Vacuum-Compatible X-Ray Shielding Cover

Abstract

Disclosed are methods and apparatus for setting up an X-ray shield within an ultra-high vacuum enclosure. A housing is fabricated, leak tested, filled with an X-ray shielding material, and sealed. An elongated, twisted X-ray shield can be deployed within the pumping channel of an electron microscope or similar device. The shield can be within a stainless steel housing with lead and have an optional low-Z cladding outside the housing. Other variations are disclosed.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims priority to U.S. Application No. 17 / 533,610, filed on November 23, 2021, and entitled "Vacuum-Compatible X-Ray Shield". Technical Field

[0003] The present disclosure relates to X-ray shields. Background Art

[0004] X-ray shields are required in a wide range of applications, including electron microscopes and other systems where high-energy particle beams impinge on a material to produce X-rays. For geometric reasons, an X-ray shield located closer to the X-ray generation site requires less shielding material than a shield placed farther away. However, systems that generate X-rays typically operate under ultra-high vacuum (UHV), and some common shielding materials are not compatible with ultra-high vacuum. Accordingly, there is still a need for improved technology that enables the use of a compact X-ray shield within ultra-high vacuum. Summary of the Invention

[0005] Briefly, examples of the disclosed technology provide X-ray shielding material within a self-contained vacuum-sealed enclosure that can be deployed within an ultra-high vacuum environment.

[0006] In a first aspect, the disclosed technology may be implemented as a method of manufacturing an X-ray shield. A housing defining a chamber and having one or more ports is manufactured. The housing is tested to verify that the housing is leak-free. The tested housing is filled with X-ray shielding material. The one or more ports of the filled housing are sealed.

[0007] In some examples, the housing may be manufactured by an additive manufacturing process that may incorporate one or more of the following: direct metal laser sintering (DMLS), selective laser melting (SLM), electron beam melting (EBM), or binder jetting (BJ). In various examples, the housing may be rigid; may incorporate stainless steel; and / or may have an intermediate wall thickness in the range of 0.1 mm to 1.0 mm. The rigid housing may incorporate a material having a first average atomic number Z1, and the method may include coating the rigid housing with another material having a second average atomic number Z2 that is less than Z1.

[0008] In additional instances, the X-ray shielding material may incorporate metal, and the filling operation may include introducing the metal in a molten state into the chamber. The X-ray shielding material may incorporate a resin carrying metal particles. The one or more ports may include a first port for introducing the X-ray shielding material into the chamber during the filling operation and a second port for releasing the discharged fluid from the chamber during the filling operation.

[0009] In other instances, the seal may include fusing a respective cap to each of the one or more ports. During the duration of the containment test, the housing may be temporarily isolated from the environment surrounding the housing. The test may have a leak rate threshold of less than or equal to 10 -7 mbar·l / s.

[0010] In other instances, the disclosed technology may be implemented as a method for reducing X-ray emissions from an electron microscope housed in a vacuum enclosure. The X-ray shielding enclosure may be manufactured by any of the above methods or variations. The X-ray shielding enclosure may be fixed within the internal volume of the vacuum enclosure. The X-ray shielding enclosure may be fixed within the pump coupler of the electron microscope and may be oriented to block at least 80% of the X-rays emitted through the inlet aperture of the pump coupler and parallel to the longitudinal axis of the pump coupler.

[0011] In a second aspect, the disclosed technology may be implemented as an apparatus having a vacuum enclosure and an X-ray shielding enclosure positioned within the vacuum enclosure. The X-ray shielding enclosure includes a reverse vacuum bottle containing an X-ray shielding material.

[0012] In some instances, the apparatus may be an electron microscope having a column axis and may further include a pump coupler. The X-ray shielding enclosure may be positioned within the pump coupler and oriented to block at least 80% of the X-rays emitted from an X-ray generation site within the vacuum enclosure and through the inlet aperture of the pump coupler. The vacuum conductance of the pump coupler is reduced by no more than 20% due to the X-ray shielding enclosure compared to when there is no X-ray shielding enclosure.

[0013] The reverse vacuum bottle may incorporate stainless steel. The stainless steel may be coated with a material having an average atomic number of less than or equal to 14. The X-ray shielding enclosure may be formed to include a twisted elongated member. The X-ray shielding material may incorporate at least 50 wt% lead. The pressure within the vacuum vessel may be maintained below 10-9 mbar.

[0014] In another aspect, the disclosed technology may be implemented as a method in which a reverse vacuum bottle containing an X-ray shielding material is placed inside the vacuum enclosure of an electron microscope, and the vacuum enclosure is pumped down to a pressure below 10-9 mbar.

[0015] In some instances, the vacuum container may have a pump coupler, and the placement may include securing a reverse vacuum bottle within the pump coupler.

[0016] The above and other objects, features, and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the reference drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figures 1A to 1B is a cross-sectional view of a portion of an electron microscope suitable for deploying the disclosed technology.

[0018] FIG. 2 is a cross-sectional view of an apparatus having an X-ray shield conventionally deployed outside a vacuum enclosure.

[0019] Figure 3 is a cross-sectional view of an apparatus having an X-ray shield housing according to a first example of the disclosed technology deployed inside a vacuum enclosure.

[0020] Figure 4 is a cross-sectional view of an apparatus having an X-ray shield housing according to a second example of the disclosed technology deployed inside a vacuum enclosure.

[0021] Figure 5 is a flow chart of a method according to a first example of the disclosed technology.

[0022] Figures 6A to 6D is a view of an X-ray shield housing according to a first example of the disclosed technology.

[0023] Figure 7 is a flow chart of a method according to a second example of the disclosed technology.

[0024] Figure 8 is a block diagram of an apparatus having an X-ray shield housing according to the disclosed technology.

[0025] Figure 9 is a flow chart of a method according to a third example of the disclosed technology.

[0026] Figures 10A to 10B is a view of an X-ray shield housing according to a second example of the disclosed technology.

[0027] Figure 11 is a view of an X-ray shield housing according to a third example of the disclosed technology.

[0028] Figures 12A to 12C is a view of an X-ray shield housing according to a fourth example of the disclosed technology.

[0029] Figure 13 is a view of an X-ray shield housing according to a fifth example of the disclosed technology.

[0030] Figures 14A to 14D It is a view of an X-ray shield according to a sixth example of the disclosed technology.

[0031] Figure 15 Illustrates a generalized example of a suitable computing environment in which the described embodiments, techniques, and technologies regarding the disclosed nonlinear optical devices may be implemented. Detailed Description

[0032] Introduction

[0033] For reasons of personnel safety, X-ray shielding is typically used around X-ray generating equipment. X-rays can be generated within electron microscopes (e.g., TEM and SEM), focused ion beam machines, other analytical equipment (e.g., performing electron scattering, X-ray diffraction, or similar techniques), or other equipment where a high-energy particle beam impacts a material.

[0034] In an electron microscope, X-ray generation due to stray electrons impacting the aperture plate or walls of the microscope column can be controlled or minimized through careful design. However, the incidence of the electron beam on the sample is a fundamental aspect of electron microscope operation and cannot be eliminated. Additionally, electron microscopes typically use beam voltages in excess of 60 keV, and the resulting X-rays can be significant. Similar considerations apply to other particle beam devices.

