Temporal characterization of oscillator signals in charged particle microscopy

Abstract

To provide a charged particle microscope system for synchronizing various signals.SOLUTION: A method for characterizing a light beam in a charged particle column includes directing a light beam pulse toward a sample in a charged particle column, directing a charged particle beam pulse toward the sample, detecting charged particles that have interacted with the sample based at least in part on the light beam pulse and the charged particle beam pulse, determining a time delay between the charged particle beam pulse and the light beam pulse based at least in part on the charged particles, and determining at least one characteristic of the light beam pulse based at least in part on the time delay.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application claims priority to U.S. Provisional Application No. 63 / 645,747, filed May 10, 2024, the entire contents of which are incorporated herein by reference for all purposes.

[0002] FIELD OF THE DISCLOSURE Embodiments of the present disclosure are directed to charged particle microscope systems. More particularly, the present disclosure describes beam synchronization techniques in charged particle microscopy. [Background technology]

[0003] Charged particle microscopy can be used to study materials and structures that are either biological or inorganic in nature. Scanning and transmission electron microscopes (SEM / TEM) create images by focusing a beam of electrons and / or photons onto a target, such as a protein or semiconductor wafer. Some particles can interact with the target and convey information about the target to the microscope user. Some microscopy techniques may additionally use laser-based techniques in conjunction with the charged particle beam. When using laser-based techniques, photoemitter relaxation time characteristics, saturation effects, and residual emission are typically addressed by beam chopping methods. The use of a chopper / beam blanker in a TEM, in turn, involves active synchronization between two sources (pump and probe), each essentially having its own clock. Synchronization on the picosecond time scale presents significant challenges. Summary of the Invention

[0004] According to certain embodiments, a method for characterization of a light beam in a charged particle column includes directing a light beam pulse toward a sample in the charged particle column; directing a charged particle beam pulse toward the sample; detecting charged particles that have interacted with the sample based at least in part on the light beam pulse and the charged particle beam pulse; determining a time delay between the charged particle beam pulse and the light beam pulse based at least in part on the charged particles; and determining at least one characteristic of the light beam pulse based at least in part on the time delay.

[0005] According to some embodiments, the charged particle beam is a charged particle beam pulse and the light beam is a light beam pulse, and determining the time delay further comprises synchronizing the charged particle beam pulse with the light beam pulse and determining a plurality of time steps, the time step of the plurality of time steps representing a temporal offset of the charged particle beam pulse relative to the light beam pulse.

[0006] According to some embodiments, the light beam is a light beam pulse, and determining the time delay further comprises synchronizing the charged particle beam pulse with the light beam pulse and determining a plurality of time steps, wherein the time steps among the plurality of time steps represent a phase delay of the charged particle beam pulse relative to the light beam pulse.

[0007] According to some embodiments, the light beam is a light beam pulse including a temporal pulse profile, and the method further includes directing the charged particle beam through an energy dispersive spectrometer configured to generate detector data representative of an energy distribution of the charged particle beam, generating sets of detector data representative of a plurality of energy distributions for a corresponding plurality of time steps, and generating profile data using the sets of detector data, the profile data representative of the temporal pulse profile.

[0008] According to some embodiments, generating the set of detector data includes sampling the generated detector data concurrently with a period of interaction of the light beam and the charged particle beam, the detector data characterized by a sampling period that is approximately an order of magnitude smaller than a pulse duration represented by the at least one characteristic, the at least one characteristic being a temporal pulse profile of the intensity of the light beam.

[0009] According to some embodiments, the charged particle beam is a charged particle beam pulse, and generating the set of detector data includes integrating the detector data for a given time step using a plurality of charged particle pulses.

[0010] According to some embodiments, an operational parameter scheme corresponding to the at least one characteristic is generated, the operational parameter scheme representing one or more operational parameters of the charged particle beam system, the at least one characteristic including a temporal pulse profile of the intensity of the light beam.

[0011] According to some embodiments, determining at least one characteristic of the light beam includes measuring an effective pulse duration of the light beam using photon-induced near-field electron microscopy (PINEM) spectroscopy.

[0012] According to some embodiments, the method further includes characterizing the temporal intensity distribution of the light beam based at least in part on the effective pulse duration.

[0013] One or more machine-readable storage media having executable instructions stored thereon that, when executed, cause a charged particle beam system to perform operations including directing a light beam pulse toward a sample in a charged particle column; directing a charged particle beam pulse toward the sample; detecting charged particles that have interacted with the sample based at least in part on the light beam pulse and the charged particle beam pulse; determining a time delay between the charged particle beam pulse and the light beam pulse based at least in part on the charged particles; and determining at least one characteristic of the light beam pulse based at least in part on the time delay.

[0014] According to some embodiments, the charged particle column is a transmission electron microscope (TEM).

[0015] According to some embodiments, the charged particle column includes a radio frequency (RF) cavity configured to generate charged particle beam pulses.

[0016] According to some embodiments, the pulse frequency of the charged particle beam pulses is between about 25 MHz and about 100 MHz.

[0017] According to some embodiments, the operations further include coupling the light beam into an optically conductive material.

[0018] According to some embodiments, the operations further include adjusting a delay of a light beam pulse or a charged particle beam pulse towards the sample based at least in part on determining the at least one characteristic.

[0019] According to some embodiments, the operations further include adjusting an intensity, a frequency, or a phase delay of a light beam pulse directed toward the sample based at least in part on determining the at least one characteristic.

[0020] 1. A charged particle beam device comprising: one or more processors; and one or more machine-readable storage media operably coupled to the control circuitry, the media storing executable instructions that, when executed, cause the device to perform operations including directing a light beam pulse toward a sample within the charged particle beam device; directing a charged particle beam pulse toward the sample; detecting charged particles that have interacted with the sample based at least in part on the light beam pulse and the charged particle beam pulse; determining a time delay between the charged particle beam pulse and the light beam pulse based at least in part on the charged particles; determining at least one characteristic of the light beam pulse based at least in part on the time delay; and determining at least one characteristic of the light beam pulse based at least on the time delay.

[0021] According to some embodiments, the at least one characteristic of the light beam includes a characterization of a temporal asymmetry of the light beam.

[0022] According to some embodiments, the at least one characteristic of the light beam includes pulse duration or laser chirp.

[0023] According to some embodiments, at least one characterization is used to characterize one or more optical modes within the microresonator. [Brief explanation of the drawings]

[0024] The foregoing aspects and many of the attendant advantages of the present disclosure will become more readily appreciated as the same becomes better understood by reference to the following detailed description, when considered in conjunction with the accompanying drawings. [Figure 1] FIG. 1 is an exemplary schematic diagram illustrating an exemplary charged particle beam system, according to some embodiments of the present disclosure. [Figure 2] FIG. 1 is an exemplary schematic diagram illustrating a system for controlling a pulsed optical source and a pulsed charged particle source, according to some embodiments of the present disclosure. [Figure 3] FIG. 1 is an exemplary block flow diagram illustrating a technique for generating control signals in a pulsed light source and pulsed charged particle source system, according to some embodiments of the present disclosure. [Figure 4] 1 is an exemplary schematic diagram illustrating a technique for gating a pulsed charged particle source using a control signal from the light source, according to an embodiment of the present disclosure. [Figure 5] FIG. 10 is an exemplary composite diagram illustrating periodic operation of a beam blanker, according to an embodiment of the present disclosure. [Figure 6] 1 is an exemplary schematic diagram illustrating a technique for interrogating a pulsed light beam using a charged particle beam pulse, according to an embodiment of the present disclosure. [Figure 7] 10A-10C are a set of exemplary diagrams illustrating example data of different pulsed light beam profiles, according to embodiments of the present disclosure. [Figure 8] FIG. 1 is an exemplary block flow diagram illustrating an exemplary process for synchronizing and interrogating charged particle beam pulses and pulsed light beams, according to an embodiment of the present disclosure. [Figure 9] FIG. 1 is an exemplary block flow diagram illustrating an exemplary process for synchronizing and interrogating charged particle beam pulses and pulsed light beams, according to an embodiment of the present disclosure. [Figure 10] FIG. 1 is an exemplary block flow diagram illustrating an exemplary process for synchronizing and interrogating charged particle beam pulses and pulsed light beams, according to an embodiment of the present disclosure. [Figure 11] FIG. 1 is an exemplary block flow diagram illustrating an exemplary process for coarse and fine alignment of a charged particle beam and a pulsed light beam, according to an embodiment of the present disclosure. [Figure 12] FIG. 1 is an exemplary block flow diagram illustrating an exemplary process for synchronizing a charged particle beam and an amplified pulsed light beam, according to an embodiment of the present disclosure. [Figure 13] FIG. 1 is an exemplary block flow diagram illustrating an exemplary process for characterizing a light beam, according to an embodiment of the present disclosure. [Figure 14] 1 is an exemplary block system diagram according to an embodiment of the present disclosure. In the drawings, like reference numbers refer to like parts throughout the various views unless otherwise specified. To reduce clutter in the drawings where appropriate, not every instance of an element is necessarily labeled. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles being described. DETAILED DESCRIPTION OF THE INVENTION

[0025] While illustrative embodiments have been illustrated and described, it will be understood that various modifications may be made without departing from the spirit and scope of the present disclosure. The following paragraphs describe embodiments of charged particle beam systems, components, and methods for synchronizing pulsed beams of photons and charged particles in systems including such subsystems. For simplicity of explanation, the embodiments of the present disclosure focus on transmission electron microscopes and related instruments. To that end, the embodiments are not limited to such systems, but rather are contemplated for charged particle beam systems configured for use in “ultrafast” techniques for probing sample dynamics on relatively short timescales (e.g., picosecond, femtosecond, etc.). Advantageously, synchronization of pulsed light beams and charged particles can improve the performance of ultrafast microscopy techniques, at least in part, by decoupling the light source from the charged particle source (e.g., by using an RF resonant cavity to generate charged particle beam pulses rather than an optically excited photoemitter). Furthermore, independent control of the pulsed light beam and the charged particle beam pulses allows the time delay to serve as an independent variable in a variety of techniques for optical interrogation of materials (e.g., microcavities) and for the temporal characterization of the pulsed light beam itself.

