Positioning device for analytical equipment in vacuum chambers

Abstract

A positioning device for an analytical instrument (e.g., an atom probe microscope or other nanoscale microscope) includes a primary carriage translatable relative to a vacuum chamber wall, and a secondary carriage connected to the primary carriage by a plurality of spaced actuators that allow the secondary carriage to translate and / or tilt relative to the primary carriage. An arm then extends from the secondary carriage through the vacuum chamber wall and connects to the instrument. The instrument may be rapidly extended or retracted within the vacuum chamber via its connection to the primary carriage, and may be more finely translated and / or tilted via its connection to the secondary carriage. A damping arrangement isolates the instrument from vibrations.

Description

[Technical Field]

[0001] This document relates generally to an invention relating to a positioning device for an analytical instrument within a vacuum chamber, and more particularly to a positioning device that allows the analytical instrument to be properly positioned within the vacuum chamber relative to the sample to be analyzed. [Background technology]

[0002] Many analytical instruments used to perform nanoscale analysis of material samples, such as transmission electron microscopes (TEMs), scanning transmission electron microscopes (STEMs), atomic force microscopes (AFMs), scanning tunneling microscopes (STMs), and atom probe microscopes (APMs), require high-vacuum conditions for operation. Having a combined arrangement of these instruments to allow different types of analysis to be performed on a sample without the need to move the sample from one instrument to another is useful, especially because preparation for analysis (e.g., the need to pump the chamber to high or ultra-high vacuum) can be time-consuming. However, these instruments are not only bulky but can also be sensitive to the presence of other instruments, making it difficult to accommodate two or more instruments in a vacuum chamber (which is usually small; larger chambers tend to increase preparation time and other operational issues). As an example, an APM must be positioned very close to the sample being analyzed, and its presence tends to interfere with measurements from other instruments due to its electromagnetic fields and radiative heat dissipation. This problem potentially requires that the APM and other instruments be swapped with one another, each moving toward the sample when it is their turn to make a measurement and then moving away from the sample when the measurement is complete. This is difficult to achieve without increasing the size of the vacuum chamber, leading to the problems mentioned above. Furthermore, moving the instruments presents its own problems. Most instruments must be positioned very precisely relative to the sample, and it is difficult to devise an extend / retract arrangement that retracts and re-extends the instrument and then precisely repositions it back to its original position.

[0003] Because most of the following discussion focuses on the use of APMs as a typical analytical instrument, a brief overview of the structure and operation of a typical APM follows. A typical APM includes a sample mount and an ion detector. During a typical analysis, the sample is positioned within the sample mount, and a positive charge (e.g., baseline voltage) is applied to the sample so that the electrostatic field near the apex of the sample (the surface closest to and facing the detector) is approximately 90% of the electrostatic field required to spontaneously ionize surface atoms (typically about 5–50 volts per nanometer). The detector is spaced from the apex (tip) of the sample and may be grounded or negatively charged. A local electrode may be positioned between the sample and the detector and has an aperture aligned between the sample and the detector. The local electrode may be grounded or negatively charged. (The local electrode is sometimes referred to as the "extraction electrode." Furthermore, because the electrodes in an APM typically function as electrostatic lenses, the term "lens" is sometimes used instead of the term "electrode.") Energy beam pulses (e.g., laser beam pulses, electron beam pulses, ion beam pulses, etc.), positive electrical pulses (above a baseline voltage), and / or other energy pulses (e.g., RF pulses) are intermittently applied to the sample to increase the probability of ionizing surface atoms on the sample. Alternatively or additionally, pulses of negative voltage can be applied to any local electrode synchronized with the aforementioned energy pulse(s).

