Support device for an optical body, apparatus for detecting defects in an optical body comprising such support device and method for detecting defects in an optical body

Abstract

A support device (1) for a disc-shaped optical body (A) perimetrically delimited by a circular edge (B) which defines a reference axis (X). The support device (1) comprises a support structure (2), three support elements (3) associated with the support structure (2) and which can be associated with respective edge portions (B') which are angularly spaced from each other of the circular edge (B) to define, for the optical body (A), an operative configuration, and constraint means (4) for keeping the optical body (A) in the operative configuration. The constraint means (4) comprise a concavity (5) belonging to each support element (3), the three concavities (5) being configured to house, respectively, the edge portions (B') when the optical body (A) is in operative configuration so as to prevent the optical body (A) from translating according to the reference axis (X) and perpendicularly thereto, at the same time allowing it to rotate around the reference axis (X).

Description

[0001] “SUPPORT DEVICE FOR AN OPTICAL BODY, APPARATUS FOR DETECTING DEFECTS IN AN OPTICAL BODY COMPRISING SUCH SUPPORT DEVICE AND METHOD FOR DETECTING DEFECTS IN AN OPTICAL BODY”

[0002] DESCRIPTION

[0003] Field of the invention

[0004] The present invention relates to the technical field of metrology, in particular the detection of defects in an optical body, such as a lens or a mirror.

[0005] More particularly, the present invention relates to a support device for the optical body mentioned above.

[0006] The present invention also relates to an apparatus for detecting defects in an optical body, the measuring apparatus comprising the support device mentioned above.

[0007] Furthermore, the present invention relates to a method for detecting defects in an optical body.

[0008] State of the prior art

[0009] The lenses and mirrors used in optical instruments, in the present application collectively referred to as "optical bodies", have more or less significant defects, called "aberrations", which cause the distortion of the images transmitted or reflected by such bodies.

[0010] It should be observed that, in the present application, an optical body is intended as a generally disc-shaped body, perimetrically delimited by a circular edge which defines a reference axis substantially coincident with the optical axis, the optical body substantially having the same cross-section according to all planes passing through the reference axis.

[0011] The circular edge mentioned above is used as reference for assembling the optical body in the instrument. The optical body defines, on one or both faces, respective concavity or convexity which correspond to those optically active and on which the aberrations are to be detected.

[0012] For the optical bodies used in high precision applications, for example in terrestrial or satellite astronomical observations, there is needed to detect the aberrations mentioned above with precision before assembling the optical body in the instrument, so as to be able to correct the subsequent processing operations so as to remove the aberrations.

[0013] It is known to carry out the detection mentioned above by means of interferometers, that is instruments which, directing a first portion of a coherent light beam towards the optical body and making it interfere with a second portion of the beam not interacting with the optical body, provide an indication of the aberrations.

[0014] The detection method is carried out after mounting the optical body on a support structure suitably positioned with respect to the interferometer and which is capable of defining a stable operative configuration for the optical body. A support structure of the known type mentioned above comprises three support elements arranged substantially according to vertices of a triangle which act as an equivalent number of rest elements for the optical body. The support structure is provided with screw clamps in order to constrain the optical body to the support elements mentioned above in a substantially rigid manner.

[0015] The aberrations can be classified into symmetrical and asymmetrical with respect to the optical axis of the body. In order to detect the asymmetrical aberrations, one has to carry out multiple detections, with the optical body rotated by a certain angle around the reference axis between one detection and the other. For example, it is well known to carry out 4 detections with the optical body rotated by 90° between one detection and the other.

[0016] In order to obtain the rotation described above, the prior art provides for releasing the optical body from the support structure by loosening the aforementioned clamps, after positioning the optical body in the rotated configuration, it is constrained again by tightening the clamps once again.

[0017] The prior art method mentioned above has some acknowledged drawbacks.

[0018] A first drawback of the method lies in the complexity thereof given that it requires multiple cycles for loosening and tightening the clamps, to be repeated for each clamp, implying an increase in the time required for the method.

