Stick-slip positioner

Abstract

The invention relates to a positioner (1) comprising: - two blocks (2, 3); - an actuator (4) comprising: O a transducer (41) mounted on one of the blocks comprising a piezoelectric body (42) covered with a wiper (43) in contact with the piezoelectric body (42) and covering the piezoelectric body (42); O a pad (44) mounted on the other block that is movable in a stick-slip manner over the wiper (43) when an electrical signal is applied to the piezoelectric body (42) in order to move the blocks relative to one another along an axis X; and - a member (6) for heating the actuator (4).

Description

[0001] Description

[0002] Title: Sticky Slide Positioner

[0003] Technical field

[0004] The present invention relates to the field of sticky slip motors, more particularly sticky slip motors intended for applications in cryogenic conditions.

[0005] Prior art

[0006] It is known to move objects with nanometric precision by means of motors comprising one or more piezoelectric actuators. In particular, this type of motor may comprise two blocks in contact which can be moved relative to each other by a stick-slip motion mechanism. In order to implement this mechanism, the piezoelectric actuator is powered by an electrical voltage which induces its deformation, thus resulting in a succession of phases of sliding and solid friction of the blocks relative to each other and therefore their relative movement. Such motors are for example described in US 10,505,470 B2 and US 9,225,266 B2.

[0007] However, when used in cryogenic conditions, for example at a temperature below 10 K, these engines are often inoperative. In particular, residual gas, especially dihydrogen, is adsorbed by a cryosorption mechanism on the contacting faces of the blocks. This adsorbed gas cannot be evacuated, even by implementing a high vacuum in the enclosure containing the engine. It then acts as a glue that binds the blocks and prevents their relative movement, causing the engine to jam.

[0008] This blockage can be resolved by heating the piezoelectric actuators to a temperature above 30 K in order to desorb the gas.

[0009] In near-field microscopy, for example in scanning tunneling or atomic force microscopy, it is known to heat the entire microscope to bring the actuators up to temperature. However, in most cryogenic applications, a working temperature below 10 K, for example around 4 K, is desirable. Heating the entire microscope therefore has the major disadvantage of requiring a long time to return to the working temperature of the said microscope, starting from the heating temperature. In addition, this method of heating the actuators is energy-intensive. It requires heating the entire microscope, while the piezoelectric actuators represent only a small mass, compared to all the constituent elements of the positioner and the microscope.

[0010] There is therefore a need to quickly and with little energy desorb the residual gas adsorbed on the engine.

[0011] Furthermore, another disadvantage of known sticky sliding motors is the difficulty of ensuring a floating force between the blocks which remains substantially constant, under cryogenic conditions, during the solid friction phases during the sticky sliding movement. Indeed, the transition from ambient temperature to working temperature induces thermal expansions of the various constituent elements of the motor, which are difficult to take into account for the designer of the positioner, and which can induce such variations in the contact force.

[0012] There is therefore a further need to overcome this drawback.

[0013] Summary of the invention

[0014] The invention aims to meet these needs and achieves this through a positioner comprising:

[0015] - two blocks,

[0016] - an actuator comprising: o a transducer mounted on one of the blocks and comprising a piezoelectric body and a wiper in contact with the piezoelectric body and covering the piezoelectric body, o a pad mounted on the other block and movable by sticky sliding on the wiper when an electrical signal is applied to the piezoelectric body, in order to move the blocks relative to each other along an X axis, and

[0017] - an actuator heating member.

[0018] Since the heating element is integrated into the positioner, the actuator can be heated directly, without the need to heat the entire instrument in which the positioner can be installed. The gases released by the local heating of the actuator can be adsorbed by cooler walls of other components of the positioner. The pad and the piezoelectric body, thus freed from the gas(es), can perform a sticky sliding movement relative to each other, reducing the risk of jamming. In addition, the actuator heats up quickly, and the energy required to heat the actuator is low. Finally, the direct heating of the piezoelectric body increases the piezoelectric coefficient, which increases the power of the positioner.

[0019] Furthermore, the invention limits the thermal expansion of the positioner components by concentrating the heat produced by the heating member on the actuator. This avoids the effects resulting from this thermal expansion, which are complex and difficult to understand when designing the positioner.

[0020] The "sticky sliding" movement of the pad on the collector is induced by a deformation of the piezoelectric body when an electrical voltage is applied to the transducer. In the "sticky" phase during which the voltage is applied gradually, the deformation of the piezoelectric body causes a displacement of the block comprising the pad relative to the block comprising the collector due to the friction between the pad and the collector. In the sliding phase during which the voltage is rapidly decreased, the piezoelectric body abruptly returns to its initial position without the two blocks moving, due to the sliding of the pad on the collector. A repetition of cycles each comprising a sticky phase and a sliding phase allows the continuous displacement of one block relative to the other.

[0021] Heating organ

[0022] Preferably, in order for the heat produced to be efficiently transferred to the actuator, the heating member is less than 5 mm, preferably less than 1 mm, from the actuator.

