Positioning support structure

Abstract

A structure for supporting objects, such as optical components, is provided, that enables said objects to be precision adjusted in a plane, and in some embodiments for the plane to be tilted. The structure comprises at least two, and preferably three concentric rings that are each connected to a neighbouring ring by a pair of opposed flexures that permit movement only in one axis of a plane. Where there are three concentric rings then there are two sets of opposed flexures, one set associated with each pair of neighbouring rings, and wherein each set is arranged to allow adjustment on an orthogonal axis to the other. Some embodiments also allow a tilt of the plane. Adjustment of the position may be achieved using threaded members arranged to engage against an inner ring whilst being threaded with an outer ring. The threaded members may also be arranged to lock the rings into position.

Description

The present invention relates to positioning systems, as are often employed on optical systems, and precision engineering mounting systems. More particularly it relates to systems where a degree of adjustment of position, is required when holding an object in an otherwise stable position. It is commonplace when working with optical systems for certain optical elements, such as lenses, mirrors, light sources, and other components to be mounted in a manner that allows some fine-tuning of the positions of the elements. This may be, for example, to adjust a mirror position to reflect into a particular spot, or to move a lens to align it with other lenses or other optical components. Given the very small wavelengths involved, high precision is often required. There are optical stages that allow fine adjustment of position available, from companies such as Newport Corporation, and Thorlabs Inc., but these tend to be quite large, and are mainly meant for experimental work in laboratories etc. under carefully controlled conditions. As such, they are often not suited to application where they will be fixed in place into production systems. The applications to which optical equipment is put in industrial or operational environments often mean that the systems need to be sturdy and resistant to (or tolerant of) vibration, movement and rough handling. It is therefore desired to provide an alternative to the prior art that overcomes or mitigates problems or issues therewith, and which provides a degree of rigidity whilst allowing positional adjustment, with an ability to lock an element into a chosen position. According to a first aspect of the present invention there is provided a positioning support structure for mechanically supporting an object, the object having a primary axis, and being supportable on a plane perpendicular to that primary axis, and allowing an amount of adjustment of position of the object on at least one axis when so supported, the movement axis being in the plane, the structure comprising a floating central support frame for mounting the object, and a concentric surrounding frame comprising a chassis, and between the central support frame and the chassis, and on opposed sides thereof, and which together define an axis of movement, a pair of flexures that allow the central frame to move linearly between limits in the defined movement axis in relation to the chassis when subject to pressure, and wherein a locking means is arranged to lock the floating central support frame in a position between the limits of movement. Thus, embodiments of the invention allow an object, such as a lens, a mirror, an optical fibre, or some other optical, or non-optical component, to be held securely in position, in or against the central support frame, yet be precision adjustable to different positions as required. It therefore allows convenient commissioning of systems, such as complex arrays of optical components, and / or recalibration and adjustment of the positions of those components. It further allows for a compact design, allowing the location of multiple embodiments relatively close together as compared to prior art positioners, which is useful for example when there is to be an array of components close together. Note that a flexure, in the context of the application, is an element of the structure that permits movement of one support frame relative to an adjacent support frame, such as by a resilient means such as a spring or a flexible region of the structure. Note that, where the object is a lens, the primary axis of the object is generally the optical axis. In most lenses, the optical axis of the lens runs perpendicular to the surface of the lens at its centre. Of course the object may not always be a lens, but the primary axis will be the same as that that of a lens mounted centrally and symmetrically within the structure. In some embodiments the structure allows movement or flexure in two axes, and wherein, between the floating central support frame and chassis, there are two pairs of opposed flexures, each pair being located on orthogonal axes, X and Y, both axes being on the plane, each pair being associated with an axis, and each pair allowing linear movement only along their respective axis. Such embodiments therefore cater to many applications where positioning and fixing the position of an object is required in two orthogonal axes. Advantageously, the structure allows adjustment in one axis without having any