[0019] A further drawback lies in the fact that, when repositioning the optical body with respect to the support elements, there may be introduced precession errors due to imprecisions in repositioning the optical body and the limited repeatability of the rotation, therefore jeopardising the metrological process and detecting the aberrations erroneously.

[0020] The severity of the drawbacks mentioned above increases proportionally to the size of the optical body.

[0021] Summary of the invention

[0022] An object of the present invention is to at least partly overcome the drawbacks mentioned above.

[0023] More particularly, the invention has the object of providing a device for supporting an optical body which allows to carry out the method for detecting defects in the optical body in a simple and quick manner compared to what is allowed by the prior art mentioned above.

[0024] Another object of the present invention lies in the fact that the support device mentioned above allows to rotate the optical body between one detection and the other so as to reposition it precisely, without introducing precessions or, in any case, limiting the precessions compared to what can be obtained with prior art methods.

[0025] Last but not least, an object of the invention lies in the fact that the support device is adapted to also support relatively large optical bodies.

[0026] The objects mentioned above are attained by a device for supporting an optical body according to claim 1 .

[0027] The objects mentioned above are also attained by an apparatus for detecting defects in an optical body comprising the support device mentioned above, according to claim 14.

[0028] The objects mentioned above are also attained by a method for detecting defects in an optical body according to claim 15.

[0029] Further characteristics and advantages of the invention are specified in the relative dependent claims.

[0030] Advantageously, the swiftness of the detection method allowed by the support device of the invention allows to carry out a larger number of detections considering the same amount of time.

[0031] Still advantageously, the high precision for repositioning the optical body allowed by the invention allows to carry out more precise detections of the aberrations compared to what can be obtained with the prior art.

[0032] These and other objects and advantages which will be mentioned below will be more apparent from description outlined below of some preferred embodiments of the invention, which are shown by way of non-limiting example with reference to the attached drawings.

[0033] Brief description of the drawings

[0034] Fig. 1 partially shows the support device of the invention, in axonometric view.

[0035] Fig. 2 shows a component of the device of Fig. 1 , in axonometric view.

[0036] Fig. 3 partially shows the component of Fig. 2 in operative conditions, in a cross-sectional view according to a plane passing through the axis Y.

[0037] Fig. 4 partially shows the support device of the invention, in a front view according to a view direction parallel to the axis X of Fig. 1 and directed from left to right.

[0038] Detailed description of some preferred embodiments

[0039] The support device of the invention is indicated in Fig. 1 in its entirety with 1 and it is particularly adapted to support a disc-shaped optical body A, perimetrically delimited by a circular edge B which defines, for the optical body A, a reference axis X, generally coinciding with the optical axis thereof. The optical body A defines at least one generally concave or convex face C delimited by the circular edge B mentioned above and designed to process the light beams during the operation. The method for detecting defects described above is therefore arranged facing the face C mentioned above.

[0040] The support device 1 mentioned above comprises a support structure 2, schematically shown in Fig. 4, with which there are associated the three support elements 3. The circular edge B of the optical body A can be associated with the support elements 3 in respective edge portions B', which are angularly spaced from each other around the reference axis X, so as to define for the optical body A the operative configuration shown in Fig. 1.

[0041] Given the circularity of the edge B, it is clear that, once the optical body A has been coupled to the support device 1 in the operative configuration mentioned above, the reference axis X takes a precise position, coinciding with the axis of the circumference tangent to the support elements 3 mentioned above and irrespective of the rotation of the optical body A around such axis. Therefore, in the present application, the reference axis X will be mentioned intending it in its position as defined by the support elements 3.

[0042] For the same reason, the operative configuration mentioned above comprises all the positions of the optical body A obtained by a rotation thereof around the reference axis X. As a matter of fact, the operative configuration solely determines the aforementioned direction of the reference axis X and the position of the optical body A along the direction of the reference axis X.

[0043] Furthermore, it is clear that the invention does not rule out variant embodiments in which the support elements 3 are more than three, although they are preferably three given that it is the only number that defines a stable operative configuration without introducing unnecessary constraints on the optical body A.

[0044] The present description refers to the variant with three support elements 3, but it can be immediately extended to the variants with a larger number of support elements.

