Light guide components for electron microscopes

Abstract

Light guide assembly for electron microscope. This disclosure describes embodiments of an electron microscope system comprising an electron column pole shoe and a light guide assembly operatively coupled together. The light guide assembly further comprises one or more detectors and a reflector having a pressure-limiting aperture through which an electron beam from an electron source passes. The reflector is further configured to reflect light and collect backscattered electrons and secondary electrons.

Description

Technical Field

[0001] The present invention generally relates to electron microscopes capable of Raman spectroscopy and / or cathodoluminescence detection. Background Art

[0002] It is widely known in the art that combining Raman spectroscopy or cathodoluminescence detection with electron microscopy offers numerous advantages, particularly when used in conjunction with a technique commonly referred to as environmental scanning electron microscopy (ESEM). For example, Raman microscopy can be used for materials identification, and when combined with scanning electron microscopy, it can unambiguously identify samples that may have different characteristics in composition and / or structure. ESEM techniques can be operated in a mode that allows imaging in low-vacuum, relatively humid environments, thereby reducing sample movement due to sample drying and thus reducing image resolution. However, it is also widely known in the art that low-vacuum, high-humidity environments can negatively impact electron microscope imaging performance. In the examples described herein, a so-called pressure-limited aperture (PLA) has been used to separate the high-vacuum environment beneficial for electron microscopy from the low-vacuum environment beneficial for ESEM techniques.

[0003] The combination of electron microscopes with optical elements for Raman spectroscopy or cathodoluminescence detection and PLA is well known, an example of which is described in U.S. Patent No. 7,718,979, entitled "Optical Apparatus for Simultaneous Observation of a Sample with Particles and Photons," which is incorporated herein by reference in its entirety for all purposes. For example, the '979 patent describes a mirror with a hole at its center positioned between the electron rod shoe and the sample. An electron beam propagates from the source, passes through the hole in the mirror, and interacts with the sample. The mirror also has a surface that reflects and directs light from the light source and redirects it toward the sample, and is positioned to collect light from the sample and direct it to a photodetector.

[0004] However, the previously described embodiments also have some serious drawbacks. First, the mirror is limited to use in high vacuum environments. Furthermore, because the mirror, used to reflect light, is located between the sample and the electron rod shoe, it significantly reduces the ability of electrons to reach the electron rod shoe from the sample, thereby greatly reducing the efficiency of the electron microscope detector. Furthermore, it is highly desirable to keep the working distance of the electron beam path as short as possible. However, the previously described PLA configuration increases the working distance, thereby reducing the imaging performance of the electron microscope.

[0005] Therefore, the design of an electron microscope configured to enable Raman spectroscopy in a low vacuum environment without the negative effects of signal blockage and increased working distance would have significant advantages over previous embodiments. Summary of the Invention

[0006] Systems, methods, and products that address these and other needs are described herein by way of illustrative, non-limiting embodiments. Various alternatives, modifications, and equivalents are possible.

[0007] An embodiment of an electron microscope system is described, comprising an electron column shoe and a light guide assembly operatively coupled together. The light guide assembly also includes one or more detectors and a reflector having a pressure-limiting aperture through which an electron beam from an electron source passes. The reflector is further configured to reflect light and collect backscattered electrons and secondary electrons.

[0008] In some embodiments of an electron microscope system, an electron column shoe and a light guide assembly are placed in a chamber having a low vacuum environment, and an electron beam is delivered to a sample, which responds to the electron beam by generating backscattered and secondary electrons. In some cases, the light guide assembly is effectively coupled to an electron lens of the electron column shoe.

[0009] Furthermore, the light guide assembly and the electronic post piece can be configured to be operatively coupled to a pressure seal. More specifically, the reflector can provide a pressure seal for the electronic post piece. Alternatively, the light guide assembly and the intermediate element can be configured to be operatively coupled to a pressure seal, and the intermediate element and the electronic post piece can be configured to be operatively coupled to a pressure seal.