significant effect on a position set in the orthogonal axis. To this end, some embodiments of the invention comprise a structure wherein, between the floating central support frame and the chassis is a floating intermediate support frame, and wherein the first pair of flexures connect the chassis to the floating intermediate support frame and are associated with movement in an X axis, and the second pair of flexures connect the floating intermediate support to the floating central support frame, and are associated with movement in the Y axis. Thus, adjustment of the position of the floating intermediate support frame by means of causing the first pair of flexures to flex will move both the intermediate support frame, and with it the floating central support frame in the same direction. Advantageously, in some embodiments, at least one threaded hole is formed into the chassis for each of the first pair of flexures for coupling with an associated screw or bolt, and the screw (or bolt) arranged to bear against the floating intermediate support frame to allow pressure to be put against it to allow movement and locking thereof. In this way the screw can push against the floating intermediate support frame to push it (and with it the floating central support frame) to a preferred position along its axis of movement. Once in position, then a second screw can be fastened and tightened into the matching hole in the other of the pair of flexures, so locking the flexure, and hence the floating intermediate support frame, in position. Preferably, there is at least one threaded hole associated with each such flexure. By suitable adjustment of the screws, planar translational movement of an object being held in the support structure can be made. The screws associated with a pair of flexures are advantageously located on an axis, at opposed sides of the support frame for which they are associated, and be axially aligned. Thus, adjustment of such screws will provide movement of the support frame on which they are arranged to bear against only in the associated axis. Advantageously, in some embodiments, at least one hole is formed into the chassis and into the floating intermediate support frame for each of the second pair of flexures, with the hole in the floating intermediate support frame being threaded for coupling with an associated screw, and the screw arranged to bear against the floating central support frame to allow pressure to be put against it to allow movement and locking thereof. In a similar manner to that explained above, this would then provide means for adjusting the position of the floating central support frame in relation to the floating intermediate support frame , and so allow for adjustment of the floating central support frame along its axis of movement. Thus, two orthogonal axes of movement can be obtained by adjusting screws associated with each pair of flexures. Preferably, there is at least one threaded hole associated with each such flexure. When there is at least one threaded hole associated with each flexure, by suitably tightening the screws when a chosen position of the floating elements has been obtained, the floating elements may be locked in the chosen position. In some embodiments the locking means allows the central support frame to be locked in a position whereby the central support frame is tilted relative to an axis Z (i.e. the primary axis), orthogonal to either or both of the X and Y axes. In some embodiments this is achieved by using two screws for each flexure, each located at different positions on the Z axis. This allows a different force to be applied along the Z axis for each of the screws in a pair of screws associated with a given flexure, which can impart a twist to the flexure, and hence to the floating element it is connected to. This therefore provides a tilt in the Z axis, that may be locked by suitable tightening of the screws. Advantageously, in some embodiments, the flexures comprise flexible, resilient elements. Advantageously, in some embodiments, the chassis, the flexures and the floating intermediate and central support frames are all formed from a single solid. The solid may be made from anything suitable, such as a plastic, a metal, for example aluminium or steel of some type, or any other suitable material, dependent upon size, weight and stiffness constraints given by a particular application. Advantageously, in some embodiments the chassis, flexures, floating central support frame and, if present, the floating intermediate support frame, are defined in the solid by cuts made therein. These cuts may be made, in some embodiments where the material is electrically conductive, using an electro-discharge machining technique. This may be, for example, a wire eroder, or similar. Otherwise, known manufacturing methods such as a mechanical saws, injection moulding, etc. may be used, dependent on the material chosen, as would be understood by a normally skilled person. Advantageously, in some embodiments, each flexure is arranged to allow movement in one of the axes X or Y, but not in the other. In some embodiments the flexures comprise a strip of resilient material having a plane that is orthogonal to the axis, X or Y, in which it is arranged to allow movement. By having a flexure arranged in this manner, movement of the flexure in its intended movement axis causes no, or very little significant movement in the orthogonal (Y or X) axis. The strip of material is advantageously a thin strip, such that it allows flexibility in axes other than those in the plane of the material. Advantageously, in some embodiments, the strip of material is arranged to have the appearance of being folded back on itself to produce a pair of parallel planes. The fold point, line, zone or region, may be at an approximately half way point along the strip. This allows further flexibility and range of movement along its intended axis of movement. Clearly, this need not be done by an actual folding process, but, in some embodiments at least, the cuts in the material may have such a folded appearance, with one part of the strip being alongside, and parallel to another. Advantageously, each part of the strip on each side of the fold point, line, zone or region may be of substantially equal length. The strip that comprises each flexure has two ends, or regions, that join onto respective adjacent elements of the support structure (these adjacent elements being the chassis and floating intermediate support frame, and the floating intermediate support frame and floating central support frame, for an embodiment having an intermediate support). Advantageously, the ends of the strip, in those embodiments where the strip has the folded back appearance, are attached to their respective adjacent elements at adjacent parts thereof. Thus, the attachment points of each of the strip ends are adjacent to each other, separated by the cut or gap between the respective supports. This minimises movement in an unintended axis when positional adjustment along the intended axis is made, and also minimises any twisting, in the X-Y plane of one support frame with respect to another as relative movement takes place. It also means that there is no, or negligible, rotational movement of the object about the primary axis, as the position of the object is moved in the X or Y directions. In other words, adjustment in one axis, X or Y, causes no or negligible movement in the other axis in the plane, Y or X respectively. In some embodiments each flexure may also be regarded as a pair of parallel members, preferably of approximately equal length, that are joined together at an articulation point, and each having a connection to a respective support frame. The members, along with the articulation, are elastically compliant, and hold the support frames to which they are attached in a manner that allows relative movement if pressure is applied along the axis (X or Y) for which they are arranged to allow movement, but to be stiff if pressure is applied in an orthogonal axis (Y or X respectively). The articulation point may be a point at which most of the flexure takes place, when relative pressure is applied along the movement axis, although some flexure may occur at any point on the members. In some embodiments the flexures in an opposed pair have mirror symmetry about a plane orthogonal to the axis defined by the flexures, i.e. the intended axis of movement. Other embodiments may have rotational symmetry instead of mirror symmetry. According to a second aspect of the invention there is provided a method of manufacturing a structure, the structure being as described in any of the appended device claims, and made from a conductive material, comprising taking a single block of material and using a wire eroding process to make multiple cuts therein so as to define the flexures, chassis, central support frame and, where present, an intermediate support frame. The invention will now be described, by way of example only, with reference to the following Figures, of which: Figure 1 diagrammatically illustrates, in an isometric view, an embodiment of the invention, comprising a support structure allowing lateral movement in two dimensions; Figure 2 diagrammatically illustrates a plan view of the same embodiment; and Figure 3 shows different views of the same embodiment with different positional adjustments applied to the intermediate support frame and centre support frame thereof. Shown in Figures 1 and 2 are two different views of an embodiment of the present invention, the embodiment comprising a support structure 10 for supporting an object. It comprises a single block of stainless steel (Ferralium 255) that has been machined into the general form shown by cutting tools using well-known methods, in this case using a wire eroder. The support structure 10 is arranged to be bolted to a baseplate, or other such structure according to the particular application for which it is intended. Bolt holes12 located around the perimeter of the support structure permit convenient fastening to such a baseplate etc. In the centre of the structure 10 is a collar 14 for holding an object (not shown), such as a lens or similar which may need to be positioned precisely, and to be held securely in the chosen position. The collar is formed as part of a floating central support frame 16. The floating central support frame 16 connects, via flexures 18, to a floating intermediate support frame 20. This floating intermediate support frame 20 connects in turn, via flexures 22 to chassis 30. The flexures have been formed by making cuts as shown, e.g. 24, 26, through the block in the Z axis using a wire eroder. These cuts also separate the adjacent support frames from each other. It will be appreciated that the width of the cuts defines the maximum degree of movement that