[0023] Preferably, the heating member is in contact with the actuator and / or one of the blocks. Preferably, it is in contact with the actuator, preferably the piezoelectric body, so that the heat it produces is efficiently transferred by conduction to the actuator.

[0024] Preferably, the heating member is fixed, more preferably glued, in particular with a thermal glue, on the actuator and / or on one of the blocks and / or is in the form of a layer covering the actuator and / or one of the blocks. The layer can extend over a surface area of ​​between 5 mm 2 and 50 mm 2The thickness of the layer may be between 0.5 and 5 mm. The layer may comprise a resistive wire, for example shaped like a coil, immersed in a binder, for example a thermal glue. The opposite ends of the wire may be connected to electrical connectors, for a power supply by means of an electric current generator. The electrical connectors are for example arranged on an external face of one of the blocks.

[0025] Alternatively, the heating member may be distant from the actuator. The distance between the heating member and the actuator may be between 0.01 mm and 1 mm, preferably between 0.01 mm and 0.5 mm, more preferably between 0.01 mm and 0.1 mm.

[0026] Preferably, the heating member has a volume of less than 250 mm 3This makes it possible to produce a compact positioner that can be easily implemented within a microscope. In addition, the heating element therefore concentrates the heat produced in a small volume and can transfer it locally, for example by conduction when it is in contact with the actuator. The heating element can in particular have a thickness of between 0.5 mm and 5 mm.

[0027] The pad may be sandwiched between the heater and the transducer. Alternatively, the transducer may be sandwiched between the heater and the pad.

[0028] The heating element can be resistive or thermoelectric.

[0029] The heating member may be configured to increase the temperature of the actuator, in particular of the piezoelectric body, by at least 30 K, or even by at least 50 K. Prior to heating, the temperature of the actuator is, for example, less than 30 K, or even less than 5 K.

[0030] Actuator

[0031] The actuator is preferably configured to translate the blocks relative to each other along the X axis.

[0032] Preferably, the actuator is compressed between the blocks. In this way, in the absence of an electrical signal powering the actuator, it is ensured that the blocks remain stationary relative to each other.

[0033] The block on which the transducer is mounted may comprise a housing in which the transducer, in particular the piezoelectric body, is received. The housing and the transducer are preferably of complementary shape to ensure optimal retention of the transducer on the block. Preferably, the positioner comprises at least one group of actuators comprising two, preferably three actuators distributed opposite each other. Advantageously, this avoids unwanted movements of one block relative to the other along one or more axes transverse to the X axis.

[0034] Preferably the actuators of the actuator group are distributed, preferably regularly around the X axis.

[0035] Preferably, each actuator of the actuator group is heated by a corresponding heating member.

[0036] In particular, in order to avoid rotation of one or other of the blocks around an axis transverse to the X axis, the positioner comprises two groups of actuators arranged at a distance from each other, each group of actuators preferably comprising three actuators facing each other.

[0037] One of the blocks may comprise a support, the actuators being in contact with the support. Preferably, the actuators are distributed around the support.

[0038] The actuators may be arranged between the support and the other block, the pad of each actuator preferably being arranged between the support and the friction member of said actuator. The heating member of each actuator may be arranged between the support and the pad of the actuator that it is intended to heat.

[0039] Preferably, the support is cylindrical of revolution or, preferably, prismatic, in particular with a triangular base, for example equilateral.

[0040] The wiper and / or the pad may be made of a material chosen from sapphire, alumina, bronze, graphite, adamantine carbon and mixtures thereof.

[0041] Preferably, the wiper is made of sapphire and / or the pad is made of alumina.

[0042] The actuators may be distributed across the support facing each other. Alternatively, the number of actuators may be greater than three, for example a multiple of three.

[0043] The actuators may each be arranged between the support and the other block. The pad of each actuator may be arranged between the support and the wiper of said actuator.

[0044] Blocks

[0045] Either block may have several parts that move relative to each other, or parts that are fixed to each other. Alternatively, it may be monolithic. Preferably, each block is metallic, for example, stainless steel for non-magnetic applications or titanium, brass, or aluminum for applications in magnetic fields. The different constituent parts of each block may be made of different alloys.

[0046] Preferably, at least one of the blocks comprises a base part, a support part and a spring, transverse to the X axis, deformed, such that the actuator is compressed between the blocks. Preferably, the compressive force exerted on the actuator is oriented perpendicular to the X axis.

[0047] Preferably, the spring is made of a metallic material, preferably an alloy, in particular a bronze alloy, for example CuSn6, or a beryllium bronze alloy. The spring material can be adapted to the experimental conditions. For example, the spring can be made of stainless steel for non-magnetic applications or of titanium, brass, copper, for applications in magnetic fields.

[0048] The spring is preferably annular, ring-shaped, or helical, in order to easily accommodate thermal deformations that develop in the components of the positioner during large temperature variations, such as those that may occur when placing a sample on the positioner at room temperature and studying it at a temperature below 20 K.

[0049] Preferably, in particular according to a variant where the device comprises several actuators, the device comprises several, for example four, springs to ensure uniform compression. Preferably, the springs have identical rigidity, or are even identical.

