Optical extraction probe for electron microscopes and other vacuum chambers

Abstract

A beam extraction system is provided. The beam extraction system includes a first focusing optic, a second focusing optic, and an optical repeater coupled to the first focusing optic and the second focusing optic. The first focusing optic is configured to cause light collected from a sample positioned at a focal point of the first focusing optic to form a light beam. The second focusing optic is configured to couple the light beam to the detector. The optical repeater provides an optical path for the light beam from the first focusing optics to the second focusing optics.

Description

Technical Field

[0001] The present invention relates to an optical extraction probe and in particular to an optical extraction probe configured to extract sample light into and from different environments. Background Art

[0002] To perform spectroscopic work inside a vacuum chamber, a light beam must typically be directed in and out of the chamber so that the specimen inside can be observed by a spectrometer outside. The optics need to maintain image quality for a particular field of view without excessive blurring or vignetting. In addition, the optics typically must share space with other instruments and detectors in the chamber, such as the beam of a scanning electron microscope (SEM).

[0003] U.S. Patent No. 6,885,445 (the '445 patent) describes an arrangement of off-axis parabolic (OAP) mirrors in which one mirror is held above the specimen and a hole in the mirror allows the electron beam to pass through. In addition, the '445 patent describes pairing such mirrors so that one mirror cancels the optical aberration introduced by the other mirror. Figure 1A A first arrangement is shown, which is an optical aberration elimination arrangement, comprising a pair of OAP mirrors 101, 102. Two plane mirrors 104 are also included for redirecting the light in the beam 105. The OAP mirrors 101, 102 are arranged to have focal points in the same horizontal plane 106, so that the matched OAP mirrors are positioned to focus the light at the same horizontal plane 106. In contrast, Figure 1B A pairing is shown, wherein the two OAP mirrors 101, 102 are arranged such that the focus of the OAP mirror 102 is in a horizontal plane 108 that is different from the horizontal plane 106. This second arrangement exacerbates optical aberrations.

[0004] As paired focusing optics such as OAP mirrors 101 and 102 are separated by increasing distances, the field of view decreases and the image appears vignetted and blurred. This occurs because light rays 105 introduced along the optical axis will pass from one mirror to the other, but off-axis rays 105' such as observed over an extended sample area will be collected by one mirror and missed by the other. Figure 1C This is illustrated by the figure showing how an off-axis ray 105' from the OAP mirror 101 misses the OAP mirror 102 by a large distance. This also happens in the opposite direction. For example, in a Raman spectroscopy instrument, the probe laser would be collected by one mirror in an imaging experiment and miss the second mirror.

[0005] Therefore, there remains a need for methods and systems for moving a sample beam across distances to and from different environments while maintaining image quality. Summary of the invention

[0006] With respect to the following illustrative, non-limiting implementations, systems, methods, and products are described herein for addressing the needs identified above and other needs. Various alternatives, modifications, and equivalents are also possible.

[0007] According to a first aspect, a beam extraction system is provided. The beam extraction system includes a first focusing optic, a second focusing optic, and an optical relay coupled to the first focusing optic and the second focusing optic. The first focusing optic is configured to form a beam of light collected from a sample, the sample being positioned at a focus of the first focusing optic. The second focusing optic is configured to couple the beam to a detector. The optical relay provides an optical path for the beam from the first focusing optic to the second focusing optic.

[0008] According to a second aspect, a spectroscopic system is provided. The spectroscopic system includes a housing, the housing including a first focusing optic, the first focusing optic being configured to form a light beam from light collected from a sample, the sample being positioned in the housing and at a focus of the first focusing optic. A second focusing optic of the system is configured to couple the light beam to a detector, the detector being positioned outside the housing. An optical relay is coupled to the first focusing optic and the second focusing optic. The optical relay provides an optical path for the light beam from the first focusing optic to the second focusing optic. The system also includes an extraction window in the optical path.

