Tilting device for an optical element for measuring the optical performance of said optical element

Abstract

This device (1) for tilting an optical element (3) for measuring the optical performance of said optical element (3) comprises a platform (5) for positioning the optical element (3), and an armature (7) supporting said platform (5), the armature (7) being intended to rest on a fixed plane (9) and comprising a first sliding system (15) such that the platform (5) is movable in translation along a first direction (A) relative to the fixed plane (9), the armature (7) further comprising a rotation system (25) such that the platform (5) is movable in rotation about an axis corresponding to a second direction (B) perpendicular to the first direction (A). Figure for the abbreviation: Fig. 3

Description

Title of the invention: Device for tilting an optical element for measuring the optical performance of said optical element. Technical field

[0001] The present invention relates to the characterization of optical elements, in particular the characterization of optical elements comprising an optical treatment, such as a thin film treatment, deposited on one of their surfaces.

[0002] In particular, the present invention relates to the characterization of the optical performance of optical elements whose surface to be characterized is curved or of complex shape. Previous techniques

[0003] Thin film treatments are currently deposited on different types of optical elements such as lenses, whose geometries are more or less complex depending on the needs.

[0004] Among the optical elements on which thin films are deposited, there are planar optical elements such as blades or windows, but most of the optical elements treated with thin films are lenses with curved surfaces.

[0005] Currently, in order to verify the conformity of the optical performance of the optical elements, particularly in reflection, the optical elements are positioned on a platform hollow in its center, also called a substrate holder, through which it is possible to pass a reflected light flux towards a spectrophotometer. To obtain a calibrated measurement, the performance measurement is first carried out on one or more flat samples, serving as a reference.

[0006] This flat witness is considered in the prior art as representative in terms of optical performance of the optical performance of optical elements with curved surface, whereas this is not the case since the measurement is only carried out at the center of the optical element.

[0007] However, until now, it was not possible to directly measure a treated curved lens, particularly due to its curvature and the optical aberrations it generates. The actual optical performance of a curved optical element was therefore not measurable. Description of the invention

[0008] The present invention therefore aims to overcome the aforementioned drawbacks and to provide a device enabling the measurement of optical performance, in particular a reflection rate, of an optical element of complex shape, for example curved.

[0009] The present invention relates to a device for tilting an optical element for measuring the optical performance of said optical element, comprising a platform for placing the optical element, and an armature supporting said platform, the armature being intended to rest on a fixed plane and comprising a first sliding system so that the platform is movable in translation along a first direction relative to the fixed plane, the armature comprising a rotation system so that the platform is movable in rotation around an axis corresponding to a second direction perpendicular to the first direction.

[0010] Thus, the device allows, through a rotation system, to measure in reflection of curved optical element surfaces and to access the real optical performance of the optical element.

[0011] This device not only allows for measurement at the center of the optical element, but also at various locations on the curved surface, thus enabling evaluation of the homogeneity of the optical treatment across the entire treated surface. This information is crucial in the case of narrow, sensitive optical filters, whose optical performance must be strictly controlled.

[0012] In addition, this device makes it possible to control the different curved surfaces purchased and treated by external suppliers in order to verify their actual performance, which is not possible in the current state.

[0013] Advantageously, the frame includes a second sliding system so that the platform is movable in translation along a third direction orthogonal to the first and second directions.

[0014] In a particular embodiment, the frame includes a third slide system whose translation is carried out along the first direction and whose adjustment step of said translation is finer than the adjustment step of the first slide system.

[0015] Advantageously, each slide system includes a slide and a screw adjustment system for the position of the slide.

[0016] Advantageously, the rotation system includes a pivot and a locking brake for said pivot.

[0017] In one embodiment, when the fixed plane is positioned horizontally, the first direction is vertical.

[0018] Advantageously, the platform includes an orifice so that a luminous flux can be reflected onto the optical element placed on the platform through said orifice.