[0026] In charged particle microscopy, characterizing various parameters of a target (e.g., a circuit, a wafer, a biological sample, etc.) can involve probing the target with a charged particle beam, such as an electron beam. The electrons can interact with the target and may be detected by a detector for analysis and review. Typically, the process of characterizing the target requires multiple cycles of pulsing the electron beam at the target to acquire an image. Thus, imaging in charged particle microscopy is typically based, at least in part, on elastic interactions between electrons and the target. These elastic interactions may not result in energy gain or loss and can provide information about the structure and bonding of the target. In contrast, inelastic interactions involve a loss of energy due to electron excitation within the target and are investigated with electron energy loss spectroscopy (EELS).

[0027] In a UTEM, a light beam (e.g., a laser) is applied on a short time scale, often on the order of femtoseconds (10 -15 Lasers are used to study dynamic processes in the femtosecond (fs) range. One function of lasers is to provide ultrafast excitation to the sample. Synchronized electron pulses can be used for imaging during illumination, thereby enabling the capture of transient states and how the sample evolves in real time. Achieving synchronization between the laser and electron beams in a UTEM presents technical challenges, particularly in the context of time-resolved EELS. Precise temporal alignment between the light pulse used to excite the sample and the electron pulse used for spectroscopic interrogation is necessary to elucidate dynamic phenomena on the femtosecond time scale. Deviations in synchronization can reduce time resolution and impair the ability to accurately capture transient states within the sample. Even slight variations in the timing of either the light excitation or the generation of the electron pulse can result in time mismatches, thereby affecting the accuracy of the EELS measurement and limiting the system's ability to elucidate ultrafast dynamics.

[0028] Maintaining stability and coherence in both the laser and electron pulses poses an even greater challenge. For time-resolved EELS spectroscopy, ultrafast lasers produce highly stable pulses on the order of femtoseconds, while the electron pulses retain a consistent energy distribution and shape. External factors such as thermal drift, mechanical vibrations, and electronic noise can introduce jitter or temporal drift into either the laser and / or electron pulse trains. Such instabilities can disrupt synchronization and reduce the reliability and accuracy of the spectroscopy data.

[0029] Embodiments of the present disclosure can tightly synchronize the arrival times of charged particles and laser pulses at the sample with sub-picosecond jitter and vary the repetition rate to match the detected sample response.

[0030] According to embodiments described herein, techniques are provided for synchronizing various signals. For example, a radio frequency (RF) cavity may generate charged particle pulses, and a laser oscillator may generate optical beam pulses, which may operate at approximately the same frequency. Synchronizing the charged particle pulses and the optical beam pulses involves ensuring that the charged particle pulses and the optical beam pulses are operating at exactly the same frequency and controlling the phase and / or time delay between the charged particle pulses and the optical beam pulses. Synchronization is achieved by mixing signals from an RF driver coupled to the RF cavity and an optical driver coupled to the light source to generate a “coarse” or “rough” beat signal for these two signals. The mixed signal may be used as feedback to the optical driver to synchronize the optical driver with the RF cavity. Additionally, “fine” or “precise” synchronization may be implemented by switching harmonic frequencies of signals from either the RF driver or the optical driver to minimize the time / phase delay between the two signals. In some embodiments, a beam blanker may receive a signal from the optical driver to control blanking, and a signal may be sent to the optical driver based on the signal from the RF driver.

[0031] According to embodiments described herein, a pulse picking technique is provided to adjust the repetition rate of the charged particle beam. This adjustment can be performed after synchronization is performed as discussed above. In this manner, the light source can emit amplified light beam pulses as a function of the response time of the beam blanker and / or the sample. The delay generator can receive a signal and trigger the beam blanker to rapidly unblanket the charged particle beam so that the charged particle beam pulse reaches the sample only when the amplified light beam pulse is emitted toward the sample. In this manner, the beam blanker can operate with a fixed time delay relative to the RF cavity by receiving a signal from the optical driver, and the trigger signal has an inverse time delay so that the beam blanker blanks the charged particle beam when the light source is not emitting, so that the sample is simultaneously interrogated by both the charged particle pulse and the light beam pulse.

[0032] According to the embodiments described herein, temporal characterization of a light beam can be performed. For example, a charged particle pulse and a light beam pulse can interact in a sample, which can lead to the splitting of the charged particle energy distribution into multiple sidebands. The more intense the light beam, the broader the energy spectrum can be. The time delay between the laser and the charged particle beam can then be measured to generate a temporal profile of the light beam intensity. This output can reflect the true asymmetric temporal profile of the light beam, while conventional devices can only provide symmetric profiles. These techniques are not only applicable to free space, but can also be usefully extended to light pulses in photonic nanostructures. Information obtained from the temporal characterization of a light beam can be useful for interpreting probe experiments performed in charged particle microscopes.

[0033] Advantageously, embodiments of the present disclosure may allow the repetition rate of the electron pulses to be reduced to any frequency (e.g., set by the laser system) while maintaining the pulse characteristics and timing precision of the RF cavity-generating pulses. In contrast, the electron pulse frequency of conventional photoemission-based ultrafast TEM is determined by the pulse frequency of the laser beam delivered to the photocathode. Such technology is limited by the challenges of optical delay lines, discussed with reference to the discussion above.

[0034] I. Exemplary System charged particle beam system FIG. 1 is a schematic diagram illustrating an exemplary charged particle beam system 100 according to some embodiments of the present disclosure. In the following description, details of the internal components and functions of the exemplary system 100 are omitted for brevity and to focus on the embodiments of the present disclosure. The exemplary system 100 includes a charged particle source section, a TEM column (e.g., a charged particle column) including the charged particle source section 105, a TEM column 110, an objective section 115, and an imaging section 120 (e.g., with an electron energy loss spectrometer 125). The exemplary system 100 includes one or more components to enable “ultrafast” operation, such as a radio frequency (RF) cavity 130, a beam blanker 155, and one or more light sources 160. In the context of the present disclosure, “ultrafast” operation refers to a TEM system configured to generate detector data on the picosecond time scale, for example, through the use of a pulsed beam for stroboscopic analysis. As such, the relative positions and order of the RF cavity 130 and the beam blanker 155 may vary in different embodiments of the present disclosure. For example, RF cavity 130 can precede beam blanker 155, and components can be located at different locations within exemplary system 100 for various approaches to producing a pulsed beam of electrons.

[0035] The charged particle source section 105 may include electronics configured to activate a charged particle source, which may include a high-voltage field emission source or other source of emitted electrons, so that an electron beam is formed and conducted through vacuum into the TEM column 110. The electron beam may be modulated using a beam blanker 155 to generate a train of pulses. The pulses may be generated by repeatedly deflecting the beam according to a trigger signal provided to the beam blanker, as described in more detail with reference to FIGS. 2-8. The beam blanker 155 may be an electrostatic or electromagnetic element. In some cases, the relaxation time of the magnetic field may limit the compatibility of electromagnetic elements with ultrafast operation. To that end, embodiments of the present disclosure may include an electrostatic beam blanker configured to periodically interrupt a continuous electron beam as an approach to generate a train of pulses characterized by frequencies between about 1 kilohertz (kHz) and about 100 megahertz (MHz).

[0036] The RF cavity 130 can be positioned downstream of the beam blanker 155 relative to the charged particle source section 105 such that the train of pulses passes through the body 135 of the RF cavity 130 through an aperture 140 defined in the body 135. The aperture 140 is substantially centered relative to a beam axis of the exemplary system 100, and the components of the RF cavity 130 are arranged substantially symmetrically about the axis. The RF cavity 130 can include one or more antennas 150 disposed within the body 135. The antennas 150 can be electrically coupled to an RF power circuit and used to drive the antennas 150 at one or more RF frequencies. The antennas 150 can be disposed within a dielectric or insulating insert 145 substantially concentric with the aperture 140. The behavior of the RF field within the aperture, such as the location of standing waves, can be based at least in part on the various distances 137, 139, 141, 151 of the components of the RF cavity. For example, the distance 151 between the antennas 150 can affect the interaction of the two RF fields when each antenna can be driven at a respective RF frequency. The RF cavity 130 can be described in more detail in U.S. Patent US11328892B2, European Patent EP3772745A3, and Korean Patent KR102586724B1 and Korean Patent Application KR20230127968A, as well as Japanese Patent JP7378366B2 entitled "Coating on dielectric insert of a resonant RF cavity," and Chinese Patent CN112349571B entitled "Radio frequency cavity and apparatus and system for use in charged particle microscopy," the disclosures of which are incorporated herein by reference in their entireties.

