Cryogenic analysis assemblies and cryogenic analysis methods

Abstract

To provide cryogenic analysis assemblies and methods.SOLUTION: The assemblies and / or methods can be configured for optical sample analysis. The assemblies and / or methods can include: an objective assembly operatively aligned with a sample support assembly, both the objective assembly and sample support assembly residing within a vacuum housing, where the objective assembly defines an objective mount housing an objective coupled to a mounting ring within a chamber below a heater assembly; and an insulative member between the objective mount and the mounting ring, the insulative member supporting the objective mount and thermally isolating the objective mount from the mounting ring.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application is a continuation-in-part of U.S. Application No. 14 / 666,093, filed March 23, 2015, which claims priority to and the benefit of U.S. Provisional Application No. 61 / 968,651, filed March 21, 2014, the entire disclosures of each of which are incorporated herein by reference.

[0002] (Technical field) CRYOGENIC ANALYSIS ASSEMBLY AND METHODS FIELD OF THE DISCLOSURE In certain embodiments, the present disclosure relates to assemblies and methods involving the use of microscope objectives during cryogenic analysis. [Background technology]

[0003] Many cryogenic researchers use optical microscopes to observe single molecules. This is accomplished by using a microscope objective to focus and / or collect light from a sample held at cryogenic temperatures. Microscope objectives are a set of precisely manufactured lenses that can only be used at room temperature. High light collection efficiency also requires that the objective has a very small working distance between its tip and the sample. Researchers have previously sacrificed objective performance for a longer working distance to allow the objective to be mounted outside the cryostat. Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a cryogenic analysis assembly and a cryogenic analysis method, embodiments of which overcome one or more of the shortcomings of prior art cryogenic analysis assemblies and methods, particularly those that use microscope objective lenses. [Means for solving the problem]

[0005] A cryogenic analysis assembly and method is provided. The assembly and / or method may be configured for optical sample analysis. The assembly and / or method may include an objective lens assembly operatively aligned with a sample support assembly, both of which reside within a vacuum housing, the objective lens assembly defining an objective lens mount that houses an objective lens coupled to a mounting ring within a chamber below a heater assembly; and an insulating member between the objective lens mount and the mounting ring, the insulating member supporting the objective lens mount and thermally isolating the objective lens mount from the mounting ring.

[0006] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. [Brief description of the drawings]

[0007] [Figure 1] 1 is a portion of a cryogenic analytical assembly according to one embodiment. [Diagram 2] 1 illustrates another configuration of a portion of a cryogenic analytical assembly according to one embodiment of the present disclosure. [Diagram 3] 1 is a cryogenic analytical assembly according to one embodiment of the present disclosure. [Figure 4] FIG. 4 is an exploded view of the cryogenic analytical assembly of FIG. 3 according to one embodiment of the present disclosure. [Diagram 5] 4 illustrates a portion of the cryogenic analytical assembly of FIG. 3 according to one embodiment of the present disclosure. [Figure 6] 1 illustrates an isometric cross-sectional view of a portion of a cryogenic analytical assembly according to one embodiment of the present disclosure. [Figure 7] 4 is a depiction of the cryogenic analytical assembly of FIG. 3 according to one embodiment of the present disclosure. [Figure 8] 1 illustrates components of a cryogenic analytical assembly according to one embodiment of the present disclosure. [Figure 9] 1 illustrates further components of a cryogenic analytical assembly according to one embodiment of the present disclosure. [Figure 10] 1 illustrates an exploded view of components of a cryogenic analytical assembly according to one embodiment of the present disclosure. [Figure 11] 11 illustrates an isometric cross-sectional view of the components of FIG. 10 according to one embodiment of the present disclosure. [Figure 12] 8 illustrates a portion of the cryogenic analytical assembly of FIG. 7 according to one embodiment of the present disclosure. [Figure 13] 1 illustrates further components of a cryogenic analytical assembly according to one embodiment of the present disclosure. [Figure 14] 8 illustrates a portion of the cryogenic analytical assembly of FIG. 7 according to one embodiment of the present disclosure. [Figure 15] 1 illustrates further components of a cryogenic analytical assembly according to one embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] This disclosure is submitted in furtherance of the constitutional purpose of the United States patent laws, which is to "promote the progress of science and useful arts" (Article 1, Section 8).

