Vertical motion axis for imaging optical head

Abstract

A translating stage may include a first plate and a second plate movable relative to the first plate in a vertical direction. The stage may also include one or more magnetic counterbalances that oppose the weight of the second plate, wherein at least one of the one or more magnetic counterbalances includes a tunable magnetic counterbalance. A tunable magnetic counterbalance may include a first portion including one or more magnets and a second portion including one or more ferromagnetic materials, wherein the one or more ferromagnetic materials at least partially surround the one or more magnets in a horizontal plane. Balancing force may be adjusted by controlling at least one of a relative rotation angle or a length of a gap between the first portion and the second portion in at least one direction in the horizontal plane. The stage may also include an actuator to position the second plate.

Description

Technical Field

[0001] The present disclosure relates generally to a head assembly for a metrology system, and more particularly to a head assembly having a magnetic balance weight. Background Art

[0002] Metrology systems that provide optical imaging of a sample generally require precise control of the distance between the sample and the imaging optics (e.g., an objective lens) that may be along the optical axis of the metrology system. For example, this distance may be related to the focal height and / or depth of focus of a particular application. Furthermore, many applications require sample movement in a plane transverse to the optical axis. Thus, it may be necessary to adjust the imaging optics and / or the sample to maintain the desired distance between the sample and the imaging optics. However, such adjustments may be challenging in situations involving motion of heavy masses and / or high tracking frequencies. Therefore, there is a need to develop systems and methods that address the above-mentioned deficiencies. Summary of the invention

[0003] According to one or more illustrative embodiments of the present disclosure, a translation stage is disclosed. In one illustrative embodiment, the stage includes a first plate. In another illustrative embodiment, the stage includes a second plate, wherein the second plate is movable relative to the first plate along a vertical direction associated with the weight of the second plate. In another illustrative embodiment, the stage includes one or more magnetic balance weights coupled to the first plate and the second plate to provide a balancing force on the second plate in the vertical direction opposite to the weight of the second plate, wherein at least one of the one or more magnetic balance weights includes a tunable magnetic balance weight. In another illustrative embodiment, the tunable magnetic balance weight includes a first portion containing one or more magnets, the first portion being attached to one of the first plate or the second plate. In another illustrative embodiment, the tunable magnetic balance weight includes a second portion containing one or more ferromagnetic materials, wherein the second portion is attached to one of the first plate or the second plate that is different from the first portion. In another illustrative embodiment, the one or more ferromagnetic materials at least partially surround the one or more magnets in a horizontal plane orthogonal to the vertical direction. In another illustrative embodiment, the first portion and the second portion are separated by a gap. In another illustrative embodiment, the balancing force can be adjusted by controlling at least one of a relative rotation angle between the first portion and the second portion in the horizontal plane or a length of the gap along at least one direction. In another illustrative embodiment, the system includes an actuator configured to position the second plate relative to the first plate along the vertical direction.

[0004] According to one or more illustrative embodiments of the present disclosure, a system is disclosed. In one illustrative embodiment, the system includes a first plate. In another illustrative embodiment, the system includes a second plate, wherein the second plate can move relative to the first plate along a vertical direction associated with the weight of the second plate. In another illustrative embodiment, the second plate is configured to be connected to one or more objects. In another illustrative embodiment, the system includes one or more magnetic balance weights coupled to the first plate and the second plate to provide a balancing force on the second plate in the vertical direction opposite to the weight of the second plate. In another illustrative embodiment, at least one of the one or more magnetic balance weights includes a tunable magnetic balance weight. In another illustrative embodiment, the tunable magnetic balance weight includes a first part containing one or more magnets, wherein the first part is attached to one of the first plate or the second plate. In another illustrative embodiment, the tunable magnetic balance weight includes a second part containing one or more ferromagnetic materials, wherein the second part is attached to one of the first plate or the second plate that is different from the first part. In another illustrative embodiment, the one or more ferromagnetic materials at least partially surround the one or more magnets in a horizontal plane orthogonal to the vertical direction. In another illustrative embodiment, the first portion and the second portion are separated by a gap. In another illustrative embodiment, the balancing force can be adjusted by controlling at least one of a relative rotation angle between the first portion and the second portion in the horizontal plane or a size of the gap along at least one direction. In another illustrative embodiment, the system includes a translation stage for positioning a sample in at least the horizontal plane. In another illustrative embodiment, the system includes an actuator configured to position the second plate relative to the first plate along the vertical direction. In another illustrative embodiment, the system includes a controller to guide the actuator via one or more drive signals to provide a selected distance between the sample and one of the one or more objects on the second plate in the vertical direction.

[0005] According to one or more illustrative embodiments of the present disclosure, a method is disclosed. In one illustrative embodiment, the method includes placing a sample at a selected distance from one of one or more objects in a vertical direction, wherein the object is connected to a translation stage. In another illustrative embodiment, the translation stage includes a first plate. In another illustrative embodiment, the stage includes a second plate, wherein the second plate is movable relative to the first plate along the vertical direction, and wherein the vertical direction is associated with the weight of the second plate. In one illustrative embodiment, one or more objects are connected to the second plate. In another illustrative embodiment, the stage includes one or more magnetic balance weights coupled to the first plate and the second plate to provide a balancing force on the second plate in the vertical direction opposite to the weight of the second plate, wherein at least one of the one or more magnetic balance weights includes a tunable magnetic balance weight, wherein the tunable magnetic balance weight includes a first portion containing one or more magnets, wherein the first portion is attached to one of the first plate or the second plate. In another illustrative embodiment, the tunable magnetic balance weight includes a second portion containing one or more ferromagnetic materials, wherein the second portion is attached to one of the first plate or the second plate that is different from the first portion. In another illustrative embodiment, the one or more ferromagnetic materials at least partially surround the one or more magnets in a horizontal plane orthogonal to the vertical direction. In another illustrative embodiment, the first portion and the second portion are separated by a gap. In another illustrative embodiment, the balancing force can be adjusted by controlling at least one of the relative rotation angle between the first portion and the second portion in the horizontal plane or the size of the gap along at least one direction. In another illustrative embodiment, the stage includes an actuator configured to position the second plate relative to the first plate along the vertical direction. In another illustrative embodiment, the method includes adjusting the balancing force to be equal to the combined weight of the second plate and the one or more objects. In another illustrative embodiment, the method includes generating a measurement of at least one of the position of the sample along the vertical direction or the distance between the sample and at least one of the one or more objects on the second plate in the vertical direction. In another illustrative embodiment, the method includes maintaining, via the actuator, the selected distance between the sample and the one of one or more objects in the vertical direction based on the measurement value.

[0006] It should be understood that both the foregoing general description and the following "detailed description" are exemplary and illustrative only and do not necessarily limit the invention as claimed. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the general description, serve to explain the principles of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Those skilled in the art may better appreciate the numerous advantages of the present disclosure by referring to the accompanying drawings.

[0008] Figure 1A is a block diagram of a translation stage according to one or more embodiments of the present disclosure.

[0009] Figure 1B is a simplified schematic diagram of a translation stage according to one or more embodiments of the present disclosure.

[0010] Figure 1C is a partial perspective view of a translation stage including a plurality of magnetic balance weights according to one or more embodiments of the present disclosure.