[0037] The RF cavity 130 can be configured as a "dual-mode" cavity, supporting two resonant modes at slightly offset field frequencies in the 1 to 5 gigahertz (GHz) range, including fractions, subranges, and interpolations thereof. The difference between the frequencies can result in a relatively low-frequency deflection of charged particles across a downstream aperture (e.g., at about 75 MHz). The RF cavity 130 can include a pickup antenna so that a second frequency at a higher harmonic of the relatively low frequency can be derived from a signal from the pickup antenna inside the RF cavity. Advantageously, using a signal from the pickup antenna can reduce the effects of drift and instability in the RF cavity and associated drive circuitry, based at least in part on a synchronization signal derived from the actual field inside the RF cavity 130. However, in some cases, an electrostatic beam blanker with a bandwidth in the GHz range can be used with a single-mode RF cavity operating at about 1 GHz to about 5 GHz (e.g., about 2.4 GHz). The beam blanker can directly modulate the electronic pulses of a 2.4 GHz pulse sequence.

[0038] The TEM column 110 includes beam-forming components, including electromagnetic and / or electrostatic lenses, as well as multiple apertures for controlling the electron beam characteristics. The components of the TEM column 110 include, among others, a condenser lens, an objective lens, a projector lens, an aberration corrector, a deflector, a stigmator, and corresponding apertures. The objective section 115 houses a sample through which the electron beam can pass. The sample section can include one or more types of detectors, such as an X-ray detector, a secondary electron detector, etc.

[0039] The objective section 115 also includes an optical coupling 163 (e.g., via a connector 161) with a light source 160, which allows photons to be introduced into the vacuum environment of the system 100 and directed toward the sample. In some cases, the light source 160 includes a fiber laser. The light source 160 can be coupled to the objective section 115 via an optical fiber. In some embodiments, the light source 160 is optically coupled to the objective section 115 via one or more optical elements (e.g., optical mirrors, lenses, irises, filters, etc.). Similarly, embodiments of the present disclosure include systems in which the optical coupling 163 is included as part of the charged particle source section 105 or in the TEM column 110 outside of the objective section 115. In this manner, the exemplary system 100 can include one or more optical elements positioned within the system to direct and transform a light beam toward the sample.

[0040] The light source 160 may include a laser including an oscillator and an output stage. The oscillator may be configured to generate optical pulses at a given frequency (e.g., approximately 75 MHz) characteristic of the oscillator design. The output stage may include a gain medium, which may also include a switch for determining which pulses are actually output from the oscillator (e.g., one out of every N pulses from the oscillator). In this manner, as described in more detail with reference to FIGS. 2-5, the switch may be employed as a "pulse picker," and the switching signal may act as a trigger signal that may be used to modulate the beam blanker 155.

[0041] A state-of-the-art TEM column 110 can have as many as four focusing lenses for flexible (e.g., stepwise or progressive) demagnification and focusing of the electron beam on the sample, as many as five projector lenses for flexible expansion of the electron beam downstream of the sample relative to the detector, and as many as two aberration correctors. State-of-the-art aberration correctors can include additional lenses and multiple multipoles (e.g., four lenses and two to three or more multipoles), so that a modern TEM column 110 can include up to about 20 lenses. The coordinated action of the collection of lenses and other optical elements results in a predetermined demagnification at the sample and magnification at the detector.

[0042] The imaging section 120 includes one or more types of detectors, sensors, screens, and / or optics configured to generate images, spectra, and other data for use in sample imaging and / or microanalysis. For example, the imaging section may include, among others, a scintillator screen, binoculars, a transmission electron microscopy (TEM) detector (e.g., a pixelated electron detector, a secondary electron detector, a camera), a segmented STEM detector, and an electron energy loss spectroscopy (EELS) spectrometer 125. The EELS spectrometer 125 functions as an energy filter by, at least in part, focusing the electron beam onto an electrostatic or magnetic dispersive element (also referred to as a "prism") that applies a force to the electrons proportional to their velocity. In this way, electrons that transfer energy to or from the sample (e.g., by inelastic collision) can be redirected through the magnetic dispersive element toward the detector. The detector may include a pixelated detector (e.g., a CCD device configured to detect electrons) that generates one- or two-dimensional EELS data from which an EELS spectrum can be derived. In some embodiments, the EELS spectrometer 125 includes one or more optical elements, such as electromagnetic or electrostatic lenses and / or multipoles and / or accelerators, for conditioning and / or focusing the scattered electrons onto a detector.

[0043] Embodiments of the present disclosure relate to ultrafast electron microscopy in a TEM system, an example of which is described with reference to FIG. 1. FIGS. 2-10 relate to techniques for improving the performance of a TEM system in ultrafast mode, including techniques for synchronizing the electron beam pulser of an RF cavity (e.g., RF cavity 130 in FIG. 1) with a laser system (e.g., light source 160 in FIG. 1). The goal of this technique is to reliably phase-lock the laser signal and the electron beam signal. Another goal is to achieve a controllable time delay between the pump light beam pulse directed at a sample in the TEM and the electron pulse for probing the same sample.

[0044] In current technology relying on photoelectron emitters for laser-based ultrafast TEM, synchronization between the pump and probe of the setup is achieved by an optical circuit that splits a light beam pulse into a pump pulse and a probe pulse, one of which is used to directly illuminate the sample, while the other is used to stimulate photoemission and produce synchronized electron pulses. Disadvantages of laser-based techniques include photoemitter relaxation time characteristics, saturation effects, and residual emission, which are typically addressed by beam chopping methods. The use of a chopper / beam blanker in a TEM, in turn, essentially involves active synchronization between the two sources (pump and probe), each with its own clock. Synchronization on the picosecond time scale presents significant challenges.

[0045] An embodiment of the present disclosure addresses the synchronization challenge, at least in part, by mixing signals coming from both sources, thereby deriving a signal that scales with the time offset between the two signals, as illustrated in FIG. 3, and adjusting the length of the laser oscillator (e.g., through one or more piezo positioners) in a control loop to eliminate the time offset.

[0046] b. Signal control components FIG. 2 is an exemplary schematic diagram illustrating a system 200 for controlling a pulsed optical source and a pulsed charged particle source according to some embodiments of the present disclosure. A detailed example of this example technique, described with reference to FIGS. 2 and 8, includes using an RF signal from an RF cavity module (e.g., RF driver 305) to derive output signals for at least two frequencies, where a first frequency ("F" in FIG. 3) corresponds to the frequency of the optical source 160 and a second frequency is a harmonic of the first frequency ("H" in FIG. 3). An exemplary technique includes electronically mixing both signals with a corresponding signal from an optical beam system (e.g., optical driver 310), which may be a laser. An exemplary technique includes using a first (low-frequency) signal to define a coarse phase lock between the electronic signal and the laser signal.

[0047] 3 is an example block system 300 illustrating a technique for generating a control signal in a pulsed optical source and pulsed charged particle source system according to some embodiments of the present disclosure. As shown in FIG. 3, mixing two signals at a first frequency involves vector multiplication of the two signals to define an error signal, which can form the basis of a feedback control scheme that includes one or more parameters of the laser or reference signal 315 as control variables. Each vector multiplication symbol

number

[0048] Optimization of the error signal can be achieved through one or more control methods, such as a PID-style feedback control model using the error signal as the control variable and the characteristic length of the laser oscillator as the modulation variable, with a zero setpoint for the error signal within a tolerance. Optimization of the first error signal can correspond to a "coarse" synchronization of the laser and RF signals, after which the control technique transitions to the second frequency (H) signal for phase lock. In some embodiments, an electronic time delay is applied to one of the two high-frequency signals (e.g., the RF harmonic signal or the laser / optical harmonic signal). Two second frequency signals, one of which includes a time delay, can be used to generate the error signal. The error signal can be used to generate a feedback signal to one or more piezos in the laser oscillator so that the oscillator output remains locked to the reference signal 315. As shown in FIG. 3, the reference signal can be mixed with the second frequency (H) signal. Advantageously, one of the reference signals carries an electronic time delay (e.g., delay circuit 320). The reference signal can have a frequency between about 1 MHz and about 100 MHz, including subranges, fractions, and interpolations thereof. In some examples, the default method for varying the time delay is to apply an electronic time delay to one of the frequency signals (e.g., the higher of the frequency signals). Additionally, or alternatively, for relatively small time delays, the variation can involve adding a DC offset to the error signal. Adding a DC offset can be used to scan the time delay with high precision over a small range (±1 to 2 picoseconds (ps)).

[0049] In some embodiments, the first frequency is different from the frequency of the field inside the RF cavity and / or the frequency of the cavity's action on the electrons. The first frequency can also be a submultiple of either. For example, the first frequency can be equal to the frequency of the laser oscillator, but it can also be a multiple of the frequency of the laser oscillator (e.g., in view of the above discussion, if a fast beam blanker is used to achieve equal values ​​for the frequencies of the electron pulses and the light pulses). In this case, the first frequency (F) can be a fraction (e.g., about 75 MHz) of both the frequency of the field inside the cavity and the frequency of the cavity-generating electron pulses.

[0050] In practice, synchronization can be achieved using actuator control 330, at least in part, by a) modifying signal generator 205 (e.g., RF driver) to provide, in addition to the 75 MHz synchronization signal, an additional synchronization output of approximately 600 MHz derived from a 2.4 GHz master optical pulse signal; b) using a tunable pulsed laser module (e.g., light source 160) that includes synchronization controller 220 electronics; and c) connecting the RF synchronization output to the respective 75 MHz and 600 MHz synchronization inputs of light source 160's controller 220.