[0009] Applicants recognize that the use of conventional longer working distances places windows between the objective lens and the sample, and these windows can introduce aberrations.

[0010] Applicants also recognize that over time, a microscope may experience thermal drift due to fluctuations in room temperature: as the mount used to hold the objective lens heats up or cools down, the material expands or contracts, causing the objective lens to move in and out of focus on the sample.

[0011] Mechanical vibrations also pose problems for researchers: Applicants recognize that fragile mounts can cause the objective lens to move relative to the sample beyond its optical resolution.

[0012] The present disclosure provides an assembly and method whereby an object can be maintained at an elevated temperature while being mechanically aligned with a sample within a cryogenic system. Using the assembly and method of the present disclosure, this can be accomplished by the interaction of three components: a cryogenic base, a thermally insulating support, a heater, and a thermometer. The assembly can interface with a microscope objective lens having a working distance greater than zero to image samples between 0 and 350 Kelvin with zero aberrations caused by the window interface.

[0013] Beyond its primary application of interfacing a room temperature objective lens to a cryogenic atmosphere by isolating the thermal load, the device can be maintained at a very precise temperature with an accuracy of <10mK enabling a virtually thermal drift free environment to provide optical stability.

[0014] The assemblies and methods of the present disclosure will be further described with reference to Figures 1 through 15. Referring initially to Figure 1, a portion of a cryogenic analysis assembly 10 according to one embodiment of the present disclosure is shown including an objective lens 12 and a sample 14 on a sample support 16. According to an exemplary implementation, Figure 1 shows the operative alignment of the objective lens 12 with the sample 14 within the cryogenic assembly. The objective lens 12 may be a series of optical components and / or lenses, which may or may not be grouped together, that are configured to provide an operatively aligned field of view of the sample 14. The sample 14 may be a solid sample, and the sample support 16 may be configured to support the sample 14 in an operative field of view aligned with the objective lens 12, as well as to provide cooling or heating.

[0015] The objective lens 12 can be maintained at a temperature different from the temperature of the surroundings. For example, the temperature of the objective lens 12 can be different from the temperature of the sample and / or the sample support. The temperature of the objective lens 12 and / or the optics and / or the lens and / or the lens surface of the objective lens 12 can be different from the temperature of the sample 14 and / or the sample support assembly 16 by at least 250K and / or at least 100K. The sample 14 and / or the sample support assembly 16 can be less than about 200K, and in some embodiments, can be maintained at a temperature of less than 40K and / or about 4K. In Figs. 2 and 3, an objective lens assembly 200 of a cryogenic analysis assembly according to an embodiment of the present disclosure is presented. The assembly 200 can include the objective lens 12 and an objective lens mount 50 to which the objective lens 12 can be attached. The assembly 200 can further include a mounting ring 202 for operatively aligning the objective lens assembly 200 with the sample 14. The mounting ring 202 can be attached to the sample support assembly 16 or the heat dissipation shield 28 via screws or other mechanisms. The mounting ring 202 can be attached to a cryogenic component. The objective lens assembly 200 can further include a thermal insulation support 95 between the objective lens mount 50 and the mounting ring 202 to assist with the objective lens mount 50 and the mounting ring 202 having different temperatures. The objective lens assembly 200 can further include a thermal control or heater assembly 24 that can be controlled to maintain the objective lens 12 at room temperature, for example. To shield the sample 14 from the thermal dissipation load of the objective lens 12 at room temperature, for example, the objective lens assembly 200 can further include a heat dissipation shield 203 attached to the mounting ring 202. The heat dissipation shield 203 can further include a small opening or window 204 to allow the objective lens 12 viewing access to the sample 14.

[0016] The objective lens mount 50 is also shown in Figure 2 and can provide adjustment of the objective lens 12 closer to and further away from the sample 14, as shown in Figure 3. Additionally, the objective lens mount 50 can allow lateral movement of the objective lens 12 relative to the sample 14. The objective lens mount 50 can allow for indexing of position / distance relative to the sample support assembly 16. The objective lens mount 50 can be configured to integrate different objective lenses 12, different form factors and / or different optical properties.

[0017] 2 also shows an optional removable alignment datum 350 that allows for simplified positioning / focusing of the objective lens 12. The alignment datum 350 can be configured for various free working distances of the objective lens 12.