[0050] According to a first embodiment, the spring elastically connects the support piece to the base piece and is preferably helical. Preferably, the spring is fixed to the support piece and to the base piece.

[0051] Preferably, the spring exerts a restoring force on the support piece and base piece, which is oriented perpendicular to the X axis.

[0052] The support piece may have a “U” or “L” shaped cross section.

[0053] The support can be arranged between the base piece and the support piece.

[0054] According to the variant where the positioner comprises several actuators, at least one of the actuators can be arranged between the support and the base part and at least one other of the actuators can be arranged between the support and the support part. In particular, at least one of the actuators of a group of actuators can be arranged between the support and the base part and at least one other of the actuators of said group can be arranged between the support and the support part.

[0055] In particular, the actuator disposed between the support and the base part can be compressed by the support and the base part and the other actuator disposed between the support and the support part can be compressed by the support and the support part.

[0056] Furthermore, the heating member may be arranged between the base part and the piezoelectric body. It may be in contact with the base part and the piezoelectric body.

[0057] According to a second embodiment, the spring surrounds the base part and the support part, and preferably is in contact with the base part and the support part, and preferably is annular or in the form of a ring portion.

[0058] Preferably, it exerts a compressive force on the support piece, preferably oriented radially around the X axis, in order to maintain the actuator(s) in compression between the support and the support piece.

[0059] The block comprising the support piece and the base piece preferably comprises a tubular and hollow portion, the wall of the tubular and hollow portion comprising the support piece, the support and the actuator(s) being housed in an interior space delimited by the tubular portion.

[0060] Furthermore, the block comprising the support may further comprise a plate, for example to carry a sample to be studied, and a bracket rigidly fixed to the plate and to the support.

[0061] The support piece may be at least partially arranged between the support and the plate.

[0062] The support piece may have a through opening into which the bracket is engaged.

[0063] The support piece may be mounted freely on the base piece, Le. it may be moved along at least one, or even two, or even three perpendicular axes. In other words, preferably, the moving part is not rigidly fixed to the support piece. In particular, in order to avoid excessive axial displacement along the X axis, the positioner preferably comprises an axial spring, preferably helical, exerting a restoring force between the base piece and the support piece, and which is oriented parallel to the X axis. In order to protect the axial spring, the support piece and the base piece may each be hollowed out so as to together define a housing, the axial spring being arranged in the housing. The axial spring may be arranged between the support and the plate. Preferably, the axial spring is helical.

[0064] Alternatively, the support piece may be rigidly fixed to the base piece and may comprise a flexible portion extended by a rigid portion on which the transverse spring(s) are fixed, the flexible portion being elastically deformable during the sticky sliding of the pad on the friction member and elastically returning the rigid portion, in particular against the base piece, following the sticky sliding of the pad against the friction member.

[0065] A "flexible portion" means a portion with lower bending and / or shear rigidity than the rigid portion. A flexible portion is, however, sufficiently rigid not to deform under its own weight.

[0066] In at least one cross-section to the X axis, the flexible portion preferably has an area, preferably at least twice, or even at least ten times, smaller than the area of ​​the rigid portion. For example, the support piece may have a plate shape and the flexible portion may have a recess extending in a median plane of the plate along an axis perpendicular to the Y axis. The recess has, for example, the shape of a dumbbell.

[0067] The invention also relates to a positioning device, preferably multi-axis, comprising first and second positioners according to the invention, one of the blocks of the second positioner comprising, or even consisting of, the first positioner.

[0068] Preferably, the blocks of the first positioner are movable relative to each other by sticky sliding along a first axis and the blocks of the second positioner are movable relative to each other along a second axis that is non-parallel, preferably perpendicular, to the first axis. Thus, the positioning device is multi-axis and allows a sample to be moved along two spatial dimensions.

[0069] The positioning device may comprise a third positioner according to the invention, one of the blocks of the third positioner comprising, or even consisting of, the second positioner. Preferably, the blocks of the third positioner are movable relative to each other by sticky sliding along a third axis that is non-parallel, preferably perpendicular, to each of the first and second axes. Thus, the multi-axis positioning device allows a sample to be moved in three spatial dimensions.

[0070] Preferably, the second positioner block that is movable relative to the first positioner defines a housing in which the first positioner is received. Preferably, it has a generally tubular and hollow shape and defines an interior space in which at least one of the first positioner blocks is entirely received.

[0071] Preferably, the third positioner block that is movable relative to the second positioner defines a housing in which the second positioner is received. Preferably, it has a generally tubular and hollow shape and defines an interior space in which at least one of the second positioner blocks is fully received. Thus, the first, second and third positioners can be arranged in the manner of a Russian doll within the positioning device.

[0072] The invention also relates to a method for heating the actuator of a positioner according to the invention or of a positioning device according to the invention.

[0073] According to a first preferred embodiment, prior to heating, the temperature of the actuator is less than 10 K, or even less than 5 K.

[0074] In particular, the method may include supplying electrical power to the actuator to heat the latter, in particular by the Joule effect.