[0051] Advantageously, the techniques of the present disclosure eliminate the need for optical delay lines in the laser path, providing nominally consistent optical beam pulse characteristics on the sample. Furthermore, implementing the systems / diagrams 200, 300 illustrated in Figures 2 and 3 has little or no impact on the performance of the RF subsystem due to phase-locking. Additionally, the time delay can be selected and / or defined electronically, removing the physical constraints on the length of the time delay imposed by physical time-delay optics (e.g., allowing for potentially unlimited time delays unconstrained by the length of the delay line). Finally, the techniques of the present disclosure, while enabling higher frequency locking for better accuracy, may also result in false convergence for systems with multiple stationary points by starting from the base frequency of both systems.

[0052] While the general concept of RF and laser synchronization has been described, a significant limitation of existing methods is that the time delay is introduced using an optical delay line. Therefore, the time delay is typically implemented in one of the branches (optical delay line or RF phase shifter). Optical delay lines have the disadvantage that varying the delay inevitably affects the positioning and / or focusing of the laser beam on the sample, causing alignment and optical stability challenges. Similarly, phase shifters in the RF signal path can adversely affect the amplitude and / or phase stability of the RF signal, requiring recalibration of the TEM system's internal components. Another drawback of some systems is the need for deep integration between the laser system and the RF driver, limiting flexibility in component selection, which in turn requires dedicated TEM systems rather than flexible ultrafast modes.

[0053] To that end, embodiments of the present disclosure include "multimode" TEM systems, including ultrafast modes, that use an RF cavity and a dual-mode cavity (e.g., producing a beat frequency within the range of a typical laser oscillator) for beam chopping and / or a pickup antenna inside the RF cavity to generate a synchronization signal. In some embodiments, a pickup antenna inside the RF cavity is used to generate a synchronization signal directly from the actual standing wave of one of the modes within the cavity, thereby mitigating some sources of timing uncertainty in the RF module. This can be augmented by using a higher harmonic second frequency (e.g., higher than 600 MHz) for fine phase locking (e.g., mode selector 325 in FIG. 3). For example, using a 1.2 GHz harmonic frequency can reduce the variance of the error signal and allow pointing correction of the laser beam (before it hits the photodiode), in addition to and / or instead of reducing instability in both types of signals (e.g., using a more stable RF source). The error signal can also be used to estimate instability between RF and laser timing.

[0054] c. Charged particle beam control 4-5 relate generally to ultrafast TEM and to the use of an RF cavity-based electron beam pulser in combination with an amplified laser system, as described in more detail with reference to FIGS. 1-3. In some cases, the amplified laser system generates a pulsed light beam at a given pulse rate, and a subset of the pulses are amplified. To that end, embodiments of the present disclosure enable a pulsed particle beam system to match the repetition rate of the charged particle beam pulses with the amplified output of the pulsed laser system at any repetition rate.

[0055] 4 is an exemplary schematic diagram 400 illustrating a technique for gating a pulsed charged particle source using a control signal from a light source, according to an embodiment of the present disclosure. A resonant RF cavity 401 can operate at a substantially fixed frequency within a tuning range and can receive a charged particle beam 410. The RF cavity can be synchronized with the light source 160, as described in more detail with reference to FIGS. 2-3, and can be tuned such that the electron pulse frequency and the light beam pulse frequency can be synchronized to any pulse frequency over a relatively wide frequency range through the application of an adjustable amplifier (e.g., signal generator 205) for the pulsed laser system and a beam blanker for the charged particle beam pulses 415, as described in more detail with reference to FIG. 1.

[0056] To that end, a beam blanker 420 (e.g., beam blanker 155 of FIG. 1) can be used as a pulse picker to sample a subset of charged particle beam pulses 435 generated by the resonant RF cavity 401. The beam blanker 420 can include a voltage supply 430 coupled to the electrode 425 via an electrode 425, a radio frequency switch 431 that can be coupled to an amplifier of the laser system, and / or via a common signal generator configured to generate a trigger signal for the laser amplifier and the switch 431. In this manner, the beam blanker 420 can be synchronized with the laser amplifier or shutter, or can have both the pulse picker and the laser amplifier or shutter synchronized to a common trigger signal.

[0057] An exemplary process (e.g., FIG. 9) involves generating charged particle beam pulses from a continuous electron beam using an RF cavity 401 or another radio frequency beam modulator. The exemplary process also involves using a radio frequency beam blanker (e.g., an electrostatic beam blanker) or a second beam modulator as a "pulse picker." In this context, "pulse picker" refers to the action of an optical element to periodically block the passage of electron pulses by deflecting the pulses into a beam block, aperture 440, etc., according to a trigger signal.

[0058] An exemplary process also includes synchronizing an RF cavity synchronized to the laser oscillator, as described above and with reference to Figures 2-3. The RF cavity 401 can be configured to generate pulses at a repetition rate equal to or a multiple of the frequency of the laser oscillator. The pulses can be subsampled by controlling a pulse picker (e.g., beam blanker 420) to open at the same repetition rate as the amplified output of the laser, at which point one or more electronic pulses can be passed through.

[0059] In a typical femtosecond pulse laser design, the amplified laser output frequency is an exact submultiple of the oscillator frequency so that exactly 1 in N pulses is amplified, where N is an integer greater than 1. In this way, the laser amplifier and pulse picker can be synchronized to a common trigger signal, but the pulse picker can also be synchronized to a signal from the laser. Once the pulse picker is synchronized to the laser, an "inverse" time delay variation can be applied to the pulse picker to account for the time delay of the laser relative to the RF signal. Advantageously, the "inverse" time delay reduces or eliminates pulse picking instabilities.

[0060] FIG. 5 is an exemplary composite diagram 500 illustrating the periodic operation of a beam blanker, according to an embodiment of the present disclosure. The time delay output from the delay generator can be configured to trigger an electrostatic beam blanker (ESBB) driver. The trigger signal can be synchronized with the laser's amplifier and / or shutter, allowing the amplified output of the laser to be used at any sub-frequency. In some cases, when accommodating the hardware's response time limitations, the trigger signal can unblanket the beam blanker in time for the next laser pulse, which arrives a known period after the current pulse. A time delay of about 10 nanoseconds (ns) to about 500 ns can improve the temporal overlap of the "picked" electron pulse and the light beam pulse on the sample, although this time delay depends on various experimental parameters. In some embodiments, the time delay can be approximately equal to the time between subsequent light beam pulses (e.g., about 9.07 microseconds for a pulse frequency of about 110.3 kHz) plus a fixed offset of about -10 ns to about -1000 ns. This represents an "inverse time delay," where a positive delay is applied to the beam blanker, but results in a negative time delay for the next laser pulse (e.g., the next photon beam pulse). For long scan time delays, the RF pulse is time delayed with respect to the optical beam pulse (e.g., a negative relative delay of the laser pulse), so the ESBB time delay can be adjusted accordingly.

[0061] In this way, the time delay between the RF and laser outputs can be delayed in time by a given value (e.g., positive), and an opposite (e.g., negative) time delay can be applied between the laser and fast beam blanker, with the net result being that the RF beam pulser and beam blanker remain synchronized, provided that the electron pulse and light beam pulse are time-shifted relative to each other. Within a relatively narrow range of the time delay between the pulsed light beam and the electron pulse, the time delay between the laser and charged particle beam system can be static. However, for time delays on the order of, for example, the oscillator period or larger, the pulse picker time delay can be "scanned" relative to the laser signal to ensure that the RF beam pulser and beam blanker remain synchronized.

[0062] d. Charged particle beam and light beam technology FIG. 6 is an exemplary schematic diagram 600 illustrating a technique for interrogating a pulsed light beam using charged particle beam pulses, and FIG. 7 is an exemplary set of schematic diagrams 700 illustrating exemplary data of different pulsed light beam profiles, according to embodiments of the present disclosure. FIGS. 6-7 relate to ultrafast TEM in general and to the use of an RF cavity-based electron beam pulser in combination with a light beam source (which may be an amplified light source), as described in more detail with reference to FIGS. 1-5 . In some cases, an amplified laser system generates a pulsed light beam having a temporal pulse profile 625 (and an example is shown in FIG. 7 ) that can be controlled, at least in part, based on operating parameters of the amplified light source. To that end, embodiments of the present disclosure enable charged particle beam pulses to interrogate the temporal profile of pulses being generated by the laser system.

[0063] To that end, a process for interrogating a light beam pulse (e.g., FIG. 13 ) involves superimposing a charged particle beam pulse 601 with a light beam pulse 605 on a sample 615, for example, in a TEM configured for ultrafast operation. Inelastic scattering of an electron beam through the light beam pulse 605 generates a subset 610 of charged particles with modified energy levels that are received at an EELS spectrometer 645 (which is an example of the EELS spectrometer 125 for FIG. 1 ) and directed (along B) toward a detector (not depicted). The detector allows pulse profiles 630, 635 to be derived over multiple pulse measurements based, at least in part, on scanning relative time delays to sample the pulse profile over a series of time steps, using the principles of photon-induced near-field electron microscopy.

