Patent Publication Number: US-11378499-B2

Title: Instrumental analysis systems and methods

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a divisional of U.S. patent application Ser. No. 15/457,953 filed Mar. 13, 2017, entitled “Instrumental Analysis Systems and Methods”, which claims priority to U.S. provisional patent application Ser. No. 62/307,260 which was filed Mar. 11, 2016, entitled “Cryogenic Assemblies and Methods”, the entirety of each of which is incorporated by reference herein. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to instrumental analysis systems and methods and in particular embodiments to cryogenic analysis assemblies and methods. In particular embodiments, the present disclosure relates to systems, assemblies, and/or methods that include the use of analytical attachments to instrumental analysis systems, cryogenic assemblies and/or cryostats 
     BACKGROUND 
     Instrumental analysis has been used for decades upon decades, and during this time, scientists and laboratory personnel alike continue to demand more and more accuracy from their systems, instruments, and/or methods. The slightest change in alignment between analytical instrument attachments and a sample to be analyzed can require countless hours of additional research and/or lead to poor data which almost always amounts to poor conclusions. 
     For example, with cryogenic analysis systems such as cryogenic assemblies, researchers utilize analytical attachments to investigate samples in their frozen state. Many cryogenic researchers use analytical attachments such as optical microscopy to study single molecules. This is achieved by using a microscope objective to focus and/or collect light from a sample which is held at cryogenic temperatures. Microscope objectives are precisely manufactured chains of lenses which are conventionally designed for room-temperature use. 
     High light collection efficiency also requires the objective to have a very small working distance between its tip and a sample. Researchers have historically traded off objective performance for longer working distances to allow the objective to be mounted outside of the cryostat. 
     The present disclosure provides cryogenic assemblies and methods, embodiments of which overcome one or more of the shortcomings of the prior art. 
     SUMMARY OF THE DISCLOSURE 
     Instrumental analysis systems are provided that can include: an analytical attachment axially aligned with a sample upon a sample stage; structure supporting both the attachment and the sample stage; and at least one band affixed to the analytical attachment and symmetrically about the axis of the attachment. 
     Methods for analyzing samples are provided. The methods can include: providing at least one band supported by a structure; firmly affixing an analytical attachment to the band, and axially aligning the attachment with a sample; and providing a temperature gradient between the band and the sample while maintaining axial alignment of the objective and the sample. 
    
    
     
       DRAWINGS 
       Embodiments of the disclosure are described below with reference to the following accompanying drawings. 
         FIG. 1  is a side perspective view of an exemplary cryostation. 
         FIG. 2  is a top plan view of the cryostation of  FIG. 1  according to an embodiment of the disclosure. 
         FIG. 3  is a side elevational cutaway view of the cryostation of  FIG. 1  according to an embodiment of the disclosure. 
         FIG. 4  is a portion of a cryogenic assembly according to an embodiment. 
         FIG. 5  is another portion of cryogenic assembly according to an embodiment of the disclosure. 
         FIG. 6  is yet another portion of a cryogenic assembly according to an embodiment of the disclosure. 
     
    
    
     DESCRIPTION 
     This disclosure is submitted in furtherance of the constitutional purposes of the U.S. Patent Laws “to promote the progress of science and useful arts” (Article 1, Section 8). 
     Embodiments of the present disclosure will be described with reference to  FIGS. 1-6 . Referring first to  FIG. 1 , an exemplary cryostation  8  is depicted. Cryostation  8  can be generally configured as described in U.S. Pat. No. 8,746,008 to Mauritsen et al. and entitled, “Low Vibration Cryocooled System for Low Temperature Microscopy and Spectroscopy Applications”, the entirety of which is incorporated by reference herein. Operators may also utilize Montana Instruments Cryostation™ (Montana Instruments, Bozeman, Mont.) with the assemblies of the present disclosure to view samples using objectives. 
     Cryostation  8  can include a support  3  which supports a closed-cycle cryocooler expander unit  4  which can be operatively aligned with sample housing  1 . Unit  4  can be a Sumitomo Heavy Industries RDK-1 OID cryocooler. 