[0011] Figure 2A is a top view of a magnetic balancing weight according to one or more embodiments of the present disclosure.

[0012] Figure 2B According to one or more embodiments of the present disclosure Figure 2A Side view of the magnetic balancing weight in .

[0013] Figure 3 is a plot of balancing force provided by a magnetic balancing weight as a function of the relative position between a magnet and a ferromagnetic material according to one or more embodiments of the present disclosure.

[0014] Figure 4A is a top view of a magnetic balance weight including a ferromagnetic material with a slot and a radially polarized magnet according to one or more embodiments of the present disclosure.

[0015] Figure 4B According to one or more embodiments of the present disclosure Figure 4A Side view of a magnetic balancing weight.

[0016] Figure 4C is a plot of balancing force provided by a magnetic balancing weight as a function of the relative position between a magnet and a ferromagnetic material according to one or more embodiments of the present disclosure.

[0017] Figure 5A is a top view of a magnetic balance weight including a first portion formed as a radially polarized magnet and a second portion formed as two separate ferromagnetic materials that are individually positionable, according to one or more embodiments of the present disclosure.

[0018] Figure 5B According to one or more embodiments of the present disclosure, Figure 5A A plot of the balancing force provided by the magnetic balancing weight depicted in FIG. 1 as a function of the gap distance.

[0019] Fig. 6Ais a top view of a magnetic balancing weight including a first portion having a magnet and ferromagnetic material and a second portion having a single U-shaped ferromagnetic material according to one or more embodiments of the present disclosure.

[0020] Figure 6B is a top view of a magnetic balancing weight including a first portion having two magnets attached to a U-shaped ferromagnetic material and a second portion having a single ferromagnetic material in accordance with one or more embodiments of the present disclosure.

[0021] Figure 6C is a top view of a magnetic balancing weight including a first portion having two individually positionable magnets attached to a single ferromagnetic material and a second portion having two ferromagnetic materials in accordance with one or more embodiments of the present disclosure.

[0022] Fig. 7A is a simplified schematic diagram of a system including a translation stage oriented in a vertical direction and an additional translation stage for securing and / or positioning a sample in accordance with one or more embodiments of the present disclosure.

[0023] Figure 7B is a simplified schematic diagram of an optical metrology system according to one or more embodiments of the present disclosure.

[0024] Figure 8 is a flow chart illustrating steps performed in a method according to one or more embodiments of the present disclosure. DETAILED DESCRIPTION

[0025] Reference will now be made in detail to the disclosed subject matter illustrated in the accompanying drawings. The present disclosure has been particularly shown and described with respect to specific embodiments and specific features thereof. The embodiments set forth herein should be regarded as representative and not restrictive. It should be readily apparent to one of ordinary skill in the art that various changes and modifications in form and details may be made without departing from the spirit and scope of the present disclosure.

[0026] Embodiments of the present disclosure relate to systems and methods for providing an adjustable counterweight for orienting a translation stage in a vertical direction so that the counterweight opposes the weight of a movable element of the translation stage. As used herein, the term vertical direction is used to refer to a direction associated with the weight of an object (e.g., the direction of gravity).

[0027] In some embodiments, a translation stage includes two plates that are movable relative to each other and an actuator (e.g., a stage positioning actuator) to control the relative position of the two plates. For example, a translation stage having a first plate and a second plate can have the second plate movable relative to the first plate. For example, the first plate can be fixed to a table or other support structure, and the second plate can include an object to be positioned.

[0028] In the case of a linear translation stage oriented to provide linear motion in a vertical direction, the stage positioning actuator typically must bear the weight of the movable plate (e.g., the second plate) and any objects thereon, which may induce excessive heat and increase the demand on the stage positioning actuator. For the purposes of this disclosure, the term load is used to refer to the movable plate of the translation stage and any objects attached to the movable plate. In addition, the term load weight is used to refer to the weight of this load. For example, the size and load requirements of the stage positioning actuator typically must be sufficient to fully support the load weight of the vertical translation stage. As an illustration, a stage positioning actuator formed as a lead screw attached to an electric motor may require a large amount of motor power to simply offset the load weight, which may result in a large amount of heat generation and require an appropriately sized motor and associated components. In addition, this configuration may suffer from relatively high inertia, low acceleration, a large amount of friction, and variable pitch.

[0029] To reduce the strain on the actuator in a vertical configuration, a counterweight may be used to at least partially offset the weight of the load and thus reduce or eliminate the need for a stage positioning actuator to support the weight of the load. Thus, the size and load requirements of the stage positioning actuator may be similar to those required for a translation stage configured for horizontal motion.

[0030] In some embodiments, the translation stage includes one or more magnetic counterweights to at least partially offset the weight of the movable plate and any mounted components.

[0031] In some embodiments, the magnetic balance weight is formed into two parts configured to move relative to each other along a direction of motion (e.g., a vertical direction), wherein the first part includes one or more magnets and the second part includes one or more ferromagnetic materials arranged to at least partially surround the one or more magnets in a plane orthogonal to the direction of motion (e.g., a horizontal plane). As an illustrative example, the first part can be formed as a rod and the second part can be formed as a ferromagnetic sleeve that can at least partially surround the rod. In addition, the first and second parts of the magnetic balance weight can be connected to the fixed and movable plates of the translation stage. In a general sense, any part of the magnetic balance weight can be attached to either the movable plate or the fixed plate of the translation stage.

[0032] In this configuration, the magnetic attraction force between the first and second portions can vary based on their relative positions along the direction of motion. In particular, this force can be constant (or substantially constant) over an operating range (e.g., stroke length) as the first and second portions deviate from an equilibrium position. In some embodiments, the translation stage includes one or more magnetic weights oriented such that this magnetic attraction force operates as a balancing force against the load weight associated with the movable plate and any connected objects. Thus, the operating range of the magnetic weights can define the range of motion of the translation stage.

[0033] In some embodiments, a magnetic balancing weight as disclosed herein is formed to have a gap (e.g., an air gap) between the first and second parts to prevent friction between the first and second parts and to avoid hysteresis. This gap may be uniform or non-uniform in all directions within a plane (e.g., a horizontal plane).

[0034] In some embodiments, the translation stage includes at least one magnetic balancing weight that provides a tunable balancing force. This magnetic balancing weight is referred to herein as a tunable magnetic balancing weight. It is contemplated herein that the tunable magnetic balancing weight can be used to tune the balancing force to precisely offset the weight of the load. Thus, the stage positioning actuator can adjust the position of the movable plate within the operating range of the magnetic balancing weight without bearing the weight of the load.

[0035] Within the spirit and scope of the present disclosure, a variety of techniques may be used to tune the balancing force of a tunable magnetic balancing weight. In some embodiments, the balancing force is tuned by adjusting the relative rotation angle between the first portion and the second portion (e.g., the relative rotation angle between one or more magnets and one or more ferromagnetic materials). For example, the first portion of the magnetic balancing weight may include at least one magnet arranged in a horizontal plane with a magnetic polarization direction, and the second portion may include an asymmetric distribution of ferromagnetic materials, so that the balancing force can vary depending on the relative rotation angle between the first portion and the second portion. In some embodiments, the balancing force is tuned by adjusting the gap distance between the first portion and the second portion of the magnetic balancing weight. For example, the ferromagnetic sleeve may be formed into two or more adjustable sections, and one or more actuators may be used to adjust the position of the two or more adjustable sections relative to the magnet.