[0004] In some cases, the pulse causes the ionization of a single atom near the apex of the sample. The ionized atom(s) detach or "evaporate" from the sample surface, pass through an aperture in the local electrode (if present), and impact the surface of a detector (usually a microchannel plate (MCP)). The elemental identity of the ionized atom can be determined by measuring its time of flight (TOF). The time of flight is the time between the pulse ejecting the ion from the sample surface and its impact on the detector. The velocity of the ion (and therefore its TOF) varies based on the mass-to-charge ratio (m / n) of the ionized atom; lighter and / or more highly charged ions take less time to reach the detector. Because the TOF of an ion indicates its mass-to-charge ratio, which indicates its elemental identity, TOF can help identify the composition of the ionized atom. Furthermore, APM functions as a "point projection microscope," where the position of the ionized atom on the sample surface corresponds to the atom's impact position on the detector, allowing the original location of the ionized atom on the sample to be determined. Thus, as the sample evaporates, a three-dimensional map or image of the sample's constituent atoms can be constructed. The image represented by the map is a point projection, with atomic resolution and magnification of over one million times; however, the image can be considered more tomographic in nature, as the map / image data can be analyzed in virtually any orientation. Further details regarding APM can be found, for example, in U.S. Pat. Nos. 5,440,124, 7,157,702, 7,652,269, 7,683,318, 7,884,323, 8,074,292, 8,153,968, 8,276,210, 8,513,597, 8,575,544, 8,670,608, and 10,614,995, as well as the patents and other documents referenced therein. Summary of the Invention

[0005] The present invention (as defined by the claims at the end of this document) is directed to an equipment positioning apparatus that at least partially alleviates the aforementioned problems associated with equipment positioning and / or exchange. A basic understanding of some of the features of preferred versions of the invention can be gained by reviewing the following summary of the invention, with further details provided elsewhere in this document. To assist the reader's understanding, the following discussion makes reference to the accompanying drawings (which are briefly reviewed in the "Brief Description of the Drawings" section following this summary section of this document).

[0006] Figures 1-5 show a typical version of an instrument positioner that might appear when used to position a typical atom probe microscope (APM) within a vacuum chamber. While the vacuum chamber has been largely removed from the drawing for clarity, in Figure 1 it can be assumed to be attached to port 52 in vacuum subchamber 50, with the vacuum chamber wall generally located within the boundary indicated by imaginary dashed line 10. APM 100, and more specifically its ion optics (local electrode 102, deceleration lens 104, and deceleration lens 106) are seen protruding through vacuum subchamber port 52 (and thus into vacuum chamber 10), while positioner 200 for APM 100 is positioned behind back wall 54 of vacuum subchamber 50. Positioner 200 can either extend APM 100 through port 52 (and thus further into vacuum chamber 10 for analyzing samples therein) or retract APM 100 through port 52 (and thus further into vacuum subchamber 50 for accommodating other instruments therein for analyzing samples). 2-4 show the APM 100 and positioning device 200 without the vacuum sub-chamber 50. FIG.

[0007] A typical positioning device 200 includes a primary carriage 202. The primary carriage 202 is displaceable relative to the port 52 (and thus the vacuum chamber wall 10) via a primary actuator 204 (e.g., a pneumatic cylinder) thereon. As best seen in FIGS. 3-4 , the primary actuator 204 has a shaft 206 extending along the instrument axis (the axis directed through the instrument toward the sample mount within the vacuum chamber 10) for attachment to the vacuum sub-chamber back wall 54. A secondary carriage 208 is then displaceable relative to the primary carriage 202 via four secondary actuators 210 (e.g., servo motors) thereon (here, located near the four corners of the (square) secondary carriage 208). The secondary actuators 210 have shafts 212 extending therefrom for attachment to the primary carriage 202. Four elongated instrument support arms 214 then extend from the secondary carriage 208 through the primary carriage 202. The main carriage 202 has one or more openings (not shown) through which the instrument support arms 214 extend freely without interference. The instrument support arms 214 then extend through the subchamber back wall 54. A tight gasket (not shown) or similar means allows the instrument support arms 214 to be displaced along their length through the back wall 54 without any (or substantially any) loss of vacuum within the vacuum subchamber 50.

[0008] The APM 100 (or other instrument) is then attached to the instrument support arm end 216 within the vacuum sub-chamber 50. Thus, displacement of the primary carriage 202 relative to the vacuum chamber wall 10 causes translational movement of the secondary carriage 208, which in turn causes translational movement of any instrument attached to the instrument support arm 214 within the vacuum chamber. The primary actuator 204 that drives the primary carriage 202 preferably has a stroke / displacement sufficient to move instruments to a sample analysis position within the vacuum chamber 10 and to retract instruments from the vacuum chamber 10 so that the instruments do not interfere with analysis from other instruments. Furthermore, when the secondary actuator 210 is displaced by an equal length, the secondary carriage 208 translates relative to the primary carriage 202, which in turn causes translational movement of any instrument attached to the instrument support arm 214. However, when the secondary actuator 210 is displaced unevenly, the secondary carriage 208 tilts relative to the primary carriage 202, which in turn causes tilting of any instrument attached to the instrument support arm 214. When positioning device 200 is used with APM 100, instrument support arm 214 does not need to be pivotally mounted to secondary carriage 208 and / or the instrument because the unequal displacement of secondary actuator 210 is sufficient to tilt the instrument by approximately 1 degree (typically sufficient for APM 100). Thus, primary actuator 204 and primary carriage 202 provide coarse positioning of the instrument between an analysis position and a stowed position, while secondary actuator 210 and secondary carriage 208 provide fine positioning of the instrument to the analysis position. Advantageously, positioning device 200 provides highly repeatable positioning of the instrument, e.g., allowing it to be rapidly retracted from its analysis position to its stowed position and then re-extended to the analysis position with little or no difference between the previous and subsequent analysis positions.