[0009] According to a third aspect, a method of transferring sample light between different environments is provided. The method includes positioning a sample in a first environment, and focusing a first optical element on the sample, and forming a light beam of sample light received from the sample. The light beam extends from the first focusing optical element to the second focusing optical element through an optical relay coupled to the first focusing optical element and the second focusing optical element. The light beam is coupled to a detector in the second environment.

[0010] The beam extraction system described herein provides a method for moving a sample beam across distances to and from different environments while maintaining image quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The foregoing and other features and advantages of the present embodiments will be more fully understood from the following detailed description of illustrative embodiments taken in conjunction with the accompanying drawings.

[0012] Figure 1A is a diagram showing an optical aberration elimination arrangement using a pair of OAP mirrors. Figure 1B is a diagram showing an arrangement structure of a pair of OAP mirrors that generates optical aberrations. Figure 1C is a diagram illustrating a pair of focusing optics separated by a large distance.

[0013] Figure 2A is a diagram illustrating a bundle extraction system according to some implementations. Figure 2B is a diagram illustrating a bundle extraction system according to some other specific implementations.

[0014] Figure 3 is a diagram illustrating a spectroscopy system according to some specific implementations.

[0015] Figure 4 is a flow chart depicting a method of transferring sample light between different environments according to some implementations.

[0016] The figures mentioned above are not necessarily drawn to scale and should be understood to provide representations of specific embodiments and are merely conceptual in nature and illustrate the principles involved. The same reference numerals in the drawings are used for similar or identical components and features shown in various alternative embodiments. The beam extraction system disclosed herein will have a configuration and components determined in part by the intended application and the environment in which it is used. DETAILED DESCRIPTION

[0017] In the description of the invention herein, it is to be understood that words appearing in the singular encompass their plural counterparts, and words appearing in the plural encompass their singular counterparts, unless otherwise implicitly or explicitly understood or stated. In addition, it is to be understood that for any given component or embodiment described herein, any possible candidate or alternative listed for that component may generally be used alone or in combination with one another, unless otherwise implicitly or explicitly understood or stated. As used herein, the term "approximately" means close to or approximately a particular value within the limits of reasonable commercial engineering goals, costs, manufacturing tolerances, and capabilities in the field of radiometry. As used herein, the term "substantially" means mostly or nearly the same within the limits of reasonable commercial engineering goals, costs, manufacturing tolerances, and capabilities in the field of radiometry.

[0018] Therefore, unless otherwise indicated, the numerical parameters set forth in this specification and the appended claims should be understood to be modified by the term "about", and may vary with the desired characteristics attempted to be obtained by the subject matter proposed herein. At the very least, and without attempting to limit the scope of the application of the principle of equivalents to the claims, each numerical parameter should at least be interpreted according to the number of reported significant figures and by applying ordinary rounding techniques. Although the numerical ranges and parameters of the wide range of the subject matter proposed herein are approximate, the numerical values ​​set forth in the specific examples are reported as accurately as possible. However, any numerical value inherently contains some errors that are necessarily caused by the standard deviations present in its corresponding test measurements.

[0019] Figure 2A2 is a diagram illustrating a beam extraction system 200 according to some implementations. A first focusing optic 202 forms a beam 204 from light collected from a sample 206, which is positioned at a focal point 208 of the first focusing optic 202. A second focusing optic 210 couples the beam 204 to a detector 212. For example, the beam can be focused on an objective lens 214, which is part of a Raman spectrometer, an FTIR spectrometer, or a camera (as the detector 212). In some implementations, the beam 204 is focused directly at an entrance slit of a spectrograph, wherein the beam 204 is directly focused ... Figure 2A In FIG. 2 , the objective lens 214 is replaced by an entrance slit, and the detector 212 is a spectrograph.