[0010] Furthermore, the reflector can be configured to reflect light from the sample toward the light detector, and to reflect light from the light source toward the sample. The light source can include a laser or a light-emitting diode (LED). The reflector can also be configured to convert backscattered electrons into secondary electrons, wherein the light guide assembly can further include a collection electrode configured to collect the converted secondary electrons. Specifically, the collection electrode can include a front plate having an aperture through which the backscattered electrons and the secondary electrons travel to the reflector.

[0011] Finally, in some embodiments, the light guide assembly can further include an electrode configured to collect secondary electrons, and in some cases, the one or more detectors include one or more solid-state diode detectors.

[0012] Furthermore, an embodiment of a light guide assembly is described that includes a reflector including a pressure-limiting aperture through which an electron beam from an electron source passes, and the reflector is further configured to reflect light and collect backscattered and secondary electrons.

[0013] In some cases, the reflector and the electron column piece are configured to be operatively coupled to the pressure seal. Sometimes, the reflector is configured as an electron lens operatively coupled to the electron column piece. Alternatively, the reflector and the intermediate element are configured to be operatively coupled to the pressure seal, and the intermediate element and the electron column piece are configured to be operatively coupled to the pressure seal. Furthermore, the electron beam passes through a sample located in the chamber, wherein the sample generates backscattered and secondary electrons in response to the electron beam.

[0014] Additionally, the mirror can be configured to reflect light from the sample toward a light detector and to reflect light from a light source toward the sample. In some cases, the light source comprises a laser or a light-emitting diode (LED). Furthermore, the mirror can be configured to convert backscattered electrons into secondary electrons.

[0015] Sometimes, the light guide assembly further includes a collecting electrode configured to collect secondary electrons converted from backscattered electrons by the reflector. The collecting electrode may include a front plate having an aperture through which the backscattered and secondary electrons travel to the reflector. The light guide assembly may further include one or more detectors configured to detect the backscattered electrons, and another electrode configured to collect the secondary electrons. In particular, the one or more detectors may be solid-state diode detectors.

[0016] The above-described embodiments and implementations are not necessarily inclusive or exclusive of each other, and regardless of whether they are presented in conjunction with the same or different embodiments or implementations, the embodiments and implementations may be combined in any other possible manner that does not conflict. The description of one embodiment or implementation is not intended to be limiting with respect to other embodiments and / or implementations. Furthermore, in alternative embodiments, any one or more functions, steps, operations, or techniques described elsewhere in this specification may be combined with any one or more functions, steps, operations, or techniques described in the present disclosure. Therefore, the above-described embodiments and implementations are illustrative and not restrictive. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and other features will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. In the accompanying drawings, like reference numerals indicate like structures, elements, or method steps, and the leftmost digit of a reference numeral indicates the number of the drawing in which the referenced element first appears (e.g., element 110 first appears in FIG. Figure 1 However, all of these conventions are typical or illustrative rather than limiting.

[0018] Figure 1 is a simplified pictorial representation of one embodiment of a scanning electron microscope in communication with a computer.

[0019] Figure 2It has a light guide component Figure 1 Simplified graphical representation of one embodiment of a scanning electron microscope.

[0020] Figure 3A yes Figure 2 Simplified graphical representation of one embodiment of a side view of a light guide assembly operating in a mode in which the mirror collects secondary electrons at a pressure greater than about 1 mbar.

[0021] Figure 3B yes Figure 2 A simplified graphical representation of one embodiment of a side view of a light guide assembly operating in a mode where electrodes collect secondary electrons at a pressure of less than about 1 mbar.

[0022] Figure 4A yes Figure 2 A simplified graphical representation of one embodiment of a side view of a light guide assembly operating in a mode in which a mirror collects backscattered electrons and converts them into secondary electrons that are collected by a front plate electrode at a pressure greater than about 1 mbar.

[0023] Figure 4B yes Figure 2 A simplified graphical representation of one embodiment of a side view of a light guide assembly operating in a mode in which a mirror collects backscattered electrons and converts them into secondary electrons that are collected by electrodes at a pressure of less than about 1 mbar.