[0036] It is contemplated herein that a magnetic balancing weight may be well suited for balancing a load weight in a vertical translation state. For example, a magnetic balancing weight may provide a constant (or substantially constant) force within an operating range without introducing any friction and thus avoiding hysteresis. As another example, a magnetic balancing weight may provide a near-zero stiffness and thus may avoid resonance (e.g., a local spring / mass type resonance). As another example, a magnetic balancing weight may be relatively low-cost and have high reliability. For example, the operation of the balancing weight does not require the application of any power. Thus, a magnetic balancing weight may achieve high-precision control of the vertical position of a movable plate and a connected object at a fast tracking rate (e.g., 5 to 10 Hz or more) for a wide range of load weights.

[0037] It is further contemplated herein that magnetic balancing weights may provide various advantages over alternative balancing technologies due, at least in part, to these benefits. For example, the mass of the balancing weight may double the inertia of the system, which may limit tracking speed, acceleration, and / or accuracy. As another example, a preload spring providing a balancing force may suffer from parasitic resonance. Furthermore, this configuration only fully offsets the weight of the load at a single location, such that when the position of the movable platform deviates from this position, the linear actuator must bear an increased portion of the weight of the load. As another example, an air cylinder may require tight control of air pressure and temperature to maintain performance. Furthermore, an air cylinder may suffer from friction, which may adversely affect the accuracy of the motion.

[0038] Additional embodiments of the present disclosure are directed to a system comprising a vertical translation stage having one or more magnetic counterweights. For example, the system may include one or more objects on a movable plate. In this way, the magnetic counterweights may offset the weight of the movable plate and the objects. The position of these objects (e.g., relative to the sample) may then be controlled using one or more controllers. In some embodiments, the object includes at least one lens such that the working distance between the lens and the sample may be controlled based on the position of the movable plate.

[0039] In some embodiments, the system is an optical system. For example, the system may include one or more optical components (e.g., one or more lenses, one or more mirrors, one or more detectors, one or more illumination sources, or the like) attached to a movable plate of a translation stage as disclosed herein. In this configuration, the relative position between the sample and at least one of the optical components can be controlled based on the position of the movable plate. As an illustration, in the case of an imaging system, one or more lenses may be connected to the movable plate so that the working distance between the lens and the sample can be controlled based on the position of the movable plate. In addition, one or more additional components such as, but not limited to, detectors or illumination sources (e.g., laser sources, light emitting diodes (LEDs), or any other light source suitable for imaging) may be connected to the movable plate. As another illustration, a system including an optical head having optical components suitable for illuminating a sample with light and / or collecting light from the sample may be configured to have at least a portion of the optical head connected to the movable plate of a translation stage as disclosed herein. The optical head may include any type of optical head known in the art suitable for any application. For example, the optical head may include components suitable for, but not limited to, imaging (e.g., laser imaging, broadband imaging, or the like) or reading. In some embodiments, the optical system includes an optical metrology system in which at least some components for illuminating the sample or collecting light from the sample are connected to the movable plate.

[0040] Reference Figures 1A to 8 , according to one or more embodiments of the present disclosure, systems and methods for providing an adjustable counterweight for a translation stage oriented in a vertical direction are described in more detail.

[0041] Figure 1A is a block diagram of a translation stage 100 according to one or more embodiments of the present disclosure. Figure 1B is a simplified schematic diagram of a translation stage 100 according to one or more embodiments of the present disclosure.

[0042] In some embodiments, the translation stage 100 includes a fixed plate 102, a movable plate 104 (e.g., a first plate and a second plate), and at least one stage positioning actuator 106 (e.g., a linear actuator) for adjusting the position of the movable plate 104 relative to the fixed plate 102 in at least one translation direction.

[0043] For example, a translation stage 100 configured for unidirectional (1D) motion along a single translation direction may include a single stage positioning actuator 106. Various techniques may be used to achieve bidirectional (2D) motion. For example, two 1D translation stages 100 may be coupled to provide 2D motion. As an illustration, a fixed plate 102 of a first translation stage 100 may be mounted to a movable plate 104 of a second translation stage 100. As another example, a single translation stage 100 may include two stage positioning actuators 106 configured to adjust the position of the movable plate 104 along two directions.

[0044] The translation stage 100 may include any type of stage positioning actuator 106 known in the art. For example, the stage positioning actuator 106 may include a motor 108 coupled to a drive assembly 110 such as, but not limited to, a bearing (e.g., a mechanical bearing, an air bearing, a magnetic bearing, or the like), a gear, a belt, a screw, or a pin. As an illustration, Figure 1B A stage positioning actuator 106 is depicted having a motor 108 coupled to a fixed plate 102 and a drive assembly 110 in contact with and / or coupled to a movable plate 104. In some embodiments, the stage positioning actuator 106 includes a direct drive linear actuator (e.g., a direct drive motor), such as, but not limited to, a magnetic actuator or a piezoelectric actuator. In some embodiments, the stage positioning actuator 106 includes a voice coil actuator.

[0045] In some embodiments, the translation stage 100 includes one or more encoders 112 to provide measurements of the relative position of the movable plate 104 with respect to the fixed plate 102. The translation stage 100 may include any type of encoder 112 known in the art, including but not limited to an optical encoder 112, a capacitive encoder 112, an inductive encoder 112, or a magnetic encoder 112. In this manner, the measurements provided by the encoder 112 may be used as feedback to the stage positioning actuator 106 for controlling the relative position of the movable plate 104. This stage positioning actuator 106 may utilize any type of control technique for controlling the relative position of the movable plate 104, including but not limited to proportional-integral-derivative (PID) techniques.

[0046] In some embodiments, the translation stage 100 includes one or more guides 114 (e.g., linear guides), such as, but not limited to, rails or bearings (e.g., mechanical bearings, air bearings, magnetic bearings, or the like), to constrain the motion of the movable plate 104 relative to the fixed plate 102. For example, a translation stage 100 suitable for 1D linear motion may include a guide formed as a linear rail, wherein the fixed plate 102 and / or the movable plate 104 are connected to the rail via one or more bearings.

[0047] In some embodiments, at least the movable plate 104 includes one or more connectors 116 suitable for connecting with and / or fixing the object to be translated 118. For example, the connector 116 may include one or more screw holes or non-screw holes suitable for establishing a connection with the object to be translated 118. As another example, the connector 116 may include a clamp or other fastening device for fixing the object to be translated 118.

[0048] In some embodiments, a translation stage 100 having a movable plate 104 adapted for motion along a vertical direction may include one or more magnetic counterweights 120 designed to provide a counterbalancing force that at least partially offsets the weight (e.g., the weight of a load) of the movable plate 104 and any attached object 118. As a result, the size and load requirements of the stage positioning actuator 106 may be significantly reduced relative to a configuration in which the stage positioning actuator 106 must bear the weight of the movable plate 104 and any attached object 118.

[0049] The translation stage 100 may generally include any number of magnetic balancing weights 120 , wherein the magnetic balancing weights 120 may be distributed in any distribution and may provide the same or different balancing forces.

[0050] In some embodiments, the translation stage 100 includes a single magnetic counterweight 120 to counteract the weight of the movable plate 104 and any attached objects 118. In this configuration, the single magnetic counterweight 120 can counteract the entire load weight.