[0035] Therefore, the center of the sample chamber represents a significant X-ray generation site where the sample is typically placed for imaging by an electron microscope. The sample chamber of an electron microscope can be crowded, especially in the case of a transmission electron microscope (TEM). In some directions, positions outside the sample chamber can be placed as close as possible to the actual location where the X-ray shield is to be placed, and this shield can be deployed without considering vacuum compatibility. However, the sample chamber (and the entire electron beam channel) can be maintained under ultra-high vacuum, and for this purpose, a tube section called a connector can connect the sample chamber to a vacuum pump. To maximize the vacuum conductance, the connector can have a wide cross-section and generally does not impede the air flow. Therefore, the connector can also provide a clear path for X-rays to exit. Due to the size of the vacuum pump and the connector, an X-ray shield placed outside the connector can be large and cumbersome, and an X-ray shield may need to be placed inside the connector or between the connector and the X-ray generation site at the center of the sample chamber.

[0036] In the case of a stainless-steel shield, this internal X-ray shield positioning may be straightforward (given the reduced vacuum conductance). However, stainless steel has a relatively low stopping power for X-rays. Under typical electron-beam conditions and typical requirements for X-ray attenuation by the shield, the thickness of stainless steel required for shielding can be about 20 cm. Aluminum, with a lower atomic number, may require a greater thickness—about 40 cm.

[0037] On the other hand, lead has excellent stopping power and can provide sufficient shielding with a thickness of only 1.5 cm. However, lead is prone to outgassing, and an exposed lead surface may be undesirable within a UHV system. Additionally, a vacuum-compatible coating (usually a metal coating) applied to a lead structure may be prone to defects. That is, it may be difficult to achieve a defect-free seal coating on lead. Additionally, it may be difficult to test whether the coated structure is in fact leak-free.

[0038] The disclosed technology addresses these problems by leak testing a hollow shell and then filling it with an X-ray shielding material. The resulting X-ray shield can be deployed at any suitable location within an ultra-high-vacuum system. Only the shell material (which can be stainless steel or a low-Z vacuum-compatible material such as aluminum) is exposed to the vacuum, and the seal of the shield can be ensured. Thus, the respective advantages of stainless steel and lead can be advantageously combined, and a compact X-ray shield can be deployed within a pump coupler or at any other available location within a UHV enclosure.

[0039] For reasons of maintaining vacuum conductance through the pump coupler, complex shapes such as an elongated twisted structure can be used. Such shaped shells can be conveniently fabricated using additive machining, but this is not necessary. For example, in addition to or instead of additive manufacturing, sections of the shell can also be fabricated by forming sheet metal, extrusion, or casting and welded together.

[0040] The following section provides a brief description of a representative TEM that can benefit from the disclosed technology.

[0041] Example Electron Microscope

[0042] Figures 1A to 1B is a cross-sectional view of a part of an electron microscope and provides context for the disclosed technology described herein, for example. For illustrative purposes, Figures 1A to 1B depicts a common TEM configuration; however, the disclosed technology can be similarly applied to other devices.

[0043] Figure 1Ais a vertical section through the column axis 105. The sample chamber 110 may be located between the condenser electron optics 122 and the objective electron optics 128. The optics 122, 128, and the sample chamber 110 define a part of the electron column of the electron microscope, within which the electron beam may be guided through the channel 125.

[0044] The pole pieces 124, 126 form a magnetic field therebetween. In normal operation, the sample may be held in an intermediate position between the pole pieces 124, 126 along the column axis 105. Incidence of the electron beam on the sample may result in the generation of X-rays. Accordingly, the ellipse 115 represents the X-ray generation site.

[0045] The interior of the electron column containing the sample chamber 110 may be maintained under ultra-high vacuum during operation. Accordingly, a vacuum pump 140 may be coupled to the sample chamber 110 through a pump coupler 130, which has an inlet aperture 132 and an outlet aperture 134. The vacuum enclosure of the electron microscope includes all or part of the wall of the sample chamber 110, the coupler 130, a part of the pump 140, and additional components along the electron channel 125 above or below the sample chamber 110. The interior space of the vacuum enclosure containing the sample chamber 110 and the X-ray generation site 115 may be under ultra-high vacuum, while the external environment 103 may be an indoor environment at one atmosphere.

[0046] Figure 1B is a horizontal section through the mid-plane of the sample chamber 110, which shows a common octagonal configuration with symmetry axes 112, 114, and eight ports. In some instances, two opposite ports 181, 185 may be used for the sample loader and the sample manipulator, while the other ports 182 to 184, 186 to 187 may be used in different ways for cold fingers, instrument access, or auxiliary tools; or may not be used. In normal operation, each of the ports 181 to 187 may provide a vacuum-tight connection to the associated device, or may simply be sealed shut. The channel 180 of the sample chamber 110 may be coupled to the pump coupler 130 at the inlet aperture 132. For clarity of illustration, flanges, gaskets, or other connection details are omitted from Figures 1A to 1B omitted. The intersection point of the symmetry axes 112, 114 may be located on the column axis 105.

[0047] The term

[0048] The term "additive manufacturing" (sometimes referred to as "3-D printing") refers to a process for manufacturing an object using layer-by-layer material deposition, where the object shape is defined by computer-guided deposition of the material rather than by a preformed mold. That is, additive manufacturing creates a shape without using a mold, although a substrate may be used as a base on which additional material is deposited.

[0049] The term "atomic number" (Z) refers to the number of protons in the nucleus of an atom of an elemental substance. For a composition of multiple elements (e.g., an alloy, compound, mixture, or composite in which one material is interspersed with or within another material), the "average atomic number" Zavg can be defined as:

[0050]

[0051] where the subscript i represents the corresponding element in the composition with atomic number Zi, and fi is the fraction of the protons of the atoms of element i in the composition. That is, ∑ i f i = 1. k and 1 / k are positive exponents; k = 1 represents the simple average atomic number, and k = 2.94 represents the Khan average atomic number, sometimes referred to as the "effective atomic number". For an elemental substance, the average atomic number is simply the atomic number of the element. Although the atomic number is an integer, the average atomic number need not be an integer. Low-Z materials have an average atomic number less than or equal to 14. In some instances, aluminum (Z = 13) can be used as a low-Z cladding on the housing of an X-ray shield. High-Z materials have an average atomic number greater than or equal to 50.

[0052] In the context of X-rays or X-ray shielding, the term "blocking" refers to the interaction of X-rays with an X-ray shield, resulting in absorption or inelastic scattering. Inelastic scattering is the process by which one or more photons are produced and the original X-ray disappears, with each photon having lower energy than the incident X-ray. Incident X-rays that do not interact can be said to "pass through" the shield. Passing through can include elastic scattering. The term "blocking" can depend on the normal operation of the device. By way of illustration, a given X-ray shield can block 99% of the X-rays produced by a 10 keV electron beam (while 1% passes through), 90% of the X-rays produced by a 100 keV beam (while 10% passes through), or 50% of the X-rays produced by a 1 MeV beam (while 50% passes through).

[0053] The term "bottle" refers to a sealable container that has at least one port that connects the interior of the container to its exterior. A bottle remains a bottle when at least one port is closed. A "vacuum bottle" is a bottle that can be evacuated (e.g., through a port) to maintain a vacuum inside the bottle, where discrete objects are optionally located in the vacuum. A "reverse vacuum bottle" is a bottle that can accommodate materials sealed to the bottle from outside the vacuum. A bottle can have any of a wide variety of shapes and is not limited to being cylindrical in shape or having a narrow neck leading to a port. Some of the bottles of interest herein can have a twisted or helical shape and have one, two, or more ports.

[0054] The term "chamber" refers to the space or volume inside an enclosure. The presence of one or more ports does not prevent the enclosure from defining a chamber. A "sample chamber" is a chamber typically within an electron microscope or other analytical device, in which a sample can be placed for analysis under normal operation.