[0024] Figure 4C yes Figure 2 A simplified pictorial representation of one embodiment of a side view of a light guide assembly operating in a mode where the detector collects backscattered electrons in a high vacuum environment; and

[0025] Figure 5 is a slave with one or more detectors Figure 2 A simplified pictorial representation of one embodiment of a bottom view of a light guide assembly (eg, a view looking toward an electronic pole piece) is shown.

[0026] Like reference numerals designate corresponding parts throughout the several views of the drawings. DETAILED DESCRIPTION

[0027] As will be described in more detail below, embodiments of the present invention include a scanning electron microscope capable of Raman spectroscopy or cathodoluminescence detection. More specifically, the scanning electron microscope is configured with a light guide assembly that detects backscattered and secondary electrons at a short working distance.

[0028] Figure 1 A simplified illustrative example of a user 101 capable of interacting with a computer 110 and a scanning electron microscope 120 is provided. Embodiments of the scanning electron microscope 120 may include various commercially available scanning electron microscopes. For example, the scanning electron microscope 120 may include a Quattro or Prisma scanning electron microscope, both available from Thermo Fisher Scientific. Figure 1 Also shown is a network connection between the computer 110 and the scanning electron microscope 120, but it should be understood that Figure 1 The diagrams are exemplary only and may include more or fewer network connections. Furthermore, network connections between elements may include "direct" wired or wireless data transmission (e.g., represented by lightning in the diagrams) as well as "indirect" communication via other devices (e.g., switches, routers, controllers, computers, etc.). Therefore, the diagrams should not be considered as Figure 1 The examples are to be considered limiting.

[0029] Computer 110 may comprise any type of computing platform, such as a workstation, a personal computer, a tablet computer, a "smart phone," a server, a computing cluster (local or remote), or any other current or future computer or computer cluster. A computer typically includes known components, such as one or more processors, an operating system, system memory, memory storage devices, input-output controllers, input-output devices, and a display device. It should also be understood that more than one embodiment of computer 110 may be used to perform various operations in different embodiments, and thus Figure 1 The representation of computer 110 in FIG. 1 should not be considered limiting.

[0030] In some embodiments, computer 110 may utilize a computer program product comprising a computer-usable medium having control logic (e.g., a computer software program containing program code) stored therein. When executed by a processor, the control logic causes the processor to perform some or all of the functions described herein. In other embodiments, some functions are primarily implemented in hardware, using, for example, a hardware state machine. Implementing a hardware state machine to perform the functions described herein will be readily apparent to those skilled in the relevant art. Furthermore, in the same or other embodiments, computer 110 may utilize an Internet client, which may include a specialized software application enabled to access remote information via a network. The network may comprise one or more of many different types of networks well known to those skilled in the art. For example, the network may comprise a local area network or a wide area network that communicates using the protocols commonly referred to as the TCP / IP protocol suite. The network may comprise the global system of interconnected computer networks, including the Internet, or may also comprise various intranet architectures. Those skilled in the relevant art will also appreciate that some users in networked environments may prefer to utilize mechanisms commonly referred to as "firewalls" (sometimes also referred to as packet filters or perimeter guards) to control information traffic to and from hardware and / or software systems. For example, a firewall may include hardware or software elements, or some combination thereof, and is typically designed to enforce security policies put in place by a user, such as a network administrator.

[0031] As described herein, embodiments of the described invention include a scanning electron microscope configured with a light guide assembly that includes a mirror configured with PLA and collects backscattered electrons and secondary electrons at a short working distance.

[0032] Figure 2 An illustrative example is provided that shows an embodiment of a scanning electron microscope 120 including a chamber 203 and an electron column pole piece 202. Embodiments of the electron column pole piece 202 include any type of electron column pole piece (sometimes referred to as an electron column or pole piece) typically used in embodiments of a scanning electron microscope 120 and typically include components such as one or more coils and / or one or more electromagnetic lenses, such as a final lens 206 for focusing an electron beam 207 from an electron source 204. It should also be understood that Figure 2 This is for illustrative purposes only and should not be considered limiting. For example, Figure 2 The final lens 206 is illustrated as being elliptical, but electromagnetic lenses include a variety of configurations and shapes.