[0051] In some embodiments, the translation stage 100 includes a plurality of magnetic balancing weights 120 for distributing the balancing force. Figure 1C is a partial perspective view of a translation stage 100 including a plurality of magnetic balance weights 120 according to one or more embodiments of the present disclosure. Specifically, Figure 1C A view depicting a portion of the movable plate 104. For example, Figure 1C Seven magnetic counterweights 120 are depicted to balance the movable plate 104 and portions of the stage positioning actuator 106 and encoder 112. Note that Figure 1C Portions of the fixing plate 102 and the connections between the fixing plate 102 and various internal components are not depicted.

[0052] The use of multiple magnetic balancing weights 120 may provide various benefits. For example, distributing the balancing force among several magnetic balancing weights 120 may reduce the size and / or load requirements of each of the magnetic balancing weights 120 relative to an alternative configuration having a single magnetic balancing weight 120 adapted to balance the entire load weight. As an illustration, Figure 1C The seven magnetic balancing weights 120 depicted in FIG. 1 can distribute the balancing force along the X direction. As another example, distributing the balancing force among several magnetic balancing weights 120 can facilitate balancing unevenly distributed load weights. For example, an uneven distribution of load weight around the balancing weights can introduce undesirable friction to the guide 114 and / or rotation of the movable plate 104. However, multiple magnetic balancing weights 120, potentially providing different balancing forces, can offset this uneven weight distribution. As an illustration, Figure 1C Depicts an asymmetric distribution of magnetic weights 120 suitable for balancing uneven load weights. Specifically, Figure 1C The translation stage 100 in illustrative embodiment includes a platform 122 offset along the positive X direction, four magnetic balance blocks 120 close to the platform 122 , and three magnetic balance blocks 120 on opposite sides of the translation stage 100 .

[0053] In some embodiments, the translation stage 100 includes at least one magnetic weight 120 that provides an adjustable balancing force (e.g., an adjustable magnetic weight 120). In general, the translation stage 100 may include any combination of one or more magnetic weights 120 with fixed and / or adjustable balancing forces.

[0054] Within the spirit and scope of the present disclosure, the adjustable magnetic balancing weights 120 may be used in a variety of applications. For example, one or more adjustable magnetic balancing weights 120 may achieve a balancing force (F counterbalance ) to precisely offset the load weight, so that

[0055] F counterbalance =m·g (1)

[0056] Where m is the mass of the load (e.g., the combined mass of the movable plate 104 and any connected object 118) and g is the acceleration due to gravity. Furthermore, this fine tuning may be repeated as necessary when the mass of the object 118 connected to the movable plate 104 is changed. As another example, one or more adjustable magnetic balancing weights 120 at different locations along the translation stage 100 may enable fine tuning of the distribution of the balancing force in the presence of an unevenly distributed load weight. As an illustration, Figure 1C The magnetic balance weights 120a, 120b are adjustable.

[0057] Reference Figures 2A to 8 , according to one or more embodiments of the present disclosure, the magnetic balancing weight 120 is described in more detail.

[0058] Figure 2A is a top view of a magnetic balancing weight 120 according to one or more embodiments of the present disclosure. Figure 2B According to one or more embodiments of the present disclosure Figure 2A 1. A side view of the magnetic balancing weight 120 in FIG.

[0059] In some embodiments, the magnetic balance weight 120 includes a first portion 202 and a second portion 204 at least partially surrounding the first portion 202 in a plane orthogonal to the direction of motion. Figure 2A and 2B , the direction of motion is along the Z direction (e.g., vertical direction) and the second portion 204 of the magnetic weight 120 completely surrounds the first portion 202 in the XY plane (e.g., horizontal plane). In this configuration, the first portion 202 can slide at least partially through the second portion 204 along the direction of motion.

[0060] In some embodiments, the first portion 202 includes at least one or more magnets 206 and the second portion 204 includes one or more ferromagnetic materials 208 .

[0061] In this configuration, the magnetic attraction between at least one magnet 206 in the first portion 202 and at least one ferromagnetic material 208 in the second portion 204 can provide a magnetic force that attracts the first portion 202 and the second portion 204 to each other. This magnetic force can be utilized in any suitable manner to counteract the weight of the load. In some embodiments, one of the magnet 206 or the ferromagnetic material 208 is attached to the fixed plate 102 and the other is attached to the movable plate 104. In addition, the relative positions of the magnet 206 and the ferromagnetic material 208 can be adjusted so that the magnetic attraction counteracts the weight of the load.

[0062] For example, Figure 2A and 2B A configuration is depicted in which the first portion 202 includes a single magnet 206 and the second portion 204 includes a single ferromagnetic material 208 (e.g., a ferromagnetic sleeve). Specifically, the single magnet 206 is shaped as a rod having a long axis along the direction of motion (e.g., the vertical or Z direction) and the single ferromagnetic material 208 is shaped as a ring (or portion thereof). In addition, the movable plate 104 can be connected to the magnet 206 and the fixed plate 102 can be connected to the ferromagnetic material 208. Therefore, the load weight associated with the movable plate 104 and any connected objects 118 can be associated with a force in the -Z direction, while the magnetic attraction between the magnet 206 and the ferromagnetic material 208 can be associated with a balancing force in the +Z direction. However, it should be understood that Figure 2B The configuration in is provided for illustrative purposes only and should not be construed as limiting the present disclosure. Rather, alternative configurations in which the movable plate 104 is connected to the ferromagnetic material 208 and the fixed plate 102 is connected to the magnet 206 are within the spirit and scope of the present disclosure.

[0063] Figure 3 is a plot of the balancing force (F[N]) provided by the magnetic balancing weight 120 as a function of the relative position between the magnet 206 and the ferromagnetic material 208 according to one or more embodiments of the present disclosure. Specifically, Figure 3 The X-axis of is related to the relative position between the top edge of the magnet 206 and the bottom edge of the ferromagnetic material 208, where negative numbers indicate the gap between the magnet 206 and the sleeve in the Z direction, and positive numbers indicate that the magnet 206 is at least partially in the ferromagnetic material 208. Figure 3 , the magnetic balancing weight 120 can provide a substantially linear balancing force within an operating range 302. Thus, the stage positioning actuator 106 can adjust the relative position of the movable plate 104 with respect to the fixed plate 102 across this range without changing the balancing force and, therefore, the load on the stage positioning actuator 106.

[0064] In some embodiments, the first portion 202 and the second portion 204 of the magnetic balance weight 120 are separated by a gap 210 and are located in a plane orthogonal to the direction of motion (e.g., Figure 2A and 2B The gap 210 may be, but is not required to be, uniform in the XY plane of the magnet 206. This gap 210 may be filled with any suitable material. In some embodiments, the gap 210 is an air gap and is filled with ambient atmosphere. It is contemplated herein that the air gap 210 between the magnet 206 and the ferromagnetic material 208 may provide frictionless operation and thus avoid hysteresis and other negative effects.