[0020] The beam extraction system 200 also includes an optical relay 218. The optical relay 218 is optically coupled to the first focusing optic 202 and the second focusing optic 210. The optical relay 218 provides an optical path for the light beam 204 from the first focusing optic 202 to the second focusing optic 210. The optical relay 218 may include optics such as lenses, mirrors, and combinations of these that extend the light beam 204. In some implementations, the optical relay 218 collimates or re-collimates the light beam 204 while extending it.

[0021] According to some implementations, the optical relay 218 includes a third focusing optic 220 having a focal length F and a fourth focusing optic 222 also having a focal length F. The optical relay 218, in combination with the first focusing optic 202 and the second focusing optic 210, provides an optical path length of 4F from the first focusing optic 202 to the second focusing optic 210. The optical relay 218 is coupled to the first focusing optic 202 at one end through the third focusing optic 220 and to the second focusing optic 210 at a second end through the fourth focusing optic 222. In some implementations, the sum of the distances from the third focusing optic 220 to the first focusing optic 202 and from the fourth focusing optic 222 to the second focusing optic 210 is 2F. In some implementations, as Figure 2A As shown, the distance from the third focusing optic 220 to the first focusing optic 202 and the distance from the fourth focusing optic 222 to the second focusing optic 210 are each F. In some implementations, the distance from the third focusing optic 220 to the fourth focusing optic 222 is 2F.

[0022] In some implementations, the third focusing optic 220 is matched with the fourth focusing optic. As used herein, a "matched" optic or an optic that "matches" another optic means that they are selected to be equivalent in performance. For example, for the light under consideration (e.g., light beam 204), the matched optics have the same focal length, transmittance, aberration, curvature, reflectivity, reflective surface area, and transmissive area. The matched optics can be selected by purchasing items with the same part number and the same specifications from a commercial source.

[0023] In some specific implementations, such as Figure 2A As shown, the third focusing optical element 220 and the fourth focusing optical element 222 are lenses, such as glass lenses. In some other embodiments of the beam extraction system 200, the third focusing optical element 220 and the fourth focusing optical element 222 are lenses, such as glass lenses. Figure 2B Mirrors are used as shown. According to the present implementation, the optical relay 218 includes a first concave mirror 224 positioned to reflect the light beam 204 formed by the first focusing optic 202 and a second concave mirror 226 positioned to reflect the light beam 204 to the second focusing optic 210. The sum of the distances from the first concave mirror 224 to the first focusing optic 202 and from the second concave mirror 226 to the second focusing optic 210 is 2F. In some implementations, the first concave mirror 224 is positioned at a distance F from the first focusing optic 202, and the second concave mirror 226 is positioned at a distance F from the second focusing optic 210.

[0024] In some specific implementations, the first concave mirror 224 and the second concave mirror 226 are matched concave mirrors and are positioned substantially back to back. Here, "back to back" means that the first concave mirror 224 is positioned as close as possible to the second concave mirror 226, wherein the backs of these mirrors refer to the non-reflective surface opposite to the reflective surface of the corresponding mirror. For example, if the installation requirements allow the backs of the concave mirrors 224 and 226 to contact, they will be positioned to contact each other. This is usually not possible due to the requirement for a certain degree of alignment adjustment or the presence of a mounting frame requirement. In some specific implementations, at least one point at the back of the concave mirrors 224 and 226 is no more than 1 cm apart (e.g., no more than 0.5 cm apart, or no more than 1 mm apart).

[0025] Since the concave mirrors 224 and 226 reflect the light beam 204 back generally in the direction of the first focusing optic 202 and the second focusing optic 210, respectively, the optical relay 218 in this embodiment includes a plane mirror relay configured to reflect the light beam 204 from the first concave mirror 224 to the second concave mirror 226 across a distance 2f. The plane mirror relay may include two or more plane mirrors. In some embodiments, the plane mirror relay includes a first plane mirror 228 and a second plane mirror 230, wherein the first plane mirror is positioned in the light beam 204 at a distance n from the first concave mirror 224 and the second plane mirror is positioned in the light beam 204 at a distance Fn from the second concave mirror 226. Here, n is a real number greater than zero and less than the focal length F of the concave mirrors 224, 226 (i.e., 0<n<F). In some embodiments, n is about 0.5. In some implementations, the first plane mirror 228 and the second plane mirror 230 are matched mirrors.