[0009] In the above-described arrangement, the secondary actuators 210 are preferably spaced apart equidistantly from the instrument axis and arranged around an actuator path extending about the instrument axis, with each secondary actuator 210 spaced equally apart from an adjacent secondary actuator 210 along the actuator path. Similarly, the instrument support arms 214 are preferably spaced apart equidistantly from the instrument axis and arranged around an arm path extending about the instrument axis, with each secondary actuator 210 spaced equally apart from an adjacent instrument support arm 214 along the arm path. This arrangement increases the predictability of the instrument support arm 214 movement, thereby facilitating control of the instrument positioning. Furthermore, the circumference of the actuator path is preferably greater than the circumference of the arm path, because this increases the leverage of the secondary actuators 210, resulting in greater instrument tilt with less effort from the secondary actuators 210.

[0010] The APM 100 shown in the drawings provides acceptable ion mass resolution and position measurement, while remaining in a particularly compact design. A local electrode 102 is located at the end of the APM 100 closest to the sample, followed by a deceleration lens 104 (electrode) that tends to slow and spread the sample ions extracted by the local electrode 102, and then by an elongated, conical acceleration electrode 106 that tends to collimate the sample ions and transmit them onto an ion detector 108. The detector 108 is located within a vacuum subchamber 50, which effectively functions as an extension of the vacuum chamber 10. Advantageously, the vacuum subchamber 50 can be pumped to a higher vacuum than that within the vacuum chamber 10, which can help improve the performance of the detector 108.

[0011] The positioning device 200 preferably also includes dampers 250, shown in FIGS. 4a and 4b. The dampers 250 help isolate the APM 100 (or other equipment) from vibrations as it is moved to and from its analysis location. In FIGS. 4a and 4b, the dampers 250 are shown mounted on the walls of the vacuum subchamber 50 and extending into the vacuum subchamber 50. Each damper 250 includes a conduit 252 extending from the periphery of the vacuum subchamber 50 to a collapsible bellows 254, which opens onto a cylinder 256 containing a piston 258 sandwiched between viscoelastic members 260. An elongated damping member 262 then extends from the damping member's pivot end 264 at the piston 258, through the bellows 254 and the conduit 252, and into the vacuum subchamber 50, where it terminates at the damping member's equipment end 266. When the vacuum sub-chamber 50 is at (or approaching) ambient pressure, the bellows 254 expands, causing the instrument end 266 of the damping member to be spaced from but pointed toward the instrument. However, when the vacuum sub-chamber 50 is evacuated, the ambient pressure causes the bellows 254 to compress, forcing the damping member 262 into the vacuum sub-chamber 50 until the instrument end 266 of the damping member engages with the instrument (here, within the socket 110 defined adjacent the detector 108 in FIG. 2 ). The bellows 254 and viscoelastic member 260 of each damper 250 elastically press the damping member 262 against the instrument and allow the damping member 262 to pivot as the instrument is displaced in and out of the vacuum chamber 10 (more specifically, the vacuum sub-chamber 50), thereby allowing the instrument to move between the storage position and the analysis position while damping external vibrations that may be transmitted to the instrument. By placing opposing dampers 250 around the device (as can be seen particularly in Figure 4b), their forces cancel out so that neither damper deflects the device's movement away from the device axis.