[0075] Preferably, the heating induces an increase in the temperature of the actuator of less than 50 K.

[0076] The positioner can be arranged in a near-field microscope, for example a scanning tunneling microscope or an atomic force microscope.

[0077] Preferably, the method comprises, after heating, the movement of a sample carried by one of the two blocks, by electrically supplying the actuator.

[0078] According to a second mode of implementation, prior to heating, the temperature of the actuator is between 260 K and 273 K, the heating being carried out to defrost the contacting faces of the pad and the friction member.

[0079] The invention finally relates to a system comprising:

[0080] - a microscope, in particular a near-field microscope, comprising an enclosure,

[0081] - a positioner according to the invention or a positioning device according to the invention arranged in the enclosure, - optionally, a cooling module for cooling the enclosure to a temperature below 30 K, in particular approximately 4 K.

[0082] Brief description of the drawings

[0083] The invention may be better understood by reading the detailed description which follows, non-limiting examples of its implementation, and by examining the attached drawing, in which:

[0084] [Fig. 1] is a perspective view of a positioner according to a first embodiment of the invention,

[0085] [Fig. 2] is a side view of the positioner according to the first embodiment,

[0086] [Fig. 3], [Fig. 4] and [Fig. 5] are sectional views of the positioner according to the first embodiment according to planes (AA), (BB) and (CC) respectively,

[0087] [Fig. 6], [Fig. 7] and [Fig. 8] are perspective views of different parts of the positioner according to the first embodiment,

[0088] [Fig. 9] is an enlarged view of two specific arrangements of the heating member of the positioner according to the first embodiment,

[0089] [Fig. 10] is a perspective view of a positioner according to a second embodiment of the invention,

[0090] [Fig. 11] is a side view of the positioner according to the second embodiment,

[0091] [Fig. 12] and [Fig. 13] are sectional views along planes (DD) and (EE) respectively,

[0092] [Fig. 14] is a longitudinal sectional view of a positioner according to a third embodiment of the invention, and

[0093] [Fig. 15] is a longitudinal sectional view of a multi-axis positioning device according to the invention integrating the positioner according to the third embodiment of the invention.

[0094] Detailed description

[0095] Figures 1 to 10 illustrate a first example of a positioner 1 according to the invention. The positioner 1 comprises two blocks 2, 3, six actuators 4 and heating members 6 of the respective actuators 4. This number of actuators 4 and heating members 6 is however not limiting.

[0096] The actuators 4 and the heating members 6 are arranged between the blocks 2, 3.

[0097] Blocks 2,3 which will subsequently be referred to as the first 2 and second 3 blocks respectively, can be moved relative to each other and are movable along an X axis.

[0098] The first block 2 comprises a base piece 5 and a support piece 7 which surmounts the base piece 5, lower pins 8, upper pins 9 and transverse springs 10 to the X axis and helical which, in the example presented, extend vertically.

[0099] The first block 2 may have a length measured along the X axis, between 15 and 50 mm, a width between 15 and 25 mm, and a height, measured along the vertical direction, between 15 and 25 mm.

[0100] The base part 5, illustrated in FIG. 6, has a lower wall 50 which extends horizontally along the X axis and a side wall 51, perpendicular to the X axis, which extends vertically from a lateral edge of the lower wall 50. Seen from the side, the base part 5 thus has a general shape of an “L”.

[0101] The side wall 51 comprises a positioning notch 52 of prismatic shape, for example with a substantially triangular base, which opens onto the inner face 54 of the side wall 51. The recess 52 may be through, as can be seen for example in FIG. 10.

[0102] A recess 53 of circular section is also provided in the side wall 51 and opens onto the inner face 54.

[0103] The base part 5 comprises a relief structure 55 which extends vertically from the lower wall 50.

[0104] The relief structure 55 comprises two rectilinear ribs 56 parallel to the axis X spaced from each other and from the longitudinal edges of the lower wall 50. The ribs 56 define with the lower wall 50 a groove 57 of axis X. The ribs 56 have longitudinal faces, delimiting the groove 57, which are inclined relative to the vertical direction and which comprise rib positioning recesses 58 each receiving two actuators 4. The relief structure 55 further comprises two pairs of lateral reinforcements 59, each pair extending from one of the ribs 56 to a longitudinal edge of the lower wall 50. The lateral reinforcements 59 comprise holes 60 of axis parallel to the axis X. In a variant not shown, the relief structure 55 may comprise two lateral reinforcements 59 which are arranged on either side of the axis X.

[0105] The lower pins 8 are arranged on either side of the axis X and are parallel to the axis X. Each lower pin 8 is engaged in the holes 60 of a corresponding pair of lateral reinforcements 59 and passes through said holes 60 from one side to the other and projects axially on either side of the pair of lateral reinforcements 59 in which it is engaged.

[0106] The support piece 7, illustrated in Figure 7, is arranged between the base piece 5 and the second block 3.

[0107] It has a plate 70 extending parallel to the X axis and legs 71 which extend perpendicular to the X axis downwards, each from an opposite longitudinal edge of the plate 70. The plate 70 has through openings 72 running right through its thickness and which extend along the X axis.