[0045] Irrespective of the number of support elements 3, they are preferably configured so that the corresponding edge portions B' of the optical body A reproduce the positions of the supports used conventionally.

[0046] For example, a possible configuration provides for three support elements 3 arranged so that the edge portions B’ are arranged on a circumference having a centre in the reference axis X and with angles, respectively, equal to about 0°, 135° and 225°.

[0047] The configuration just described above allows to reproduce the stable configuration and reduce the aberrations produced by the so-called "V-mount” support. In a variant embodiment, the support elements 3 are arranged so that the edge portions B’ are arranged according to the vertices of an even polygon which, in the case of three support elements 3, is an equilateral triangle.

[0048] Advantageously, the abovementioned arrangements of the support elements 3 allow an optimal constraint of the optical body A to the support device 1.

[0049] Still preferably, the support elements 3 are arranged so that the reference axis X is substantially horizontal. As a result, in operative configuration, the face C of the optical body A which is subject matter of detection is arranged according to a substantially vertical plane. Advantageously, the latter configuration allows to distinguish the aberrations relating to the optical body, which rotate together with it, from those due to gravity, which instead remain stationary.

[0050] The support device 1 also comprises constraint means 4 for keeping the optical body A in the operative configuration mentioned above.

[0051] In particular and as observable in greater detail in Fig. 2, the constraint means 4 comprise a concavity 5 belonging to each of the three support elements 3 mentioned above. The three concavities 5 are configured to house, respectively, the three edge portions B' mentioned above when the optical body A is in operative configuration and they are configured so as to constrain the edge portions B' and maintain their positions along the reference axis X and their distances with respect to the latter, simultaneously allowing it to slide around the reference axis X.

[0052] As regards the description outlined above, it is clear that the combined action of the concavity 5 on the circular edge B allows, on the one hand, to stably define the operative configuration mentioned above for the optical body A and, on the other hand, allows it to rotate around the reference axis X.

[0053] As a result, the optical body A may be rotated without having to release it from the support elements 3 but, simply, by sliding the circular edge B thereof on the concavity 5, attaining the object of simplifying the repositioning of the optical body A and, therefore, simplifying the method for detecting the defects, as will be more apparent below.

[0054] Furthermore, due to the particular concave configuration of the surfaces 5, the operative configuration of the optical body A remains unvaried during the rotation mentioned above. In particular, the direction of the reference axis X remains unvaried, therefore avoiding to introduce precession errors and attaining a further object of the invention.

[0055] Preferably, each concavity 5 is made of low friction material, so as to facilitate the rotation of the optical body A.

[0056] Still preferably, the aforementioned low friction material is a polymer material which, advantageously, avoids damaging and cracks on the circular edge B when coupling with the concavity 5.

[0057] Even more preferably, the polymer material is polytetrafluoroethylene (PTFE), which is particularly effective in attaining the advantages mentioned above.

[0058] With regard to, in greater detail, each concavity 5, preferably and as observable in Fig. 3 it is defined by two surface portions 5a, 5b which diverge from each other towards the reference axis X, which in Fig. 3 is not visible but arranged downwards. More precisely, the two surface portions 5a, 5b are configured so that the distance, measured in the direction parallel to the reference axis X, between their two cross- sectional profiles according to a plane perpendicular to the reference axis X increases as it approaches the latter.

[0059] In this manner, the two surface portions 5a, 5b are arranged tangent to the edge portion B' in two respective areas of the latter, which are mutually opposite in the direction of the reference axis X.

[0060] Advantageously, the configuration just described above allows to keep the position of the circular edge B with respect to the reference axis X unvaried during the rotation of the optical body A, to the benefit of the positioning precision.

[0061] The configuration just described above also allows to limit the contact between the concavity 5 and the circular edge B at the tangency areas mentioned above of the edge portion B', exploiting the high precision of the circular edge B to the further benefit of the positioning precision of the optical body A.

[0062] Still advantageously, the limited width of the contact areas between the concavity 5 and the circular edge B limits friction in the rotation of the latter. Still advantageously, the aforementioned divergence between the two surface portions 5a, 5b allows to house optical bodies A comprising circular edges B with various thicknesses, by simply modifying the contact points between the circular edge B and the two portions 5a, 5b while maintaining the same benefits described above.