[0012] The present invention is not limited to typical positioning devices and can be provided in a variety of forms. More broadly, the present invention encompasses a positioning device having three or more elongated equipment support arms. Each equipment support arm extends through a wall of a vacuum chamber to an end of the equipment support arm within the vacuum chamber and is configured for translational movement along its length within the vacuum chamber wall. Uniform translational movement of the equipment support arms relative to the vacuum chamber wall results in translational movement of any equipment attached to the end of the equipment support arm within the vacuum chamber, while unequal translational movement of the equipment support arms relative to the vacuum chamber wall results in tilting of any equipment attached to the end of the equipment support arm within the vacuum chamber.

[0013] The present invention also encompasses a positioning apparatus having a secondary carriage configured for displacement relative to a wall of a vacuum chamber, and an elongated equipment support arm rigidly attached to the secondary carriage, displaceable along its length within the vacuum chamber wall, and having an equipment mounted thereto within the vacuum chamber, wherein uniform displacement of the equipment support arm relative to the vacuum chamber wall will displace any equipment mounted on the end of the equipment support arm within the vacuum chamber, while unequal displacement of the equipment support arm relative to the vacuum chamber wall will cause any equipment mounted on the end of the equipment support arm to tilt within the vacuum chamber.

[0014] The present invention further encompasses a positioning device having a primary carriage displaceable relative to a vacuum chamber wall, a secondary carriage having an equipment support arm extending from the secondary carriage and passing through the vacuum chamber wall, and secondary actuators, each secondary actuator displacing the secondary carriage relative to the primary carriage. Displacement of the primary carriage relative to the vacuum chamber wall displaces the secondary carriage, thereby displacing any equipment attached to the equipment support arm within the vacuum chamber. Furthermore, uniform displacement of the secondary actuators displaces the secondary carriage relative to the primary carriage, thereby displacing any equipment attached to the equipment support arm within the vacuum chamber, while unequal displacement of the secondary actuators causes the secondary carriage to tilt relative to the primary carriage, thereby tilting any equipment attached to the equipment support arm within the vacuum chamber.

[0015] Any one or more of the following features may also be present in any of the versions of the invention described above. (1) The positioning device may include a secondary carriage, each with an equipment support arm extending therefrom, the secondary carriage having three or more secondary actuators, each configured to translate the secondary carriage relative to the vacuum chamber wall, such that uniform translation of the secondary actuators causes the secondary carriage and the equipment support arms extending therefrom to translate relative to the vacuum chamber wall, thereby translating any equipment attached to the end of the equipment support arms within the vacuum chamber, and unequal translation of the secondary actuators causes the secondary carriage to tilt relative to the vacuum chamber, thereby causing unequal translation of the equipment support arms extending from the secondary carriage, thereby tilting any equipment attached to the end of the equipment support arms within the vacuum chamber. (2) The positioning device can include a primary carriage translatable relative to the vacuum chamber wall, with each secondary actuator extending between the primary and secondary carriages. Translational movement of the primary carriage relative to the vacuum chamber wall causes translational movement of the secondary carriage and the equipment support arm extending therefrom, which in turn causes translational movement of any equipment attached to the end of the equipment support arm within the vacuum chamber. (3) The positioning device may include a primary actuator (e.g., a pneumatic cylinder) configured to translate or otherwise displace the secondary carriage relative to the primary carriage. The primary actuator preferably has a wider range of motion than the secondary actuator. (4) The instrument support arm can be rigidly attached to the analytical instrument (preferably in a vacuum chamber) and / or to the subcarriage. (5) An equipment support arm may extend from the secondary carriage through the primary carriage. (6) Each of the secondary actuators may be spaced equidistant from an instrument axis extending through the secondary carriage and the vacuum chamber wall, and may be arranged around an actuator path extending around the instrument axis, with each secondary actuator being equally spaced from an adjacent secondary actuator along the actuator path. (7) Each of the equipment support arms may be spaced an equal distance from the equipment axis and arranged around an arm path extending around the equipment axis, and each secondary actuator may be spaced equally apart from an adjacent equipment support arm along the arm path. The circumference of the actuator path may be greater than the circumference of the arm path. (8) A positioning device may be used to position the APM. A preferred APM includes an elongated conical electrode (preferably an ion accelerating electrode) spaced from an instrument support arm by an ion detector. This arrangement may further include a local electrode and an ion deceleration electrode, the ion deceleration electrode being located between the local electrode and the conical electrode. (9) When the positioning device is used to position an instrument (e.g., an APM) including an ion detector, the positioning device and / or the instrument may include a vacuum subchamber within the vacuum chamber, the vacuum subchamber configured to provide a higher vacuum than the vacuum chamber. (10) The positioning device may include damping members each extending between a pivot end flexibly attached to the vacuum chamber wall and an equipment end adjacent the equipment. The damping members may be configured such that a vacuum within the vacuum chamber biases the damping members to mate the equipment ends of the damping members with the equipment. The equipment ends of the damping members may be removably mated to the equipment, for example, by receiving a socket within the equipment.