[0055] An "electron microscope" is a type of analytical instrument in which a sample is irradiated with an electron beam and the resulting particles or electromagnetic radiation are used to form an image. A scanning electron microscope (SEM) images the surface of a sample based on reflected, secondary, or backscattered particles or radiation from the surface of the sample upon incidence of the electron beam. Since the beam interactions detected by the SEM occur at or near this surface, the SEM can operate on samples of any thickness. In contrast, a transmission electron microscope (TEM) images the surface of a sample based on transmitted electrons (including scattered electrons). The TEM operates on samples having a thickness of about 10 nm to 150 nm, which can be mounted on a grid for mechanical support and thermal conduction; subsequently, the grid can be held in a sample holder. The TEM can provide magnifications up to and exceeding 50 million, while the magnification of the SEM is typically limited to about 2 million. In the present disclosure, a scanning transmission electron microscope (STEM) that performs imaging of transmitted electrons is considered a TEM. The electron beam in an electron microscope can be generated in an electron gun and accelerated, focused, or manipulated through a series of stages toward the sample chamber. Typically, the electron gun, intermediate stages, sample chamber, and downstream imaging stages can be arranged in a columnar structure referred to as an "electron microscope column" or simply a "column". The longitudinal axis of the column is referred to as the "column axis".

[0056] The term "enclosure" refers to a structure that defines an internal space (e.g., a chamber). Although some enclosures described herein are sealed, this is not required, and other enclosures can have one or more ports that allow substances to move freely between the internal space and the external space. Specifically, some of the described enclosures can have ports that are initially open but then temporarily closed (e.g., for leak testing) or permanently closed (e.g., before the enclosure is put into use).

[0057] The term "filled", as applied to a chamber (or housing), is to be understood to mean that at least 50 volume % of the chamber (the internal space of the housing) is occupied by a filling material such as an X-ray shielding material.

[0058] The term "fluid" refers to a substance in a liquid or gaseous phase that can assume the shape of the surrounding enclosure. A fluid can be homogeneous or heterogeneous.

[0059] The term "isolated", in the context of an enclosure, refers to the absence of a clear path connecting two spaces. An enclosure that does not have an open port can be used to isolate its internal volume from the external space. The presence of a leak in an enclosure does not prevent the spaces from being isolated.

[0060] The term "leak" as a noun refers to an unintended path through the wall of an enclosure. As a verb, the term refers to the act of passing through a leak point. A path through a wall can be considered a leak if its leak rate is between 10 -3 mbar·l / s and a predetermined leak rate threshold (e.g., 10 -12 mbar·l / s).

[0061] The term "leak rate" refers to the rate at which a material passes through a surface under a given pressure differential and is typically measured in units similar to millibar liters per second (abbreviated as mbar·l / s). Air can pass through a 10 μm diameter hole in a thin wall across an atmospheric pressure differential at approximately 10 -2 mbar·l / s. For helium at 25 °C with a 1000 mbar (one atmosphere) pressure differential, the leak rates of interest herein for ultra-high vacuum systems can be in the range of 10 -3 mbar·l / s to 10 -12 mbar·l / s.

[0062] The term "port" refers to a visible opening in an enclosure. Generally, a port can have a lateral spatial extent in the range of 0.1 mm to 10 cm, sometimes 1 mm to 1 cm, but this is not necessary. A port can be circular, but this is not necessary, and ports with square, oval, elongated slot shape or other shapes can also be used. A "pumping port" is a port of a vacuum enclosure that is connected to a vacuum pump.

[0063] The term "pump coupler" refers to the section that connects the main chamber of a vacuum enclosure to the vacuum enclosure of a vacuum pump. The interface region between the pumping port and the main chamber within the vacuum enclosure is called the "inlet aperture" of the pump coupler. The interface between the pump coupler and the vacuum pump can be the pumping port of the vacuum enclosure, sometimes called the "outlet aperture" of the pump coupler. That is, fluid atoms or molecules extracted from the main chamber by the vacuum pump can enter the pump coupler from the main chamber through the inlet aperture and then enter the vacuum pump through the outlet aperture.

[0064] The term "resin" refers to a viscous fluid. A resin is said to be "loaded" when it serves as a medium for holding suspended particles such as particles of an X-ray shielding material. Some resins can be epoxy resins or other curable resins that cure into rigid solids, but this is not necessary. Other resins can sustainably maintain their viscous fluid properties.

[0065] The term "rigid" means that a housing or other solid object has a definite shape under normal use. For illustration, a glass bottle is rigid, while an ordinary plastic bag is not rigid. Minor shape deformations caused by vibration, thermal expansion, changes in the pressure difference between the interior and exterior of the housing, or similar effects do not prevent the object from being considered rigid.

[0066] The term "seal" as a verb refers to the act of closing the ports of a housing. The ports can be closed, for example, by welding a lid onto the port. When all the ports of the housing are sealed, the interior volume of the housing can be isolated from the external space.

[0067] The term "housing" refers to a thin-walled enclosure. The housing can be rigid, but this is not necessary. A bellows structure, whether made of stainless steel or another material, can be a flexible housing. The wall thickness of some of the housings of the disclosed examples can be in the range of 30 μm to 3 mm, 100 μm to 1 mm, or about 0.3 mm. The wall thickness can vary between different parts of the housing. For illustration, a housing with an intermediate thickness of 0.3 mm can have a base section with a thickness of about 1 mm and a flange section with a thickness of about 3 mm.

[0068] The term "vacuum" refers to a chamber condition where the fluid pressure is below 10 –3 mbar. "Ultra-high vacuum" (UHV) refers to a pressure below 10 -9 mbar. 1 mbar is approximately 10 2 Pa, 10 2 N / m 2 or 0.75 Torr.

[0069] The term "vacuum conductance" refers to the ratio of the mass flow rate between two planes in a vacuum divided by the pressure difference between the planes. For illustration, the two planes can be the inlet and outlet pores of a pump connector. Under the conditions of molecular flow, the mass flow rate through the pump connector is proportional to the pressure difference between the inlet and outlet pores. Generally, the presence of an object (e.g., an X-ray shield) within the pump connector, bends, non-uniformities in the cross-section of the pump connector, or surface roughness can cause the vacuum conductance of the pump connector to be lower than that of a straight-through orifice pump connector of the same or similar size.

[0070] The term "vacuum housing" refers to a structure configured to isolate the vacuum inside a housing from an environment that is not under vacuum. In some examples, the environment can be air, but this is not necessary and other gas or liquid environments can be used. Alternatively, the environment outside the vacuum housing can be at a pressure higher than the vacuum inside the housing. The vacuum housing can be formed by a mixture of one or more housings, other structures, ports, or gaskets in any combination.

[0071] The term "vacuum pump" refers to a device that can be used to extract fluid atoms or molecules from the internal space of a vacuum enclosure to which it is connected. The vacuum pumps found in a UHV system can include turbomolecular pumps, cryopumps, ion pumps, or getters, which can be assisted by mechanical pumps, diffusion pumps, or other types of roughing pumps.

[0072] The term "welding" refers to a process for joining two solid objects, where the materials of the two objects are temporarily heated or liquefied near the joint. For metallic objects, heating can be accompanied by liquefaction, for example, by using a welding torch, or heating can be performed without liquefaction, for example, by using the acoustic energy in ultrasonic welding. For non-metals, such as polymers, heating or liquefaction can be performed by using acoustic energy or by using a solvent. Some common welding processes, such as tungsten inert gas (TIG) and metal inert gas (MIG) welding, can use filler materials. Other welding processes, such as laser welding or ultrasonic welding, can dispense with filler materials.

[0073] The term "within" means completely contained inside. Thus, the innovative X-ray shield can be deployed within the vacuum enclosure and can be removed from the vacuum enclosure. After removing the X-ray shield, the vacuum enclosure can be resealed and evacuated, intact and with the same configuration whether or not it has the X-ray shield.