[0064] Photon-induced near-field electron microscopy (PINEM) allows for the investigation of time-varying nanoscale electromagnetic fields in an electron microscope, enabled on the picosecond timescale using ultrafast TEM. For visible light, inelastic coupling between electrons and light is physically prohibited in free space but is made possible by confining near-field radiation on a surface or nanostructure. In PINEM, confinement on the sample 615 generates a transiently confined near-field with a broad momentum distribution, reaching high intensities in the nanoconfined space and thus also increasing the cross-section of electron-light coupling. In this manner, the disclosed process involves recording a PINEM spectrum and scanning the time delay between the electron and light beam pulses to record one or more additional spectra. Together, the PINEM spectrum is used to measure the effective pulse duration of the laser pulse and can be used to characterize the temporal intensity distribution of the pulsed laser. This method allows for a complete characterization of the temporal profile of the laser intensity.

[0065] Traditionally, autocorrelators are used to characterize ultrashort (e.g., picosecond-to-femtosecond) optical beam pulses. A drawback of autocorrelators is that the time scale has no "sign" and the output is always symmetric about the peak intensity (e.g., the time of maximum overlap). This limitation, which compromises the flexibility and robustness of ultrafast systems, can be addressed by cross-correlating the optical beam pulse signal with a different signal, such as an electronic pulse signal.

[0066] For example, the amplified output of a pulsed laser can be used for PINEM experiments. If the laser system has a built-in pulse compressor in the laser's amplified output path, variations in final pulse duration from approximately 100 femtoseconds (fs) to approximately 100 picoseconds (ps) can be applied. Using time-delay scans of the optical beam pulse at various compressor settings, PINEM spectra of varying widths can be collected as a function of relative time, representing intensity fluctuations during the laser pulse. In contrast, commercially available autocorrelators capable of characterizing the temporal profile of optical beam pulses always produce symmetric outputs that lack information about the temporal asymmetry of the laser pulse. Advantageously, information about the asymmetry of optical beam pulses can improve the accuracy and precision of microanalysis involving ultrafast optical beam pulse exposures. To that end, the disclosed techniques include processes for deriving the temporal intensity profile of one or more optical beam pulses, as well as the pulse duration and laser chirp. Laser chirp can be measured, for example, by varying the peak separation of the PINEM spectrum as a function of time delay. The techniques of the present disclosure can be extended to applications in photonics and functional materials. In an illustrative example, optically active materials can be investigated using the described pulsed beam technique as an approach to temporally characterize one or more optical modes in a microresonator. Optical modes include solitons or pulses that give rise to frequency combs. Measuring the temporal properties of optically active materials relies on synchronization of electronic pulses to the modes of the microresonator being investigated and can benefit from relatively short pulse durations to improve the temporal resolution of the mode shapes.

[0067] II. Exemplary Processes a. Signal Synchronization Process Synchronizing light beam pulses with charged particle beam pulses in transmission electron microscopy (TEM) is technically challenging. These challenges stem from inherent differences in how light beam pulses and charged particle beam pulses are generated, directed, and / or modulated. While light beam pulses (e.g., generated by laser oscillators) can operate at high frequencies with femtosecond-scale precision, charged particle beams, such as charged particle beam pulses, are limited by the charged particle beam source, beam blanker, and switching electronics. Achieving synchronization requires a precise timing control system that aligns light beam pulses and charged particle beam pulses from both sources with respect to phase, duration, frequency, and arrival time at the sample. Misalignment can occur due to trigger signal jitter, beam path length variations, and / or differences in pulse duration.

[0068] If the light beam pulse and the charged particle beam pulse are not synchronized, the sample can be affected in several ways. For pump-probe experiments, synchronization ensures that the light beam pulse excites the sample substantially simultaneously with the arrival of the charged particle beam pulse, allowing images and video to be captured in real time. Without synchronization, the charged particle beam pulse may interrogate the sample before or after the light beam pulse-induced excitation occurs, resulting in incomplete and / or misleading data regarding the intermediate (e.g., transient) state of the sample. This can lead, for example, to misinterpretations (by the user or machine) of the sample's structural or thermal properties. Additionally, or alternatively, asynchronous pulses can cause repetitive or uneven energy delivery to the sample, potentially damaging sensitive materials or inducing thermal effects that obscure results.

[0069] Lack of synchronization can also lead to significant time inefficiencies in experimental workflows. When a sample receives excitation from an asynchronous pulse, it may not immediately return to its equilibrium state, requiring a waiting period for relaxation before the next pulse sequence can be applied. This waiting time accumulates over the course of an experiment, slowing data collection, reducing throughput, and increasing production time and costs. Additionally, repeating measurements multiple times to address inaccuracies caused by asynchronous pulses can add additional time. Synchronizing the arrival of light beam pulses and charged particle beam pulses can reduce the time spent performing analysis of a sample, improving the quality of the analysis and reducing the processing power required to perform an experiment.

[0070] FIG. 8 is an exemplary block flow diagram illustrating an exemplary process 800 for synchronizing and interrogating a charged particle beam pulse and a pulsed optical beam according to an embodiment of the present disclosure. In some examples, process 800 may be performed by some or all components of systems, devices, and / or include processes, methods, or techniques, such as those described in connection with FIGS. 1-7 and 9-14. In some embodiments, process 800 may include more or fewer steps than depicted in FIG. 8. It should be understood that the steps may be performed in any suitable order. Process 800 begins with step 805, which involves aligning and / or synchronizing a pulsed electron beam with a pulsed optical beam (e.g., a pulsed photon beam), as illustrated with respect to FIGS. 1-6. Process 800 may include synchronizing an RF signal and an optical pulse signal. Process 800 may include generating a composite signal 810 using the RF signal, the optical pulse signal, and a reference signal. Process 800 may also include aligning and / or synchronizing a composite signal 815.

[0071] In some embodiments, the RF signal represents a frequency generated by the action of an RF cavity on the electron beam. The action of the RF cavity on the electron beam can include sweeping the electron beam 820 (e.g., a charged particle beam pulse) across an aperture disposed in the path of the electron beam. The pulse frequency of the light pulse signal (e.g., a pulsed light beam) 825 can range from about 25 MHz to about 125 MHz.

[0072] In some embodiments, the RF signal and the optical pulse signal are frequency matched. A frequency matched signal may correspond to a condition where a first harmonic frequency of the RF signal is substantially equal to a first harmonic frequency of the optical pulse signal.

[0073] In some embodiments, synchronizing the RF signal and the optical pulse signal includes generating an error signal using a first harmonic frequency component of the RF signal and a first harmonic frequency component of the optical pulse signal. Synchronizing the RF signal and the optical pulse signal can also include modifying one or more parameters of the pulsed light source as part of optimizing the error signal. Generating the error signal can include generating a vector product of the RF signal and the optical pulse signal and filtering the vector product to remove high-frequency components of the vector product. The high-frequency components can include harmonic frequencies higher than the fundamental frequency component.

[0074] In some embodiments, the pulsed light source is a pulsed laser source. The one or more parameters can include a characteristic length of a laser oscillator of the pulsed laser source. The characteristic length can represent a path length of the oscillator between two reflectors, one or more of which are movable relative to the gain medium.

[0075] In some embodiments, generating the composite signal includes generating the RF composite signal using a vector product of a harmonic frequency component of the RF signal and a reference signal, and generating the optical composite signal using a vector product of a harmonic frequency component of the optical pulse signal and a reference signal. The harmonic frequency may refer to a harmonic order higher than the first or fundamental frequency. Generating the optical composite signal may include adding a time delay to the vector product of the harmonic frequency component of the optical pulse signal and the reference signal. The time delay may be a variable time delay.

[0076] In some embodiments, the reference signal has a frequency of about 5 MHz to about 50 MHz. Optionally, the frequency may be about 20 MHz.

[0077] In some embodiments, synchronizing the composite signal includes generating an error signal using the composite signal. Synchronizing the composite signal can also include modifying one or more parameters of the pulsed light source as part of optimizing the error signal. Generating the error signal can include generating a vector product of the RF composite signal and the optical composite signal, and filtering the vector product to remove frequency components of the vector product outside a passband that include harmonic frequency components of the optical pulse signal and the RF composite signal.

[0078] 9 is an example block flow diagram illustrating an example process 900 for synchronizing a charged particle beam pulse and a pulsed light beam according to an embodiment of the present disclosure. In some examples, process 900 may be performed by some or all components of systems, devices, and / or include processes, methods, or techniques such as those described in connection with FIGS. 1-8 and 10-14. In some embodiments, process 900 may include more or fewer steps than depicted in FIG. 9. It should be understood that steps may be performed in any suitable order. Where applicable, some, certain, or all steps may be performed in the time domain and / or frequency domain depending on the signal processing implementation.

[0079] At 902, an optical pulse signal is generated from a light source that emits an optical beam pulse toward a sample. The charged particle column may include (or be attached to) an optical driver (e.g., optical driver 310 with respect to FIG. 3) for generating or determining an optical pulse signal at a first frequency (e.g., "F" in FIG. 3). The first frequency "F" may be a fraction of both the frequency of the field in the RF cavity and the frequency of the cavity-generated charged particle beam pulse (e.g., charged particle beam pulse 415).

[0080] At 904, a radio frequency (RF) signal (e.g., from RF driver 305 with reference to FIG. 3 ) associated with an RF cavity that pulses the charged particle beam toward the sample is generated. For example, the association can be obtained directly from an RF driver that transmits the RF signal to the RF cavity, or the association can be that the RF signal is measured from the RF cavity (or a suitable equivalent) and then used to generate a composite signal (as discussed in FIG. 3 ). To that end, the RF signal, in some examples, can be used to control the RF cavity as well as provide an RF signal for composite vector multiplication, or may not be used to control the RF cavity. The RF signal is received by an RF cavity (e.g., RF cavity 130 with reference to FIG. 1 ). The RF cavity can be a dual-mode cavity. Additionally or alternatively, the RF cavity can include a pickup antenna. In some examples, an RF signal that can be used for synchronization can be derived directly from the RF signal (e.g., from RF driver 305). Additionally or alternatively, a pickup antenna can be used to determine the RF signal. Thus, the RF signal used for synchronization, which may be vector-multiplied with the optical pulse signal to generate a composite signal, may be the same as the RF signal for controlling the RF cavity, or may be the result of an RF signal detected by the pickup antenna.