one support frame may have in relation to an adjacent one. Note that the axes are as labelled at 28 in Figure 1, and as labelled in Figure 2. Threaded holes 32, 34 in the chassis and through flexure 22a are arranged to receive screws (not shown), which, when inserted, are able to bear against the floating intermediate support frame. As they are tightened, then ends of the screws press against the floating intermediate support frame and will push it, and with it the floating central support frame in the direction of travel of the screws, so changing the position of the central support frame with respect to the chassis. As the intermediate and central support frames move, the flexures 22 act as springs that allow movement in one axis (in this case the X axis), but do not move the floating central support frame in the orthogonal (Y) axis. A similar pair of holes (not visible in the figures) are present on the opposed side of the chassis so as to allow screws to bear on the floating intermediate support frame from the opposed direction, to allow movement of the central support frame with respect to the chassis to be made in that opposing direction. Thus, the respective holes allow the floating central support frame to be positioned in the X axis. Once it is in a desired position then the screws in holes 32, 34, and the opposing holes can be tightened to floating intermediate support frame in that axis to lock it in position in that axis. Holes 36, 38 are drilled into the chassis, and through the floating intermediate support frame and flexure 18. The hole as it passes through the floating intermediate support frame is threaded, and able to receive screws (not shown) that, when suitably tightened, will bear against the floating central support frame . In similar fashion to that described above, tightening these screws will move the central support frame in relation to the intermediate support frame in the Y axis, by flexing of flexures 18. Again, a complementary pair of holes are located on an opposed side of the structure, allowing screws to be used to move the central support frame in the opposite direction. Appropriate tightening of the screws on both sides allow the central support frame to be locked in position on this Y axis in relation to the intermediate support frame . In this embodiment, two holes (32, 34, and 36, 38) are provided per flexure. Some embodiments may have a single hole, and hence a single screw for use in moving the floating intermediate or central support frame as appropriate. However, by having two holes per flexure, it allows a different degree of pressure to be used for each screw, which has the effect of providing a tilt to the floating central support frame off the Z axis. This allows flexibility for applications where adjustment of an angle of a component in the X-Y plane is required. For example, by fastening a screw in hole 32 to a greater degree than a similar screw in hole 34, the floating intermediate support frame , and with it the floating central support frame, will be tilted on the X axis, with collar 14 tilted in a top-right direction. Conversely, if a screw in hole 34 is tightened more than a screw in hole 32, then the collar 14 will be tilted in the X axis in a bottom-left direction. Similar tilting along the Y axis can be done by appropriate tightening of screws in holes 36 and 38. It can be seen from the figures that each flexure, e.g. 22a comprises of two parallel leaf springs formed by a wire eroding process, so giving the folded appearance. These planar leaf springs are connected at one end by a free floating extended radius 23 to reduce localised stresses as they flex, with the other ends of each plane of the flexure connected to the chassis 30 and intermediate support frame 20 respectively. Each end of the flexure thus joins onto the main part of its respective support frame in close proximity to the other, separated by the void in the material that has been removed by the eroding process. This helps to keep unintended relative axial movement of the support frames to a minimum when positional adjustments are made. Figures 3a-d shows the same embodiment 10 as is described above, with four different positional settings being applied to the intermediate and central support frames by means of screws (not shown). A top-view of the embodiment is shown, looking down the Z axis. Each representation shows flexures 22a, 22b associated with movement in the X axis, and coupled between chassis 30 and floating intermediate support frame 20. Also shown are flexures 18a, 18b associated movement in the Y axis, and connected between floating intermediate support frame 20 and floating central support frame 16. Figure 3a shows both the central and the intermediate support frames in a neutral position, such that the central support frame is located midway in its potential range of travel with respect to the chassis 30. This position is achieved in the present embodiment by either not having screws located in holes 32, 34, 36, 38 (as shown in Figure 1) (and similar in the corresponding holes associated with the opposed flexures), or having screws present but with equal pressures being applied to the respective support frames. An advantage of having screws present is that it then locks the frames in their relative positions, so countering any unwanted movement that may occur due to vibration etc. Figure 3b shows the same embodiment, but