[0016] Further potential advantages, features, and objects of the present invention will be apparent from the remainder of this document taken in conjunction with the associated drawings. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 2 shows a typical analytical instrument positioning device 200 used to position an atom probe microscope (APM) 100 within a vacuum chamber 10, with the APM's lenses 102, 104, and 106 shown protruding from the vacuum subchamber port 52, and the APM's ion detector (not shown) located within the vacuum subchamber 50. [Figure 2] 2 shows the arrangement of FIG. 1 with the vacuum subchamber 50 removed, thereby revealing the ion optics of the APM (local electrode 102, deceleration lens 104, and deceleration lens 106) along with its ion detector 50. [Figure 3a] FIG. 3 is a side view of the arrangement of FIG. 2, showing the APM 100 in an at least partially retracted position. [Figure 3b] FIG. 3 is a side view of the arrangement of FIG. 2, showing the APM 100 in an at least partially extended position. [Figure 4a] FIG. 2 is a top view of the arrangement of FIG. 1. [Figure 4b]4a is a cross-sectional view taken along line AA of FIG. 4a, showing an exemplary damper 250 used to stabilize the APM 100 during extension and retraction. DETAILED DESCRIPTION OF THE INVENTION

[0018] FIG. 1 illustrates a typical version of a positioning device 200 that may be used to position an atom probe microscope (APM) 100 within a vacuum chamber. Only the APM's ion optics (its local electrode 102, deceleration lens 104, and deceleration lens 106) are visible in FIG. 1; the remainder of the APM 100 (primarily its detector) is located within a vacuum subchamber 50 in an arrangement such as that described in U.S. Pat. No. 1,061,4995. The vacuum subchamber 50 has a port 52 configured to mount onto the vacuum chamber 10 of another instrument (e.g., a transmission electron microscope (TEM)), such that the vacuum subchamber 50 effectively defines a portion of the vacuum chamber 10. The APM's local electrode 102, deceleration lens 104, and deceleration lens 106 are shown protruding from the vacuum subchamber 50 into the vacuum chamber. Within the vacuum subchamber 50, the APM 100 is attached to the positioning device 200, specifically, to the end of an instrument support arm 214 that extends through the back wall 54 of the vacuum subchamber 50. Thus, the APM 100 can be moved within the vacuum sub-chamber 50 (and within the vacuum chamber 10) by the positioning device 200 so that its local electrode 102 can be positioned immediately adjacent to the sample undergoing TEM analysis within the vacuum chamber 10.

[0019] Because the presence of the APM 100 can interfere with TEM imaging of the sample, a primary actuator 204 is provided to rapidly move the APM 100 away from (and then toward) the sample. The primary actuator 204 (e.g., a pneumatic cylinder) has its axis of movement aligned with the instrument axis (i.e., the axis of the ion flight cone when the APM 100 is in its default position). The primary actuator 204 has one actuating part (e.g., its body / cylinder 207) attached to the primary carriage 202 (shown as a generally square plate shape) and another actuating part (e.g., a shaft / piston 206 that translates within the body / cylinder 207) attached to the vacuum subchamber back wall 54. Thus, operation of the primary actuator 204 translates the primary carriage 202 toward or away from the vacuum subchamber back wall 54, and thus toward or away from the vacuum subchamber 50 and the TEM vacuum chamber 10.