[0026] Concave mirrors 224, 226 are also angled so that the major axis is not aligned with Figure 2B In some implementations, the mirrors forming the optical relay 218 are angled such that the mirrors 228 and the mirrors 230 do not obstruct the light beam 204. That is, the first concave mirror 224 is angled such that substantially all of the light reflected from the first concave mirror 224 (e.g., at least 95% of the light or at least 99% of the light) is reflected by the first plane mirror 228, and the first plane mirror 228 does not obstruct the light beam 294 in the first branch between the first focusing optic 202 and the first concave mirror 224. Similarly, the second concave mirror 226 is angled such that substantially all of the light reflected from the second concave mirror 226 is reflected by the second plane mirror 230, and the second plane mirror 230 does not obstruct the light beam 204 in the second branch between the second focusing optic 210 and the second concave mirror 226. In some implementations, the axes of concave mirrors 224, 226 are each angled so that mirror 228 and mirror 230 are as close as possible to contact beam 204, i.e., distance 229 is as close as possible to 0 length units. In some implementations, the axes of concave mirrors 224, 226 are each independently angled from the horizontal plane by at least 1 degree, at least 2 degrees, at least 5 degrees, at least 10 degrees, at least 20 degrees, or at least 30 degrees.

[0027] In some implementations, each of the first focusing optic 202 and the second focusing optic 210 is independently selected from an OAP mirror, a Schwarzschild objective, and a lens. In some implementations, each of the first focusing optic 202 and the second focusing optic 210 is independently selected from an OAP mirror and a Schwarzschild objective. Figure 2A and Figure 2BAs shown, the first focusing optic 202 and the second focusing optic 210 are OAP mirrors. The choice of focusing optics can be selected by a technician in the field who is familiar with current optical technology. For example, Schwarzschild objectives, glass lenses, and OAP mirrors can be used to control Raman excitation light; while mirrors are currently known to be best suited for infrared (IR) light control. Similarly, for light generated by cathode fluorescence, some wavelengths of interest, such as in the ultraviolet (UV) range, are greatly attenuated by glass lenses, making mirrors and Schwarzschild objectives currently better choices. Similar factors can be considered when selecting other optical elements such as the third focusing optic 220 and the fourth focusing optic 222.

[0028] In some implementations, the first focusing optic 202 and the second focusing optic 210 are matched OAP mirrors. This provides an option where the first focusing optic 202 and the second focusing optic 210 are positioned to reflect light in the same horizontal plane. That is, the focal point 208 and the objective lens 214 at the focal point of the second focusing optic 210 are in the same horizontal plane. The benefit of using the same horizontal plane is to reduce optical aberrations, as previously described with reference to Figures 1A to 1C described.

[0029] In some implementations, the beam extraction system 200 further includes an extraction window 304 positioned between the first focusing optics 202 and the second focusing optics 210. The extraction window 304 is positioned in the path of the light beam 204 and is selected to be at least partially transparent to the light beam 204. For example, the extraction window 304 allows at least 90% (e.g., at least 95% or at least 99%) of the light beam 204 to pass through the window. The extraction window 304 can be mounted to a wall that is part of a structure such as a vacuum chamber containing the sample 206, a housing containing the detector 212, or a tube enclosing the optical relay 218. The extraction window 304 is designed to be impermeable to fluids (air, gases). In some implementations, the extraction window 304 can withstand a high vacuum (e.g., up to 10 -12 (Trust).