[0108] The plate 70 further comprises a plate positioning recess 73 provided on the lower face of the plate 70, which faces the relief structure 55 of the base part 5. The plate positioning recess 73 can extend parallel to the X axis between the through openings 72.

[0109] The plate 70 comprises a recess 75 of circular section, extending along an axis parallel to the axis X and which coincides with the extension axis of the recess 53 formed in the side wall 51 of the base part 5.

[0110] A helical axial spring 11 is arranged parallel to the axis X in the housing delimited by the recesses 75 and 53. It bears by one of its ends on the side wall 51 of the base part 5 and by its opposite end on the plate 70. The axial spring 11 exerts a restoring force of the base part 5 against the support part 7.

[0111] Each leg 71 has a leg relief 74 which projects from its lower face 76. Each of the leg reliefs 74 is engaged in a respective notch 77 defined by the relief structure 55 between the lateral reinforcements 59 and the rib 56 on the same side of the axis X as the leg relief 74. The leg relief 74 bears on one of the reinforcements 59 by means of the axial spring 11, which allows rigid support for the support piece 7 during the sliding phase of the actuator. Each leg 71 has a leg hole 78 with an axis parallel to the axis X in which an upper pin 9 is engaged.

[0112] Each upper pin 9 projects axially on either side of the leg hole 78 in which it is engaged.

[0113] The lower pins 8 and upper pins 9 each comprise two annular grooves 81, arranged outside the legs 71 and the lateral reinforcements 59. The annular groove 81 of each upper pin 9 is superimposed in the vertical direction on one of the annular grooves 81 of one of the lower pins 8.

[0114] The helical springs 10 are each fixed by their lower 11 and upper 12 ends to the lower 8 and upper 9 pins respectively. In particular, they have at their lower 11 and upper 12 ends hooks engaged in a lower groove 81 and a corresponding upper groove 81.

[0115] The helical springs 10 are chosen so that, over a wide temperature range, for example between 5 K and 300 K, the actuators 4 are compressed by the first 2 and second 3 blocks.

[0116] The second block 3 comprises a support 13, a plate 14 and two brackets 15 and 16. In a variant not shown, the second block comprises a single bracket.

[0117] The plate 14 comprises an upper wall 141 having for example a parallelepiped shape extending longitudinally along an axis parallel to the axis X and a side wall 142 extending vertically downwards from a lateral edge of the upper wall 141. The support piece 7 is arranged between the side wall 51 of the base piece 5 and the side wall 142 of the plate 14. It is further arranged between the upper wall 141 of the plate 14 and the lower wall 50 of the base piece 5.

[0118] The brackets 15 and 16 are fixed to the plate 14, in particular to the upper wall 141 of the plate 14, for example by a mortise and tenon type connection as illustrated in FIG. 3.

[0119] Furthermore, the support 13 is rigidly fixed to the plate 14, in particular to the lateral face 142 of the plate 14, for example by means of a screw 131 as illustrated in FIG. 4.

[0120] The support 13 and the upper wall 141 of the plate 14 are separated from each other by the plate 70. The brackets 15 and 16 connect the support 13 to the plate 14. They are rigidly fixed to the support 13. In particular, they can be made of the same material as the support 13, as in the example illustrated.

[0121] Each bracket 15 and 16 is fixed in one of the through openings 72 of the plate 70. It is distant from the lateral face of the opening.

[0122] The support 13 is a right prism with axis X. In the example illustrated, it has an equilateral triangular section. However, other shapes can be considered.

[0123] In one configuration of the positioner, the face 132 of the support 13, opposite the face 133 fixed on the plate 14, can be engaged in the positioning notch 52 formed in the side wall 51 of the base part 5. It can be extracted therefrom following the movement of the support 13 along the X axis.

[0124] The support 13 has two faces 134 and 135 which are each parallel to the inclined face of one of the ribs 58 which faces them. It also has a face 136 which is parallel to the lower face of the plate 70.

[0125] The actuators 4 are arranged between the support 13 and the base part 5. In particular, the actuators 4 are arranged in two groups formed of three actuators each, the actuators 4 of each group being at the same abscissa along the X axis.

[0126] Among each group of actuators, two actuators 4 are arranged obliquely and each sandwiched between the inclined face of one of the corresponding ribs 56 and the face of the support 13 which faces it. The third actuator 4 of each group is sandwiched between the support 13 and the plate 70.

[0127] Each actuator 4 comprises a transducer 41 comprising a piezoelectric body 42 and a wiper 43 in contact with the piezoelectric body 42. The wiper 43 covers a face of the piezoelectric body 42 which faces the support 13.

[0128] In order to prevent them from sliding along the slopes of the inclined faces of the ribs 56, the piezoelectric bodies 42 are arranged in the positioning hollows 58 of the ribs 56 which have a width equal to the width of the base of said piezoelectric bodies. Furthermore, the piezoelectric body 42 of the actuator arranged between the support 13 and the support piece 7, is housed in the positioning hollow 73 of the plate 70 which thus blocks its movement in a direction transverse to the axis X.