[0020] Similarly, each secondary actuator 210 has one actuating part (e.g., its body / cylinder 213) attached to the primary carriage 202 and another actuating part (e.g., its shaft / piston 212) coupled to the secondary carriage 208. Actuation of two adjacent secondary actuators 210 tilts the secondary carriage 208 about a horizontal or vertical axis on the secondary carriage 208, while actuation of two non-adjacent secondary actuators 210 (or all three secondary actuators 210) by different respective distances tilts the secondary carriage 208 about both the horizontal and vertical axes. Actuation of the secondary actuators 210 by the same amount causes the secondary carriage 208 to translate along the machine axis. The secondary carriage 208 has instrument support arms 214 located on opposite sides of the tilt axis of the secondary carriage 208 (e.g., near the corners of the secondary carriage 208), which extend through one or more openings (not shown) in the vacuum subchamber back wall 54 to the APM 100 (more specifically, to the APM mount 112 adjacent the APM's detector). Thus, when the secondary carriage 208 is tilted, selected instrument support arms 214 extend into or retract out of the vacuum subchamber back wall 54, thereby tilting the APM 100 and deflecting its local electrode 102 (and the ion flight cone) from the instrument axis. Because the airtight fit of the instrument support arms 214 within the vacuum subchamber back wall 54 allows only limited tilting of the APM 100, this deflection is small (but sufficient), with the ion flight cone axis tilted by only about 1 degree from the instrument axis.

[0021] Thus, the primary actuator 204 allows the APM 100 to rapidly translate over greater distances toward or away from the sample (and the TEM within the vacuum chamber 10). Its actuation moves the primary carriage 202 toward or away from the vacuum subchamber back wall 54, thereby also carrying the secondary carriage 208 (coupled to the primary carriage 202 by the secondary actuator 210) and the APM 100 (coupled to the secondary carriage 208 by the instrument support arm 214). The secondary actuator 210 can perform fine positioning by adjusting the secondary carriage 208 to translate and / or tilt the APM 100 relative to the instrument axes. Preferably, in practice, after the APM 100 is positioned near the sample via the primary actuator 204, the secondary actuator 210 is used to focus the APM's local electrode 102 on the sample so that APM measurements can be taken. However, the primary actuator 204 allows the APM 100 to quickly retract from the sample when TEM measurements are to be taken, and then extend back toward the sample when the TEM measurements are finished, with the local electrode 102 at or very near its original measurement position. This is of significant value because aligning the local electrode 102 with the area of ​​interest on the APM sample can be a time-consuming process.

[0022] The above-described arrangement is enhanced by a damping system that helps reduce or eliminate vibrations in the APM 100. Because the APM 100 is supported in a cantilever arrangement (via an equipment support arm 214 extending from the vacuum sub-chamber back wall 54), it may be susceptible to environmental vibrations (e.g., transmitted from the floor or other ambient conditions, or audible noise) and / or extension / retraction vibrations, which may interfere with TEM or other analyses. As seen in FIG. 1, dampers 250 are provided on the vacuum sub-chamber 50, and are shown in further detail in FIGS. 4a-4b. Each damper 250 includes a damping member 262. The damping member 262 has a damping member equipment end 266 receivable within a concave damping receptacle (socket) 110 (seen in FIGS. 2 and 4b) in the APM mount 112, and an opposing damping member pivot end 264 having a thin piston 258. A thin piston 258 is sandwiched (or otherwise cushioned) within a cylinder 256 by a viscoelastic member 260 (e.g., a sorbothane disk). A vacuum-tight bellows 254 connects the cylinder 256 to the vacuum sub-chamber 50. When the vacuum sub-chamber 50 is evacuated, atmospheric pressure compresses the bellows 254, forcing the damping member 262 into the vacuum sub-chamber 50 until the damping member's device end 266 mates with the damping receptacle 110 in the detector housing. The flexible bellows 254 allows the first end of the damper's 250 connecting rod to follow (and bias) the APM mount 112 as the linear actuator translates and / or tilts the APM 100 and its detector. Viscoelastic member 260, and to some extent bellows 254, then usefully dampen vibrations of APM 100, and dampers 250 on opposite sides of APM 100 resist displacement of APM 100 from the instrument axis as it translates within sub-chamber 50. At the same time, dampers 250 maintain the vacuum in vacuum sub-chamber 50 and chamber 10, generating little or no heat that could potentially interfere with TEM or APM analysis.

[0023] Ideally, the APM 100 (or at least most of it) is spaced as far away from the sample as possible when retracted so as not to interfere with the TEM measurement. Therefore, the ion optics of a typical APM 100 are interesting because they increase the length of the ion flight path between the local electrode 102 and the detector 108, thereby further spacing the detector 108 from the sample (and increasing the flight time, thus increasing the mass resolution of the APM). This is accomplished by having the local electrode 102 equipped with an ion-decelerating electrostatic lens, which tends to increase the spread of ions emitted from the sample, followed by an ion-accelerating electrode, which collimates the spread ions and sends them onto the detector 108. Thus, for example, ions from a positively charged sample might be accelerated toward the local electrode 102, which is at ground potential, then decelerated through an opening in the negatively charged electrostatic lens 104, and then accelerated onto the detector by the positively charged conical accelerating electrode 106.

