successive poses without the need to create many more chambers than will actually be used.

[0148] In particular, the drive may include at least one electric motor, at least one control unit operably connected to the at least one electric motor for driving the at least one electric motor, and at least one motion transmission system operably connected to the at least one electric motor and the support for rotating the support based on at least one signal generated by the control unit.

[0149] These features are particularly useful in compensating for apparent deviations in the celestial sphere. [Brief description of the drawings]

[0150] The features and advantages of the present solution will best be obtained from the detailed description of preferred embodiments thereof, illustrated in a non-limiting manner with reference to the accompanying drawings, in which: [Figure 1] FIG. 1 shows a schematic perspective view of an optical system according to an embodiment of the present solution; [Diagram 2]1 is a cross-sectional view showing a schematic diagram of an optical device according to an embodiment of the present solution; [Figure 3A] FIG. 1 is a perspective view showing a schematic representation of an optical device according to an embodiment of the present solution; [Figure 3B] FIG. 2 is a cross-sectional view showing a schematic block and frame portion according to an embodiment of the present solution; [Figure 4] 1 is a partial schematic diagram of an optical system according to an embodiment of the present solution; [Diagram 5] 1 is a partial schematic diagram of an optical system according to an embodiment of the present solution; [Figure 6] 1 is a partial schematic diagram of an optical system according to an embodiment of the present solution; [Figure 7] 4 shows the correct overlay of the fields of view of each chamber provided with an optical correction unit according to an embodiment of the present solution. [Figure 8] 1 shows a schematic diagram of an optical system having a receiving device including an arrangement according to an embodiment of the present solution; [Figure 9] 9 shows a schematic diagram of an optical system having a receiving device including a different configuration than in FIG. 8 according to an embodiment of the present solution. [Figure 10] 10 shows a schematic diagram of an optical system having a receiving device including a different configuration from that of FIGS. 8 and 9 according to an embodiment of the present solution. FIG. [Figure 11] FIG. 2 shows a schematic representation of an optical system with a support for a chamber rotatable about an axis of rotation parallel to the Earth's axis of rotation according to an embodiment of the solution. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0151] Referring to the accompanying drawings, an optical system made in accordance with the present invention is indicated generally by the reference numeral 100 .

[0152] With particular reference to FIGS. 1 and 2, the device 100 includes an optical device 1 having a spherical shape and a central portion 2 .

[0153] The optical device 1 has a first spherical surface 3 centered on a central portion 2 of the optical device 1 , the first spherical surface 3 defining a spherical cavity 4 within the optical device 1 .

[0154] A plurality of adjacent 2×2 blocks 5 cover the first spherical surface 3. The blocks are lenses made of optical glass, are transparent to light and define the outer surface (spherical surface) 6 of the optical device 1.

[0155] In detail, the block 5 has a first surface 7 and a second surface 8 opposite the first surface 7, where the first surface 7 forms the inner surface of the optical device 1, i.e. the first spherical surface 3, and the second surface 8 forms the outer surface 6 mentioned above.

[0156] In a preferred embodiment of the invention, the first spherical surface 3 and the outer surface 6 are concentric, the first spherical surface 3 has a radius R1 equal to 0.95 m and the outer surface 6 has a radius R2 equal to 1 m.

[0157] With particular reference to FIG. 3A, block 5 consists of a spherical portion having a polygonal, specifically pentagonal, outer shape.

[0158] The optical system 100 includes at least a filler material 9 having a low refractive index and high transparency, which is contained within the spherical cavity 4 .

[0159] Preferably, the filling material 9 is a fluid. It may correspond to a mixture of two or more fluids having respective refractive indices different from each other.

[0160] In a preferred embodiment of the invention, the filling material 9 has a refractive index equal to 1.25 and a transparency of 0.3 m -1 It is a fluid equal to

[0161] The optical system 100 includes a frame 10 provided with a plurality of adjacent 2×2 apertures 11 defining respective seats 12 adapted to receive respective blocks 5 .

[0162] Preferably, the frame 10 is made of metal.

[0163] In a preferred embodiment of the invention, frame 10 forms a regular dodecahedron with each face corresponding to a pentagonal aperture 11 .

[0164] With particular reference to FIG. 3B, each opening 11 in the frame 10 is defined by an edge 13 of the frame 10 that is provided with a groove 14 shaped to receive a peripheral edge 15 of a block 5 .

[0165] Optical system 100 further includes a gasket 16 (O-ring) corresponding to each seat 12 of frame 10. Gasket 16 is disposed between block 5 and frame 10, extends into groove 14 that receives peripheral edge 15 of block 5, and abuts outer portion 17 of edge 13 of frame 10 and block 5 itself.