[0018] 3 and 4, the cryogenic analysis assembly 20 is shown in both cross-sectional and exploded views and includes an objective lens assembly 200 configured such that the objective lens 12 is operatively aligned with the sample 14 in the sample support assembly 16. The assembly 20 can include the sample support assembly 16 that physically supports the sample. The assembly 20 can include a vacuum housing 26 and a vacuum housing lid 22 that can be maintained at room temperature. Around the sample 14 and within the housing 26 can be a shield 28 that can be configured to reduce heat radiation transmission between the sample 14 and the housing 26. The shield 28 can prevent the transmission of 40K heat radiation into the housing 26, for example, by insulating the sample 14 from the housing 26. The shield 28 can be constructed of aluminum, for example. The positioning device 29 can be piezo-driven and can be below the sample 14.

[0019] 3 and 4, the cryogenic assembly 20 includes an objective lens assembly 200 in operative alignment with the specimen support assembly 16 and the specimen shield 28 within a vacuum housing 26. The objective lens assembly 200 may be configured such that the objective lens 12 is in operative alignment with the specimen 14. The vacuum housing 26 may include a housing viewing port 260. The assembly 20 may include a vacuum housing lid 22, which may be maintained at room temperature.

[0020] Between the objective lens assembly 200 and the sample support assembly 16, there can be a sample heat dissipation shield 28 that can be operatively aligned around the sample 14 and within the housing 26. The sample shield 28 can be configured to prevent heat dissipation transmission between the sample 14 and the housing 26. The shield 28 can be constructed of a thermally conductive material (e.g., aluminum, copper) and can also include a sample observation port 280 that, when operatively aligned, allows for observation of the sample 14 through the ports 260 and 280. The shield 28 can be maintained at the same temperature as portions of the sample support assembly (e.g., first stage 40K). By maintaining the shield 28 at these lower temperatures, higher temperatures, such as portions of the objective lens assembly and / or housing 26, can be shielded from the sample 14. As part of the sample support assembly 16, a positioner 29 can be piezo-driven and can be below the sample 14.

[0021] The objective lens assembly 200 may further include a heater assembly 24 that may be controlled to maintain the objective lens 12 at a predetermined temperature, e.g., higher than the temperature of the mounting ring 202, the heat dissipation shield 203, the specimen heat dissipation shield 28 (see, e.g., FIG. 3), the specimen 14, and / or the specimen support assembly 16. As an example, the heater assembly 24 may maintain the mount 50 and the objective lens 12, as well as further parts of the objective lens assembly 200, at 300 K, while the mounting ring 202, the heat dissipation shield 203, the specimen heat dissipation shield 28 (see, e.g., FIG. 3), the specimen 14, and / or the specimen support assembly 16 are maintained at 40 K or lower. To shield the specimen 14 from the heat dissipation load of the hotter objective lens 12, the objective lens assembly 200 includes a heat dissipation shield 203 (see, e.g., FIG. 3) that is attached to the mounting ring 202 (see, e.g., FIG. 3). The heat dissipation shield 203 may further include an opening or window 204 that provides the objective lens 12 with an unobstructed view of the sample 14. According to an exemplary implementation, the mounting ring 202 and shield 203 may be thermally coupled to the sample heat dissipation shield 28 and maintained at or below 40 K. By providing a temperature-maintaining thermal environment around the optics 12, optical drift is significantly reduced, allowing a user to position the optics at a predetermined working distance from the sample for extended periods of time without loss of focus.

[0022] 5 and 6, FIG. 5 shows a portion of assembly 20 including vacuum housing 30, which may be at room temperature, and a portion of sample support assembly 16, which may be at cryogenic temperature. FIG. 6 shows an isometric cross-sectional view of a portion of assembly 16. Sample support assembly 16 may include a first stage support ring 32, which may be at 40K, and a second stage support ring 34, which may be at 4K. This interface between sample support assembly 16 and vacuum housing 30 is thus configured to provide efficient sample exchange by maintaining portions of the sample support assembly at two different temperatures. First stage support ring 32 may allow attachment of heat dissipation shield 28. Second stage support ring 34 may allow attachment of samples. First stage support ring 32 and second stage support ring 34 may be physically coupled to each other and to vacuum housing 30 with thermal insulation members 201 to allow first stage support ring 32, second stage support ring 34, and base housing 30 to be mechanically engaged sufficiently to provide a vacuum while maintaining different temperatures.