[0081] In some embodiments, coarse alignment of the RF signal and the optical pulse signal may be performed. For example, at 906, a composite signal may be generated using at least the RF signal and the optical pulse signal. The RF signal and the optical pulse signal may be mixed at a first frequency to generate the composite signal. Generating the composite signal may involve generating an error signal using a first harmonic frequency component of the RF signal and a first harmonic frequency component of the optical pulse signal, and modifying one or more parameters of the light source as part of optimizing the error signal. In some examples, generating the error signal includes generating a vector product of the RF signal and the optical pulse signal and filtering the vector product to remove high-frequency components of the vector product. Additionally or alternatively, the high-frequency components may include harmonic frequencies higher than the fundamental frequency component.

[0082] At 908, the light source may be controlled (e.g., by controlling one or more parameters of the light source, such as the length of the oscillator), or an RF signal for controlling the RF cavity may be controlled based at least in part on the composite signal, such that the light beam pulse and the charged particle beam pulse are synchronized at the sample (e.g., as shown in FIG. 6).

[0083] In some examples, the light source is a pulsed laser source, and modifying the one or more parameters can include modifying a characteristic length of a laser oscillator of the pulsed laser source. Additionally or alternatively, the characteristic length represents a path length of the oscillator between two reflectors, and one or more reflectors are movable relative to the gain medium (e.g., titanium-doped sapphire).

[0084] According to some embodiments, the RF composite signal is generated using a vector product of the harmonic frequency components of the RF signal and a reference signal. In this example, generating the optical composite signal may use a vector product of the harmonic frequency components of a laser oscillator and a reference signal. Additionally or alternatively, the harmonic frequency components may be at harmonic orders higher than the fundamental frequency.

[0085] In some examples, generating the RF composite signal may include using a vector product of harmonic frequency components of the RF signal and a reference signal of 5 MHz to 50 MHz (e.g., reference signal 315 with reference to FIG. 3), preferably about 20 MHz. Generating the optical composite signal may include using a vector product of harmonic frequency components of the oscillator and the reference signal, such that the harmonic frequency components may be at a higher harmonic order than the fundamental frequency. Additionally or alternatively, generating the composite signal may include adding a time delay to the vector product of the harmonic frequency components of the optical pulse signal and the reference signal. The time delay may be a variable time delay.

[0086] In some embodiments, fine matching of the RF signal and the oscillator may be performed. For example, returning to the discussion of 908, a harmonic signal may be generated based at least in part on the first frequency, and an error signal may be generated based at least in part on the composite signal. One or more parameters of the light source (e.g., intensity, frequency, phase, etc.) may be modified as part of optimizing the error signal. In some examples, the error signal may include generating a vector product of the composite signal and filtering the vector product to remove frequency components of the vector product outside a passband that includes harmonic frequency components of the optical pulse signal and harmonic frequency components of the RF signal. According to some embodiments, the first frequency may be a fundamental frequency of the RF driver and / or optical driver, and performing fine matching of the RF signal and the optical pulse signal may include switching in a mode selector (e.g., mode selector 325 with reference to FIG. 3 ) from phase locking at the first frequency to phase locking at a harmonic frequency of the RF driver and / or optical driver.

[0087] In some embodiments, the composite signal can be mixed with a harmonic signal to produce a beat frequency signal. The beat frequency signal can define feedback for a light source (e.g., a laser oscillator). The path length can be adjusted to maintain tight (e.g., less than 1 picosecond (ps) jitter) phase lock with the signal driving the RF cavity. In some examples, the delay between optical beam pulses can be adjusted electronically without moving parts.

[0088] According to some embodiments, the optical driver can be phase-locked to the RF driver based at least in part on a beat frequency signal. The beat frequency signal can serve to control the time delay and / or phase between the optical driver and the RF driver. In instances where the optical driver and the RF driver are already matched, the result can include a DC error signal representing the time delay between pulses. The time delay can be steered toward zero to maintain the light source overlapping with the charged particle beam source.

[0089] b. Beam blanking process Synchronizing the light source and beam blanker uses a signal associated with the light source as a trigger signal that the beam blanker can use to blank the charged particle beam. The beam blanker can use the trigger signal to deflect or block the charged particle beam at specific intervals to generate pulses. Variations in the timing of the trigger signal from the light source can introduce delays or inaccuracies in the beam blanker's response. Additionally, or alternatively, the mechanical and electronic components of the beam blanker can introduce delays or jitter, making precise alignment with the light source signal more difficult.

[0090] Triggering the beam blanker as a function of the light source signal can enable controlled interaction between the charged particle beam pulse and the sample during a specific period. Synchronizing the beam blanker with the light source signal synchronizes the charged particle beam pulse to transmit during a desired interval, reducing unnecessary exposure to the sample and improving the quality of the collected data (e.g., images, videos, etc.). By synchronizing the beam blanker to the light source, analysis of the transient state of the sample can enable the observation of ultrafast processes and dynamic changes in the sample's structure or properties.

[0091] FIG. 10 is a block flow diagram illustrating an exemplary process for triggering a beam blanker. By aligning the timing, frequency, and duration of the trigger signal with the optical beam pulse, the charged particle beam can be precisely blocked or unblocked in synchronization with the optical source. This can be used for pump-probe imaging, in which the interaction between the charged particle beam and the optical beam pulse is controlled to capture time-resolved data (e.g., images, videos, etc.). Process 1000 may be performed by some or all components of systems, devices, and / or include processes, methods, or techniques, such as those described in connection with FIGS. 1-9 and 11-14. In some embodiments, process 1000 may include more or fewer steps than depicted in FIG. 10. It should be understood that steps may be performed in any suitable order. FIG. 10 may occur after synchronization (e.g., phase locking) has occurred, as discussed in more detail with respect to FIGS. 8 and 9.

[0092] A trigger signal can be generated at 1005. The beam blanker can be triggered by the blanking signal to rapidly switch between "on" and "off" states, allowing precise control of the exposure time of the charged particle beam on the sample. The trigger signal, which can be a voltage or a pulse, is received by the beam blanker.

[0093] At 1010, the blanking signal uses a trigger signal. The trigger signal (e.g., a voltage pulse or digital input) can be received and processed by the beam blanker's control circuitry to generate a corresponding blanking signal. This blanking signal can control the operation of the beam blanker by directing a deflection system to redirect or block the charged particle beam. The characteristics of the blanking signal, including its amplitude, duration, and timing, can be derived from the parameters of the trigger signal to provide synchronization.

[0094] At 1015, a beam blanker (e.g., beam blanker 155 with respect to FIG. 1) can be modulated. Modulation can occur using a blanking signal. By modulating the timing, duration, and frequency of a trigger signal, the beam blanker can be controlled to achieve synchronous or periodic beam blocking, allowing time-resolved imaging of the sample.

[0095] FIG. 11 is an exemplary block flow diagram illustrating an exemplary process 1100 for synchronizing and interrogating a charged particle beam pulse and a pulsed light beam according to an embodiment of the present disclosure. Process 1100 may be performed by some or all components of systems, devices, and / or include processes, methods, or techniques such as those described in connection with FIGS. 1-10 and 12-14. In some embodiments, process 1100 may include more or fewer steps than depicted in FIG. 11. It should be understood that steps may be performed in any suitable order. FIG. 11 may occur after synchronization (e.g., phase lock) has occurred, as discussed in more detail with respect to FIGS. 8 and 9.

[0096] In 1102, a first charged particle beam pulse and a second charged particle beam pulse may be generated and output from the RF cavity. A radio frequency switch (e.g., radio frequency switch 431) may receive the first charged particle beam pulse and the second charged particle beam pulse and perform rapid blanking.

[0097] At 1104, the first charged particle beam pulse can be blanked at least in part based on the amplified light beam pulse. In some embodiments, the amplified light pulse can be generated at a multiple of the first frequency. In some examples, the multiple of the first frequency is based at least in part on a response time of the sample. According to some embodiments, the high-frequency switch can be coupled to the amplifier of the laser system and / or to the laser amplifier and the high-frequency switch via a common signal generator configured to generate a trigger signal to the laser amplifier and the high-frequency switch. In this manner, the beam blanker can be synchronized with the laser amplifier or shutter, or can have both the pulse picker and the laser amplifier or shutter synchronized to a common trigger signal.

[0098] In 1106, the second charged particle beam pulse and the amplified light beam pulse may be directed toward the sample. For example, at least a portion of the charged particle beam pulse may be blanked to generate a subset of charged particle beam pulses (e.g., 435 in FIG. 4 , 601 in FIG. 6 ) at a multiple of the first frequency. The blanking may be performed by a beam blanker (e.g., beam blanker 155 in FIG. 1 ). The beam blanker may be implemented with a fixed time delay relative to the RF cavity. The beam blanker may be triggered by a signal from the light source such that the amplified light pulse is time delayed relative to the RF signal pulse and the beam blanker receives the inverse time delay. In this way, the timing of the beam blanker may be a constant value relative to the pulses generated in the RF cavity. In some examples, this process may be performed in reverse, such that the light source is triggered by a signal from the beam blanker rather than the beam blanker being triggered by the light source. For example, the shutter of the light source may be controlled by the inverse time delay triggered by the beam blanker.