[0033] The environment within chamber 203 can comprise a high vacuum environment, but as described above, it may be more desirable to operate chamber 203 in a low vacuum or ESEM environment. For example, chamber 203 can comprise a pressure of approximately 1 mbar, which is sufficient to remove charge from the surface of a non-conductive sample irradiated by an electron beam. In some cases, chamber 203 can comprise a water vapor pressure substantially equal to approximately 6 mbar, which can be used in conjunction with embodiments of sample holder 210 having cooling features to achieve an equilibrium pressure of water (100% relative humidity). Chamber 203 can comprise a pressure of up to approximately 40 mbar to achieve an equilibrium pressure of water vapor at room temperature of approximately 25°C or higher. However, it should be understood that the equilibrium pressure of water depends on the ambient temperature, and therefore different pressures can be used.

[0034] Sample holder 210 is generally used to position sample 211 in the path of electron beam 207 and within the field of view of mirror 220. Those skilled in the art will appreciate that sample 211 may include any type of sample, such as a biological sample. Figure 2 An illustrative example of a light guide assembly 250 is also provided, comprising a reflector 220 having a pressure-limiting aperture 225 positioned to allow passage of the electron beam 207. Those skilled in the relevant art will appreciate that ESEM microscopes typically utilize two pressure-limiting apertures. For example, one pressure-limiting aperture can be located within an objective lens (e.g., final lens 206), which can have a smaller diameter to minimize impact on the field of view, while a second pressure-limiting aperture, such as pressure-limiting aperture 225, is located closer to the sample, thereby limiting the field of view. Therefore, the diameter of pressure-limiting aperture 225 is optimized to provide good field of view orientation relative to sample 211 at lower magnifications. In the embodiments described herein, the diameter of pressure-limiting aperture 225 is sufficiently small to maintain a pressure differential between chamber 203 and the environment including electron source 205. For example, the diameter of pressure-limiting aperture 225 can range from 500 μm to 1 mm, but typically exceeds 300 μm. As described above, the pressure in the chamber 203 may include a low vacuum pressure of approximately 30 mbar, which is separated from the environment including the electron source 205 by the pressure limiting hole 225. The environment may include a high vacuum pressure of less than approximately 0.1 mbar (e.g., to limit electron scattering that may occur at lower vacuum pressures). In the example described herein, the vacuum pressure may be maintained using well-known techniques (e.g., a vacuum pump, etc.).

[0035] In the embodiments described herein, the reflector 220 of the light guide assembly 250 is coupled to the electron column shoe 202 via a pressure seal. In some cases, the light guide assembly 250 is also coupled to the final lens 206 of the electron column shoe 202 via a pressure seal. Furthermore, in some embodiments, the formation of the pressure seal can be improved by using an intermediate element 230 constructed of a desired material and configured to seamlessly engage the electron column shoe 202 or final lens 206 and the reflector 220 (e.g., a pressure seal exists between the reflector 220 and the intermediate element 230, and a pressure seal exists between the intermediate element 230 and the electron column shoe 202 or final lens 206). It should also be understood that in some embodiments, the pressure-limiting orifice 225 can be coupled to the intermediate element 230 instead of the reflector 220, but it is desirable to position the pressure-limiting orifice 225 as close to the sample 211 as possible to shorten the path of the electron beam 207 in the environment of the chamber 203. For example, the intermediate element 230 can be constructed of a non-magnetic material so that the electron beam 207 is not degraded. When the reflector 220 is charged, the intermediate element 230 should provide electrical isolation (e.g., isolation to prevent current flow) between the reflector 220 and the objective lens in the pole piece 204. In some cases, the light guide assembly 250 can be configured to provide electrical isolation. In the example currently described, the intermediate element 230 is not exposed to the electron beam 207, which could charge the intermediate element 230 and thus degrade the quality of the electron beam 207.