[0024] It should be understood that the above-described versions of the invention are merely exemplary, and the invention is not intended to be limited to these versions. As one example, translation and tilt of the secondary carriage 208 can be achieved with as few as three instrument support arms 214 or with more than four instrument support arms 214. However, the symmetrical arrangement provided by the illustrated four instrument support arms 214 tends to provide easier control. As another example, the secondary carriage 208 can achieve greater tilt if the instrument support arms 214 are pivotally attached to the secondary carriage 208 and the instrument (or at least one of them), but if the instrument is an APM, greater tilt is not necessary, and a pivoting connection (e.g., by a ball-and-socket universal joint) tends to introduce positioning uncertainty. As a final example, while the described arrangement uses pneumatic cylinders as the primary actuators 204 and DC servo motors as the secondary actuators 210, different actuators could be used instead. The described arrangement has the advantage that once fine positioning is complete, the secondary (servo motor) linear actuator 210 can be depowered, thereby avoiding further heat input that could interfere with the TEM or other analysis. The pneumatic primary actuator 204 can then be activated and deactivated as needed to extend and retract the APM 100 with negligible heat input into the vacuum chamber.

[0025] The scope of the present invention is limited only by the claims set forth below, and the present invention encompasses all variations thereof falling within the scope of these claims, either literally or equivalently. Within these claims, no element therein is to be construed as a "means-plus-function" element or a "step-plus-function" element pursuant to 35 U.S.C. §112(f) unless the phrase "means for" or "step for" is expressly used in that particular element.

Claims

1. 1. A positioning apparatus for an analytical instrument in a vacuum chamber, the positioning apparatus comprising three or more elongated instrument support arms, each instrument support arm comprising: a. extending through the wall of the vacuum chamber wall to an end of an equipment support arm within the vacuum chamber; b. configured for translational movement within said vacuum chamber wall along its length; As a result, A. Equal translational movement of the equipment support arm relative to the vacuum chamber wall causes translational movement of any equipment attached to the end of the equipment support arm within the vacuum chamber; B. A positioning device whereby unequal translation of the equipment support arm relative to the vacuum chamber wall causes tilting of any equipment attached to the end of the equipment support arm within the vacuum chamber.

2. further including a secondary carriage; a. each instrument support arm extends from said secondary carriage; b. three or more secondary actuators, each secondary actuator configured to translate the secondary carriage relative to the vacuum chamber wall; As a result, A. Equal translational movement of the secondary actuator causes translational movement of the secondary carriage and the equipment support arm extending therefrom relative to the vacuum chamber wall, thereby causing translational movement of any equipment attached to the end of the equipment support arm within the vacuum chamber; B. The positioning device of claim 1, wherein unequal translation of the secondary actuator causes the secondary carriage to tilt relative to the vacuum chamber, thereby causing unequal translation of the equipment support arm extending from the secondary carriage and tilting of any equipment attached to the end of the equipment support arm within the vacuum chamber.

3. The positioning device of claim 1 , wherein the equipment support arm is rigidly attached to the secondary carriage.

4. a. further comprising a main carriage translatable relative to said vacuum chamber wall; b. each secondary actuator extends between the primary carriage and the secondary carriage, each secondary actuator configured to displace the secondary carriage relative to the primary carriage; 3. The positioning device of claim 2, wherein translational movement of the primary carriage relative to the vacuum chamber wall causes translational movement of the secondary carriage and the equipment support arm extending therefrom, thereby causing translational movement of any equipment attached to the end of the equipment support arm within the vacuum chamber.

5. The positioning device of claim 4 , wherein the instrument support arm extends from the secondary carriage through the primary carriage.

6. a. The secondary actuator is (1) each of the sub-carriage and the vacuum chamber wall is equidistantly spaced from an axis of the device extending through the sub-carriage and the vacuum chamber wall; (2) arranged around an actuator path extending around the instrument axis, each secondary actuator being equally spaced from its adjacent secondary actuator along the actuator path; b. The equipment support arm is (1) each of the sensors is spaced apart from the device axis by an equal distance; 2. The positioning device of claim 1, wherein the actuators are arranged around an arm path extending around the equipment axis, and each secondary actuator is equally spaced from an adjacent equipment support arm along the arm path.