[0030] In addition, according to some implementations, the linear distance between the first focusing optic 202 and the second focusing optic 210 is at least 10 cm, such as at least 20 cm to 100 cm, or at least 20 cm to 60 cm. In some implementations, the distance between the first focusing optic 202 and the second focusing optic 210 is less than or equal to 4F. As used herein, a "linear" distance refers to the shortest path or straight path between the first focusing optic 202 and the second focusing optic 210.

[0031] Those skilled in the art will recognize that the 4F optical path length and linear distance can be controlled (i.e., selected) based on the type of optical elements used and the focal length of the optical elements. For example, when the third focusing optics 220 and the fourth focusing optics 222 are selected as lenses ( Figure 2A ), the 4F optical path between the first focusing optical element 202 and the second focusing optical element 210 does not need to be as large as when the concave mirrors 224, 226 ( Figure 2B ) is folded as in the case of the concave mirrors 224 and 226. The linear distance can also be controlled by changing the angle with the horizontal plane in which the concave mirrors 224 and 226 are set. Obviously, the focal length F selected for the optical components will also determine the 4F optical path length and the linear distance. In some specific implementations, F is selected to be between 1 cm and 50 cm.

[0032] Another way to extend the linear distance between the first focusing optic 202 and the second focusing optic 210 is to include additional optical relays 218. For example, two or more optical relays 218 inserted in series between the first focusing optic 202 and the second focusing optic 210 are used. In some implementations, the optical relay 218 includes m 4F optical paths from the first focusing optic 202 to the second focusing optic 210, where m is an integer greater than one. In some implementations, M is 2, 3, or 4. Although the implementation of more than one 4F optical path increases the complexity of the system due to the use of more mirrors, such implementations have the following advantages: smaller diameter instruments can be used to achieve an equivalent total extracted beam length of the beam 204.

[0033] In some implementations, the beam extraction system 200 is included in the spectroscopy system 300, such as Figure 3Spectroscopic system 300 includes a housing 302 including a first focusing optic 202 configured to form a light beam 204 positioned in housing 302 and at a focal point 208 of the first focusing optic 202. A second focusing optic 210 is configured to couple the light beam 204 to a detector 212 positioned outside housing 302. An optical relay 218 is coupled to the first focusing optic 202 and the second focusing optic 210 to provide an optical path for the light beam 204 from the first focusing optic 202 to the second focusing optic 210. An extraction window 304 is as previously described and is positioned in the light beam 204 between the first focusing optic 202 and the second focusing optic 210 along the optical path. The extraction window 304 is shown mounted in a structure such as a pipe to define a tunnel 306 enclosing the optical path of the light beam 204. The extraction window 304 may be mounted at any location in the tunnel 306. The extraction window 304 may also be mounted to the opening 308 in the housing 302, or at a location 309 near the detector 212. The inner wall 303 of the housing 302, the inner wall 311 of the tunnel 306, and the wall 307 of the extraction window 304 define a space containing a first environment that is different from a second environment outside the space. As previously described, the extraction window 304 is at least partially transparent to the light beam 204, but is impermeable to fluids such as gases. Therefore, the extraction window 304 allows the light beam 204 to pass through the extraction window 304 while not allowing the fluid to pass through the window 304, thereby providing a closed fluid environment for the space defined by the housing 302.

[0034] In some implementations, the housing 302 is a controlled atmosphere chamber and provides a controlled atmosphere in the first environment. The controlled atmosphere can be an inert atmosphere, including an inert gas such as helium or argon. In some implementations, the controlled atmosphere is an atmosphere with a reduced pressure relative to the atmosphere outside the housing 302. In some implementations, the housing 302 is a vacuum chamber, such as a high vacuum chamber of a SEM or a medium vacuum chamber for an environmental SEM. For example, in some implementations, the housing 302 is part of a scanning electron microscope, including an electron beam system 310 and a platform 312 for holding and orienting the sample 206. The first focusing optics 202 may include an opening for the electron beam 314 to pass through. An auxiliary electron detector 316 and a backscatter detector 318 are also shown. The first focusing optics 202 is positioned to minimize interference or minimize shielding of the auxiliary electron detector 316 and the backscatter detector 318 (e.g., above, below, or parallel to the first focusing optics 202).