[0129] Furthermore, each actuator 4 comprises a pad 44 which is fixed on the face of the support 13 which faces the wiper 43. The wiper 43 and the pad 44 are in contact. The transducer 41 is also electrically connected by a wired electrical connection to an electric generator, not shown.

[0130] The transverse springs 10 are in tension and exert a restoring force tending to bring the support piece 7 back against the base piece 5.

[0131] The actuators 4 and the support 13 being sandwiched between the support piece 7 and the base piece 5 are thus compressed under the effect of the restoring force of the transverse springs 10.

[0132] By applying an electric current to the transducers 41, a movement along the X axis of the floats 43 on the pads 44 of which they are in contact, is thus obtained.

[0133] The positioner 1 further comprises heating members 6 which are each arranged so as to locally heat a corresponding actuator 4.

[0134] The arrangement of a heating member 6 with respect to a transducer 4L is described in detail below.

[0135] The transducer 41 may be sandwiched between the heating member 6 and the pad 44, as illustrated in FIG. 9 a). In particular, the heating member 6 may be arranged between the base part 5 and the piezoelectric body 42. It is preferably in contact with the base part 5 and the piezoelectric body 42. In particular, it may be arranged in the positioning recess 58 of the rib 56 or in the positioning recess of the plate 73. In this way, the heating member 6 first heats the piezoelectric body 42, then by diffusion of the heat produced, the float 43 and the pad 44. This arrangement is particularly effective for increasing the piezoelectric coefficient of the piezoelectric body 42 in cryogenic application.

[0136] Alternatively, as illustrated in Figure 9 b), the pad 44 can be sandwiched between the heating member 6 and the transducer 41. In particular, the heating member 6 can be taken between the support 13 and the pad 44 and be in contact with the support 13 and the pad 44. According to this arrangement, the heating member 6 being as close as possible to the pad 44 and the wiper 43, the efficiency of gas desorption is optimal.

[0137] The heating member 6 is for example a layer of area between 5 mm 2 and 20 mm 2 and of thickness equal to 2 mm, which makes it possible to produce a particularly compact positioner 1. It is preferably of the resistive type and can be electrically connected to a source of electric current, for example to the same generator as that supplying the transducers 4L

[0138] Different positions of the heating members 6 can be envisaged within the same positioner 1. For example, the heating member 6 of one of the transducers 41 can be arranged between the pad 43 and the support 13. The heating member 6 of another transducer 41 can also be arranged between the pad 43 and the support 13 or between the base part 5 and the piezoelectric body 42.

[0139] Figures 10 to 13 illustrate a second example of embodiment of the positioner 1 according to the invention.

[0140] This second example of positioner differs from that illustrated in figures 1 to 9 in particular by the following characteristics.

[0141] In particular, the support piece 7 is rigidly fixed to the base piece 5. It comprises, or even consists of, a plate 70 and may, as illustrated, be without legs. The plate 70 has a thickness, measured in the vertical direction, which is substantially constant. It is monolithic and comprises a rigid portion 79, in particular solid, extended by a flexible portion 80 fixed to the base piece.

[0142] The flexible portion 80 is made of the same material as the rigid portion 79. It has a recess 81 which passes right through its width. The recess 81 may in particular have an “H” or “dumbbell” shape. In this way, when the support 13 moves relative to the base part 5, to maintain a substantially constant compressive force of the pads 44 on the corresponding wipers 43, the flexible portion 80 can deform, in traction and / or compression in the longitudinal direction and / or in shear and / or bending in the vertical direction. The positioner according to this example is simple to manufacture because it makes it possible in particular to dispense with the installation of an axial spring 11, the presence of legs with their reliefs 74 as well as reinforcements 59.

[0143] Furthermore, the positioner 1 may comprise a single transverse spring 10 for compressing the support piece 7 onto the base piece 5. For example, the positioner 1 according to the second example comprises screws 82 fixed perpendicular to the axis X in the base piece 5 and the support piece 7, the helical transverse spring 10 being fixed on either side to the heads of said screws 82. Preferably, a second spring 10 may be fixed in an identical manner, on the other side of the piece 79. Alternatively, the transverse spring 10 may be fixed as illustrated in FIGS. 1 to 5.

[0144] Furthermore, the support 13 is rigidly fixed to the side wall 142 of the second block 3. It can further be fixed by means of a vertical bracket like the first example of positioner. Alternatively, as illustrated, it can be free of this.

[0145] Figure 14 illustrates a third example of a positioner according to the invention.

[0146] The first positioner 1 comprises first 2 and second 3 blocks movable relative to each other along a translation axis X.

[0147] The first block 2 comprises a support 13 with a vertical X axis and a plate 14 surmounting the first block 2 and which extends transversely to the X axis. The plate 14 is intended to support a sample. The second block 3 is hollow and defines an interior space into which the support 13 is introduced.

[0148] The second block 3 comprises a base piece 5 and three support pieces 7.