[0036] Furthermore, as discussed above, an important aspect of the present invention is to keep the working distance between the electron column shoe 202 and the sample 211 as short as possible to limit beam spread, but at a sufficient distance from the detection elements to allow for what is known as "cascade amplification" of secondary electrons. For example, "cascade amplification" can occur in an operating mode in the presence of water vapor. Secondary electrons interact with water molecules to produce additional secondary electrons, which in turn interact with adjacent water molecules to produce more secondary electrons, thereby "amplifying" the number of secondary electrons. However, it should be understood that water vapor is not required for cascade amplification to occur. As discussed above, it is highly desirable to optimally position the sample holder 210 near the light guide assembly 250. For example, in a low vacuum environment, the desired working distance between the pressure limiting aperture 225 and the sample 211 can include a distance in the range of approximately 10-20 mm.

[0037] Figure 2 Also shown is a light source 255, which may include any type of light source known to one of ordinary skill in the art for Raman spectroscopy (e.g., a laser, LED, or other type of light source). Figure 2Detector 257 is shown and may include any type of detector known to those skilled in the art for use in Raman spectroscopy (e.g., a CCD, a photomultiplier tube, or other type of detector). It should be understood that various optical elements known to those skilled in the art may be generally employed to guide light (not shown, such as mirrors, beam conditioning elements, and / or lenses) along an optical path 260 between light source 255 / detector 257 and sample 211 via mirror 220, and to adjust the characteristics of the light to achieve desired Raman spectroscopy performance.

[0038] Figure 3A An illustrative example is provided, showing a side view of a light guide assembly 250 having a mirror 220 that functions as a gaseous secondary electron detector (GSED) and collects secondary electrons 305 scattered from the surface of a sample 211 in response to an electron beam 207 during scanning. The electron microscope 120 operates in a mode where the pressure in the chamber 203 is greater than approximately 1-2 mbar. For example, in an operating mode, the electron beam 207 includes primary electrons that interact with the surface of the sample 211, thereby generating secondary electrons 305 that exit the sample 211 and travel toward the mirror 220, which has a positive charge (e.g., may include a positive bias of approximately 600 V). In this example, the electrode 330 and / or the front plate 315 may include a substantially neutral charge so that the secondary electrons efficiently travel to the mirror 220 (the front plate 315 may include a very small positive bias).

[0039] Figure 3B A side view of the light guide assembly 250 is shown, illustratively, when the scanning electron microscope 120 is operating in a mode in which the chamber 203 has a pressure below 1 mbar. For example, the chamber 203 may have a pressure of approximately 0.5 mbar, which may require extending the distance between the sample 211 and the detector to generate a larger signal through cascade amplification. In this mode, the mirror 220 does not collect the secondary electrons 305. Instead, the secondary electrons 305 are collected and detected by a positively biased electrode 330, rather than a mirror 220 having a substantially neutral bias (which may include a very small negative bias). In the example described herein, the electrode 330 may be spaced a distance from the mirror 220, thereby providing additional time and space for cascade amplification. Furthermore, the light guide assembly 250 may include a front plate 315 having a substantially neutral bias (which may include a very small negative bias) with an aperture 317 through which the electron beam 207 and the secondary electrons 305 from the sample 211 pass.

[0040] Figure 4AA side view of the light-guiding assembly 250 is exemplarily shown when the scanning electron microscope 120 is operated in a mode in which the pressure in the chamber 203 is greater than about 1 mbar (in which the mirror 220 serves as a conversion electrode for backscattered electrons 309). For example, the backscattered electrons 309 are collected by the mirror 220, which includes a negative electrical bias, and generate converted secondary electrons 305' by known methods, which are released from the mirror 220. The converted secondary electrons 305' are then collected and detected by a front plate 315, which serves as a gas phase backscatter detector (GBSD) collecting electrode (e.g., having a substantially electrically neutral bias, but which may include a very small negative electrical bias). In Figure 4A In the example shown, electrode 330 may include a negative electrical bias.