[0065] It should be understood that Figures 2A to 3 The and associated descriptions are provided for illustrative purposes only and should not be construed as limiting the present disclosure. For example, the magnet 206 may generally have any cross-sectional shape (e.g., Figure 2A to 2B ), such as, but not limited to, a circular, rectangular, or square shape. In addition, the ferromagnetic material 208 may be shaped to provide a uniform gap 210 or may have a non-uniform gap 210. In addition, the first portion 202 and / or the second portion 204 may have a combination of a magnet 206 and a ferromagnetic material 208 arranged to provide a balancing force along the direction of motion.

[0066] Reference Figures 4A to 6C , various designs and techniques of the magnet balance weight 120 are described in more detail according to one or more embodiments of the present disclosure.

[0067] The magnet 206 may be formed of any material suitable for forming a permanent magnet, such as, but not limited to, a ferromagnetic material, a rare earth magnetic material (e.g., a neodymium-based magnetic material or the like), or a composite material. The magnet 206 may further have any magnetic polarization direction. In some embodiments, the magnet 206 has an axial magnetic polarization along the direction of motion (e.g., the Z direction). In some embodiments, the magnet 206 has a magnetic polarization direction in a plane orthogonal to the direction of motion (e.g., in the XY plane). A magnet 206 having this configuration may be referred to as being radially polarized.

[0068] The ferromagnetic material 208 may be formed of any suitable ferromagnetic or composite material having a non-zero magnetic permeability. Furthermore, the ferromagnetic material 208 may, but is not required to, be permanently magnetized (eg, be a permanent magnet).

[0069] It is contemplated herein that the balancing force provided by the magnetic balancing weight 120 may generally be adjusted or otherwise controlled in a variety of ways within the spirit and scope of the present disclosure.

[0070] In some embodiments, the magnetic balance weight 120 includes one or more force adjustment actuators 124 for adjusting at least one of the gap 210 distance between the first portion 202 and the second portion 204 of the magnetic balance weight 120 in at least one direction in a horizontal plane or adjusting the relative orientation of the magnetic polarization direction of the magnet 206 with respect to the ferromagnetic material 208.

[0071] In some embodiments, the ferromagnetic material 208 is asymmetric in a plane orthogonal to the direction of motion (e.g., the XY plane), and the magnet 206 has a magnetic polarization direction at least partially in the XY plane. Therefore, the strength of the balancing force can be controlled by the relative rotation between the magnet 206 and the ferromagnetic material 208.

[0072] For example, the ferromagnetic material 208 may include one or more slits in a plane orthogonal to the direction of motion (eg, the XY plane), which may weaken the magnetic field flow. Figure 4A is a top view of a magnetic balance weight 120 including a ferromagnetic material 208 having a slot 402 and a radially polarized magnet 206 according to one or more embodiments of the present disclosure. Figure 4B According to one or more embodiments of the present disclosure Figure 4A 1. In this way, the ferromagnetic material 208 can be shaped as a portion of a ring in a horizontal plane (eg, an XY plane). In addition, Figure 4A and 4B The magnets 206 in are oriented with a magnetic polarization direction along the X-axis.

[0073] In some embodiments, force adjustment actuator 124 includes a rotation actuator configured to adjust relative rotation between magnet 206 and / or ferromagnetic material 208 in a horizontal plane (e.g., an XY plane). Figure 4B ) can rotate the magnet 206 relative to the ferromagnetic material 208, which can have but is not required to have a fixed rotational position. As another example, the rotational force adjustment actuator 124 connected to the ferromagnetic material 208 can rotate the ferromagnetic material 208 relative to the magnet 206, which can have but is not required to have a fixed rotational position.

[0074] Figure 4C According to one or more embodiments of the present disclosure, Figure 4A and 4B FIG. 1 is a plot of the balancing force provided by the magnetic balancing weight 120 as a function of the relative rotation angle between the magnet 206 and the ferromagnetic material 208. Figure 4C As shown in , the balancing force can be adjusted within the force range 404 by adjusting this relative rotation angle between the magnet 206 and the ferromagnetic material 208.

[0075] In some embodiments, the force adjustment actuator 124 includes at least one linear actuator configured to modify the distance of the gap 210 between the magnet 206 and the ferromagnetic material 208 along at least one direction. For example, the second portion 204 of the magnetic balance 120 may include two or more ferromagnetic materials 208, so that one or more force adjustment actuators 124 can be used to adjust the position of any of these ferromagnetic materials 208 relative to the first portion 202 (or at least one magnet 206 therein).

[0076] Figure 5A Non-limiting configurations of a magnetic balancing weight 120 (eg, an adjustable magnetic balancing weight 120 ) that provides an adjustable balancing force in accordance with one or more embodiments of the present disclosure are depicted.

[0077] Figure 5A is a top view of a magnetic balance weight 120 including a first portion 202 formed as a radially polarized magnet 206 and a second portion 204 formed as two separate ferromagnetic materials 208 that are individually positionable, in accordance with one or more embodiments of the present disclosure.

[0078] For example, Figure 5A The second portion 204 of the magnetic balance weight 120 in FIG. 1 includes a first ferromagnetic material 208-1 and a second ferromagnetic material 208-2 positioned to at least partially surround the magnet 206. In addition, the first ferromagnetic material 208-1 and the second ferromagnetic material 208-2 can be attached to a force adjustment actuator 124 (not explicitly shown) to adjust the gap 210 distance between the corresponding ferromagnetic materials 208-1, 208-2 and the magnet 206. In some embodiments, the force adjustment actuator 124 is configured to adjust the gap 210 distance between the corresponding ferromagnetic materials 208-1, 208-2 and the magnet 206. Figure 5A The first ferromagnetic material 208-1 and the second ferromagnetic material 208-2 are adjusted in a symmetrical manner along the X-axis in FIG.

[0079] Figure 5B According to one or more embodiments of the present disclosure, Figure 5A FIG. 1 is a plot of the balancing force provided by the magnetic balancing weight 120 as a function of the distance of the gap 210. For example, the force adjustment actuator 124 adjusts the positions of the first ferromagnetic material 208-1 and the second ferromagnetic material 208-2 to correspond to Figure 5B The X-axis in the embodiment has the same gap 210. Figure 5B As depicted in , the balancing force may be adjusted within a force range 502 by adjusting the gap 210 .

[0080] It should be understood that Figures 5A to 5BThe and associated descriptions are provided for illustrative purposes only and should not be construed as limiting. For example, the magnetic balancing weight 120 may include any number of ferromagnetic materials 208 having positions that can be adjusted using any number of force adjustment actuators 124. As another example, the various ferromagnetic materials 208 may be shaped to be positioned such as Figure 5A 5. The embodiment of FIG. 5 shows a slit 504 (eg, an opening, a space, or the like) at all values ​​of gap 210 depicted in FIG. 5, or may be shaped to make contact (not shown) for at least one value of gap 210. As shown in FIG.

[0081] Reference Figures 6A to 6C In some embodiments, at least one of the first portion 202 or the second portion 204 of the magnetic balance weight 120 includes both the magnet 206 and the ferromagnetic material 208 .

[0082] Fig. 6A 2 is a top view of a magnetic balance weight 120 including a first portion 202 having a magnet 206 and a ferromagnetic material 208-3 and a second portion 204 having a single U-shaped ferromagnetic material 208-4, according to one or more embodiments of the present disclosure. In this configuration, the first portion 202 and / or the second portion 204 may be mounted on one or more force adjustment actuators 124 to adjust the relative separation in the XY plane. For example, the magnet 206 may be sized to at least partially fit within the cavity 602 associated with the U-shaped ferromagnetic material 208-4.