[0023] As shown, the cryogenic analysis assembly 20 can include a base housing 30 that is coupled to the housing 26 and can be at room temperature. Also shown is a portion of the sample support assembly 16 that can be at cryogenic temperatures (e.g., 40K and 4K). The sample support assembly 16 can include a first stage support assembly 32 and a second stage sample support assembly 34. These staged assemblies can be maintained at different temperatures, e.g., the first stage at 40K and the second stage at 4K. According to an exemplary implementation, the sample heat dissipation shield 28 can be thermally coupled to the first stage and thus maintained at the same temperature as the first stage (e.g., 40K). Additionally, the first stage support assembly 32 can shield the second stage support assembly 34 from the thermal radiation of the base 30.

[0024] The first stage support assembly 32 may include a support ring 320 and a shield support 322. The support ring 320 and / or the shield support 322 may be maintained at, for example, 40K. Around the shield support 322, there may be a thermal insulation member 201. One of the thermal insulation members may be operatively engaged between the support 322 and the base support mounting ring 31. The other of the thermal insulation member may be operatively engaged between the support 322 and the second stage sample support assembly 34. The shield support 322 may be configured as a heat dissipation shield to prevent radiative heat transfer between the thermal insulation members 201.

[0025] The second stage sample support assembly 34 may include a ring 340 operatively engaged with a sample support platform 342 and a sample support platform ring 344. The second stage sample support assembly 34 may be operatively engaged with the first stage sample support assembly 32 by the other insulating member 201. According to an exemplary implementation, the first stage may be maintained at a higher temperature than the second stage. The warmer first stage components may be used to shield the cooler second stage components from room temperature components of the assembly housing or base.

[0026] As an example, assembly 32 can be maintained at 40K, while assembly 34 can be maintained at 4K. Both support assemblies 32 and 34 can be coupled to a low temperature (e.g., cryo) source configured to provide at least two cooling temperatures. If first stage support ring 320 is configured for attachment of heat dissipation shield 28, shield 28 can be maintained at a temperature lower than room temperature (e.g., 40K) but higher than the temperature of sample 14 (e.g., 4K). Second stage support ring 340 can allow attachment of sample 14. First stage support ring 320 and second stage support ring 340 can be physically coupled to each other and to base housing 30 with thermal insulation members 201 to allow first stage support ring 320, second stage support ring 340, and base housing 30 to be mechanically engaged while being held at different temperatures. Referring now to FIG. 7, another view of cryogenic assembly 20 is shown with objective lens 12 operatively aligned with sample 14. FIG. 7 includes details shown in FIGS.

[0027] With reference to Figure 8, a perspective view and a cross-sectional view of the shield 28 are shown. The shield 28 can be configured to support the objective lens assembly 200, for example, via an internal thread. A mounting ring 202 has mounting holes configured to mount the objective lens assembly 200 to the top 281 of the heat dissipation shield 28. With reference to Figures 10 and 11, an exploded view and a perspective cross-sectional view of the objective lens assembly 200 are provided for further clarity of engagement.

[0028] 9-11, detailed views of the objective lens assembly 200 are provided. The objective lens mount 50 can be configured to support and house the objective lens 12. The mount 50 can include a sleeve 52 that defines an interior chamber 54. Within the chamber 54, the objective lens can reside. The objective lens 12 can be engaged with the sleeve 52 by an objective lens coupling device 56. The objective lens coupling device 56 can be configured to move the objective lens 12 between a number of positions within the chamber 54. Thus, the objective lens 12 can be movable within the chamber 54 to focus on features of the sample 14. Around the sleeve 52, an objective lens mount housing 58 can be present. The objective lens mount housing 58 can be configured as a thermal radiation shield that shields the objective lens from temperature fluctuations within the housing 26. The sleeve 52, device 56, and housing 58 can be mechanically engaged but thermally isolated from the mounting ring 202 by a thermal insulating member 95. Thus, if the shield 28 is maintained at one temperature, the objective lens 12 can be maintained at another temperature. The mounting ring 202 has mounting holes for mounting the objective lens assembly 200 to the top of the heat dissipation shield 28.