     Referring next to  FIGS. 2 and 3 , spring dampers  5  may be operatively aligned between unit  4  and support  3 . Unit  4  can be connected to sample housing  1  and cryogenic sample support  11  by bellows  2 . The diameter of bellows  2  can be in the range from about 0.75 inches to about 3 inches and is more preferably in the range from about 1 inch to about 1.25 inches. 
     In normal use, both rigid support  3  and sample housing  1  rest on an optical bench  12  or on another rigid plane. In a more preferred embodiment, optical bench  12  is a Newport air isolated workstation. 
     The sample is preferably supported by a rigid cryogenic support  11  which holds the sample in a fixed location relative to the optical bench  12  or rigid plane on which the invention rests. The cryocooler also can be attached to the rigid support  11  by a separate flexible hermetic sealing bellows  13  that is in alignment with flexible vacuum bellows  2 . A temperature sensor  14  and a heater  15  may be located on the cryogenic support  11  near the sample to allow for an adaptive feedback loop to reduce temperature fluctuations. In at least one embodiment, the temperature sensor is a Cernox temperature sensor from Lakeshore Cryogenics Inc. 
     In more detail, system  8  allows a sample to be cryogenically cooled and rigidly mounted to the optics bench  12  and aligned separately (situated a distance away) from the axis of the cryocooler expander unit  4  such that top access to the sample housing  1  via top access port  6  may be achieved. This unique configuration in which the sample is located off axis from and a distance away from the cryocooler expander unit  4  reduces sample vibration by isolating the sample. The pair of flexible vacuum bellows  2  and  13  which connect the cryocooler expander unit  4  to the sample housing  1  and to the rigid support  3  are preferably aligned along a common axis and opposed to one another such that when there is a differential pressure on the inner and outer surfaces of the bellows  2 , there is no net force imposed on the cryocooler expander unit  4 . 
     The cold stage of a closed-cycle cryocooler fluctuates in temperature due to the cyclical alternating pressure of the cooled Helium gas with each cycle of gas entering and exiting the expander section of the cryocooler. Additionally, the parasitic and active heat loads on the cryocooler cause the cold stage to rise in temperature between each cycle. Typically, the way to minimize thermal fluctuations in cryogenic systems is to use a PID control loop; however, this method results in an unnecessary amount of heat input to the system, which significantly raises the cold stage temperature. 
     In accordance with example implementations, system  8  can be configured to include a temperature sensor  14  and a heater  15  located near (by “near,” it is located on the same temperature platform and within 2 inches) the sample on the cryogenic support  11  such that temperature can be read by an electronic device for data acquisition. 
     Specifically, the cryocooler can be operated manually until the cryogenic support  11  has reached a stable temperature near the desired measurement temperature as measured by the temperature sensor  14 . At that time the temperature profile of at least one cycle of the cryocooler is recorded. Based on this initial, uncontrolled temperature profile, a profile of heater values which is inversely proportional to the recorded temperature profile is applied using heater  15  synchronously with the cryocooler cycle and adjusted for phase relative to the cryocooler cycle to optimize the temperature minimization. 
     A second phase of optimization of the heater profile can be obtained by measuring the residual cyclical temperature variation of each value of the heater profile with sensor  14 . A correction factor to each value of the heater profile is applied using heater  15  that is proportional to each measured residual value. 
     Optical access to the cryocooled sample inside the sample housing  1  can be through the top optical access port  6  and/or through the side access ports  7 . These ports are part of what can be referred to as a viewing assembly that resides above the sample platform or cryogenic support. In accordance with example embodiments of the disclosure, this assembly can be subject to temperature differences between portions of the assembly. 
     A laser, optics and/or a microscope or other analytical attachments may be used with system  8  to interrogate and observe a cooled sample, all of which are supported by an optics bench. Operation of the system can include cooling the cryocooler expander unit  4  to cryogenic temperatures and using the optical apertures  6  and/or  7  for observation of the sample using attachments such as microscopes or other imaging devices and interrogation of the sample using lasers or other electromagnetic energy propagation devices along with detection of signals returned by the interrogated sample. It is important to keep these attachments aligned with the sample in order to obtain reliable data. Movement of the attachment in relation to the sample can make sample analysis difficult, if not impossible. 