[0063] Preferably, each of the aforementioned two surface portions 5a, 5b is configured so that the corresponding cross-sectional profiles are straight, with the advantage of keeping unvaried the contact angle between the surface portions 5a, 5b and the circular edge B irrespective of the thickness of the latter, while maintaining the advantages mentioned above in any case.

[0064] Still preferably, the two surface portions 5a, 5b are symmetrical with respect to a plane perpendicular to the reference axis X, so as to obtain the same contact conditions of each of them with the circular edge B, to the benefit of positioning stability of the optical body A and of the ease of rotation.

[0065] With regard to the angle of divergence between the two surface portions 5a, 5b, or between the respective cross-sectional profiles, it is preferably comprised between 80 and 100°, for example it is equal to 90°. This leads to, in the hypothesis just described above of symmetry between the two surface portions 5a, 5b, the respective cross-sectional profiles are both inclined by about 45° with respect to the reference axis X, as observable in Fig. 3.

[0066] With regard to, in greater detail, the three support elements 3, preferably each of them comprises a corresponding arm 6 at whose one end a support body 7 is rotatably associated through rotation means 8 which define, for the support body 7, a rotation axis Y parallel to the rotation axis Y of the two support bodies 7 belonging to other two support elements 3.

[0067] Advantageously, the provision of the rotary support bodies 7 just described above allows to further limit the frictions, facilitating the rotation of the optical body A around the reference axis X.

[0068] Clearly, in the configuration just described above, the concavity 5 is defined by a groove 9 belonging to a first portion 7a of the support body 7, the groove 9 having the same cross-section according to any plane passing through the rotation axis Y of the support body 7, so as to maintain the same conditions for contact with the circular edge B irrespective of the angular position of the support body 7 around the rotation axis Y.

[0069] In the configuration just described above, if the cross-sectional profiles of the two surface portions 5a and 5b are straight as described above, each surface portion 5a, 5b is conical.

[0070] With regard to the rotation means 8, they preferably comprise at least one rolling bearing 8a, 8b interposed between the arm 6 and the support body 7, with the advantage of limiting friction during the mutual rotation and, therefore, the friction in the rotation of the optical body A.

[0071] Still preferably, there are present two of the aforementioned rolling bearings 8a, 8b, arranged respectively at the two ends of the opposite support body 7 along the rotation axis Y.

[0072] Advantageously, the configuration just described above allows a high rotation precision of the support body 7 and, therefore, for positioning the optical body A.

[0073] Still advantageously, the operator may cause the rotation of the optical body A indirectly by acting on the support body 7, with the advantage of avoiding to directly operate the optical body A.

[0074] Still advantageously, given that the diameter of the support body 7 is significantly smaller than that of the optical body A, the actuation thereof to obtain the rotation of the optical body A allows to regulate the rotation angle in a particularly precise manner.

[0075] In order to facilitate the operation described above, one or more support bodies 7 may comprise a second portion 7b spaced apart from the aforementioned first portion 7a along the rotation axis Y, which may be operated by the operator so as to drive in rotation the support body 7 at a sufficient distance from the optical body A.

[0076] Preferably, the aforementioned second portion 7b has an ergonomic shape, for example it is generally cylindrical with axis coincident with the rotation axis Y.

[0077] In order to facilitate the aforementioned rotation by the operator, the surface of the second portion 7b is preferably knurled and / or provided with cavities, reliefs and other configurations appropriate to obtain the aforementioned effect.

[0078] Preferably, the arm 6, the support body 7 and the two rolling bearings 8a, 8b are mounted so that the bearings 8a, 8b constrain the support body 7 to the arm 6 according to the direction of the rotation axis Y.

[0079] Preferably, and as observable in Fig. 3, an elastic element 10, for example a belleville washer is interposed between the arm 6 and a first rolling bearing 8a, the elastic element 10 being configured to push the bearing 8a mentioned above according to the direction of the rotation axis Y against the support body 7 and, as a result, to push the latter against the second bearing 8b.