[0035] In some implementations, the detector 212 includes a spectrometer 320. In some implementations, the second focusing optics 210 focuses the light beam 204 directly at an entrance slit 322 of the spectrometer 320. Figure 3 In the illustrated implementation, the light beam 204 is shown as being directed toward the objective 214 of the spectrometer 320 .

[0036] In some implementations, the detector 212 includes an excitation source 324 that provides an excitation beam 326 that is combined with the light beam 204. The excitation source can include optical elements, such as an expansion lens, a collimating lens, and a beam splitter, to combine the excitation beam 326 with the light beam 204. In some implementations, the excitation source can be a laser that provides a Raman excitation beam.

[0037] In some implementations, the detector 212 includes a light imager 328, such as a CCD camera. The light imager 328 may include focusing optics and filters. The light imager may be responsive to UV light, IR light, and visible light. When the CCD camera is passed through the beam extraction system 200 ( Figure 2B ) is coupled to the electron beam system 310, a CCD camera can be used to detect cathode fluorescence. The cathode fluorescence can also be directed to the spectrometer 320 for spectral analysis. In some specific implementations, a visible light source 330 is included and provides a visible light beam 331 that merges with the light beam 204. The light source 330 can provide illumination to the sample 206, which can be observed by the light imager 328.

[0038] With excitation source 324 Figure 3A specific implementation of a Raman spectrometer system is shown. It should be understood that all components of the Raman spectrometer system for a properly functioning Raman spectrometer are not included, as these are well known in the art. Other variations known in the art, such as confocal Raman microscopy, frequency-shifted excitation Raman differential spectroscopy (SERDS), surface-enhanced Raman spectroscopy (SERS), and surface-enhanced resonance Raman spectroscopy (SERRS) may also be implemented. In addition, the Raman spectroscopy description should not be interpreted as a limiting use of the beam extraction system 200. A person of ordinary skill in the art may envision specific implementations such as including transmission FTIR (Fourier transform infrared), reflection FTIR. In transmission FTIR, a source is directed through a sample, wherein a source such as a laser 317 may direct a beam 352 from below the sample. The plane mirror 350 and the platform 312 that redirect the beam may have a hole aligned with the electron beam 314. The hole is wide enough to allow at least some of the beam 352 to pass through and transmit through the sample 206. Similarly, housing 302 can be configured for performing EDS (energy dispersive X-ray) analysis and as a TEM (tunneling electron microscope). In some implementations, electron beam system 310 is implemented in spectroscopic system 300, wherein detector 212 includes only spectrometer 320 and light imager 328 for the cathodoluminescence being analyzed. Spectroscopic system 300 can also be implemented to extract light from hazardous environments such as the hard core vacuum of space or from toxic environments.

[0039] Figure 4 is a flow chart depicting a method 400 according to some implementations of the present disclosure. The method is for passing sample light between different environments.

[0040] In a first step 402, the sample 206 ( Figure 3 ) is positioned in a first environment. For example, housing 302 can be a first environment. In some implementations, sample 206 is illuminated with a transmission light source such as one for performing an IR transmission or ultraviolet visible (UV-vis) transmission configuration. In some implementations, sample 206 is illuminated by an excitation energy source. In some implementations, the excitation energy source is selected from a visible light source, an IR light source, a UV light source, an electron beam, or a combination of these. Each of these light sources can be a laser source or a diffuse source. In some implementations, sample 206 is illuminated by a visible light source. In some implementations, sample 206 is illuminated by an IR light source. In some implementations, sample 206 is illuminated by a UV light source. In some implementations, sample 206 is illuminated by an electron beam and produces cathode fluorescence. In some implementations, sample 206 is illuminated by a visible light source and an electron beam, the visible light source being a laser, such as a Raman excitation laser, wherein sample 206 produces Raman emission light and cathode fluorescence. In some implementations, the excitation energy source is focused at sample 206 by first focusing optical element 202.