[0074] The term "X-ray" refers to electromagnetic radiation having a wavelength in the range of approximately 10 pm to 10 nm or a photon energy in the range of approximately 100 eV to 100 keV. X-rays are typically produced by the interaction of a high-energy particle beam with a stationary material, but this is not necessary. X-rays can also be produced by the interaction of higher-energy photons (e.g., gamma rays or other X-rays) with matter or by radioactive decay. In some of the disclosed examples, X-rays can occur within an electron microscope, for example, at the site where an electron beam impinges on a sample. X-rays can also be produced by a focused ion beam impinging on a sample.

[0075] The term "X-ray generation site" refers to the location within a device where X-rays are expected to be generated during normal operation of the device. For example, the sample stage or sample chamber within an electron microscope can be an X-ray generation site. A plate or block that defines a pore through which an electron beam passes can also be an X-ray generation site. Thus, the X-ray generation site exists within the device when the device is turned off or when no sample is present.

[0076] The term "X-ray shield" (or simply "shield") refers to a device that incorporates X-ray shielding material and is configured to block some X-rays. The X-rays blocked can be generated during normal operation of the device associated with the X-ray shield.

[0077] The term "X-ray shielding material" refers to a material having an average atomic number of at least 30 or in the range of 30 to 100. Some X-ray shielding materials of interest in the present disclosure include lead (atomic number Z = 82), tungsten (Z = 74), or tin (Z = 50). Antimony (Z = 51), tantalum (Z = 73), bismuth (Z = 83), or depleted uranium (Z = 92) may also be used. Common structural materials such as stainless steel (Zavg = 29) or aluminum (Z = 13) are not considered X-ray shielding materials herein.

[0078] Example X-ray Shield Deployment

[0079] FIG. 2 is a cross-sectional view 200 illustrating an X-ray shield deployed external to a vacuum enclosure. FIG. 2 depicts a representative electron microscope generally similar to Figure 1A that of an electron microscope. In a configuration similar to that described in the context of Figures 1A to 1B , an X-ray generation site 215 is positioned along a column axis 205 and within a sample enclosure 210, which is coupled to a pump 240 via a pump coupler 230. The illustrated apparatus includes electron optics 222, 228 and pole pieces 224, 226, which are also similar to Figure 1A that of an apparatus.

[0080] In FIG. 2, an X-ray shield 250 is disposed external to the vacuum enclosure (203) in a conventional configuration. Since the shield 250 is not within the internal vacuum space, vacuum compatibility need not be provided. However, the shield 250 surrounds and is larger than the pump coupler 230, and the mass of the shield 250 can be relatively large.

[0081] Figure 3 FIG. 3 is a cross-sectional view 300 of an apparatus having an X-ray shield deployed within a vacuum enclosure. Specifically, an innovative X-ray shield 350 can be placed within the vacuum enclosure, e.g., within a sample chamber 310 and proximate to an X-ray generation site 315. Figure 3 Other components in , including components 322, 324, 326, 328 along an electron column having an axis 305, as well as a pumping port assembly coupler 330 and a pump 340, are generally similar to similarly numbered components described in the context of Figure 1A and will not be described further.

[0082] Figure 4 FIG. 4 is a cross-sectional view 400 of an apparatus having another X-ray shield deployed within a vacuum enclosure. Specifically, an innovative X-ray shield 450 can be placed within the vacuum enclosure, e.g., within a pump coupler 430. Figure 4Other components in, including components 410, 422, 424, 426, 428 along an electron column having an axis 405, and a pump 440, are generally similar to the similarly numbered components described in the context of Figure 1A and will not be described further.

[0083] Many variations and extensions of the disclosed method can be implemented. In some instances, the X-ray shield can be partially placed within the sample chamber 310 and partially placed within the pump coupler 330, i.e., spanning the inlet aperture 332. In other instances, multiple X-ray shields can be deployed within the vacuum enclosure and arranged in different ways between the sample chamber 310, the pump coupler 330, or near other ports (e.g., similar to Figure 1B 181 to 187 of

[0084] First example method

[0085] Figure 5 is a flowchart 500 of a first example method for manufacturing an X-ray shield. In this method, a housing is manufactured, leak tested, filled, and sealed to obtain an X-ray shield suitable for deployment within an ultra-high vacuum enclosure.

[0086] At process block 510, a housing can be manufactured. The housing can define a chamber and can have one or more ports. At block 520, the housing can be tested to verify that the housing is leak-free. Then, at block 530, the tested housing can be filled with X-ray shielding material, and at block 540, the ports of the housing can be sealed.

[0087] Many variations and extensions of the disclosed method can be implemented. The manufacturing at block 510 can be performed by additive manufacturing and can include one or more of direct metal laser sintering (DMLS), selective laser melting (SLM), electron beam melting (EBM), or binder jetting (BJ).

[0088] The housing can be rigid. The housing material can include stainless steel. The housing can have an intermediate wall thickness of about 0.3 mm or in the range of 0.05 mm to 2.0 mm or 0.1 mm to 1.0 mm.

[0089] Before the leak test, the chamber inside the housing can be temporarily isolated from the environment outside the housing. For example, one port can be sealed with a cap and another port can be connected to a helium leak detector. The temporary isolation can be maintained for the duration of leak test 520 and then the temporary isolation can be removed so that the port can be used to fill the housing at process block 530.

[0090] Leak test 520 can be performed according to a predetermined leak rate threshold, which means that a measured leak rate above the threshold results in a failed test, while a measured leak rate below the threshold results in a passed test. The predetermined leak rate threshold can be the limit sensitivity of the helium leak detector or can be another leak rate value higher than the limit sensitivity. For illustration, the leak detector can have a sensitivity of 10 -9 mbar·l / s, and the predetermined threshold can be 10 -7 mbar·l / s. Then, a housing with a detected leak rate of 10 -8 mbar·l / s can pass the leak test and can be considered leak-free. As another illustration, the predetermined threshold can be equal to the sensitivity of the immediate leak detector such that any detected leak results in the housing failing the leak test and no detectable leak is required to pass the leak test.

[0091] In some instances, the first port can be used during filling 530 to introduce X-ray shielding material into the chamber, while the second port can be used to release pre-existing fluid (e.g., air) that is expelled from the chamber when it is being filled. In other instances, the second port can be connected to a pump to evacuate the chamber before filling to avoid trapped air pockets and ensure a void-free X-ray shield. In other instances, more than one port can be used for the filling function or the release function. Additionally, filling 530 can be performed using a single port. The single port can be connected to two valves, one valve is opened to evacuate the chamber through the pump and the other valve is opened to fill from a supply reservoir. Alternatively, the single port can be used simultaneously for filling through a feed tube inserted into the port and for releasing expelled fluid through a portion of the port not blocked by the feed tube.

[0092] The X-ray shielding material can comprise at least 50 wt% of a high-Z metal, such as lead. Filling at block 530 can comprise introducing the metal in a molten state into the chamber. The X-ray shielding material can be in the form of metal powder suspended in a resin.

[0093] Sealing at block 540 can comprise fusing the respective caps to each of one or more ports of the housing.

[0094] The housing may have an average atomic number Z1, and the method may be extended to coat the housing with another material having an average atomic number Z2 < Z1.