     Many variations of the disclosure will occur to those skilled in the art. Some variations include an inverted cryocooler expander unit  4  such that it would be located underneath the optics bench  12  and extend up through a hole in the optics bench, or extend up over the edge of the optics bench  12 . Other variations call for the cryocooler expander unit  4  being supported by structure separate from the optics bench  12  where the sample housing  1  is located. Additionally, the environment surrounding the sample may be altered or changed by adding a magnetic field, high pressure, RF field, or other types of environmental alterations. All such variations are intended to be within the scope of this disclosure. 
     The applicant recognizes that the prior art use of longer working distances places windows between the objective and the sample, and these windows can cause aberrations. The applicant recognizes that microscope use for extended periods of time can give rise to thermal drift associated with fluctuations in room temperature. As the mount used to hold the objective warms or cools, its material expands or contracts, causing the objective to go in and out of focus on a sample. Mechanical vibrations also create problems for researchers. The applicant recognizes that flimsy mounts can cause the objective to move, relative to the sample, beyond its optical resolution. 
     To address these problems recognized by the applicant and the shortcomings of the state of the art of instrumental analysis systems and/or methods, the present disclosure provides systems that can include an analytical attachment axially aligned with a sample upon a sample stage. At least one example of this is configuration is shown in  FIG. 4 . The systems can also include a chamber housing both the attachment and the sample stage. In accordance with at least one example implementation,  FIG. 5  depicts a cylindrical chamber that can house the attachment and sample stage of  FIG. 4 . In a cryogenic analysis method, the chamber may be under vacuum. The systems can include at least one band about a portion of the housing, the attachment being affixed to the band as shown in  FIG. 5 . 
     Referring to  FIG. 4 , a portion of a cryogenic assembly  40  according to an embodiment of the disclosure is shown that includes an objective  42  and a sample  44  upon a stage  46 . Objective  42  is an example analytical attachment and cryogenic assembly  40  is an example component of an instrumental analysis system. In accordance with example implementations,  FIG. 4  depicts an operable alignment of objective  42  with sample  44  within a cryogenic assembly. This operable alignment can be considered an axial alignment. Objective  42  can be a set of optics and/or lenses that may or may not be bundled, but are configured to provide a view of sample  44  operatively aligned therewith. Sample  44  can be a solid sample and stage  46  can be configured to support sample  44  in operable viewing alignment with objective  42 . Objective  42  can be firmly supported by at least one of the bands shown in  FIG. 5 , for example. 
     Objective  42  can be maintained a temperature that is different than the temperature of its surroundings. For example, the temperature of objective  42  can be different than the temperature of the sample and/or stage. Accordingly, there can be a temperature gradient between objective  42  and the sample and/or sample stage. The temperature of objective  42  and/or optics and/or lenses and/or lens surfaces of objective  42  can be at least 250 K and/or at least 100 K different than sample  44  and/or stage  46 . Sample  44  and/or stage  46  can be less than about 200 K and in some embodiments maintained at less than 40K and/or a temperature of about 4 K. 
     As is depicted in  FIG. 4 , an axis  48  can exist between sample  44  and attachment  42 . As depicted, axis  48  extends vertically between these components. This can be considered the axial alignment of these components and while shown here with the components above one another, other arrangements are contemplated. For example, the attachment, such as optics can be arranged to view in the horizontal plane or from the side of sample  44  rather than above. In this arrangement, the axial alignment of the attachment is still important as movement can impact the view of the sample. 
     Referring next to  FIG. 5 , one example portion of a cryogenic assembly  50  is shown that includes a structure supports  54  and  56 . One or both of these bands can be aligned symmetrically about axis  58  which can be an axis such as axis  48  upon which attachments and samples are aligned. The bands may be concentrically aligned in relation to one another as well. While support structure  52  is shown as a single construction, it may well be multiple constructions. Further, support structure  52  is shown as substantially cylindrical, however, non-cylindrical structures that may or may not include non-cylindrical bands are also contemplated. Additionally, assembly  50  may form a vacuum chamber housing or may be contained within a vacuum chamber housing. Accordingly, supports  54  and  56  can be within a vacuum chamber housing. 