[0019] The present invention also relates to a performance measurement system for an optical element comprising a device as defined above, a light source, a spectrophotometer, and a V-shaped deflection device comprising a prism configured to reflect a light flux onto a first face coming from the light source towards the optical element positioned on the platform of the device, and to reflect on a second face, the light flux reflected by the optical element towards the spectrophotometer.

[0020] Advantageously, the light source, the "V" deflection device and the spectrophotometer are aligned in a direction orthogonal to the first and second directions.

[0021] The present invention further relates to a method for measuring the optical performance of an optical element coated with an optical treatment using the system as defined above, comprising the implementation of the following steps, to be carried out for any angle of the rotation system for which a measurement is desired:

[0022] - Positioning of a reference optical element on the platform;

[0023] - Searching for and obtaining a position of the platform for which a maximum intensity is collected by the spectrophotometer for a given wavelength during a reflection measurement on the reference optical element using translational motion along the first direction;

[0024] - Acquisition of a set of reflection measurements on the optical element of reference for a desired wavelength range at the previously obtained plateau position;

[0025] - Insertion of the optical element coated with an optical treatment in place of the optical reference element;

[0026] - Acquisition of a set of reflection measurements on the optical element for the desired wavelength range at the previously obtained plateau position; and

[0027] - Change of angle of the rotation system and repetition of the previous steps. Brief description of the drawings

[0028] Other objects, features and advantages of the invention will become apparent from the following description, given solely by way of non-limiting example, and made with reference to the accompanying drawings in which:

[0029] [Fig.1] is a schematic cross-sectional view of a first embodiment of a tilting device for an optical element;

[0030] [Fig.2] is a schematic cross-sectional view of a second embodiment of a tilting device for an optical element;

[0031] [Fig.3] is a schematic cross-sectional view of a third embodiment of a tilting device for an optical element;

[0032] [Fig.4] is a schematic view of a performance measurement system for an optical element comprising a device as shown in [Fig. 3]; and

[0033] [Fig.5] is a schematic representation of the steps in a process for measuring the optical performance of an optical element. Detailed description of at least one embodiment

[0034] A first embodiment of a tilting device 1 for an optical element 3 for measuring the optical performance of said optical element 3 has been schematically represented in [Fig.1].

[0035] The optical element 3 is for example an optical element on which an optical treatment is applied, for example a thin film coating, also called a multi-layer coating.

[0036] More particularly, the optical element 3 is a curved optical element whose optical characteristics can be measured along its curvature by the present device. The optical element 3 is, for example, spherical, aspherical, rotationally symmetric, or freeform.

[0037] The device 1 includes a platform 5 for placing the optical element 3, and an armature 7 supporting said platform 5.

[0038] The frame 7 is mainly made of metal and comprises various parts.

[0039] The frame 7 is intended to rest on a fixed plane 9, for example a horizontal fixed plane such as a work surface or a floor. The frame 7 rests on the fixed plane 9 by means of feet or an arm.

[0040] The armature 7 comprises a first part 11 including the platform 5, and a second part 13 interacting with the first part 11 by forming a first sliding system 15 so that the platform 5 is movable in translation along a first direction A relative to the fixed plane 9. Optionally, the first part 11 and the second part 13 interact via a third part 17 forming a pivot with an axis parallel to the first direction A.

[0041] When the fixed plane 9 is positioned horizontally, the first direction A is for example vertical.

[0042] The first slide system 15 includes a slide 19 and a system 21 for adjusting the position of the slide by means of a screw.

[0043] The armature 7 further includes a fourth part 23 interacting with the second part 13 so as to form a rotation system 25 so that the plate 5 is mobile in rotation around an axis corresponding to a second direction B perpendicular to the first direction A.

[0044] Preferably, the second direction B is parallel to the posing surface defined by the plate 5.

[0045] The rotation system 25 includes a pivot 27, the second part 13 including a brake disc 29 configured to be braked by a locking brake 31 of the rotation system 25, the locking brake 31 belonging to the fourth part 23.

[0046] The pivot 27 allows rotation over a range between -60° and 60° with respect to a central reference axis, for example the first direction A.