[0080] Advantageously, the aforementioned elastic element 10 allows to recover any clearances deriving from the geometric tolerances of the various components, ensuring the positioning precision of the support body 7 according to the rotation axis Y and, as a result, ensuring the positioning precision of the optical body A.

[0081] The constraining of the bearings 8a, 8b, of the support body 7 and of the elastic element 10 to the corresponding arm 6 is preferably obtained by means of a nut 15 which, when screwed to a suitably threaded end 16 of the arm 6, sequentially pushes the elastic element 10 against the first bearing 8a, against the support body 7, against the second bearing 8b and against an abutment surface of the arm 6, as observable in Fig. 3.

[0082] Preferably, as observable in Fig. 4, one or more of the support elements 3 are associated with the support structure 2 through connection means 11 which can be actuated to move each of the aforementioned support elements 3 according to a respective predefined trajectory so as to change the distance thereof with respect to the other support elements 3.

[0083] It should be observed that, for the sake of simplicity of representation, Fig. 4 represents constraint means 4 and the optical body A shown transparent, representing only the respective profiles in plan view with dashed and dotted lines. Furthermore, for the sake of simplicity, the references are solely reported for the components corresponding to one of the three support elements 3, but they can also be used to indicate components corresponding to the other two support elements 3, which are identical except for the rotated arrangement.

[0084] Advantageously, the aforementioned connection means 11 allow to constrain the optical body A to the support device 1 and to release it with detection concluded.

[0085] Even advantageously, the connection means 11 allow to regulate the support device 1 so as to adapt it to optical bodies A of different geometry.

[0086] Still preferably, the aforementioned connection means 11 comprise a sliding guide 12 so as to allow the movement of each of the aforementioned support elements 3 according to a direction Z which is orthogonal to the reference axis X and which defines the predefined trajectory.

[0087] The aforementioned sliding guide 12 preferably comprises a corresponding straight profile 13 belonging to the support structure 2, for example a groove with an even cross-section, to which there is slidably coupled a sliding body 14 belonging to the support element 3, for example a prismatic body with a cross-section combined with the cross-section of the aforementioned groove.

[0088] Still preferably, the connection means 11 comprise stop means for locking the movement of each support element 3 in any position along the predefined trajectory so as to constrain the optical body A.

[0089] The aforementioned stop means may for example comprise screw means not shown in the drawings but per se known, so as to clamp each support element 3 to the corresponding sliding guide 12. The aforementioned screw means may for example be configured so as to allow the screwing of the sliding body 14 to the end of the arm 6 which is arranged facing the sliding guide 12. The configuration just mentioned above allows, by rotating the arm 6, to cause the approaching between the aforementioned end and the sliding body 14 so that they are clamped against two respective opposite surfaces of the sliding guide 12, so as to generate a friction which hinders the further sliding.

[0090] Operatively, the method for associating the optical body A to the support device 1 described above first and foremost provides for moving the support elements 3 through the connection means 11 so as to mutually space them apart until the circular edge B can be arranged between the respective concavities 5.

[0091] Subsequently, the support elements 3 are progressively approached to each other until they are arranged in contact with the circular edge B, so that the edge portions B' are housed in the concavities 5 so as to the constraining of the optical body A in the operative configuration described above.

[0092] At this point, the operator may drive in rotation the optical body A without having to release it from the support structure 2, by simply sliding the circular edge B in contact with the concavities 5.

[0093] The aforementioned rotation is facilitated by the presence of the rotatable support bodies 7 and further facilitated by the presence, on the latter, of the second portions 7b, on which the operator may operate to cause the rotation of the support bodies 7 in a rotation direction causing, as a result, the rotation of the optical body A in the opposite direction.

[0094] As mentioned above, the present invention also relates to an apparatus for detecting defects in an optical body A which differs from the apparatus of the known type substantially due to the fact that that it comprises the support device 1 described above, alternatively to the support structures of the known type. Therefore, the aforementioned detection apparatus is not shown in the drawings.