[0041] Figure 4B illustratively shows a side view of the light guide assembly 250 when the scanning electron microscope 120 is operated in a mode in which the chamber 203 comprises a pressure below about 1 mbar. Figure 3B In an embodiment, chamber 203 may include a pressure at which it may be necessary to use cascade amplification to generate a larger signal, and thus the converted secondary electrons 305' may be collected and detected by electrode 330, which may include a substantially positive electrical bias (e.g., mirror 220 may include a substantially negative electrical bias, and front plate 315 may include a substantially neutral electrical bias and a very small negative electrical bias).

[0042] For the embodiments of 4A and 4B, the converted secondary electrons 305' can be further amplified by cascade amplification in the internal environment of the light guide assembly 250. For example, the internal environment of the light guide assembly 250 can be substantially the same as the environment within the chamber 203, which can include a high relative humidity (e.g., approximately 100% RH) when operating in the ESEM mode. Thus, by cascade amplification in the internal environment of the light guide assembly 250, the secondary electrons 305' traveling from the mirror 220 to the front plate 315 (e.g., Figure 4A as shown) or electrode 330 (as shown Figure 4B The number of converted secondary electrons 305' will increase.

[0043] In some embodiments, as Figure 4C As shown in the example of FIG, backscattered electrons 309 can be detected by detector 320, which can include any type of detector known in the art, such as a so-called solid-state detector. This performance may be desirable when the pressure in chamber 203 and light guide assembly 250 does not provide sufficient amplification between mirror 220 and front plate 315 and / or under high vacuum conditions. It should also be understood that two or more detectors 320 can be implemented in light guide assembly 250, for example, Figure 5, which provides a view from the bottom of the light guide assembly 250 (e.g., looking toward the electron column shoe 202 without the front plate 315). It is worth noting that in embodiments of the detector 320, it can be positioned to the side of the reflector 220 so that the paths of the secondary electrons 305 and / or backscattered electrons 309 from the sample 211 to the reflector 220 are not blocked by the detector 320. Furthermore, it may be desirable to position the detector 320 a certain distance above the front plate 315 to achieve better collection efficiency of the backscattered electrons 309.

[0044] It should also be understood that in some embodiments, the pressure in chamber 203 may vary, for example, Figure 3A -B, 4A-C and 5, the pressure can be higher or lower. In some cases, changes in pressure may have an impact on performance, but may also provide other advantages and are therefore considered within the scope of the invention. In addition, Figure 5 In the example of FIG, the reflector 220 is substantially elliptical in shape, but the reflector 220 may include any shape that effectively guides light from the light source 255 to the sample 211. It is also important that the shape of the reflector 220 effectively collects light (e.g., Raman emission or cathodoluminescence) from the sample 211 and guides the light to the detector 257. It is also desirable that the working distance within the light guide assembly 250 be as short as possible. Therefore, it is not difficult to understand that Figure 2 、 3A Examples 4-B, 4A-C, and 5 are for illustrative purposes and should not be considered limiting.

[0045] By describing various embodiments and implementations, it should be apparent to those skilled in the relevant art that the foregoing is illustrative and not restrictive and is presented as examples only. In the illustrated embodiments, many other solutions may be obtained by distributing the various functions among various functional elements. The functions of any element may be implemented in various ways in different embodiments.

Claims

1. An electron microscope system comprising: Electronic pole piece; and A light-guiding assembly is operatively coupled to the electron column shoe and includes one or more detectors, and a reflector including a pressure-limiting aperture through which an electron beam from an electron source passes, wherein the reflector is configured to reflect light, collect backscattered electrons and secondary electrons, and convert the backscattered electrons into secondary electrons.

2. The electron microscope system according to claim 1, further comprising: A chamber with a low vacuum environment is provided, wherein the electron column pole shoe and the light guide assembly are located in the chamber.

3. The electron microscope system according to claim 2, wherein: The electron beam reaches a sample located in the chamber, wherein the sample generates the backscattered electrons and the secondary electrons in response to the electron beam.

4. The electron microscope system according to claim 1, wherein: The light guide assembly is operatively coupled to a final lens of the electronic rod shoe.

5. The electron microscope system according to claim 1, wherein: The light guide assembly and the electronic pole piece are configured to be operatively coupled to a pressure seal.