[0047] Optionally, the fourth part 23 includes a second slide system 33 so that the plate 5 is movable in translation along a third direction C orthogonal to the first direction A and the second direction B.

[0048] Thus, when the fixed plane 9 is positioned horizontally, the second and third directions B and C are horizontal.

[0049] The second slide system 33 allows, when the rotation system 25 positions the plate 5 other than horizontally, to move the plate 5 laterally in order to guarantee an optical measurement at the desired location despite a shift induced by the angle of the rotation system 25.

[0050] In a preferred embodiment, the platform 5 includes an orifice 35 such that a luminous flux can be reflected on the optical element 3 placed on the platform 5 through said orifice 35, the curvature of the optical element 3 itself being able to pass through the orifice 35 as shown.

[0051] A second embodiment of a tilting device 1 for an optical element 3 for measuring the optical performance of said optical element 3 has been schematically represented in [Fig.2].

[0052] This second embodiment has identical characteristics to the first embodiment, with only a different arrangement of the reinforcement 7.

[0053] The device 1 thus comprises a platform 5 for placing the optical element 3, and an armature 7 supporting said platform 5.

[0054] The frame 7 is intended to rest on a fixed plane 9, for example a horizontal fixed plane such as a work surface or a floor. The frame 7 rests on the fixed plane 9 by means of feet or an arm.

[0055] The armature 7 comprises a first part 37 and a second part 39 interacting with the first part 37 by forming a first sliding system 15 so that the plate 5 is mobile in translation along a first direction A relative to the fixed plane 9. Optionally, the first part 37 and the second part 39 interact via a third part 41 forming a pivot with an axis parallel to the first direction A.

[0056] When the fixed plane 9 is positioned horizontally, the first direction A is for example vertical.

[0057] The first slide system 15 includes a slide 19 and a system 21 for adjusting the position of the slide by means of a screw.

[0058] The armature 7 further includes a fourth part 43 comprising the plate 5 and interacting with the second part 39 so as to form a rotation system 25 such that the plate 5 is mobile in rotation around an axis corresponding to a second direction B perpendicular to the first direction A.

[0059] Preferably, the second direction B is parallel to the posing surface defined by the plate 5.

[0060] The rotation system 25 includes a pivot 27, the second part 13 including a brake disc 29 configured to be braked by a locking brake 31 of the rotation system 25, the locking brake 31 belonging to the fourth part 23.

[0061] The pivot 27 allows rotation over a range between -60° and 60° with respect to a central reference axis, for example the first direction A.

[0062] Optionally, the first part 37 includes a second slide system 33 so that the plate 5 is movable in translation along a third direction C orthogonal to the first direction A and the second direction B.

[0063] Thus, when the fixed plane 9 is positioned horizontally, the second and third directions B and C are horizontal.

[0064] The second slide system 33 allows, when the rotation system 25 positions the plate 5 other than horizontally, to move the plate 5 laterally in order to guarantee an optical measurement at the desired location despite a shift induced by the angle of the rotation system 25.

[0065] In a preferred embodiment, the platform 5 includes an orifice 35 such that a luminous flux can be reflected on the optical element 3 placed on the platform 5 through said orifice 35, the curvature of the optical element 3 itself being able to pass through the orifice 35 as shown.

[0066] A third embodiment of a tilting device 1 for an optical element 3 for measuring the optical performance of said optical element 3 has been schematically represented in [Fig.3].

[0067] This third embodiment has identical characteristics to the first embodiment, with only the additional presence of a third sliding system as detailed below.

[0068] The device 1 includes a platform 5 for placing the optical element 3, and an armature 7 supporting said platform 5.

[0069] The frame 7 is mainly made of metal and comprises various parts.

[0070] The frame 7 is intended to rest on a fixed plane 9, for example a horizontal fixed plane such as a work surface or a floor. The frame 7 rests on the fixed plane 9 by means of feet or an arm.

[0071] The armature 7 comprises a first part 11 including the platform 5, and a second part 13 interacting with the first part 11 by forming a first sliding system 15 so that the platform 5 is movable in translation along a first direction A relative to the fixed plane 9. Optionally, the first part 11 and the second part 13 interact via a third part 17 forming a pivot with an axis parallel to the first direction A.