[0095] The detection apparatus mentioned above also comprises, for example an interferometer, configured to optically interact with the face C of the optical body A when the latter is arranged in the operative configuration defined by the support device 1 , so as to detect the defects thereof. Right from now, it should be observed that the face C may be any of the two opposite faces of the optical body A. It cannot be ruled out that, in variant embodiments of the invention, the measurement be carried out on both faces of the optical body A.

[0096] The detection apparatus just described above is particularly adapted to perform the following method for detecting the defects of the optical body A, also comprised in the present invention.

[0097] The method mentioned above comprises an operation which provides for coupling three concavities 5, for example those defined by a support device 1 described above, to corresponding portions B' of the circular edge B of the optical body A, angularly spaced from each other, so as to obtain the optical body A in a predefined operative configuration with respect to the optical detection device.

[0098] In particular, the aforementioned operative configuration is such that the optical body A is constrained according to the direction of the reference axis X and according to any direction perpendicular to the reference axis X. In other words, any translation of the optical body A is prevented, only the rotation thereof around the reference axis X thereof remaining allowed.

[0099] After the aforementioned coupling operation, the method provides for detecting the defects of the face C of the optical body A by means of the optical detection device, in a per se known manner.

[0100] After the aforementioned operation for detecting the defects, the method further provides for rotating the optical body A around the reference axis X by moving the circular edge B in contact with the concavities 5.

[0101] The aforementioned movement of the circular edge B may be carried out by sliding the latter in contact with concavities 5 which remain fixed and which, in this case, are preferably made of a low friction material.

[0102] Alternatively, the aforementioned movement may provide for the simultaneous rotation of the concavity 5 in contact with the circular edge B, for example when the concavity 5 belonging to the rotary support bodies 7 of the type described above.

[0103] In both cases, the optical body A remains stably in contact with the concavities 5 during the rotation and, therefore, the contact points between the circular edge B and the concavities 5 maintain their spatial position unvaried.

[0104] As a result, the rotation of the optical body A does not introduce precessions, to the advantage of the defect detection precision.

[0105] After rotating the optical body A in the new desired angular position, the method provides for repetition of the operation for detecting defects by means of the optical detection device.

[0106] The repetition of the detections carried out with the optical body A in respective angular positions different from each other advantageously allows to also detect the asymmetric aberrations of the optical body.

[0107] Preferably, there are carried out four detections, interspaced by rotations of the optical body A with angular width amounting to 90°.

[0108] Clearly, variant embodiments of the method of the invention may provide for any number of detections, interspaced by rotations of the optical body A with any angular widths, not necessarily equal to each other.

[0109] In any case, the invention is adapted to allow to carry out the detections, irrespective of their number and extent.

[0110] In the light of the above, it is clear that the invention attains the pre-established objects.

[0111] In particular, the possibility of rotating the optical body without having to release it from the support structure facilitates the method for detecting the defects and makes it quick compared to what is allowed by the prior art mentioned above.

[0112] Furthermore, the particular configuration or the concavities allows to rotate the optical body without substantially introducing precessions.

[0113] Furthermore, the support device is adapted to also support the optical bodies that are relatively large in size.

[0114] The invention is susceptible to modifications and variants all falling within the inventive concept outlined in the attached claims. In particular, the elements of the invention can be replaced by other technically equivalent elements.

[0115] Furthermore, the materials may be selected depending on the needs, without departing from the can scope of protection of the invention.

[0116] Should the technical elements specified in the claims be followed by reference signs, such reference signs are included with the sole purpose of improving the intelligibility of the invention and, therefore, they do not entail any limitation to the claimed scope of protection.

Claims

CLAIMS1. Support device (1 ) for supporting a disc-shaped optical body (A) perimetrically delimited by a circular edge (B) which defines a reference axis (X), said support device (1 ) comprising: a support structure (2); at least three support elements (3) associated with said support structure (2) and which can be associated with respective edge portions (B') which are angularly spaced from each other of said circular edge (B) to define an operative configuration for said optical body (A); constraint means (4) for keeping said optical body (A) in said operative configuration; characterised in that said constraint means (4) comprise a concavity (5) belonging to each of said at least three support elements (3), the at least three concavities (5) being configured to house, respectively, said edge portions (B') when said optical body (A) is in said operative configuration so as to prevent said optical body (A) from translating according to said reference axis (X) and perpendicularly thereto, at the same time allowing it to rotate around said reference axis (X).