[0149] The base part 5 has a generally tubular shape with axis X and comprises a cylindrical portion of revolution. Three recesses, distributed regularly around the axis X, are provided in the wall 83 of the cylindrical portion and pass right through said wall 83.

[0150] Each of the support pieces 5 are portions of a cylinder of revolution with a shape complementary to each of the recesses provided in the wall 83.

[0151] The first positioner 1 further comprises two pairs of three actuators 4 whose pads are layers covering the support 13. The actuators 4 comprise transducers 41 each comprising a piezoelectric body 42 and a wiper 43 in contact with a corresponding pad 44. Each transducer 41 of a pair is fixed on the radially inner face of one of the support blocks.

[0152] Furthermore, in order to ensure compression of the wipers 43 on the pads 44, the first positioner 1 comprises an annular transverse spring 84, in contact with and which surrounds the base part 5 and the support parts 7. It may in particular have a diameter equal, at least at a temperature between 293 K and 313 K to the diameter of the radially outer wall of the base part 5 and the support parts 7. Alternatively, the first positioner 1 may comprise a transverse spring in a ring portion, clipped onto the base part 5 and the support parts 7. The transverse spring 10 is thus in contact with the base part 5 and the support parts 7 and surrounds them. Figure 15 finally illustrates an example of a positioning device 90 according to the invention.

[0153] The positioning device 90 comprises first 1, second 91 and third 100 positioners which are all according to the invention, the first positioner 1 being that illustrated in Figure 14. It comprises blocks 2, 3 movable relative to each other along a vertical X axis.

[0154] The second positioner 91 comprises first and second blocks 92, 93 movable relative to each other along a horizontal Y axis, perpendicular to the X axis. The first block 92 of the second positioner 91 is formed by the first positioner 1. In other words, the first positioner 1 is movable relative to the second block 93 of the second positioner 91 along the Y axis.

[0155] The second block 93 of the second positioner 91 has a generally cylindrical and hollow shape which delimits an interior space of the second positioner in which the first block 2 of the first positioner 1 is fully received.

[0156] Three actuators 94 are arranged between the second block 93 of the second positioner 91 and the second block 3 of the first positioner 1. In other words, the second block 3 of the first positioner 1 acts as a support 95 of the second positioner 91.

[0157] Furthermore, the second block 93 of the second positioner 91 comprises a base part 96 and a support part 97. One of the actuators 94 is arranged between and in contact with the support part 97 of the second positioner 91 and the second block 3 of the first positioner 1. The second positioner 91 further comprises a transverse helical spring, not shown, which is housed in a housing 98 formed in the support part 97. The transverse helical spring 98 compresses the support part 97 of the second positioner 91 against the second block of the first positioner 1. In this way, a substantially constant normal force of axis X is exerted between the wiper 43 and the pad 44 of the actuator 94.

[0158] The other actuators 94 of the second positioner 91 are not visible in the illustrated sectional view.

[0159] The third positioner 101 comprises first and second blocks 102, 103 movable relative to each other along a horizontal Z axis, perpendicular to the X and Y axes. The first block 102 of the third positioner 101 is formed by the second positioner 91. In other words, the second positioner 91 is movable relative to the second block 103 of the third positioner 101 along the Z axis.

[0160] The second block 103 of the third positioner 101 has a generally cylindrical and hollow shape which delimits an interior space of the third positioner in which the first block 92 of the second positioner 91 is fully received.

[0161] Three actuators 104 are arranged between the second block 103 of the third positioner 101 and the second block 93 of the second positioner 91. In other words, the second block 93 of the second positioner 91 acts as a support 105 of the third positioner 101.

[0162] Furthermore, the second block 103 of the third positioner 101 comprises a base part 106 and a support part 107. One of the actuators 104 is arranged between and in contact with the support part 107 of the third positioner 101 and the second block 93 of the second positioner 91. The third positioner 101 further comprises a transverse helical spring, not shown, which is housed in a housing 108 formed in the support part 107. The transverse helical spring compresses the support part 107 of the third positioner 101 against the second block 93 of the second positioner 91. In this way, a substantially constant normal force of axis X is exerted between the wiper 43 and the pad 44 of the actuator 104. One of the three actuators 104 of the third positioner is not visible on the illustrated sectional view.

[0163] The positioning device 90 is thus multi-axis and allows movement of a sample placed on the stage along one or more of the X, Y and Z axes.

[0164] The invention is obviously not limited to the embodiments illustrated in the figures. In particular, the number of support pieces and / or transducers is not limiting. For example, each positioner may comprise a lower or higher number of transducers. Furthermore, for the sake of reading, the positioners have been illustrated with an X axis parallel or perpendicular to the vertical direction. Obviously, the latter can be arranged with an X axis in other directions in space.

Claims

Claims 1. Positioner (1) comprising: - two blocks (2,3), - an actuator (4) comprising o a transducer (41) mounted on one of the blocks and comprising a piezoelectric body (42) covered with a wiper (43) in contact with the piezoelectric body (42) and covering the piezoelectric body (42), o a pad (44) mounted on the other block and movable by sticky sliding on the wiper (43) when an electrical signal is applied to the piezoelectric body (42), in order to move the blocks relative to each other along an X axis, and - a heating member (6) of the actuator (4).