with the floating intermediate support 20 being pushed over to the left to its full extent with respect to the chassis, so moving the central support frame along with it, and of course any object that may be mounted on or in the central support frame. The gap at position 40 can be seen to be substantially gone, as compared to the same spot in Figure 3a, as the two ends of flexure 22a have come together. Likewise, the gap at position 42 is increased to its maximum extent. This movement is achieved by tightening one or more screws located in holes associated with flexure 22b (and being opposite those holes 32, 34 visible in Figure 1), and of course slackening, as necessary, any screws that may be present in holes 32, 34 to accommodate the movement of the intermediate support frame. The screws engage with threads cut into the chassis, with the screws then passing through holes cut into the flexure 22b and bearing on the intermediate support frame, so as to be able to push it into position as the screws are tightened. The central support frame remains in a neutral position with respect to the intermediate support frame. Figure 3c shows the same embodiment 10, this time with the intermediate support frame 20 being returned to its neutral position, and with the central support frame being pushed upwards, along the Y axis, to its maximum extent, with respect to the intermediate support frame. It can be seen for example that the fixture 18a is fully compressed, and there is little to no separation between the intermediate support frame and the chassis 30 at point 44, whereas fixture 18b is fully extended, with a large gap resent at point 46. This movement is achieved by inserting and tightening screws into holes 36 and / or 38 such that they engage with threads in the intermediate support frame, pass through holes in the flexures 18b and bear on the central support frame. By tightening such screws it forces the flexures 18a and 18b to bend out of their resting plane (as seen in Figure 3a), moving the central support in the Y axis relative to the intermediate support frame. The intermediate support frame remains in a neutral position with respect to the chassis, as no screw pressure has been put on flexures 22a and 22b. Figure 3d shows the embodiment 10 but with movement away from the neutral position being applied in both the X and Y axes. In this case, the movement of the central support frame is to upward along the Y axis with respect to the intermediate support frame (and of course with respect to the chassis), and movement of the intermediate support frame is to the right, along the X axis, with respect to the chassis. It will be seen that the spacings at points 48 and 50 are at a minimum, whereas at point 52, on the opposite side, the spacings are at a maximum. This movement is achieved by inserting and tightening screws into holes 32, 34 to achieve the X axis movement, and by inserting and tightening screws into holes 36, 38 to achieve the Y axis movement, as described above. Some of the extents of movement have been shown in these figures, but of course it will be appreciated that movement in the opposed directions to that shown is achieved by suitable tightening of screws from opposed sides to those described above, and that any position within the limits of movement in X and Y may be achieved. The invention has particular utility for holding optical elements such as lenses, mirrors, polarisers, gratings, optical fibres etc., but also has utility for holding any other items where precision adjustment in the plane may be required, or where a small degree of tilt may be useful. The invention may be further understood from the following paragraph: The invention may comprise a structure for supporting objects, such as optical components, that enables said objects to be precision adjusted in a plane, and in some embodiments for the plane to be tilted. The structure comprises at least two, and preferably three concentric rings that are each connected to a neighbouring ring by a pair of opposed flexures that permit movement only in one axis of a plane. Where there are three concentric rings then there are two sets of opposed flexures, one set associated with each pair of neighbouring rings, and wherein each set is arranged to allow adjustment on an orthogonal axis to the other. Adjustment of the position may be achieved using threaded members arranged to engage against an inner ring whilst being threaded with an outer ring. The threaded members may also be arranged to lock the rings into position. It will be appreciated by the person skilled in the art that features in one aspect of the invention may be applied to other aspects of the invention, in any appropriate combination. It will further be understood that the various embodiments disclosed herein have been described for the purposes of illustration, and that modifications may be made WO 2025 / 162820                                   PCT / EP2025 / 051705 11 without departing from the scope of the present disclosure. For example, some embodiments may have a single pair of flexures at either side of a chassis connecting to a floating central support frame, so allowing adjustable movement in only a single axis. Equally, there may be embodiments with more than one intermediate support frame, so 5 as to allow further adjustment from different angles, which may not just be associated with a single (X or Y) axis.