[0041] In a second step 404, the first optics 202 is focused on the sample 206, and the light beam 204 is formed from the sample light received from the sample 206. For example, the sample 206 is positioned so that the focal point 208 is focused on the sample 206. This may include moving the first focusing optics 202 relative to the sample 206. In some implementations, the sample 206 is on a platform 312 that can be moved to orient the sample 206 relative to the first focusing optics 202.

[0042] In a third step 406, the light beam 204 is extended from the first focusing optic 202 to the second focusing optic 210. The beam extension is achieved by an optical relay 218 coupled to the first focusing optic 202 and the second focusing optic 210. In some implementations, the optical relay 218 includes a third focusing optic 220 having a focal length F and a fourth focusing optic 222 having a focal length F, wherein the optical relay 218 provides a 4F optical path from the first focusing optic 202 to the second focusing optic 210.

[0043] In a final step 408, the light beam is coupled to the detector 212. The detector 212 is positioned in the second environment. In some implementations, the first environment is at a lower pressure than the second environment. For example, the first environment can be composed of the housing 302 and the extraction window 304 ( Figure 3 The second environment includes the detector 212 and the extraction window 304 ( Figure 3 Tunnel 306 on the right side of the tunnel.

[0044] Using the knowledge obtained from the present disclosure, those skilled in the art will recognize that various changes can be made to the disclosed apparatus and method in the process of obtaining these and other advantages without departing from the scope of the present disclosure. In this way, it should be understood that the features described herein are susceptible to modification, change, alteration or replacement. For example, it is clearly expected that all combinations of those elements and / or steps that perform substantially the same functions in substantially the same manner to achieve the same results are within the scope of the embodiments described herein. The replacement of elements from one described embodiment to another described embodiment is also fully anticipated and considered. The specific embodiments illustrated and described herein are for illustrative purposes only and are not limited to the embodiments set forth in the attached claims. Other embodiments will be apparent to those skilled in the art. It should be understood that the foregoing description is provided only for clarity and is merely exemplary. The spirit and scope of the present disclosure are not limited to the examples above, but are covered by the following claims. All the disclosures and patent applications cited above are incorporated by reference in their entirety to the same extent for all purposes, and their reference extent is as if each individual disclosure or patent application is specifically and individually specified to be incorporated by reference in such a manner.

Claims

1. A beam extraction system (200), the beam extraction system comprising: a first focusing optic (202) configured to form a light beam (204) from light collected from a sample (206), the sample being positioned at a focal point (208) of the first focusing optic (202); a second focusing optic (210) configured to couple the light beam (204) to a detector (212); and An optical relay (218) coupled to the first focusing optic (202) and the second focusing optic (210), the optical relay (218) providing an optical path for the light beam (204) from the first focusing optic (202) to the second focusing optic (210).

2. The beam extraction system (200) according to claim 1, wherein: The optical relay (218) includes a third focusing optic (220) having a focal length F and a fourth focusing optic (222) having the focal length F, wherein the optical relay provides a 4F optical path from the first focusing optic (202) to the second focusing optic (210).

3. The beam extraction system according to claim 2, wherein: The optical repeater (218) comprises: a first concave mirror (224) positioned to reflect the light beam (204) formed by the first focusing optic (202), and a second concave mirror (226) positioned to reflect the light beam (204) toward the second focusing optic (210), Wherein, the sum of the distances from the first concave mirror (224) to the first focusing optical element (202) and from the second concave mirror (226) to the second focusing optical element (210) is 2F.

4. The beam extraction system according to claim 3, wherein: The first concave mirror (224) is positioned at a distance F from the first focusing optic (202), and the second concave mirror (226) is positioned at a distance F from the second focusing optic (210).