2. Positioner according to claim 1, the heating member (6) being less than 5 mm, preferably less than 1 mm, distant from the actuator (4).

3. Positioner according to claim 2, the heating member (6) being in contact with the actuator (4), preferably the piezoelectric body (42).

4. Positioner according to any one of the preceding claims, the heating member (6) being fixed, preferably glued to the actuator (4) and / or one of the blocks (2, 3) or being in the form of a layer coating the actuator (4) and / or one of the blocks (2, 3).

5. Positioner according to any one of the preceding claims, the pad (44) being sandwiched between the heating member (6) and the transducer (41).

6. Positioner according to any one of claims 1 and 4, the transducer (41) being sandwiched between the heating member (6) and the pad (44).

7. Positioner according to any one of the preceding claims, the heating member (6) being resistive or thermoelectric.

8. Positioner according to any one of the preceding claims, the actuator (4) being configured to move the blocks (2, 3) by translation relative to each other along an X axis.

9. Positioner according to any one of the preceding claims, the actuator (4) being compressed by the blocks (2,3).

10. Positioner according to any one of the preceding claims, one of the blocks comprising a cylindrical support (13), the actuators (4) being distributed around the support (13).

11. Positioner according to the preceding claim, the actuators (4) each being arranged between the support (13) and the other block, preferably the pad (44) of each actuator (4) being arranged between the support (13) and the wiper (43) of said actuator (4).

12. Positioner according to any one of the preceding claims, the heating member (6) of each actuator (4) being able to be arranged between the support (13) and the pad (44) of the actuator (4) which it is intended to heat.

13. Positioner according to any one of the preceding claims, the wiper (43) and / or the pad (44) being made of a material chosen from sapphire, alumina, bronze, graphite, adamantine carbon and mixtures thereof.

14. Positioner according to the preceding claim, the wiper (43) being made of sapphire and / or the pad (44) being made of alumina.

15. Positioner according to any one of the preceding claims, at least one of the blocks comprising a base part (5), a support part (7) and a transverse spring (10) to the X axis, helical or annular, deformed so that the actuator (4) is compressed between the blocks (2, 3).

16. Positioner according to claim 14, the spring (10) elastically connecting the support piece (7) to the base piece (5).

17. Positioner according to any one of claims 15 and 16, the transverse spring (10) being helical.

18. Positioner according to any one of claims 15 to 17, the spring (10) exerting a restoring force on the support part (7) and the base part (5), which is oriented perpendicular to the X axis.

19. Positioner according to any one of claims 15 to 18, the support piece (7) being rigidly fixed to the base piece (5) and comprising a flexible portion (80) extended by a rigid portion (79) on which the transverse spring(s) (10) are fixed.

20. Positioner according to the preceding claim, the flexible portion (80) being elastically deformable during the sticky sliding of the pad (44) on the wiper (43). and elastically recalling the rigid portion (79), in particular against the base part (5).

21. Positioner according to any one of claims 1 to 15, the transverse spring (10) surrounding the base part (5) and the support part (7), and preferably being in contact with the base part (5) and the support part (7), and preferably being annular.

22. Positioner according to the preceding claim, the block which comprises the support piece (7) and the base piece (5), comprising a tubular and hollow portion.

23. Positioner according to the preceding claim, the wall (83) of the tubular and hollow portion comprising the support piece (7), the support (13) and the actuator(s) (4) being housed in a delimited interior space of the tubular portion.

24. Positioning device (90), preferably multi-axis, comprising first and second positioners (1, 91) according to any one of the preceding claims, one of the blocks of the second positioner (91) comprising or even consisting of the first positioner (1).

25. Device according to the preceding claim, comprising a third positioner (101) according to any one of claims 1 to 23, one of the blocks of the third positioner (101) comprising, or even consisting of, the second positioner (91).

26. Device according to any one of claims 24 and 25, the blocks of the third positioner (101) being movable relative to each other by sticky sliding along a third non-parallel axis (Z), preferably perpendicular, to each of the first and second axes (X,Y).

27. Method for heating the actuator of a positioner according to any one of claims 1 to 23 or of a positioning device (90) according to any one of claims 24 to 26, in which prior to heating, the temperature of the actuator (4) is less than 10 K, or even less than 5 K.

28. Method according to the preceding claim, the heating inducing an increase in the temperature of the actuator (4) of less than 50 K.

29. Method according to any one of claims 27 and 28, the positioner (1) being arranged in a near-field microscope, in particular the method comprising, after heating, the movement of a sample carried by one of the two blocks (2, 3), by electrically supplying the actuator (4).

30. System comprising: - a microscope, in particular a near-field microscope, comprising an enclosure, - a positioner (1) according to any one of claims 1 to 23 or a positioning device (90) according to any one of claims 24 to 26 arranged in the enclosure, - optionally, a cooling module to cool the enclosure to a temperature below 30 K, in particular around 4 K.

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