2. Support device (1 ) according to claim 1 , wherein said concavity (5) is defined by two surface portions (5a, 5b) that are mutually divergent towards said reference axis (X) of said optical body (A) arranged in said operative configuration so as to be arranged tangent to the corresponding edge portion (B') in two respective areas thereof that are mutually opposite according to said reference axis (X).

3. Support device (1 ) according to any one of the preceding claims, wherein each of said at least three support elements (3) comprises an arm (6) and a support body (7) rotatably associated with an end of said arm (6) through rotation means (8) to define, for said support body (7), a rotation axis (Y) parallel to the rotation axes (Y) of the support bodies (7) belonging to the other two support elements (3), said concavity (5) being defined by a groove (9) belonging to said support body (7) and having an even cross-section around said rotation axis (Y).

4. Support device (1 ) according to claim 3, wherein said support body (7) ofeach of said at least three support elements (3) includes a first portion (7a) comprising said groove (9), said support body (7) of at least one of said at least three support elements (3) including an opposite second portion (7b) along said rotation axis (Y) which can be operated by a user to drive in rotation said support body (7).

5. Support device (1 ) according to claim 4, wherein said second portion (7b) is knurled and / or provided with cavities and / or reliefs.

6. Support device (1 ) according to claim 4 or 5 or 3 when combined with claim 2, wherein the cross-sectional profile of each of said two surface portions (5a, 5b) according to a cross-sectional plane perpendicular to said reference axis (X) is straight.

7. Support device (1 ) according to claim 4 or 5 or 6 or 3 when combined with claim 2, wherein said two surface portions (5a, 5b) are symmetrical with respect to a plane perpendicular to said reference axis (X).

8. Support device (1 ) according to any one of claims 3 to 7, wherein said rotation means (8) comprise one or more rolling bearings (8a, 8b).

9. Support device (1 ) according to claim 8, wherein said rotation means (8) include two rolling bearings (8a, 8b) respectively arranged at the opposite ends of said support body (7) along said rotation axis (Y).

10. Support device (1 ) according to any one of the preceding claims, wherein said concavity (5) is made of polymeric material.11 . Support device (1 ) according to any one of the preceding claims, wherein at least one of said support elements (3) is associated with said support structure (2) through connection means (11 ) which can be actuated to change the distance of said at least one support element (3) with respect to the other support elements (3).

12. Support device (1 ) according to claim 11 , wherein said connection means (11 ) comprise a sliding guide (12) which allows to move said at least one support element (3) according to a direction (Z) orthogonal on said reference axis (X).

13. Support device (1 ) according to any one of the preceding claims, wherein said support elements (3) are three.

14. Apparatus for detecting defects in a disc-shaped optical body (A)perimetrically delimited by a circular edge (B) which defines a reference axis (X), said detection apparatus comprising a support device (1 ) according to any one of the preceding claims and an optical detection device configured to interact with said optical body (A) when arranged in the operative configuration defined by said support device (1 ) to detect said defects.

15. Method for detecting defects in a disc-shaped optical body (A) perimetrically delimited by a circular edge (B) which defines a reference axis (X) by means of a support device (1 ) for an optical body (A) according to one or more of claims 1 to 13 and an optical detection device, said method comprising: coupling at least three concavities (5) to corresponding portions (B') of said circular edge (B) that are angularly spaced from each other so as to define for said optical body (A) an operative configuration in which said optical body (A) is constrained according to the direction of said reference axis (X) and according to any direction perpendicular to said reference axis (X); detecting said defects of said optical body (A) in said operative configuration by means of the optical detection device; rotating said optical body (A) around said reference axis (X) moving said circular edge (B) in contact with said concavities (5); repeating said detection of said defects by means of the optical detection device.

16. Method according to claim 15 when said support device (1 ) is according to claim 4 or 5, wherein the movement of said circular edge (B) in contact with said concavity (5) of said rotation step occurs indirectly by moving said second portion (7b) of said support body (7) around said rotation axis (Y) by a user.

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