[0072] When the fixed plane 9 is positioned horizontally, the first direction A is for example vertical.

[0073] The first slide system 15 includes a slide 19 and a slide position adjustment system 21 by screw.

[0074] The armature 7 further includes a fourth part 45 interacting with the second part 13 so as to form a rotation system 25 so that the plate 5 is mobile in rotation around an axis corresponding to a second direction B perpendicular to the first direction A.

[0075] Preferably, the second direction B is parallel to the posing surface defined by the plate 5.

[0076] The rotation system 25 includes a pivot 27, the second part 13 including a brake disc 29 configured to be braked by a locking brake 31 of the rotation system 25, the locking brake 31 belonging to the fourth part 45.

[0077] The pivot 27 allows rotation over a range between -60° and 60° with respect to a central reference axis, for example the first direction A.

[0078] Optionally, the armature 7 includes a fifth part 47 comprising a second slide system 33 so that the plate 5 is movable in translation along a third direction C orthogonal to the first direction A and the second direction B.

[0079] Thus, when the fixed plane 9 is positioned horizontally, the second and third directions B and C are horizontal.

[0080] The second slide system 33 allows, when the rotation system 25 positions the plate 5 other than horizontally, to move the plate 5 laterally in order to guarantee an optical measurement at the desired location despite a shift induced by the angle of the rotation system 25.

[0081] The fifth part 47 interacts with the fourth part 45 to form a third slide system 49 whose translation is along the first direction A and whose adjustment pitch is finer than that of the first slide system 15. The third slide system 15 also includes a slide 19 and a screw adjustment system 21 for the slide position. The finer adjustment pitch allows for more precise adjustment of the height of the platform 5. a more precise vernier and the combination of the first 15 slide system with the third 49 slide system.

[0082] Optionally, the fourth part 45 and the fifth part 47 interact through a sixth part 49 forming a pivot with an axis parallel to the first direction A.

[0083] In a preferred embodiment, the platform 5 includes an orifice 35 such that a luminous flux can be reflected on the optical element 3 placed on the platform 5 through said orifice 35, the curvature of the optical element 3 itself being able to pass through the orifice 35 as shown.

[0084] Figure 4 shows a perspective view of a performance measurement system 51 for an optical element comprising a device 1 according to the third embodiment, a light source 53, a spectrophotometer 55 and a V-shaped deflection device 57 comprising a prism 59 configured to reflect on a first face a light flux from the light source 53 towards the optical element 3 positioned on the platform of the device, and to reflect on a second face, the light flux reflected by the optical element 3 towards the spectrophotometer 55.

[0085] Advantageously, the light source 53, the "V" deflection device 57 and the spectrophotometer 55 are aligned along a direction orthogonal to the first and second directions A and B, i.e. along the third direction C.

[0086] This system allows the optical performance measurement process to be implemented, as schematically represented in [Fig.5].

[0087] This method allows, for example, the determination of the uniformity of an optical coating deposit on an optical element 3.

[0088] In the implementation of this method, a first step El is carried out of positioning a reference optical element on the platform 5.

[0089] The reference optical element is, for example, an optical element similar to the optical element 3 to be measured, but without optical treatment. The present method therefore makes it possible to measure the optical performance of said optical treatment applied to the optical element 3.

[0090] Then, a step E2 is carried out to search for and obtain a position of the platform 5 along the first direction A for which a maximum intensity is collected by the spectrophotometer 55 for a given wavelength during a reflection measurement on the reference optical element using the translational movement along the first direction A.

[0091] A step E3 of acquiring a set of reflection measurements on the reference optical element for a desired wavelength range at the previously obtained position of the platform 5 is then carried out. This acquisition of measurements constitutes a reference measurement.

[0092] Following this acquisition, a step E4 is performed involving the insertion of the optical element 3 coated with an optical treatment in place of the reference optical element. In this embodiment, the surface containing the optical treatment must be oriented towards the prism 59.