6. The electron microscope system according to claim 5, wherein: The reflector provides the pressure seal for the electronic pole piece.

7. The electron microscope system according to claim 5, wherein: The light guide assembly and the intermediate element are configured to be operatively coupled to the pressure seal, and the intermediate element and the electronic post piece are configured to be operatively coupled to the pressure seal.

8. The electron microscope system according to claim 1, wherein: The mirror is configured to reflect light from the sample to a light detector.

9. The electron microscope system according to claim 8, wherein: The reflector is configured to reflect light from a light source toward the sample, wherein the light source comprises a laser or a light emitting diode (LED).

10. The electron microscope system according to claim 1, wherein: The light guide assembly further includes a collecting electrode configured to collect the converted secondary electrons.

11. The electron microscope system according to claim 10, wherein: The collecting electrode comprises a front plate, wherein the front plate comprises an aperture through which the backscattered electrons and secondary electrons travel to the reflector.

12. The electron microscope system of claim 1 , wherein: The light guide assembly also includes an electrode configured to collect secondary electrons.

13. The electron microscope system of claim 1 , wherein: The one or more detectors are configured to detect backscattered electrons, wherein the one or more detectors include one or more solid-state diode detectors.

14. A light guide assembly comprising: A reflector includes a pressure-limiting aperture through which an electron beam from an electron source passes, wherein the reflector is configured to reflect light, collect backscattered electrons and secondary electrons, and convert the backscattered electrons into secondary electrons.

15. The light guide assembly according to claim 14, wherein: The light guide assembly is operatively coupled to an electronic post piece and the reflector and the electronic post piece are configured to be operatively coupled to a pressure seal.

16. The light guide assembly according to claim 15, wherein: The mirror is configured as a final lens operatively coupled to the electronic pole piece.

17. The light guide assembly according to claim 14, further comprising: The reflector and the intermediate element are configured to be operatively coupled to a pressure seal, and the electronic pole piece to which the intermediate element and the light guide assembly are operatively coupled is configured to be operatively coupled to a pressure seal.

18. The light guide assembly according to claim 14, wherein: The electron beam reaches a sample located in a chamber comprising a low vacuum environment, wherein the light guide assembly and an electron column shoe to which the light guide assembly is operatively coupled are located within the chamber and the sample generates the backscattered electrons and the secondary electrons in response to the electron beam.

19. The light guide assembly according to claim 14, wherein: The mirror is configured to reflect light from the sample to a light detector.

20. The light guide assembly of claim 14, wherein: The reflector is configured to reflect light from a light source toward the sample, wherein the light source comprises a laser or a light emitting diode (LED).

21. The light guide assembly of claim 14, further comprising: The collecting electrode is configured to collect the converted secondary electrons.

22. The light guide assembly of claim 21, wherein: The collecting electrode comprises a front plate, wherein the front plate comprises an aperture through which the backscattered electrons and secondary electrons travel to the reflector.

23. The light guide assembly of claim 14, further comprising: An electrode is configured to collect secondary electrons.

24. The light guide assembly of claim 14, further comprising: One or more detectors are configured to detect backscattered electrons, wherein the one or more detectors include one or more solid-state diode detectors.

25. An electron microscope system comprising: Electronic pole piece; and A light-guiding assembly operatively coupled to the electron column shoe and comprising one or more detectors, and a reflector comprising a pressure-limiting aperture through which an electron beam from an electron source passes, wherein the reflector is configured to reflect light from a light source comprising a laser or a light-emitting diode (LED) to a sample and to reflect light from the sample to a light detector, and the reflector is further configured to collect backscattered electrons and secondary electrons and convert the backscattered electrons into secondary electrons.

26. A light guide assembly comprising: A reflector comprising a pressure-limiting hole through which an electron beam from an electron source passes, wherein the reflector is configured to reflect light from a light source comprising a laser or a light-emitting diode (LED) to a sample and to reflect light from the sample to a light detector, and the reflector is further configured to collect backscattered electrons and secondary electrons and convert the backscattered electrons into secondary electrons.

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