5. The beam extraction system according to claim 3, wherein: The first concave mirror (224) and the second concave mirror (226) are matched concave mirrors and are positioned substantially back to back.

6. The beam extraction system according to claim 3, wherein: The optical relay (218) includes a plane mirror relay configured to reflect the light beam (204) from the first concave mirror (224) to the second concave mirror (226) across a distance 2f.

7. The beam extraction system according to claim 6, wherein: The plane mirror repeater includes a first plane mirror (228) and a second plane mirror (230), wherein the first plane mirror is positioned in the light beam (204) at a distance n from the first concave mirror, and the second plane mirror is positioned in the beam (204) at a distance Fn from the second concave mirror, wherein n is greater than zero and less than F (0<n<F).

8. The beam extraction system of claim 7, wherein: n is 0.

5.

9. The beam extraction system of claim 7, wherein: The first plane mirror (228) and the second plane mirror (230) are matched mirrors.

10. The beam extraction system of claim 1, wherein: Each of the first focusing optic (202) and the second focusing optic (210) is independently selected from an off-axis parabolic (OAP) mirror and a Schwarzschild objective lens.

11. The beam extraction system of claim 10, wherein: The first focusing optic (202) and the second focusing optic (210) are matched OAP mirrors.

12. The beam extraction system of claim 11, wherein: The matching OAP mirrors are positioned to focus light at the same horizontal plane (106).

13. The beam extraction system of claim 1, further comprising an extraction window positioned between the first focusing optic (202) and the second focusing optic (210).

14. The beam extraction system of claim 1, wherein: A linear distance between the first focusing optic (202) and the second focusing optic (210) is at least 10 cm.

15. The beam extraction system of claim 1, wherein: The optical relay (218) includes m 4F optical paths from the first focusing optic (202) and the second focusing optic (210), where m is an integer greater than one.

16. A spectroscopy system (300), comprising: a housing (302) comprising a first focusing optic (202) configured to form a light beam (204) from light collected from a sample (206), the sample being positioned in the housing (302) and at a focal point (208) of the first focusing optic (202); a second focusing optic (210) configured to couple the light beam (204) to a detector (212) positioned outside of the housing (302); an optical relay (218) coupled to the first focusing optic (202) and the second focusing optic (210), the optical relay (218) providing an optical path for the light beam (204) from the first focusing optic (202) to the second focusing optic (210); and An extraction window (304) is in the optical path.

17. The spectroscopy system according to claim 16, wherein: The housing (302) is a controlled atmosphere chamber.

18. The spectroscopy system according to claim 16, wherein: The housing (302) includes an electron beam system (310) configured to provide an electron beam (314) through an opening in the first focusing optic.

19. The spectroscopy system according to claim 16, wherein: The detector includes a spectrometer (320).

20. The spectroscopy system according to claim 16, wherein: The detector (212) includes an excitation source (324) that provides an excitation beam (326) that is combined with the light beam (204).

21. The spectroscopy system according to claim 16, wherein: The detector (212) includes a light imager (328).

22. A method (400) of passing sample light between different environments, the method comprising: Position the specimen in the first environment; focusing a first optical element (202) on the sample (206) and forming a light beam (204) from sample light received from the sample (206); Extending the light beam (204) from the first focusing optic (202) to the second focusing optic (210) through an optical relay (218) coupled to the first focusing optic (202) and the second focusing optic (210); as well as The light beam (204) is coupled to a detector (212) positioned in a second environment.

23. The method according to claim 22, wherein: The optical relay (218) includes a third focusing optic (220) having a focal length F and a fourth focusing optic (222) having a focal length F, wherein the optical relay (218) provides a 4F optical path from the first focusing optic (202) to the second focusing optic (210).

24. The method according to claim 22, wherein: The sample (206) is illuminated by an excitation energy source.

25. The method according to claim 22, wherein: The first environment is at a lower pressure than the second environment.

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