[0166] The optical system 100 also includes a resilient preloader 18 for each seat of the frame 10, disposed in the groove 14 opposite the gasket 16. The resilient preloader 18 is on an inner portion 19 of the edge 13 of the frame 10 and on the block 5, and exerts a pressure on the block 5 that prevents leakage of the fill material 9 contained within the spherical cavity 4.

[0167] The optical system 100 also includes a thermal compensator 20 (made of DELRIN or TEFLON) that has a thermal expansion coefficient greater than the thermal expansion coefficient of the material that constitutes the block 5. The thermal compensator is disposed in a seat 12 between the block 5 and the frame 10.

[0168] 4, optical system 100 includes a curved focal plane 21 onto which the image produced by optical device 1 is focused when illuminated. Curved focal plane 21 extends onto a second spherical surface 22 that surrounds optical device 1, centered on central portion 2 of optical device 1.

[0169] With particular reference to FIGS. 1-4, the optical system 100 includes a receiving device 23 that includes a plurality of chambers 23 a disposed in a curved focal plane 21 .

[0170] In particular, the chambers 23a are adjacent to each other such that the receiving device 23 seamlessly covers a portion of the second spherical surface 22.

[0171] In a preferred embodiment of the present invention, optical system 100 includes one or more arms 10 a extending from frame 10 to base 10 b to maintain frame 10 and optical device 1 spaced apart from receiving device 23 .

[0172] Each chamber 23a includes a field lens 24. The field lens 24 is disposed in the curved focal plane 21 with an optical axis 25 passing through the central portion 2 of the optical device 100. Each chamber 23a also includes an aperture 26. The aperture 26 is disposed downstream of the field lens 24 with respect to the central portion 2 of the optical device 100.

[0173] The diaphragm 26 extends within a solid angle 27 subtended by a half line 28 having its origin at the centre 2 of the optical device 1 and passing through an outline 29 of the field lens 24 .

[0174] The centre of the aperture 26 lies on the optical axis 25 of the relative field lens 24, and the optical projection of the aperture 26 through the field lens 24 onto the optical device 1 defines a virtual aperture 30 extending into the optical device 1 and centred on the centre 2 of the optical device 1.

[0175] The diaphragm 26 of each chamber 23a is arranged perpendicular to the optical axis 25 of the relative field lens 24. This defines a corresponding equivalent aperture of the optical system 100.

[0176] 5, each chamber 23a further includes an optical correction unit 31 arranged downstream of the diaphragm 26 with respect to the central portion 2 of the optical device 1. The optical correction unit 31 has the same optical axis as the relative field lens 24.

[0177] The optical correction unit 31 is arranged to correct spherical surface aberrations and chromatic aberrations present in the image projected onto the field lens 24 of the relative chamber 23a.

[0178] In a preferred embodiment of the present invention, the optical correction unit 31 includes an aspheric surface 32 of suitable shape for correcting the aberrations mentioned above.

[0179] Additionally, the optical correction unit 31 is positioned to straighten out the curvature of the curved focal surface 21 .

[0180] In a preferred embodiment of the present invention, optical correction unit 31 includes a planarizing lens 33 shaped to straighten out the curvature of curved focal surface 21 .

[0181] Each chamber 23 a of the optical system 100 further comprises an optical detector 34 (CMOS) arranged downstream of the optical correction unit 31 with respect to the central portion 2 of the optical device 1 .

[0182] In particular, the field lens 24 , the aperture 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 .

[0183] Preferably, the optical correction unit 31 is positioned to straighten the curvature of the curved focal plane 21 so that light entering the chamber 23a through the field lens 24 illuminates the optical detector 34 with optical quality on the order of a few arcseconds.

[0184] With particular reference to FIGS. 6 and 7, the width of the field of view 35 of the optical detector 34 is greater than the nominal field of view 36 that the relative field lens 24 accommodates.

[0185] The field of view 35 of the optical detector 34 is thereby enlarged by scattering of light due to the spherical surface aberration introduced by the optics.

[0186] FIG. 8 shows a schematic representation of a possible configuration of the receiving device 23.

[0187] In particular, Figure 8 shows a schematic diagram of the optical system 100 of Figure 1, where the receiving device 23 occupies the full extension of the hemisphere 22a of the second spherical surface 22. The receiving device 23 also extends below a horizontal plane 37 passing through the central portion 2 of the optical device 1.

[0188] In this case, optical system 100 can accommodate half of the celestial sphere by accommodating vignetting of the light source at the edge of the field of view that multiple chambers 23a correspond to.

[0189] 9 and 10 show a different configuration of the receiving device 23. Here, the receiving device 23 occupies a part of the second spherical surface 22 obtained by dividing the second spherical surface 22 by two cut surfaces 37a, 37b that include the central portion 2 of the optical device 1.

[0190] One of the cut surfaces 37a, 37b in FIG. 9 corresponds to a horizontal plane, and the other corresponds to an inclined surface that forms an angle equal to 150° with the horizontal plane.