[0083] Figure 6B is a top view of a magnetic balance weight 120 including a first portion 202 having two magnets 206 attached to a U-shaped ferromagnetic material 208-5 and a second portion 204 having a single ferromagnetic material 208-6, according to one or more embodiments of the present disclosure. Additionally, the second portion 204 can fit within an internal cavity 604 formed by the first portion 202. In this configuration, the first portion 202 and / or the second portion 204 can be mounted on one or more force adjustment actuators 124 to adjust relative separation in the XY plane.

[0084] Figure 6C 2 is a top view of a magnetic balance weight 120 including a first portion 202 having two individually positionable magnets 206 attached to separate ferromagnetic materials 208-7, 208-8 and a second portion 204 having two ferromagnetic materials 208-9, 208-10, according to one or more embodiments of the present disclosure. Additionally, the second portion 204 may fit within an internal cavity 606 formed by the first portion 202. In this configuration, the first portion 202 and / or the second portion 204 may be mounted on one or more force adjustment actuators 124 to adjust relative separation in the XY plane.

[0085] It should be understood that Figures 6A to 6CThe and associated descriptions are provided for illustrative purposes only and should not be construed as limiting. For example, the magnetic balancing weight 120 may include any combination of magnets 206 and ferromagnetic materials 208 on the first portion 202 and / or the second portion 204 suitable for providing a balancing force. In addition, any number of force adjustment actuators 124 may be used to position any portion of the first portion 202 and the second portion 204 of the magnetic balancing weight 120.

[0086] Reference again Figure 1A , various additional aspects of the translation stage 100 are described in more detail according to one or more embodiments of the present disclosure.

[0087] In some embodiments, translation stage 100 includes a controller 126 having one or more processors 128 configured to execute a set of program instructions maintained in memory 130 (eg, a memory device).

[0088] The one or more processors 128 of the controller 126 may include any processor or processing element known in the art. In this sense, the one or more processors 128 may include any microprocessor-type device configured to execute algorithms and / or instructions. For the purposes of this disclosure, the term "processor" or "processing element" may be broadly defined to encompass any device having one or more processing or logic elements (e.g., one or more microprocessor devices, one or more application specific integrated circuit (ASIC) devices, one or more field programmable gate arrays (FPGAs), or one or more digital signal processors (DSPs)). In this sense, the one or more processors 128 may include any device configured to execute algorithms and / or instructions (e.g., program instructions stored in a memory). In some embodiments, the one or more processors 128 may be embodied as a desktop computer, a mainframe computer system, a workstation, an image computer, a parallel processor, a networked computer, or any other computer system configured to execute a program configured to operate the translation stage 100 or operate in conjunction with the translation stage 100, as described throughout this disclosure. In addition, different subsystems of the translation stage 100 may include processors or logic elements suitable for implementing at least a portion of the steps described in the present disclosure. Therefore, the above description should not be interpreted as a limitation on the embodiments of the present disclosure, but is merely illustrative. In addition, the steps described in various places in the present disclosure may be implemented by a single controller or alternatively multiple controllers. In addition, the controller 126 may include one or more controllers housed in a common housing or in multiple housings. In this way, any controller or combination of controllers can be individually packaged as a module suitable for integration into the translation stage 100.

[0089] The memory 130 may include any storage media known in the art suitable for storing program instructions that can be executed by the associated one or more processors 128. For example, the memory 130 may include a non-transitory storage medium. By way of another example, the memory 130 may include, but is not limited to, a read-only memory (ROM), a random access memory (RAM), a magnetic or optical storage device (e.g., a disk), a tape, a solid-state drive, and the like. It should be further noted that the memory 130 may be housed in a common controller housing with the one or more processors 128. In some embodiments, the memory 130 may be remotely located relative to the physical location of the one or more processors 128 and the controller 126. For example, the one or more processors 128 of the controller 126 may access a remote memory (e.g., a server) that is accessible via a network (e.g., the Internet, an intranet, and the like).

[0090] Controller 126 may include or be coupled with any component or combination of components in translation stage 100. Furthermore, controller 126 may receive data from any component in translation stage 100 and / or control any component in translation stage 100 via drive signals. For example, controller 126 may be coupled with force adjustment actuator 124 and thereby generate drive signals to adjust the position of first portion 202 or second portion 204 of magnetic balance weight 120 (or any component thereof). In this manner, controller 126 may be communicatively coupled to translation stage 100 or any component therein.

[0091] Reference Figures 7A to 7B , according to one or more embodiments of the present disclosure, the integration of the translation stage 100 within a larger system is described in more detail.

[0092] Fig. 7A is a simplified schematic diagram of a system 702 including a translation stage 100 oriented in a vertical direction and an additional translation stage 704 for securing and / or positioning a sample 706 in accordance with one or more embodiments of the present disclosure.

[0093] In some embodiments, various components of system 702 are mounted to movable plate 104 (e.g., as object 118) of translation stage 100. In this configuration, the load weight may include the combined weight of movable plate 104 and any attached components. Precision balancing using one or more magnetic weights 120 and, optionally, one or more tunable magnetic weights 120 may then provide precise, tunable control of the position of the components relative to sample 706.

[0094] It is contemplated herein that a system 702 having at least some components mounted to a translation stage 100 as disclosed herein may be well suited for, but not limited to, metrology applications in which a distance between a sample 706 and one or more components of a metrology system is measured. For example, the system 702 may include an optical system, such as, but not limited to, an optical metrology system or an imager. As another example, the system 702 may include a non-optical metrology system.

[0095] Figure 7B is a simplified schematic diagram of an optical metrology system 702 according to one or more embodiments of the present disclosure.

[0096] In some embodiments, the system 702 may be configured according to a metrology recipe to generate metrology measurements associated with the sample 706 based on the metrology recipe. For example, the system 702 may direct an illumination beam 708 from an illumination source 710 to the sample 706 (e.g., via an illumination path 712), collect light or other radiation emitted from the sample 706 in response (referred to herein as measurement light 714) (e.g., via a collection path 716), and generate metrology data from at least one detector 718 based on the measurement light 714. For example, the metrology data may be associated with diffraction of the illumination beam 708 from the sample 706. The illumination path 712 and the collection path 716 may further include additional optical elements such as, but not limited to, a lens 720 and a beam manipulation component 722 (e.g., a polarizer, a spectral filter, a spatial filter, a beam blocker, an aperture, or the like) at any suitable location. In some embodiments, as Figure 7B As illustrated in FIG. 7 , system 702 includes one or more beam splitters 724 to allow simultaneous illumination and collection through a common objective lens 726 or other focusing element.

[0097] The system 702 may include one or more detectors 718 at any suitable location for collecting metrology data. For example, the system 702 may include at least one detector 718 at a field plane (e.g., a plane conjugate to the sample 706) that is located at a certain position. Figure 7B 714. As another example, although not illustrated, the system 702 may include at least one detector 718 at a pupil plane (e.g., a diffraction plane corresponding to the angular distribution of light from the sample 706). Furthermore, although not illustrated, the system 702 may include multiple channels, each with a separate detector 718. The system 702 may further include optical components to modify the properties of the measurement light 714 within each channel, such as, but not limited to, a polarizer, a polarization rotator, a spectral filter, a spatial filter, or a pupil filter (e.g., a beam stop or aperture in the pupil plane to block or pass selected diffraction orders).