[0099] In some examples, the delay generator may generate a trigger signal based at least in part on a multiple of the first frequency and send the trigger signal to a beam blanker or an optical driver to trigger at least one of the beam blanker or the light source. Additionally or alternatively, sending the subset of charged particle beam pulses and the amplified light pulses may include generating, by the delay generator, a time delay output for triggering an amplifier of the beam blanker or the light source. In some examples, the time delay output may be varied between generating the subset of charged particle beam pulses and the amplified light pulses while applying inverse time delays to the light source and the beam blanker, and the subset of charged particle beam pulses may be time shifted with respect to the amplified light pulses to compensate for a time delay of the light source relative to the RF signal.

[0100] In some embodiments, generating the trigger signal includes communicating a pulsed signal from a pulsed optical beam controller to a delay generator. Generating the trigger signal can include receiving a control signal including timing information for a beam blanker and a pulsed optical beam controller. Modulating the beam blanker can include temporarily extinguishing an electromagnetic field applied by the beam blanker, wherein, in the presence of the electromagnetic field, electrons are deflected from the beam axis.

[0101] In some embodiments, generating the blanking signal includes combining the trigger signal with a delay offset. Generating the blanking signal can include receiving the delay offset from a control system. The delay offset can be an element in a set of offset data. Generating the blanking signal can include selecting the delay offset from the set of offset data according to a process for studying the dynamic system.

[0102] In some embodiments, the trigger signal is characterized by a frequency of about 0.1 kHz to about 10 MHz. Process 1100 can include synchronizing the pulsed electron beam and the pulsed light beam by operations including synchronizing the RF signal and the pulsed light signal, generating a composite signal using the RF signal, the pulsed light signal, and the reference signal, and synchronizing the composite signal.

[0103] In some embodiments, modulating the beam blanker temporarily unblocks the pulsed electron beam, allowing one or more electron pulses to pass through the beam blanker substantially without deflection.

[0104] In some embodiments, the process 1100 includes generating a pulse of photons using a pulsed photon source simultaneously with generating the trigger signal. The pulsed light beam can be a pulsed laser. The beam blanker can be an electrostatic beam blanker.

[0105] c. Beam Characterization Process Time-resolved imaging relies on capturing phenomena that can evolve on ultrafast time scales (picoseconds or femtoseconds). The temporal pulse profile of a light beam provides information about the timing of excitation events and, when paired with a charged particle beam pulse, enables precise measurement of the sample's dynamic response. The beam intensity and pulse duration of the light source can be adjusted to minimize sample damage caused by excessive energy delivery in sensitive materials. The temporal pulse profile of the light beam can affect how photons interact with the sample's electrons, atoms, or molecules.

[0106] Additionally, the temporal pulse profile is useful for calibrating setups including optical delay lines, trigger synchronization systems, and detectors. Once the temporal pulse profile of a light beam is determined, it can be manipulated (e.g., through pulse shaping methods) to provide selective excitation of modes or maximize signal contrast. The temporal pulse profile can define the light beam intensity variation over time, including pulse duration, rise and fall times, and peak intensity (as shown in Figure 7). The temporal pulse profile can be used to synchronize the light pulse with the charged particle beam pulse, ensuring that both beams interact with the sample with the desired temporal overlap. In pump-probe experiments, the temporal profile of the light beam can determine how energy is delivered to the sample during investigation. Understanding this temporal pulse profile can help optimize conditions such as matching the light beam pulse duration to the characteristics of the charged particle beam for energy transfer or dynamic imaging.

[0107] FIG. 12 is an exemplary block flow diagram illustrating an exemplary process 1200 for synchronizing and interrogating charged particle beam pulses and pulsed light beams according to an embodiment of the present disclosure. Process 1200 may be performed by some or all components of systems, devices, and / or include processes, methods, or techniques, such as those described in connection with FIGS. 1-11, 13, and 14. In some embodiments, process 1200 may include more or fewer steps than depicted in FIG. 12. It should be understood that the steps may be performed in any suitable order. Process 1200 may include directing a photon beam across a beam axis 1205 of a charged particle beam system. Process 1200 may include generating a beam 1210 of charged particles, the beam being substantially aligned with the beam axis. Process 1200 may include directing the beam of charged particles into an energy dispersive spectrometer 1215 configured to generate detector data 1220 representing the energy distribution of the beam of charged particles. The process 1200 may also include generating detector data sets representing multiple energy distributions for corresponding multiple time steps.

[0108] In some embodiments, the beam of charged particles is a pulsed beam and the beam of photons is a pulsed beam. Process 1200 can include synchronizing the beam of charged particles with the beam of photons. Process 1200 can also include defining a plurality of time steps, where a time step in the plurality of time steps can represent a temporal offset or phase delay of the beam of charged particles relative to the beam of photons.

[0109] In some embodiments, the beam of photons includes pulses of photons that define a temporal profile. The method can include generating profile data using a set of detector data, the profile data representing the temporal profile. Generating the set of detector data can include sampling the detector data generated simultaneously during an interaction of the pulse of photons and the beam of charged particles. The detector data can be characterized by a sampling period that is approximately an order of magnitude smaller than a pulse duration represented by the temporal profile. The method can include generating an operational parameter scheme corresponding to the temporal profile, the operational parameter scheme representing one or more operational parameters of the charged particle beam system.

[0110] In some embodiments, the beam of charged particles includes pulses of charged particles. Generating the set of detector data can include combining detector data for a given time step using multiple pulses of charged particles. The charged particles can be electrons. Directing the photon beam across the beam axis can include coupling the photon beam into an optically conductive material, the material being at least partially transparent to the charged particles. The material can be at least partially disposed on the beam axis. The optically conductive material can include a photonic nanostructure, a microresonator, or a photonic metamaterial.

[0111] In some embodiments, the charged particle beam system is an electron microscope. The electron microscope can be a transmission electron microscope (TEM). The electron microscope can include a radio frequency (RF) cavity configured to generate a pulsed beam of charged particles having a pulse frequency of about 25 MHz to about 100 MHz. Optionally, the pulse frequency can be about 75 MHz.

[0112] FIG. 13 is an example block flow diagram illustrating an example process 1000 for synchronizing and interrogating a charged particle beam pulse and a pulsed light beam according to an embodiment of the present disclosure. Process 1000 may be performed by some or all components of systems, devices, and / or include processes, methods, or techniques such as those described in connection with FIGS. 1-9 and 11-14. In some embodiments, process 1000 may include more or fewer steps than depicted in FIG. 10. It should be understood that steps may be performed in any suitable order. FIG. 10 may occur after phase lock has occurred, as discussed in more detail with respect to FIGS. 8 and 9.

[0113] In 1302, a light beam (e.g., light beam pulse 605 with respect to FIG. 6) may be directed toward a sample (e.g., sample 615 with respect to FIG. 6) in a charged particle column (e.g., charged particle system 100 with respect to FIG. 1). In some examples, the light beam is a pulsed light beam. The light beam may include a temporal profile (and a spatial profile).

[0114] In 1304, a charged particle beam (e.g., charged particle beam pulse 415 or a subset of charged particle beam pulses 435 with respect to FIG. 4) can be directed towards the sample. In some examples, the charged particle beam is a charged particle beam pulse.

[0115] In 1306, the charged particles that interacted with the sample can be detected. An EELS spectrometer (e.g., EELS spectrometer 125 for FIG. 1 ) can receive the charged particles (e.g., charged particle beam pulse 610 for FIG. 6 ) and perform energy loss analysis on the charged particle beam pulse. A relative time delay between the light beam and the charged particle beam can be determined. Determining the time delay can include synchronizing the charged particle beam pulse with the pulsed light beam and determining a number of time steps. The time steps can represent a time offset or phase delay of the charged particle beam pulse relative to the pulsed light beam.

[0116] According to certain embodiments, determining the relative time delay may include directing the charged particle beam into an energy dispersive spectrometer (e.g., EELS spectrometer 125) configured to generate detector data representative of the energy distribution of the charged particle beam and generating sets of detector data representative of multiple energy distributions for corresponding multiple time steps (see FIG. 7 ). Generating the sets of detector data may include sampling the generated detector data simultaneously with the period of interaction of the light beam and the charged particle beam, such that the detector data may be characterized by a sampling period approximately one order of magnitude smaller than the pulse duration represented by at least one characteristic, the at least one characteristic being a temporal pulse profile of the intensity of the light beam pulse. Generating the sets of detector data may include integrating the detector data for a predetermined time step using multiple charged particle pulses. Additionally or alternatively, the sets of detector data may be used to generate profile data, the profile data representing a temporal pulse profile of the pulsed light beam (e.g., temporal pulse profile 625 for FIG. 6 ).

[0117] At 1308, a time delay between the charged particle beam and the light beam pulse can be determined based at least in part on the charged particles. The interaction between the light beam pulse and the charged particle beam pulse at the sample can generate a measurable signal (e.g., a change in the diffraction pattern or induced sample dynamics). In some examples, the delay can be estimated using a computational model or algorithm that considers the wavelength of the light beam pulse and / or the duration of the charged particle beam pulse. According to some embodiments, the light source (e.g., a laser oscillator) and the charged particle beam pulse can be synchronized using a trigger signal or independent triggers that are timed relative to each other. The timing of the trigger signal can be used to establish a reference for the arrival time at the sample.