[0191] The cut faces 37a, 37b in FIG. 10 correspond to a plane of incidence in a horizontal plane and form an interior angle equal to 150°.

[0192] The configuration of the receiving device 23 shown in FIGS. 9 and 10 makes it possible to establish a privileged direction of the light beam 38 entering the optical device 1 which is not affected by the vignetting phenomenon.

[0193] 11, the optical system 100 includes a support 39 on which the chamber 23a is mounted. The support 39 is rotatable about an axis of rotation 40 that is parallel to the axis of rotation of the Earth.

[0194] In a preferred embodiment of the present invention, the optical system 100 further includes an electrical driver 41 operably connected to the support 39 of the chamber 23a. The driver 41 includes: Rotating the support 39 around the axis of rotation 40 in synchronism with the movement of the earth through a predetermined angle, moving the support 39 from a rest position to an end position; a subsequent step of rotating the support 39 about the axis of rotation 40 to move the support 39 from the end position to the rest position at a rotation speed higher than in the previous step; are arranged so as to be periodically repeated.

[0195] In detail, the electric drive 41 includes an electric motor 42, a control unit 43 operably connected to the electric motor 43 for driving the electric motor 43, and a motion transmission system 44 operably connected to the electric motor 43 and the support 39 for rotating the support 39 based on at least one signal 45 generated by the control unit 43.

Claims

1. An optical system (100), comprising: An optical device (1) having a central portion (2), which is a solid, light-transmitting sphere or has a spherical shape, a first spherical surface (3) centered on the central portion of the optical device, the first spherical surface defining a spherical cavity (4) within the optical device; a plurality of adjacent 2×2 blocks (5) covering said first spherical surface, said plurality of blocks (5) being optically transparent lenses and defining an outer surface (6) of said optical device; and A filling material (9) that is at least optically transparent and contained in the spherical cavity. An optical device (1) comprising: a curved focal surface (21) on which an image produced by the optical device is focused when illuminated, the curved focal surface (21) extending on a second spherical surface (22) surrounding the optical device and centered on the central portion of the optical device; A receiving device (23) including a plurality of chambers (23a) disposed in the curved focal plane, each of the chambers comprising: a field lens (24) positioned in the curved focal plane with an optical axis (25) passing through the center of the optical device; and a diaphragm (26) disposed downstream of the field lens with respect to the center of the optical device and extending within a solid angle (27) bounded by a half line (28) passing through an outline (29) of the field lens with the center of the optical device as its origin; A receiving device (23) including: Including, the center of the aperture is on the optical axis of the field lens, and optical projection of the aperture through the field lens onto the optical device defines a virtual aperture (30) extending into the optical device and centered on the central portion of the optical device. Optical system.

2. 2. The optical system of claim 1, wherein the filling material (9) has a low refractive index and / or a high transmission.

3. 3. The optical system according to claim 1 or 2, wherein the filling material (9) is a fluid or an aerogel, the fluid being a mixture of two or more fluids each having a different refractive index.

4. 4. The optical system according to claim 1, comprising a frame (10) provided with a plurality of adjacent 2x2 openings (11) defining respective seats (12) adapted to receive respective said blocks (5) of said optical device (1).

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

6. The optical system according to any one of the preceding claims, wherein the block (5) consists of a spherical section having a polygonal, preferably pentagonal, outline.

7. 7. The optical system according to claim 1, wherein at least one of the chambers (23a) further comprises an optical correction unit (31) arranged downstream of the diaphragm (26) with respect to the central portion (2) of the optical device (1), the optical correction unit being arranged to correct spherical surface aberrations present in an image projected onto the field lens (24) of the relative chamber (23a).

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

9. 9. The optical system according to claim 7 or 8, wherein at least one of the chambers (23a) further comprises an optical detector (34) arranged downstream of the optical correction unit (31) with respect to the central portion (2) of the optical device (1).

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

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

12. The optical system according to any one of claims 9 to 11, wherein the width of the field of view (35) of the optical detector (34) is larger than the nominal field of view (36) corresponding to the relative field lens (24).

13. The optical system according to any one of claims 1 to 12, comprising a support (39) on which the chamber (23a) is mounted, the support being rotatable about an axis of rotation (40) parallel to the axis of rotation of the Earth.

14. a drive (41) operably connected to the support (39), the drive comprising: Rotating said support about said axis of rotation (40) through a predetermined angle in synchronism with the motion of the earth to move said support from a rest position to an end position; a subsequent step of rotating the support about the axis of rotation to move the support from an end position to a rest position; are arranged so as to be periodically repeated.

14. The optical system of claim 13.

15. 15. The optical system according to claim 14, wherein the drive is arranged such that movement of the support about its axis of rotation from an end position to a rest position is faster than the movement of the support when rotating synchronously with the movement of the Earth.

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