[0098] Generally speaking Fig. 7A and 7B, any component of the system 702 may be mounted to the movable plate 104 of the translation stage 100 (e.g., as an object 118). For example, such an object 118 mounted to the movable plate 104 may include at least one lens (e.g., an objective lens 726 and a detector 718). In this way, the system may operate as an imaging system and adjustment of the position of the movable plate 104 (e.g., by the controller 126) may provide control of the separation distance 728 (e.g., the working distance) between the lens and the sample 706. In some embodiments, as Figure 7B , such an object 118 mounted to the movable plate 104 may further include an illumination source 710. In some embodiments, such an object 118 mounted to the movable plate 104 may include a photomask, wherein the photomask and lens are configured to project an image of the photomask onto the sample 706. In this manner, the system 702 may operate as an optical projection system, a photolithography system (e.g., a scanner or stepper), or the like.

[0099] In some embodiments, the system 702 includes one or more sensors 730 to monitor the position of the sample 706. For example, the sensor 730 may measure, track, or otherwise monitor the position of the sample 706 along a vertical direction. As another example, the sensor 730 may measure, track, or otherwise monitor the separation distance 728 between the sample 706 and at least one of the one or more objects 118 (e.g., a lens or the like) on the movable plate 104.

[0100] Sensor 730 may include any type of device known in the art suitable for determining the position of sample 706 or its change over time, such as but not limited to a proximity sensor or a distance sensor. In addition, sensor 730 may utilize any technology, such as but not limited to optical technology or capacitive technology.

[0101] In some embodiments, the system 702 may maintain (e.g., via a drive signal from the controller 126 to the stage positioning actuator 106) a selected distance between the sample 706 and one or more objects 118 on the translation stage 100. For example, the system 702 may maintain this selected distance while the sample 706 is translated by the additional translation stage 704 (e.g., along a horizontal plane).

[0102] It is contemplated herein that balancing the translation stage 100 using one or more magnetic balancing weights 120 as disclosed herein (where the balancing force is fine-tuned to match the load weight using at least one tunable magnetic balancing weight 120 as disclosed herein) can achieve relatively high frequency height control. In particular, the stage positioning actuator 106 used to control the position of the movable plate 104 does not need to bear the load weight. In some applications, the height can be controlled at the order of 10 Hz or more (e.g., hundreds of Hz, kHz, or more).

[0103] Figure 8 is a flow chart illustrating the steps performed in method 800 according to one or more embodiments of the present disclosure. Applicants mention that the embodiments and implementation techniques previously described herein in the context of translation stage 100 should be interpreted as extending to method 800. However, it should be further noted that method 800 is not limited to the architecture of translation stage 100.

[0104] In some embodiments, the method 800 includes a step 802 of placing the sample 706 at a selected distance in a vertical direction from one of the one or more objects 118 of the movable plate 104 connected to the translation stage 100. For example, in the case of an optical system, the selected distance may correspond to the working distance of the lens. In some embodiments, the method 800 includes a step 804 of adjusting the balancing force of one or more magnetic balance weights 120 on the translation stage 100 to be equal to the combined weight of the movable plate 104 and the one or more objects 118. For example, at least one of the magnetic balance weights 120 may have an adjustable balancing force. In this way, the stage positioning actuator 106 used to control the position of the movable plate 104 and therefore the associated object 118 connected thereto does not need to bear the associated load weight. Therefore, high frequency dynamic height control with minimal heat is achieved. In some embodiments, the method 800 includes a step 806 of generating a measurement of at least one of a position of the sample 706 along a vertical direction or a distance in the vertical direction between the sample 706 and at least one of the one or more objects 118 on the movable plate 104. For example, the measurement may be generated using one or more sensors 730. In some embodiments, the method 800 includes a step 808 of maintaining a selected distance in the vertical direction between the sample 706 and one of the one or more objects 118 based on the measurement. For example, the selected distance may be maintained while translating the sample 706 along a horizontal plane.

[0105] The objects described herein sometimes illustrate different components contained in or connected to other components. It should be understood that such depicted architectures are exemplary only, and in fact many other architectures that realize the same functionality can be implemented. In a conceptual sense, any component arrangement for realizing the same functionality is effectively "associated" so as to realize the desired functionality. Therefore, any two components combined to realize a specific functionality herein can be considered to be "associated" with each other so as to realize the desired functionality, without considering the architecture or intermediate components. Similarly, any two components so associated can also be considered to be "connected" or "coupled" to realize the desired functionality, and any two components that can be so associated can also be considered to be "coupleable" to realize the desired functionality. Specific examples that can be coupled include but are not limited to physically interactable and / or physically interactive components, and / or wirelessly interactive and / or wirelessly interactive components, and / or logically interactive and / or logically interactive components.

[0106] It is believed that the present disclosure and its many attendant advantages will be appreciated from the foregoing description, and it will be appreciated that various changes may be made in the form, construction and arrangement of components without departing from the disclosed object or sacrificing all of its material advantages. The forms described are merely illustrative, and the appended claims are intended to cover and encompass such changes. Furthermore, it should be understood that the invention is defined by the appended claims.

Claims

1. A translation stage, comprising: First board; a second plate, wherein the second plate is movable relative to the first plate in a vertical direction associated with the weight of the second plate; one or more magnetic balancing weights coupled to the first plate and the second plate and providing a balancing force on the second plate in the perpendicular direction opposite to the weight of the second plate, wherein at least one of the one or more magnetic balancing weights comprises a tunable magnetic balancing weight, wherein the tunable magnetic balancing weight comprises: a first portion comprising one or more magnets, wherein the first portion is attached to one of the first plate or the second plate; and a second portion comprising one or more ferromagnetic materials, wherein the second portion is attached to one of the first plate or the second plate that is different from the first portion, wherein the one or more ferromagnetic materials at least partially surround the one or more magnets in a horizontal plane orthogonal to the vertical direction, wherein the first portion and the second portion are separated by a gap, wherein the balancing force can be adjusted by controlling at least one of a relative rotation angle between the first portion and the second portion in the horizontal plane or a length of the gap along at least one direction; and An actuator is configured to position the second plate relative to the first plate along the vertical direction.

2. A translation stage according to claim 1, wherein at least one of the one or more magnets has a magnetic polarization direction at least partially in the horizontal plane, wherein the one or more ferromagnetic materials are distributed in the horizontal plane with at least one slit, and wherein the balancing force can be adjusted by controlling the relative rotation angle between the first part and the second part in the horizontal plane.

3. The translation stage according to claim 2, further comprising: An additional actuator is connected to at least one of the first portion or the second portion to control the relative rotation angle between the first portion and the second portion in the horizontal plane.

4. The translation stage of claim 2, wherein the one or more magnets comprise: A single magnet having said magnetic polarization direction at least partially in said horizontal plane.

5. The translation stage of claim 4, wherein the single magnet is shaped as a rod having a long axis along the vertical direction.

6. The translation stage of claim 5, wherein the rod has a circular cross-section in the horizontal plane.

7. The translation stage of claim 5, wherein the rod has a rectangular cross-section in the horizontal plane.

8. The translation stage of claim 4, wherein the one or more ferromagnetic materials include: A single ferromagnetic material shaped as part of a ring in said horizontal plane.