[0095] Example procedures for reducing X-ray emission

[0096] In some examples, the disclosed techniques may be applied to reduce X-ray emission from an electron microscope or from other X-ray generating devices. The electron microscope or other device may have an X-ray generating site located within a vacuum enclosure. The X-ray shield may be fabricated by Figure 5 or Figure 7 the methods shown in the corresponding figures or using any of the variations or extensions described herein, in any combination. The X-ray shield may then be fixed within the interior volume of the vacuum enclosure. In some examples, the X-ray shield may be positioned, for example, within a pump coupler along the path between the X-ray generating site and the vacuum pump and may be oriented to block greater than a first threshold fraction of the X-rays emitted through the inlet aperture of the pump coupler and parallel to the longitudinal axis of the X-ray shield. In different examples, the first threshold fraction may be 50%, 80%, 90%, 95%, 98%, or 99%.

[0097] Example X-ray shields

[0098] Figures 6A to 6D are views 601 through 604 of a first example X-ray shield according to the disclosed techniques. Views 601 through 602 are cross-sectional views of the X-ray shield. For clarity of illustration, the X-ray shielding material has been omitted from views 601 through 602 but will be described below.

[0099] Figure 6A Shows a housing 610 having a curved and twisted surface with a wall 612 and defining a chamber 620. A portion of the housing 610 also has a base 614 and a mounting flange 616. In some examples, at least the wall 612 may be fabricated using additive manufacturing techniques. In different examples: for example, in the same process operation as the wall 612, one or both of the base 614 and the flange 616 may also be fabricated by additive manufacturing; one of the base 614 and the flange 616 may be provided as a base on which the wall 612 is additively manufactured; or one or both of the base 614 and the flange 616 may be fabricated separately from the wall 612 in separate process operations and joined to the wall 612. Thus, the base 616, the wall 612, and the flange 614 may be formed of the same material or different materials in any combination. In some examples, the base 616, the wall 612, and the flange 614 may all be stainless steel. In Figure 6AIn [the figure], chamber 620 is shown as hollow to better illustrate the structure of the X-ray shield of the present invention. When deployed for service, chamber 620 may be filled with X-ray shielding material. The XYZ axes 608 are also shown.

[0100] Figure 6B is another view 602 through the mid-plane of flange 616, which shows the structure of port 622 sealed (temporarily or permanently) by cover 632. Generally, cover 632 can be regarded as part of the complete X-ray shield, rather than part of housing 610. In Figure 6B In [the figure], the dashed line 609 indicates the furthest extent of housing 610 in the direction of the Z-axis of the coordinate axes 608 shown in Figure 6A in the direction of cover 632.

[0101] Figures 6C to 6D are semi-transparent cross-sectional views 603 to 604 of pump coupler 630, which show X-ray shield 650 (not in the cross-sectional view and filled with X-ray shielding material) positioned within pump coupler 630. Flange 636 can be regarded as part of pump coupler 630

[0102] The illustrated extended and twisted shape of housing 610 can be advantageously used in or near a pump coupler (similar to Figures 3 to 4 the X-ray shields 350, 450). On the one hand, the azimuthal scan of the twisted shape around the Z-axis of 608 blocks high-fraction X-rays parallel to the Z-axis and within the lateral extent of housing 610. On the other hand, the narrow lateral profile and gentle helical scan of housing 610 provide low impedance for molecular flow through the associated pump coupler.

[0103] The illustrated shape of housing 610 is merely exemplary. In some instances, the azimuthal twist of housing 610 can be about 195° from flange 616 to base 614, or within the range of 180° to 210°. In other instances, various lateral profiles and azimuthal scans can be used. A housing having a cross-shaped lateral cross-section (with four arms) can be manufactured to have an azimuthal twist of only about 100° or within the range of 90° to 110°. Alternatively, the housing can be manufactured as a single blade (e.g., extending from around port 622 to edge 627 relative to view 602) rotating approximately 390° around the Z-axis from flange to base. In other instances, the curved surface of housing 610 can be approximated as a set of flat surfaces.

[0104] Second example method

[0105] Figure 7 is a flow chart 700 of a second example method according to the disclosed technology. This method also has for Figure 5Some of the described changes or extensions. At process block 710, a rigid housing may be fabricated by additive manufacturing. The housing may define a chamber and may have one or more ports. At process block 720, to facilitate leak testing at block 730, the interior and exterior of the housing may be temporarily isolated from each other. Block 720 may be performed by closing the ports or coupling the ports to a He leak detector in any combination. At block 730, the housing may be tested to verify that the housing is leak-free according to a predetermined leak rate threshold.

[0106] Once it is verified that the housing is leak-free, then at optional process block 740, a low-Z cladding may be applied to the exterior of the leak-tested (and leak-free) housing. At block 750, the tested housing may be filled with an X-ray shielding material. In some instances, block 750 may be performed using block 752 by injecting a molten metal (e.g., molten lead or molten tin) into the interior chamber of the housing. In other instances, block 750 may be performed using block 754. Granular metal in a liquid state may be injected into the interior chamber of the housing. In some instances, the granular metal may be granules or powder of a metal such as lead or tungsten.

[0107] Once filled, the housing may be sealed at block 760. In some instances, block 760 may be performed using block 762 by welding a cap to each port of the filled housing. Other techniques may also be used. As another example, the housing ports may be fabricated as tubes, and the tubes may be curled to close the ports and then welded to seal the closed ports. Fabrication of the X-ray shield may be completed after block 760.

[0108] At block 770, the fabricated X-ray shield may be secured within the interior volume of a vacuum enclosure. At block 780, the vacuum enclosure with the X-ray shield inside may be pumped down to an ultra-high vacuum. Thus, an X-ray shield having an ultra-high vacuum on its exterior and materials (e.g., lead or resin) inside that may be incompatible with the vacuum may be regarded as a reverse vacuum bottle as described herein.

[0109] In a variant of this method, block 740 may be performed later, such as between process blocks 750 and 760 or between block 760 and 770.

[0110] Example device

[0111] Figure 8 is a block diagram of a device 800 having an X-ray shield. Device 800 has a vacuum enclosure 802 in which there is an X-ray generation site 815. The X-ray shield 850 may also be located within the vacuum enclosure 802 and may include a reverse vacuum bottle 852 containing an X-ray shielding material 854.

[0112] In some instances, device 800 can be an electron microscope having a column axis. Device 800 can include a pump coupler (similar to Figure 1A 130). An X-ray shield 850 can be positioned within the pump coupler and oriented to block at least 80% of the X-rays emitted from the X-ray generation site 820 through the inlet aperture of the pump coupler. In other instances, an X-ray shield 830 positioned within the pump coupler can reduce the vacuum conductance of the pump coupler by up to 20%. The pressure within the vacuum enclosure 802 can be maintained below 10 -9 mbar. The X-ray shielding material 854 can be lead or can include at least 50 wt% lead. The reverse vacuum bottle 852 can be made of stainless steel. In additional instances, the reverse vacuum bottle 852 can be coated with a low-Z material having an average atomic number less than or equal to 14. The X-ray shield 850 can include twisted elongate members.

[0113] Third example method

[0114] Figure 9 is a flowchart 900 of a third example method according to the disclosed technology. At process block 910, a reverse vacuum bottle containing X-ray shielding material can be placed inside the vacuum enclosure of an electron microscope. Then, at process block 920, the vacuum enclosure can be pumped down to a pressure less than or equal to 10 -9 mbar.

[0115] In some instances, the vacuum enclosure can include a pump coupler, and at block 910, the reverse vacuum bottle can be secured within the pump coupler.

[0116] Additional example X-ray shield

[0117] Figures 10A to 10B are views 1001 to 1002 of a second example X-ray shield according to the disclosed technology. Compared to the Figures 6A to 6D example, the shield 1050 of the present invention has two ports 1022. Figures 10A to 10B Both show a housing 1010 (e.g., fabricated at a process block similar to 510). For clarity of illustration, the port covers and X-ray shielding material are omitted from Figures 10A to 10B the views.