[0093] We then carry out a step E5 of acquiring a set of reflection measurements on the optical element 3 for the desired wavelength range at the previously obtained position of the platform 5.

[0094] Comparing the measurements obtained for the reference optical element and optical element 3 makes it possible to determine whether the applied optical treatment meets its specifications. In particular, if a thin-film filter is applied to optical element 3, this method makes it possible to verify that the filter remains well centered at different points of optical element 3, the measurement at the different points being obtained using the rotation system 25.

[0095] To this end, a step E6 is performed to change the angle of the rotation system 25, and the preceding steps are repeated for each angle, that is, for each point on the surface of the optical element 3, for which a measurement is to be taken. It should be noted that the measurement acquisition must be carried out with a luminous flux striking the optical element 3 substantially orthogonally at an angle of incidence equal to half the angular distance between the first and second faces of the prism 59; the adjustment of the sliding and rotation systems must be made for this purpose.

Claims

Demands

1. Device (1) for tilting an optical element (3) for measuring the optical performance of said optical element (3), comprising a platform (5) for placing the optical element (3), and an armature (7) supporting said platform (5), the armature (7) being intended to rest on a fixed plane (9) and comprising a first sliding system (15) such that the platform (5) is movable in translation along a first direction (A) relative to the fixed plane (9), characterized in that the armature (7) comprises a rotation system (25) such that the platform (5) is movable in rotation about an axis corresponding to a second direction (B) perpendicular to the first direction (A).

2. Device (1) according to claim 1, wherein the frame (7) includes a second slide system (33) such that the plate (5) is movable in translation along a third direction (C) orthogonal to the first direction (A) and the second direction (B).

3. Device (1) according to any one of claims 1 and 2, wherein the frame (7) comprises a third slide system (49) whose translation is carried out along the first direction (A) and whose adjustment pitch of said translation is finer than the adjustment pitch of the first slide system (15).

4. Device (1) according to any one of claims 1 to 3, wherein each slide system (15; 33; 49) comprises a slide (19) and a screw adjustment system (21) for the position of the slide (19).

5. Device (1) according to any one of claims 1 to 4, wherein the rotation system (25) comprises a pivot (27) and a locking brake (31) for said pivot (27).

6. Device (1) according to any one of claims 1 to 5, wherein when the fixed plane (9) is positioned horizontally, the first direction (A) is vertical.

7. Device (1) according to any one of claims 1 to 6, wherein the platform (5) includes an orifice (35) such that a luminous flux can be reflected onto the optical element (3) placed on the platform (5) through said orifice (35).

8. System (51) for measuring the performance of an optical element (3) comprising a device (1) according to any one of claims 1 to 7, a light source (53), a spectrophotometer (55) and a "V" deflection apparatus (57) comprising a prism (59) configured to reflect on a first face a light flux from the light source (53) towards the optical element (3) positioned on the platform (5) of the device (1), and to reflect on a second face, the light flux reflected by the optical element (3) towards the spectrophotometer (55).

9. System (51) according to claim 8, wherein the light source (53), the "V" deflection device (57) and the spectrophotometer (59) are aligned in a direction orthogonal to the first and second direction (A; B).

10. A method for measuring the optical performance of an optical element (3) coated with an optical treatment using the system (51) according to any one of claims 8 and 9, comprising carrying out the following steps, to be carried out for any angle of the rotation system (25) for which a measurement is desired: - Positioning (step E1) of a reference optical element on the platform (5); - Finding and obtaining a position (step E2) of the platform (5) for which a maximum intensity is collected by the spectrophotometer (55) for a given wavelength during a reflection measurement on the reference optical element using translational movement along the first direction (A); - Acquiring (step E3) a set of reflection measurements on the reference optical element for a desired wavelength range at the previously obtained position of the platform (5);- Insertion of the optical element (3) coated with an optical treatment in place of the reference optical element; - Acquisition (step E5) of a set of reflection measurements on the optical element (3) for the desired wavelength range at the previously obtained position of the platform (5); and; Change the angle of the rotation system (25) and repeat the previous steps.