[0029] A portion of the assembly 20 is shown in FIG. 12 as a detailed view of the thermal control assembly 24 coupled to the objective lens mount 50 around a bezel 72, which may be coupled to the objective lens mount 50 by, for example, bolting. The objective lens mount 50 may be coupled to the thermal control assembly 24 (shown in FIG. 13). The heater assembly 24 may include a top cap 76 that forms a housing for the circuitry 78. The heater assembly 24 may also include an inner section 79. The section 79 may be a wire wound inside a groove, such as a copper wire. This section may be pressed into the outer section. The heater assembly 24 may also include a heater ring 77, which may be held in place by the cap 76.

[0030] The heater assembly 24 can be configured to provide heat to create a warm region of the objective lens mount by using a resistive element to provide thermal energy by Joule heating. The temperature can be controlled using a processing circuit such as a proportional integral derivative controller (PID) to allow for 2 mK stability. As described, the heater assembly 24 can include five components: an inner section, an outer shell, a printed circuit board (PCB), a top cap, and a retaining ring. The wire wound on the inner section can be a resistive element. The inner section can be pressed into the outer shell. A processing circuit in the form of a PCB can be mounted on the outer shell. The processing circuit can include a thermistor, connectors, vias for resistive element connection, and a thermostat. The thermistor can be used in combination with a primary heater winding for PID control, while a thermostat is used in combination with a secondary winding to create an uninterruptible power supply (UPS) and fail-safe backup. A top cap 76 is mounted on top of the PCB and bolted to the outer shell to allow for strong thermal coupling through the heater ring system. The retaining ring 79 is threaded onto the objective lens mount 50 to provide a strong thermal coupling with the mounting area. The retaining ring may be sandwiched between the top cap 76 and the inner section 77.

[0031] Another portion of the assembly 20 is shown in FIG. 14 as a detailed view of the engagement of the objective lens mount 50 in the assembly 20. The thermal insulation support 95 extends to the mounting ring 202 at a point that can provide a surface for the epoxy joint 94. The thermal insulation support 95 can be G10 (fiberglass, PEEK, and / or Teflon) insulation. A threaded interface 96 can connect the mounting base 97 of the thermal insulation assembly 91 to the assembly 20. 98 is a threaded connection that allows the retaining ring 99 to connect and / or engage with the thermal insulation member 203. According to FIG. 15, the objective lens assembly 200 can also include a heat dissipation shield assembly 205. The heat dissipation shield assembly 205 can further include a member 203 that can be a beryllium copper aperture about 100 microns thick. The member 203 can be transparent and / or define an opening for the objective lens 12 to receive and / or provide emission from and / or to the sample. According to an exemplary implementation, the objective lens 12 can be configured to provide emission to the sample that can cause excitation of the sample, and the objective lens 12 can be configured to receive emission in the form of light for observing the sample. Also, the member 203 can be integrated as part of the objective lens and / or optics, for example. The thermal insulating member can be between the retaining ring 99 and the base 97.

[0032] The heat dissipation shield assembly 203 can be threaded onto the mounting ring 202 of the objective lens assembly 200. The heat dissipation shield assembly 203 can include a mounting base, a thin aperture disk, and a retaining ring. The mounting base can maintain the temperature of the aperture at the temperature of the heat dissipation shield. The small aperture on the thin disk limits heat dissipation from warm areas moving to the sample stage to reduce heating of the sample. The thin disk also allows for a small working distance due to its thickness of 100 microns, which is thinner than the working distance of the microscope objective lens. The retaining ring maintains the position of the aperture disk while at the same time maintaining good thermal contact between the disk and the mount base.

[0033] The objective lens assembly 200, the heat dissipation shield 28, and the specimen support assembly 16 can be configured to function independently and / or in concert to reduce vibration between the objective lens 12 and the specimen 14. The objective lens assembly 200 can provide the majority of the interface as well as the majority of the thermal insulation for the objective lens 14. The objective lens assembly 200 interfaces with the shield 28. The objective lens assembly 200 can provide thermal insulation by utilizing the thermal resistance of the thermal insulation support 95 that couples the female threaded lens tube to the heat dissipation shield mount. The G10 thermal insulation support 95 can add significant thermal resistance to the system and can maintain the female threaded lens tube and microscope objective at a temperature of ∼295K, while the 40K heat dissipation shield mount can be maintained at ∼40K. The objective lens assembly 200 also protects the microscope objective from cooling due to thermal losses by encasing it in the female threaded lens tube.