9. The translation stage of claim 1, wherein the tunable magnetic balance further comprises one or more additional actuators connected to at least one of the first portion or the second portion to adjust the length of the gap in the at least one direction.

10. The translation stage of claim 9, wherein the one or more ferromagnetic materials include: Two or more ferromagnetic materials, wherein the one or more additional actuators adjust a gap distance between at least one of the two or more ferromagnetic materials and at least one of the one or more magnets.

11. The translation stage according to claim 1, further comprising: One or more guides for constraining movement between the first plate and the second plate to the vertical direction.

12. The translation stage of claim 1, wherein the first portion comprises one or more additional ferromagnetic materials, wherein the one or more ferromagnetic materials and the one or more additional ferromagnetic materials at least partially surround the one or more magnets.

13. The translation stage of claim 1, wherein the actuator comprises a linear direct drive actuator.

14. A system comprising: First board; a second plate, wherein the second plate is movable relative to the first plate in a vertical direction associated with a weight of the second plate, wherein the second plate is configured to be connected to one or more objects; one or more magnetic balancing weights coupled to the first plate and the second plate and providing a balancing force on the second plate in the perpendicular direction opposite to the weight of the second plate, wherein at least one of the one or more magnetic balancing weights comprises a tunable magnetic balancing weight, wherein the tunable magnetic balancing weight comprises: a first portion comprising one or more magnets, the first portion being attached to one of the first plate or the second plate; and a second portion comprising one or more ferromagnetic materials, the second portion being attached to the first plate or one of the second plates that is different from the first portion, wherein the one or more ferromagnetic materials at least partially surround the one or more magnets in a horizontal plane orthogonal to the vertical direction, wherein the first portion and the second portion are separated by a gap, wherein the balancing force can be adjusted by controlling at least one of a relative rotation angle between the first portion and the second portion in the horizontal plane or a length of the gap along at least one direction; and a translation stage that positions the sample in at least the horizontal plane; an actuator configured to position the second plate relative to the first plate along the vertical direction; and a controller communicatively coupled to the at least one adjustable magnetic balancing weight, the controller comprising one or more processors configured to execute program instructions causing the one or more processors to: The actuator is directed via one or more drive signals to provide a selected distance between the sample and one of the one or more objects on the second plate in the vertical direction.

15. The system of claim 14, wherein the one or more processors are further configured to execute program instructions that cause the one or more processors to direct the at least one tunable magnetic balancing weight via one or more additional drive signals to adjust the balancing force to be equal to the combined weight of the second plate and the one or more objects.

16. The system of claim 14, wherein positioning the second plate relative to the first plate along the vertical direction positions at least one of the one or more objects on the second plate relative to the sample.

17. The system of claim 14, further comprising: a sensor for measuring at least one of a position of the sample along the vertical direction or a distance between the sample and at least one of the one or more objects on the second plate in the vertical direction, wherein the one or more processors are further configured to execute program instructions to cause the one or more processors to maintain the selected distance between the sample and the one of the one or more objects on the second plate in the vertical direction via the one or more drive signals sent to the actuator.

18. A system according to claim 14, wherein at least one of the one or more magnets has a magnetic polarization direction at least partially in the horizontal plane, wherein the one or more ferromagnetic materials are distributed in the horizontal plane with at least one slit, and wherein the balancing force can be adjusted by controlling the relative rotation angle between the first part and the second part in the horizontal plane.

19. The system of claim 18, further comprising: An additional actuator is connected to at least one of the first portion or the second portion to control the relative rotation angle between the first portion and the second portion in the horizontal plane.

20. The system of claim 18, wherein the one or more magnets include: A single magnet having said magnetic polarization direction at least partially in said horizontal plane.

21. The system of claim 20, wherein the single magnet is shaped as a rod having a long axis along the vertical direction.

22. The system of claim 21, wherein the rod has a circular cross-section in the horizontal plane.

23. The system of claim 21, wherein the rod has a rectangular cross-section in the horizontal plane.

24. The system of claim 20, wherein the one or more ferromagnetic materials include: A single ferromagnetic material shaped as part of a ring in said horizontal plane.

25. The system of claim 14, wherein the tunable magnetic balance further comprises one or more additional actuators connected to at least one of the first portion or the second portion to adjust the length of the gap in the at least one direction.

26. The system of claim 25, wherein the one or more ferromagnetic materials include: Two or more ferromagnetic materials, wherein the one or more additional actuators adjust a gap distance between at least one of the two or more ferromagnetic materials and at least one of the one or more magnets.

27. The system of claim 14, further comprising: One or more guides for constraining movement between the first plate and the second plate to the vertical direction.

28. The system of claim 14, wherein the one or more objects connected to the second plate include a lens, wherein the selected distance between the sample and the one of the one or more objects on the second plate in the vertical direction corresponds to a distance between the sample and the lens.

29. The system of claim 28, wherein the one or more objects further comprise a detector configured to image at least a portion of the sample through the lens.

30. The system of claim 29, wherein the one or more objects further comprise an illumination source to illuminate the at least the portion of the sample.

31. The system of claim 29, wherein the system comprises a metering system.

32. The system of claim 29, wherein the system comprises an imaging system.

33. The system of claim 28, wherein the one or more objects further comprise a photomask, wherein the photomask and the lens are configured to project an image of the photomask onto the sample.

34. A method comprising: placing the sample at a selected distance in a vertical direction from one of the one or more objects, wherein the object is coupled to a translation stage, wherein the translation stage comprises: First board; a second plate, wherein the second plate is movable relative to the first plate along the vertical direction, wherein the vertical direction is associated with a weight of the second plate, wherein the one or more objects are connected to the second plate; one or more magnetic balancing weights coupled to the first plate and the second plate and providing a balancing force on the second plate in the perpendicular direction opposite to the weight of the second plate, wherein at least one of the one or more magnetic balancing weights comprises a tunable magnetic balancing weight, wherein the tunable magnetic balancing weight comprises: a first portion comprising one or more magnets, the first portion being attached to one of the first plate or the second plate; and a second portion comprising one or more ferromagnetic materials, the second portion being attached to the first plate or one of the second plates that is different from the first portion, wherein the one or more ferromagnetic materials at least partially surround the one or more magnets in a horizontal plane orthogonal to the vertical direction, wherein the first portion and the second portion are separated by a gap, wherein the balancing force can be adjusted by controlling at least one of a relative rotation angle between the first portion and the second portion in the horizontal plane or a size of the gap along at least one direction; and an actuator configured to position the second plate relative to the first plate along the vertical direction; adjusting the balancing force to be equal to the combined weight of the second plate and the one or more objects; generating a measurement of at least one of a position of the sample along the vertical direction or a distance in the vertical direction between the sample and at least one of the one or more objects on the second plate; The selected distance between the sample and the one of one or more objects in the vertical direction is maintained based on the measurement via the actuator.

35. The method of claim 34, wherein maintaining the selected distance between the sample and the one of one or more objects in the vertical direction based on the measured value via the actuator comprises: The selected distance between the sample and the one of one or more objects in the vertical direction is maintained based on the measurement via the actuator while translating the sample in the horizontal plane.

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