     In addition, a sample may be aligned along axis  58  and an attachment may be aligned to view along an axis that is normal to axis  58 . In this alignment, the attachment may well be coupled to one of the structure supports  54  or  56 . In accordance with example implementations, the structure the attachment is coupled to may be maintained at a constant temperature. 
     In accordance with example implementations, assembly  50  can include a structure  52  extending between support such as band  54  and support structure  56 , such as another band. Band  54  and/or structure  56  can be a portion of a complete piece that includes structure  52 , or band  54  and/or structure  56  can be separate pieces that are coupled to structure  52 . Band  54  can take the form of a ring that encompasses structure  52  for example. Structure  56  can also take the form of a ring that encompasses support structure  52 , but structure  56  may also take many other forms such as partially or fully rectangular, for example. Band  54 , support structure  52 , and structure  56  may be symmetrical in comparison with the axis when the entirety of these components is the same temperature. 
     In accordance with example implementations, there can be a temperature gradient between  54  band and structure  56  which may define regions, portions or zones about the assembly of the system. For example, band  54  can be associated with one portion  60  and structure  56  can be associated with another portion  62 . Structure  56  can be firmly affixed to a sample stage for example and a temperature gradient controlled through these portions by controlling the temperatures of band  54  and structure  56 . In accordance with example embodiments, support structure  52  can be sufficiently pliable to provide support but allow for expansion and/or contraction of related portions. 
     As is depicted in  FIG. 5 , band  54  resides above structure  56 . This arrangement is for purposes of example only. Other arrangements including band  54  below structure  56  are contemplated as well. Regions  60  and  62  are depicted to demonstrate temperature controlled  60  and uncontrolled  62 . In the controlled region  60 , a cryo environment can be provided for example. In the uncontrolled region  62  an ambient region can be provided, but the regions may both be controlled with substantial temperature differences existing between them. In accordance with other implementations, there may be temperature differences between regions  60  and  62 , with one or both of the temperatures of each of the regions being thermally controlled. Implementations are contemplated wherein region  62  is above ambient temperature and region  60  may be at a temperature lower than the temperature of region  62 . 
     As  FIG. 5  depicts, an axis  58  can extend within the portion and band  54  and structure  56  can have a relationship to this axis. For region  62 , the temperature changes can cause structure  56  to expand and/or contract as depicted by the arrows. This change in structure  56  can deform support structure  52  and impact band  54  which can impact the relation of the attachment with a sample where the attachment is coupled to band  54 . However, it has been discovered that where a band is utilized, this impact is minimized. For example, in a configuration without a band, a simple coupling of the attachment to a bar along the housing or to the housing itself, the change in region  62  changes the relation of the attachment to the sample. 
     Referring next to  FIG. 6 , region  60  is depicted as part of a viewing assembly that includes a portion configured to receive optics  42 . Utilizing bands  54 , optics  42  can be restrained in a working relationship with a sample. 
     Although some embodiments are shown to include certain features, the Applicant specifically contemplates that any feature disclosed herein may be used together or in combination with any other feature on any embodiment of the invention. It is also contemplated that any feature may be specifically excluded from any embodiment of the invention. 
     The systems of the present disclosure can be utilized to analyze a sample. For example, a cylindrical housing having at least one band about the cylindrical housing can be provided. An analytical attachment can be firmly affixed to the band, and the attachment can be axially aligned with a sample within the cylindrical housing. A temperature gradient can be provided between portions of the cylindrical housing while maintaining axial alignment of the objective and the sample. 
     The methods can also include providing another band about the housing. The one and the other bands can have different temperatures. In accordance with example implementations thermal energy can be transferred between the two bands. With these two portions at different temperatures, steady optical performance can be maintained between the objective and the sample. A constant distance can be maintained between the attachment and the sample and/or peak-to-peak displacements of the attachment can be maintained below the diffraction limit. 
     In compliance with the statute, embodiments of the invention have been described in language more or less specific as to structural and methodical features. It is to be understood, however, that the entire invention is not limited to the specific features and/or embodiments shown and/or described, since the disclosed embodiments comprise forms of putting the invention into effect.