[0118] Figure 10A is an isometric view of the shield 1050. Figure 10B is a cross-sectional view depicting a wall 1012 and a chamber 1020 that is arranged in an elongate twisted shape from a base 1014 to a flange 1016. The depicted shape is illustrative, and other shapes can be used. The XYZ coordinate axes 1008 are also shown.

[0119] Figure 11Concept view 1100 illustrates the shape of the third example X-ray shield 1150. Like other examples disclosed herein, the shield 1150 has a housing 1110 that encloses a chamber 1120. The walls 1112 of the housing 1110 are shown as solid lines. For simplicity of illustration, end caps, ports, flanges, or filled shielding materials are omitted from Figure 11 the drawing. The shield 1150 has a cross-section that is thinner closer to the longitudinal axis 1105 than farther away from the axis 1105. Redistributing the shielding material farther from the axis 1105 can improve shielding of X-rays that are farther from the axis 1105 or that diverge from the axis, and can remove excess shielding material that only provides marginal benefit on axis. Thus, the illustrated configuration can improve the shielding effectiveness of a given mass of X-ray shielding material. The shield 1150 is illustrated as having an azimuthal twist of approximately 270°, but this is not required and the illustrated concept can be applied to shields having other twists or other shapes.

[0120] Figures 12A to 12C Concept views 1201 to 1203 illustrate the shape of the fourth example X-ray shield 1250. For simplicity of illustration, mechanical details such as the housing, chamber, and ports are omitted from FIG. 12, and the mechanical details can be similar to other examples disclosed herein. Figure 12A A cross-sectional view of the shield 1250 is shown, which has a twist of approximately 360° about the longitudinal axis 1205. Figure 12B A perspective view of the shield 1250 is shown, while Figure 12C shows the shield 1250 assembled inside a cylindrical tube 1230, which can be part of a pump coupling. Compared to shields with less twist, the additional twist of the shield 1250 with respect to other disclosed examples can provide improved shielding, e.g., blocking a greater percentage of X-rays, especially X-rays at different angles to the axis 1205.

[0121] Figure 13 Concept view 1300 illustrates the shape of the fifth example X-ray shield 1350. The shape of the shield 1250 has two intertwined helical edges 1257 about the axis 1205, while the shield 1350 has one helical edge 1357 about the axis 1305 and one straight edge 1355 that is generally collinear with the axis 1305. Compared to the shield 1250, the shield 1350 can provide comparable shielding effectiveness at a lower vacuum impedance for X-rays parallel to the axis 1305. The shield 1350 has a helical twist of approximately 390° about the axis 1305.

[0122] Figures 14A to 14DIt is a conceptual view showing the shape of the X-ray shield 1450 of the sixth example. For simplicity of illustration, mechanical details such as the housing, chamber, and ports are omitted from FIG. 14, and the mechanical details may be similar to those disclosed in other examples herein. Figure 14A Shows a cross-sectional view of the shield 1450, which has an elongated twisted member 1453 and a sleeve member 1456. Figure 14B Shows an end view of the shield 1450, while Figure 14C Shows an isometric view of the shield 1450, and Figure 14D Shows a cut-away cross-section of the shield 1450. As in other disclosed examples, the internal volume 1420 within the twisted member 1453 may be filled with an X-ray shielding material. The twisted member 1453 has a twist of approximately 360° about the longitudinal axis 1405, similar to the shield 1250. In some examples, the sleeve 1456 may be a double-walled tube (e.g., an annular hollow housing) that surrounds a chamber that is the same as or different from the interior of the twisted member 1453. This configuration, combined with the high level of shielding provided by the twisted member 1453 for X-rays parallel to the axis 1405, can advantageously improve the shielding for X-rays emitted at different angles to the axis 1405. In other examples, the sleeve 1456 may be a single-walled tube, which may not significantly increase the X-ray shielding effect of the shield 1450, but it can improve mechanical rigidity or facilitate the installation of the shield 1450 within a pump coupler or other vacuum enclosure.

[0123] General computer environment

[0124] Figure 15 Illustrates a general example of a suitable computing system 1500 in which the described examples, techniques, and technologies for controlling the manufacture of an X-ray shield can be implemented. The computing system 1500 is not intended to impose any limitation on the scope of use or functionality of the present disclosure, as the innovations can be implemented in various general-purpose or special-purpose computing systems. The computing system 1500 can control an additive manufacturing process, another manufacturing process, a leak testing process, a pumping process, or the operation of an electron microscope, or associated instrumentation; or can acquire, process, output, or store measurement or operation data.

[0125] Refer to Figure 15 , the computing environment 1510 includes one or more processing units 1522 and a memory 1524. In Figure 15In this case, this basic configuration 1520 is contained within the dashed line. The processing unit 1522 can execute computer-executable instructions, such as for control or data acquisition as described herein. The processing unit 1522 can be a general-purpose central processing unit (CPU), a processor in an application-specific integrated circuit (ASIC), or any other type of processor. In a multiprocessing system, multiple processing units execute computer-executable instructions to increase processing power. The computing environment 1510 can also include a graphics processing unit or a coprocessing unit 1530. The tangible memory 1524 can be volatile memory (e.g., registers, cache, or RAM), non-volatile memory (e.g., ROM, EEPROM, or flash memory), or some combination thereof that is accessible by the processing units 1522, 1530. The memory 1524 stores software 1580 that implements one or more of the innovations described herein in the form of computer-executable instructions suitable for execution by the processing units 1522, 1530. For example, the software 1580 can include software 1581 for controlling an additive manufacturing process, software 1582 for controlling a coating process, software 1583 for controlling a leak test, or other software 1584. The illustration shown for the software 1580 in the storage device 1540 can equally apply to Figure 15 the software 1580 elsewhere in

[0126] The computing system 1510 can have additional features, such as one or more of a storage device 1540, an input device 1550, an output device 1560, or a communication port 1570. An interconnection mechanism (not shown), such as a bus, a controller, or a network, interconnects the components of the computing environment 1510. Generally, an operating system software (not shown) provides an operating environment for other software executing in the computing environment 1510 and coordinates the activities of the components of the computing environment 1510.

[0127] The tangible storage device 1540 can be removable or non-removable and includes a magnetic disk, a magnetic tape, or a tape cartridge, a CD-ROM, a DVD, or any other medium that can be used to store information in a non-transitory manner and is accessible within the computing environment 1510. The storage device 1540 stores instructions (including instructions and / or data) for the software 1580 that implements one or more of the innovations described herein. The storage device 1540 can also store image data, measurement data, reference data, calibration data, configuration data, or other databases or data structures described herein.

[0128] The input device 1550 can be a mechanical, touch-sensing, or proximity-sensing input device (such as a keyboard, mouse, pen, touch screen, or trackball), a voice input device, a scanning device, or another device that provides input to the computing environment 1510. The output device 1560 can be a display, printer, speaker, optical disc writer, or another device that provides output from the computing environment 1510. Input or output can also be communicated to or from a remote device via a network connection through the communication port 1570.

[0129] The communication port 1570 enables communication with another computing entity through a communication medium. The communication medium conveys information such as computer-executable instructions, audio or video input or output, or other data in a modulated data signal. A modulated data signal is a signal whose one or more characteristics are set or changed in such a manner as to encode information in the signal. By way of example and not limitation, the communication medium can use electrical, optical, RF, acoustic, or other carriers.

[0130] The data acquisition system can be integrated into the computing environment 1510 as the input device 1550 or coupled to the communication port 1570, and can include an analog-to-digital converter or a connection to an instrument bus. The instrument control system can be integrated into the computing environment 1510 as the output device 1560 or coupled to the communication port 1570, and can include a digital-to-analog converter, switches, or a connection to an instrument bus.