[0034] The heat shield 28 shields the sample from room temperature radiation while also providing a stable location for the attached objective lens assembly 200. The heat shield can be rigidly attached to the first stage ring 32 of the sample support 16 which is maintained at a temperature of 40 K with a temperature stability of around 50 mK, thereby resulting in the heat shield being maintained at this temperature and stability. The heat shield has a window which allows optical access from the side of the sample volume, allowing flexibility in imaging techniques.

[0035] The cryogenic assembly of the present disclosure may operate using additional components of cryogenic equipment as described in U.S. Patent No. 8,746,008, the entire disclosure of which is incorporated herein by reference. Additionally, an operator may utilize a Montana Instruments Cryostation™ (Montana Instruments, Bozeman MT.) with the assembly of the present disclosure to observe the sample using an objective lens. In particular, the present disclosure may utilize cryopower of cryogenic equipment via thermal conduction to achieve temperatures as low as 4K. Conductively coupling certain parts and / or components of the cryogenic analytical system of the present disclosure and / or heating coupled parts of the system may provide temperatures of these components at the levels described herein.

[0036] In accordance with the statute, embodiments of the invention have been described in more or less specific terms with respect to structural and methodological features. However, since the disclosed embodiments include detailed descriptions of the invention, it is to be understood that the entire invention is not limited to the specific features and / or embodiments shown and / or described. [Explanation of symbols]

[0037] 12 Objective Lens 16 Sample Support Assembly 20 Cryogenic analysis assembly 24 Heater assembly 26 Vacuum housing 50 Objective Lens Mount 95 Insulation materials 200 Objective lens assembly 202 Mounting ring

Claims

1. 1. A cryogenic analysis assembly configured for optical sample analysis, comprising: an objective lens assembly in operative alignment with a specimen support assembly, both of the objective lens assembly and the specimen support assembly residing within a vacuum housing, the objective lens assembly defining an objective lens mount supporting an objective lens coupled to a mounting ring below a heater assembly; a thermal insulation member between the objective lens mount and the mounting ring, the thermal insulation member supporting the objective lens mount and thermally isolating the objective lens mount from the mounting ring; 1. A cryogenic analytical assembly comprising:

2. 10. The assembly of claim 1, further comprising a specimen heat shield operatively engaged between said objective lens assembly and said specimen support assembly.

3. The assembly of claim 2 , wherein the specimen heat shield defines at least one opening configured to allow visual inspection of a specimen within the cryogenic analytical assembly.

4. 2. The assembly of claim 1, wherein the specimen support assembly further comprises a first stage support assembly operatively aligned about the second stage specimen support assembly, a first insulating member engaging the first stage support assembly and the second stage specimen support assembly.

5. The assembly of claim 4 , wherein the first stage support assembly comprises a support ring that engages a shield support.

6. The assembly of claim 5 further comprising a second thermal insulation member between a base of said assembly and said first stage support assembly.

7. 5. The assembly of claim 4, wherein said first stage support assembly thermally and operatively engages a specimen heat shield aligned between said specimen support assembly and said objective lens assembly.

8. 10. The assembly of claim 1, wherein the objective lens assembly further comprises an objective lens coupled to a sleeve, the objective lens and the sleeve being thermally engaged so as to be maintained at the same temperature.

9. The assembly of claim 8 , wherein the objective lens is movable between a plurality of positions within a chamber defined by the sleeve.

10. The assembly of claim 1 , further comprising a housing around said objective lens assembly and said sample support assembly.

11. The assembly of claim 10 , wherein the housing defines an inlet configured to view a sample within the assembly.

12. The assembly of claim 11 , further comprising a specimen heat shield engaged between the objective lens assembly and the specimen support assembly.

13. 13. The assembly of claim 12, wherein the sample support assembly includes a first stage sample support and a second stage sample support separated by a sample support insulation member.

14. The assembly of claim 13 , wherein the specimen heat shield is thermally engaged with the first stage support.

15. The assembly of claim 14 , wherein the mounting ring is thermally engaged with the specimen heat shield and the first stage support.

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