Claims

1. A positioning support structure for mechanically supporting an object, the object having a primary axis, and being supportable on a plane perpendicular to that primary axis, and allowing an amount of adjustment of position of the object on at least one movement axis when so supported, the movement axis being in the plane, the structure comprising a floating central support frame for mounting the object, and a concentric surrounding frame comprising a chassis, and between the central support frame and the chassis, and on opposed sides thereof, and which together define an axis of movement, a pair of flexures that allow the central frame to move linearly between limits in the defined movement axis in relation to the chassis when subject to pressure, and wherein a locking means is arranged to lock the floating central support frame in a position between the limits of movement.

2. A structure as claimed in claim 1 wherein, between the floating central support frame and chassis, there are two pairs of opposed flexures located on orthogonal axes, X and Y, both axes being on the plane, each pair being associated with an axis and each pair allowing linear movement only along their respective axis.

3. A structure as claimed in claim 2 wherein, between the floating central support frame and the chassis is a concentric floating intermediate support frame, and wherein the first pair of flexures connect the chassis to the floating intermediate support frame, and are associated with the X axis , and the second pair of flexures connect the floating intermediate support frame to the floating central support frame, and are associated with the Y axis.

4. A structure as claimed in claim 3 wherein at least one threaded hole is formed into the chassis for each of the first pair of flexures for coupling with an associated screw or bolt, and the screw arranged to bear against the floating intermediate support frame to allow pressure to be put against it to allow movement and locking thereof.

5. A structure as claimed in claim 4 wherein, for each pair of flexures, there are a pair of opposed, axially aligned screws providing adjustment of the intermediate support frame.

6. A structure as claimed in any of claims 3 to 5 wherein at least one hole is formed into the chassis and into the floating intermediate support frame for each of the second pair of flexures, with the hole in the floating intermediate support frame being threaded for coupling with an associated screw, and the screw arranged to bear against the floating central support frame to allow pressure to be put against it to allow movement and locking thereof.

7. A structure as claimed in any of the above claims wherein the locking means allows the floating central support frame to be locked in a position whereby the floating central support frame is tilted relative to an axis Z, orthogonal to either or both of the X and Y axes.

8. A structure as claimed in claim 7 wherein the locking means comprises screws as claimed in claims 4 or 5, and wherein there are two screws associated with each of the X and Y axes, the screws for a given axes each being located at different positions on the Z axis.

9. A structure as claimed in any of the above claims wherein the flexures comprise flexible, resilient elements.

10. A structure as claimed in any of the above claims wherein the chassis, the flexures and the supporting frames are all formed from a single solid.

11. A structure as claimed in claim 10 wherein the solid is a metal.

12. A structure as claimed in claim 110 wherein the chassis, flexures, floating central support frame and, if present, the floating intermediate support frame, are defined in the solid by cuts made therein.

13. A structure as claimed in claim 12 wherein the cuts are made using an electrodischarge machining technique.

14. A structure as claimed in any of the above claims wherein each flexure is substantially planar, or parallel-planar, and has flexibility in an axis orthogonal to its plane(s), and is stiff in the axes of the plane(s).

15. A structure as claimed in claim 14 wherein each flexure comprises of a strip of resilient material having a plane that is orthogonal to the axis, X or Y in which it is arranged to allow movement.

16. A structure as claimed in claim 15 wherein the strip of material is arranged to fold back on itself to produce a pair of parallel planes.

17. A structure as claimed in claim 15 or claim 16 wherein, for each of the flexures connected between a floating support frame and its immediately surrounding support frame, the strip, having two ends, has each end joined to adjacent parts of the respective region.

18. A structure as claimed in any of claims 14 to 17 wherein the flexures in an opposed pair have mirror symmetry about a plane orthogonal to the axis defined by the flexures.

19. A method of manufacturing a structure, the structure being as claimed in any of the above claims, and made from a conductive material, comprising taking a single block of material and using a wire eroding process to make multiple cuts therein so as to define the flexures, chassis, floating central support frame and, where present, a floating intermediate support frame.

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