[0131] In some instances, the computer system 1500 can also include a computing cloud 1590 where instructions implementing all or part of the disclosed technology are executed. Any combination of the memory 1524, the storage device 1540, and the computing cloud 1590 can be used to store the software instructions and data of the disclosed technology.

[0132] The innovation can be described in the general context of computer-executable instructions, such as those included in program modules, that can be executed in a computing system on a target real or virtual processor. Generally, program modules or components include routines, programs, libraries, objects, classes, components, data structures, etc., that perform particular tasks or implement particular data types. In various embodiments, the functionality of program modules can be combined or split as needed. The computer-executable instructions for program modules can be executed within a local or distributed computing system.

[0133] The terms "computing system", "computing environment", and "computing device" are used interchangeably herein. Unless the context otherwise clearly indicates, none of the terms implies any limitation as to the type of computing system, computing environment, or computing device. Generally, a computing system, computing environment, or computing device can be local or distributed and can include any combination of dedicated hardware and / or general-purpose hardware and / or virtualized hardware, as well as software that implements the functionality described herein.

[0134] General Notes

[0135] Unless the context otherwise clearly dictates, as used in this specification and the claims, the singular forms "a / an" and "the" include the plural forms. Additionally, the term "comprising" means "including". Further, the term "coupled" does not exclude the presence of intermediate elements between the coupled items. Additionally, as used herein, the terms "or" and "and / or" mean a combination of any one or more of the terms in the phrase.

[0136] The systems, methods, and devices described herein should not be construed in any way as limiting. In fact, the present disclosure is directed to all novel and non-obvious features and aspects of the various disclosed embodiments, whether individually or in various combinations and sub-combinations with each other. The disclosed systems, methods, and devices are not limited to any specific aspect or feature or combination thereof, and the disclosed systems, methods, and devices do not require the presence of any one or more specific advantages or the solution of any one or more specific problems. The technology from any instance can be combined with one or more of the technologies described in any other instance. Any theory of operation is for ease of explanation, but the disclosed systems, methods, and devices are not limited to such theory of operation.

[0137] Although the operations of some of the disclosed methods are described in a particular sequential order for ease of presentation, it should be understood that this description covers rearrangements unless the specific language set forth below requires a particular ordering. For example, in some cases, the operations described in sequence can be rearranged or performed concurrently. Additionally, for simplicity, the figures may not show the various ways in which the disclosed systems, methods, and devices can be used in conjunction with other systems, methods, and devices. Further, the specification sometimes uses terms such as "generate", "provide", or "test" to describe the disclosed methods. These terms are high-level abstractions of the actual operations performed. The actual operations corresponding to these terms will vary depending on the particular implementation and can be readily discerned by one of ordinary skill in the art.

[0138] In some instances, a value, procedure, or device is referred to as "lowest", "best", "minimum", etc. It will be understood that such descriptions are intended to indicate that a choice can be made among several alternatives or many alternatives, and that such a choice need not be better, smaller, or otherwise preferred to alternatives not considered.

[0139] The operating theories, scientific principles, or other theoretical descriptions presented herein with reference to the devices or methods of the present disclosure have been provided for purposes of better understanding and are not intended to be limiting in scope. The devices and methods in the appended claims are not limited to those that operate in the manner described by such operating theories.

[0140] Any of the disclosed methods can be controlled or implemented as computer-executable instructions or a computer program product stored on one or more computer-readable storage media (e.g., tangible non-transitory computer-readable storage media) and executed on a computing device (e.g., any available computing device, including tablets, smartphones, or other mobile devices incorporating computing hardware). A tangible computer-readable storage medium is any available tangible medium that can be accessed within a computing environment (e.g., one or more optical media discs such as DVDs or CDs, volatile memory components such as DRAM or SRAM, or non-volatile memory components such as flash memory or hard disk drives). By way of example, and with reference to Figure 15 , the computer-readable storage media includes memory 1524 and storage device 1540. The terms computer-readable storage medium or computer-readable medium do not include signals and carriers. Additionally, the terms computer-readable storage medium or computer-readable medium do not include communication ports (e.g., 1570).

[0141] Any of the computer-executable instructions for implementing the disclosed techniques and any data created and used during the implementation of the disclosed embodiments can be stored on one or more computer-readable storage media. The computer-executable instructions can be, for example, a dedicated software application or part of a software application accessed or downloaded via a web browser or other software application (e.g., a remote computing application). Such software can be executed using one or more networked computers, for example, on a single local computer (e.g., any suitable commercially available computer) or in a network environment (e.g., via the Internet, wide area network, local area network, client-server network, cloud computing network, or other such network).

[0142] For clarity, only certain selected aspects of the software-based implementation are described. Other details well known in the art are omitted. For example, it should be understood that the disclosed technology is not limited to any specific computer language or program. For instance, the disclosed technology can be implemented by writing software in Adobe Flash, C, C++, C#, Curl, Dart, Fortran, Java, JavaScript, Julia, Lisp, Matlab, Octave, Perl, Python, Qt, R, Ruby, SAS, SPSS, SQL, WebAssembly, any of its derivatives, or any other suitable programming language, or in some instances, markup languages such as HTML or XML, or with any combination of suitable languages, libraries, and data packets. Similarly, the disclosed technology is not limited to any particular type of computer or hardware. Certain details of suitable computers and hardware are well known and need not be elaborated in detail in this disclosure.

[0143] In addition, any of the software-based embodiments (including, for example, computer-executable instructions for causing a computer to perform any of the disclosed methods) can be uploaded, downloaded, or accessed remotely via suitable communication means. Such suitable communication means include, for example, the Internet, the World Wide Web, an intranet, software applications, cables (including fiber optic cables), magnetic communication, electromagnetic communication (including RF, microwave, infrared, and optical communication), electronic communication, or other such communication means.

[0144] Given that the principles of the disclosed subject matter can be applied to many possible embodiments, it should be recognized that the illustrated embodiments are only preferred examples of the disclosed subject matter and should not be considered as limiting the scope of the claims. Rather, the scope of the claimed subject matter is defined by the appended claims. Accordingly, we claim all that falls within the scope of these claims.

[0145] In addition, the invention as disclosed herein can be described by or be consistent with one or more of the following items:

[0146] Item 1. A method of manufacturing an X-ray shielding enclosure, comprising:

[0147] manufacturing a housing defining a chamber and having one or more ports;

[0148] testing the housing to verify that the housing is leak-free;

[0149] filling the tested housing with an X-ray shielding material; and

[0150] sealing the one or more ports of the filled housing.

[0151] Item 2. The method according to item 1, wherein the housing is manufactured by an additive manufacturing process.

[0152] Item 3. The method according to item 2, wherein the additive manufacturing process includes direct metal laser sintering (DMLS), selective laser melting (SLM), electron beam melting (EBM), or binder jetting (BJ).

[0153] Item 4. The method according to any one of the preceding items, further comprising:

[0154] Temporarily isolating the chamber from the environment surrounding the housing during the duration of the containment test.

[0155] Item 5. The method according to any one of the preceding items, wherein the test has a leak rate threshold of less than or equal to 10 -7 mbar·l / s.

[0156] Item 6. The method according to any one of the preceding items, wherein the housing is rigid.

[0157] Item 7. The method according to any one of the preceding items, wherein the housing comprises stainless steel.

[0158] Item 8. The method according to any one of the preceding items, wherein the housing has an intermediate wall thickness in the range of 0.1 mm to 1.0 mm.

[0159] Item 9. The method according to any one of the preceding items, wherein the X-ray shielding material comprises a metal, and the filling operation comprises introducing the metal in a molten state into the chamber.