7. The positioning device of claim 6 , wherein the circumference of the actuator path is greater than the circumference of the arm path.

8. 10. The positioning apparatus of claim 1, further comprising an instrument rigidly mounted on the end of said instrument support arm within said vacuum chamber.

9. The positioning apparatus of claim 8 , wherein the instrument comprises an atom probe ion detector.

10. a. the device includes an elongated conical electrode; 10. The positioning device of claim 9, wherein the ion detector is located between the conical electrode and the end of the instrument support arm.

11. a. the device includes an electrode array, the electrode array comprising: (1) a local electrode; (2) an ion acceleration electrode; (3) an ion deceleration electrostatic lens between the local electrode and the ion acceleration electrode; 10. The positioning device of claim 9, wherein the ion detector is located between the electrode array and the end of the instrument support arm.

12. a. the apparatus includes a vacuum subchamber configured to provide a higher vacuum than the vacuum chamber; 10. The positioning apparatus of claim 9, wherein the ion detector is located within the vacuum subchamber.

13. a. an instrument mounted on the end of the instrument support arm within the vacuum chamber; b. Damping members, each damping member comprising: (1) a pivoted end portion of a damping member flexibly attached to the vacuum chamber wall; (2) a damping member extending between the device end of the damping member adjacent the device; The positioning device of claim 1 , wherein the vacuum in the vacuum chamber extends to the damping member, and an end of the damping member mates with the device.

14. a. an instrument mounted on the end of the instrument support arm within the vacuum chamber; b. Damping members, each damping member comprising: (1) a pivoted end portion of a damping member flexibly attached to the vacuum chamber wall; (2) a damping member extending between the device end of the damping member adjacent the device; The positioning device of claim 1 , wherein the vacuum in the vacuum chamber extends to the damping member, and an end of the damping member mates with the device.

15. a. an instrument mounted on the end of the instrument support arm within the vacuum chamber; b. Damping members, each damping member comprising: (1) a pivoted end portion of a damping member flexibly attached to the vacuum chamber wall; 2. The positioning device of claim 1, further comprising a damping member extending between said device end and said damping member, said damping member receiving a socket in said device.

16. a. an instrument mounted on the end of the instrument support arm within the vacuum chamber; b. Damping members, each damping member comprising: (1) a pivoted end of a damping member mounted on an inflatable member attached to the vacuum chamber wall; 2. The positioning device of claim 1, further comprising: a damping member extending between said device and a device end of said damping member configured to mate with said device.

17. 1. A positioning device for an analytical instrument in a vacuum chamber, said positioning device comprising: a. a secondary carriage configured to be displaced relative to a wall of the vacuum chamber; b. An elongated equipment support arm, (1) rigidly attached to the secondary carriage; (2) capable of translational movement along its length within the vacuum chamber wall; (3) an elongated equipment support arm to which an equipment is attached within the vacuum chamber; As a result, A. Equal translational movement of the equipment support arm relative to the vacuum chamber wall causes translational movement of any equipment attached to the end of the equipment support arm within the vacuum chamber; B. A positioning device whereby unequal translation of the equipment support arm relative to the vacuum chamber wall causes tilting of any equipment attached to the end of the equipment support arm within the vacuum chamber.

18. a. a main carriage; b. a primary actuator configured to displace the primary carriage relative to a wall of the vacuum chamber; c. a secondary actuator mounted between the primary carriage and the secondary carriage; a primary actuator configured to displace the secondary carriage relative to the primary carriage.

19. 1. A positioning device for an analytical instrument in a vacuum chamber, said positioning device comprising: a. a main carriage displaceable relative to a vacuum chamber wall; b. a secondary carriage having an equipment support arm extending therefrom through said vacuum chamber wall; c. secondary actuators, each secondary actuator displacing the secondary carriage relative to the primary carriage; As a result, A. Displacement of the primary carriage relative to the vacuum chamber wall displaces the secondary carriage, thereby displacing any equipment mounted on the equipment support arm within the vacuum chamber; B. Equal displacement of the secondary actuator displaces the secondary carriage relative to the primary carriage, thereby displacing any equipment attached to the equipment support arm within the vacuum chamber; C. A positioning device wherein unequal displacement of the secondary actuators causes the secondary carriage to tilt relative to the primary carriage, thereby tilting any equipment mounted on the equipment support arm within the vacuum chamber.

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