[0160] Item 10. The method according to any one of items 1 to 8, wherein the X-ray shielding material comprises a resin carrying metal particles.

[0161] Item 11. The method according to any one of the preceding items, wherein the one or more ports include a first port for introducing the X-ray shielding material into the chamber during the filling operation and a second port for releasing the discharged fluid from the chamber during the filling operation.

[0162] Item 12. The method according to any one of the preceding items, wherein sealing includes welding a corresponding cap to each of the one or more ports.

[0163] Item 13. The method according to any one of the preceding items, wherein the rigid housing comprises a material having a first average atomic number Z1, and the method further comprises:

[0164] The rigid housing is coated with another material having an average atomic number Z2 less than Z1.

[0165] Item 14. A method for reducing X-ray emission from an electron microscope housed in a vacuum enclosure, the method comprising:

[0166] Manufacturing an X-ray shield according to the method of item 1; and

[0167] Fixing the X-ray shield within the internal volume of the vacuum enclosure.

[0168] Item 15. The method according to item 14, wherein the X-ray shield is fixed within a pump coupler of the electron microscope and is oriented to block at least 80% of the X-rays emitted through an inlet aperture of the pump coupler and parallel to a longitudinal axis of the pump coupler.

[0169] Item 16. An apparatus comprising:

[0170] A vacuum enclosure; and

[0171] An X-ray shield positioned within the vacuum enclosure and comprising:

[0172] A reverse vacuum bottle containing an X-ray shielding material.

[0173] Item 17. The apparatus according to item 16, wherein the apparatus is an electron microscope having a column axis, and the apparatus further comprises:

[0174] A pump coupler, wherein the X-ray shield is positioned within the pump coupler and is oriented to block at least 80% of the X-rays emitted from an X-ray generation site within the vacuum enclosure and through an inlet aperture of the pump coupler.

[0175] Item 18. The apparatus according to item 17, wherein the vacuum conductance of the pump coupler is reduced by at most 20% due to the X-ray shield as compared to when there is no X-ray shield.

[0176] Item 19. The apparatus according to any one of items 16 to 18, wherein the pressure within the vacuum vessel is less than 10 - 9 mbar.

[0177] Item 20. The apparatus according to any one of items 16 to 19, wherein the X-ray shielding material comprises at least 50% by weight of lead.

[0178] Item 21. The apparatus according to any one of items 16 to 20, wherein the reverse vacuum bottle comprises stainless steel.

[0179] Item 22. The apparatus according to item 21, wherein the stainless steel is coated with a material having an average atomic number less than or equal to 14.

[0180] Item 23. The apparatus according to any one of items 16 to 22, wherein the X-ray shield includes a twisted elongated member.

[0181] Item 24. A method, comprising:

[0182] placing a reverse vacuum bottle containing an X-ray shielding material inside a vacuum enclosure of an electron microscope; and

[0183] pumping the vacuum enclosure to a pressure below 10 -9 mbar.

[0184] Item 25. The method according to item 24, wherein the vacuum container includes a pump coupler, and the placing includes fixing the reverse vacuum bottle within the pump coupler.

Claims

1. A method of manufacturing a vacuum-compatible X-ray shield located within a vacuum enclosure for an electron microscope, which comprises: manufacturing a housing defining a chamber and having one or more ports, wherein the housing comprises stainless steel or a low-Z vacuum-compatible material; temporarily isolating the chamber from the environment surrounding the housing; testing the housing to verify that the housing is leak-free, wherein the temporary isolation of the chamber is for the duration covering the test; filling the tested housing with an X-ray shielding material; and sealing the one or more ports of the filled housing.

2. The method according to claim 1, wherein the housing is manufactured by an additive manufacturing process.

3. The method according to claim 2, wherein the additive manufacturing process comprises direct metal laser sintering (DMLS), selective laser melting (SLM), electron beam melting (EBM), or binder jetting (BJ).

4. The method according to any one of claims 1 to 3, wherein the test has a leak rate threshold of less than or equal to 10 -7 mbar·l / s.

5. The method according to any one of claims 1 to 3, wherein the housing is rigid.

6. The method according to any one of claims 1 to 3, wherein the housing has an intermediate wall thickness in the range of 0.1 mm to 1.0 mm.

7. The method according to any one of claims 1 to 3, wherein the X-ray shielding material comprises a metal, and the filling comprises introducing the metal in a molten state into the chamber.

8. The method according to any one of claims 1 to 3, wherein the X-ray shielding material comprises a resin loaded with metal particles.

9. The method according to any one of claims 1 to 3, wherein the one or more ports comprise a first port for introducing the X-ray shielding material into the chamber during the filling and a second port for releasing displaced fluid from the chamber during the filling.

10. The method according to any one of claims 1 to 3, wherein the sealing comprises welding a respective cap to each of the one or more ports.

11. The method according to any one of claims 1 to 3, wherein the housing is a rigid housing, the rigid housing comprises a material having a first average atomic number Z1, and the method further comprises: coating the rigid housing with another material having a second average atomic number Z2 less than Z1.

12. A method of reducing X-ray emission from an electron microscope housed within a vacuum enclosure, the method comprises: manufacturing a vacuum-compatible X-ray shield for an electron microscope by the method according to claim 1; and fixing the X-ray shield within the internal volume of the vacuum enclosure.

13. The method according to claim 12, wherein the X-ray shield is fixed within a pump coupler of the electron microscope and is oriented to block at least 80% of the X-rays emitted through an inlet aperture of the pump coupler and parallel to the longitudinal axis of the pump coupler.

14. An apparatus comprising an X-ray shield, which comprises: a vacuum enclosure configured to isolate a vacuum inside the enclosure from the environment outside the enclosure; and A vacuum-compatible X-ray shield for an electron microscope, positioned within the vacuum enclosure and comprising: A reverse vacuum bottle that hermetically houses an X-ray shielding material, wherein the X-ray shielding material is isolated from the external vacuum of the reverse vacuum bottle, and the reverse vacuum bottle comprises stainless steel or a low-Z vacuum-compatible material.

15. The apparatus of claim 14, wherein the apparatus is an electron microscope having a column axis, and the apparatus further comprises: A pump coupler, wherein the X-ray shield is positioned within the pump coupler and oriented to block at least 80% of the X-rays emitted from an X-ray generating site within the vacuum enclosure and passing through the inlet aperture of the pump coupler.

16. The apparatus of claim 15, wherein the vacuum conductance of the pump coupler is reduced by at most 20% due to the X-ray shield as compared to when there is no X-ray shield.

17. The device according to any one of claims 14 to 16, wherein the pressure inside the vacuum enclosure is less than 10 - 9 mbar.

18. The apparatus of any one of claims 14 to 16, wherein the X-ray shielding material comprises at least 50 wt% lead.

19. The apparatus of claim 14, wherein the stainless steel is coated with a material having an average atomic number less than or equal to 14.

20. The apparatus of any one of claims 14 to 16, wherein the X-ray shield comprises a twisted elongate member.

21. A method of placing a reverse vacuum bottle, which comprises: Placing a reverse vacuum bottle hermetically housing an X-ray shielding material inside a vacuum enclosure of an electron microscope, wherein the X-ray shielding material is isolated from the external vacuum of the reverse vacuum bottle, the vacuum enclosure being configured to isolate the vacuum inside the enclosure from the environment outside the enclosure, and the reverse vacuum bottle comprises stainless steel or a low-Z vacuum-compatible material; and Pump the vacuum enclosure to a pressure below 10 -9 mbar.

22. The method of claim 21, wherein the vacuum enclosure comprises a pump coupler, and the placing comprises securing the reverse vacuum bottle within the pump coupler.

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