[0118] At 1310, at least one characteristic of the light beam may be determined based, at least in part, on the time delay. The at least one characteristic may include a temporal pulse profile of the intensity of the light beam. In some embodiments, determining the characteristic may include measuring the effective pulse duration of the light beam using PINEM spectroscopy (discussed in more detail with respect to FIG. 6). The characteristic may include, but is not limited to, temporal asymmetry of the light beam (shown in FIG. 7), pulse duration, and / or laser chirp. This characterization may be used to characterize one or more optical modes within the microresonator.

[0119] II. Exemplary Control System FIG. 14 is an example block diagram 1400 of a controller 1401 for implementing methods, processes, techniques, and the like for a microscope system according to certain aspects of the present disclosure. An example microscope system (e.g., a charged particle column) may include some or all of the components of the microscope systems from FIGS. 1-6. Example methods, processes, techniques, and operations may include some or all of the methods, processes, techniques, and operations of FIGS. 7-13. As shown, the controller 1401 may include control circuitry including a processor 1402 communicatively coupled to a memory 1404. The processor 1402 may include one processing device or multiple processing devices. Non-limiting examples of the processor 1402 include a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), a microprocessor, or any combination thereof. The processor 1402 may execute instructions 1410 stored in the memory 1404 to implement the microscope, process, scan, and method operations of FIGS. 1-13. In some examples, instructions 1410 may include processor-specific instructions generated by a compiler or interpreter from code written in any suitable computer programming language, such as C, C++, C#, Python, or Java.

[0120] The memory 1404 may include one memory device or multiple memory devices. The memory 1404 may be non-volatile and may include any type of memory device that retains stored information when powered off. Non-limiting examples of the memory 1404 include electrically erasable programmable read-only memory (EEPROM), flash memory, or any other type of non-volatile memory. At least a portion of the memory 1404 may include a non-transitory computer-readable medium from which the processor 1402 can read instructions 1410 via a bus 1406. The bus 1406 may be a communication and / or power bus that allows the processor 1402 to communicate with the memory 1404. The non-transitory computer-readable medium may include an electronic, optical, magnetic, or other storage device capable of providing instructions 1410 or other program code to the processor 1402. Non-limiting examples of the non-transitory computer-readable medium include a magnetic disk, a memory chip, a RAM, an ASIC, or any other medium from which a computer processor can read instructions 1410.

[0121] The memory 1404 may further include operational information regarding parameters 1412 (e.g., calibration, image capture, detector sensitivity, power), RF cavity chopper 1420 (e.g., frequency, synchronization, calibration), image processor 1424 (e.g., dark field, bright field, calibration, intensity, synchronization), light source 1426 (e.g., duty cycle, pulse frequency, synchronization, alignment, calibration), beam blanker 1422 (e.g., frequency, synchronization, calibration), energy filter settings 1428 (e.g., position, adjustment, calibration), and target stage 1430 (e.g., position, orientation, translation). The controller 1401 may receive information regarding the operational parameters from a microscope such as a TEM, SEM, or the like. At least some of the information regarding any of the controller 1401 may be pre-stored and associated with various scanning paths (e.g., acquisitions). The parameters 1412 may include operational parameters related to the electron microscope system, such as the desired energy / primary energy of the electron beam, the energy spread of the energy loss spectrum, lock-up mechanisms, feedback loops, etc. In some examples, some of the parameters 1412 may be compared to a predetermined threshold (eg, a known sequence, a known sample type, etc.).

[0122] Detailed Exemplary Embodiments Examples of inventive subject matter according to the present disclosure are described in the following paragraphs.

[0123] According to a particular embodiment, a method for mixed signal synchronization for a charged particle column includes generating an optical pulse signal from an optical source that emits optical beam pulses toward a sample in the charged particle column; generating a radio frequency (RF) signal associated with an RF cavity that pulses the charged particle beam toward the sample; generating a composite signal using at least the RF signal and the optical pulse signal; and controlling at least one of i) the optical source or ii) the RF signal for the RF cavity based at least in part on the composite signal such that the optical beam pulses and the charged particle beam pulses are synchronized at the sample.

[0124] 10. The method of any of the preceding embodiments, wherein the method includes generating a first charged particle beam pulse and a second charged particle beam pulse output from an RF cavity; blanking the first charged particle beam pulse by a beam blanker at least partially based on the amplified light beam pulse; and directing the second charged particle beam pulse and the amplified light beam pulse toward the sample.

[0125] The method of any of the previous examples, wherein the light source emits the amplified light beam pulses at a frequency determined at least in part based on a response time of the sample.

[0126] 10. The method of claim 1, further comprising: generating, by a delay generator, a trigger signal based at least in part on the frequency multiple; and transmitting, by the delay generator, the trigger signal to trigger at least one of a beam blanker or a light source.

[0127] generating a second charged particle beam pulse and an amplified light pulse; 10. The method of claim 9, further comprising generating, by a delay generator, a time delay output for triggering a beam blanker or an amplifier of the light source, wherein the time delay output is varied between generating the second charged particle beam pulse or the amplified light pulse while applying an inverse time delay to the light source or the beam blanker, and wherein the second charged particle beam pulse is time shifted relative to the amplified light pulse to compensate for the time delay of the light source relative to the RF signal.

[0128] The method of any of the preceding embodiments, wherein generating the composite signal further includes generating an error signal using harmonic frequency components of the RF signal or harmonic frequency components of the optical pulse signal, and controlling further includes modifying one or more parameters of the RF cavity or light source as part of optimizing the error signal.

[0129] 10. The method of claim 9, wherein generating the error signal comprises generating a vector product of the RF signal and the optical pulse signal, and filtering the vector product to remove high frequency components of the vector product, the high frequency components comprising harmonic frequencies higher than a fundamental frequency component of the RF signal or the optical pulse signal.

[0130] 10. The method of any of the previous examples, wherein the light source is a pulsed laser source, and the one or more parameters include a characteristic length of a laser oscillator of the light source, the characteristic length representing a path length of the laser oscillator between two reflectors, and one or more reflectors are movable relative to the gain medium.

[0131] The method according to any of the previous embodiments, wherein generating the composite signal includes: generating an RF composite signal using a vector product of harmonic frequency components of the RF signal and a reference signal; and generating an optical composite signal using a vector product of harmonic frequency components of a laser oscillator of the light source and the reference signal, wherein the harmonic frequency components are at least one harmonic order higher than the fundamental frequency of the RF signal or the optical pulse signal.

[0132] 10. The method according to any of the preceding embodiments, wherein generating the optical composite signal comprises adding a time delay to a vector product of the harmonic frequency components of the optical pulse signal and the reference signal.

[0133] 10. The method according to any of the previous examples, wherein the reference signal has a frequency of about 5 MHz to about 50 MHz, optionally the frequency is about 20 MHz.

[0134] The method according to any of the preceding embodiments, wherein controlling the optical pulse signal or the RF signal further comprises switching in the mode selector from phase locking at a frequency related to the optical pulse signal or the RF signal to phase locking at a harmonic frequency of the optical pulse signal or the RF signal.

[0135] 10. The method of any of the preceding embodiments, wherein the method further includes generating an error signal based at least in part on the composite signal, and modifying one or more parameters of the light source as part of optimizing the error signal.

[0136] The method according to any of the previous examples, wherein generating the error signal includes generating a vector product of the composite signal, and filtering the vector product to remove frequency components outside a passband of the vector product, including harmonic frequency components of the optical pulse signal and harmonic frequency components of the RF signal.

[0137] According to certain embodiments, one or more machine-readable storage media storing executable instructions that, when executed, cause a charged particle beam column to perform operations including: generating a light pulse signal from a light source that emits light beam pulses toward a sample within the charged particle column; generating a radio frequency (RF) signal associated with an RF cavity that pulses the charged particle beam toward the sample; generating a composite signal using at least the RF signal and the light pulse signal; and controlling at least one of i) the light source or ii) the RF signal for the RF cavity based at least in part on the composite signal such that the light beam pulses and the charged particle beam pulses are synchronized at the sample.

[0138] The machine-readable medium or method of any preceding embodiment, wherein the RF cavity is a dual-mode cavity.

[0139] The machine-readable medium or method of any of the preceding embodiments, wherein the operations further include generating an RF signal using at least a pickup antenna of the RF cavity or receiving an RF signal from an RF driver coupled to the RF cavity.

[0140] The machine-readable medium or method of any of the preceding embodiments, wherein the charged particle beam system is an electron microscope.

[0141] 1. A charged particle column comprising: one or more processors; and one or more machine-readable storage media operably coupled to the control circuitry, the media storing executable instructions that, when executed, cause operations including: generating an optical pulse signal for a light source that emits an optical beam pulse toward a sample in the charged particle column; generating a radio frequency (RF) signal associated with an RF cavity that pulses the charged particle beam toward the sample; generating a composite signal using at least the RF signal and the optical pulse signal; and controlling at least one of i) the light source or ii) the RF signal for the RF cavity based at least in part on the composite signal such that the optical beam pulse and the charged particle beam pulse are synchronized at the sample.

[0142] 10. The machine-readable medium, method, or charged particle column of any of the preceding embodiments, wherein the charged particle column further comprises a delay generator and a beam blanker coupled to the delay generator, wherein the delay generator is configured to trigger the beam blanker based at least in part on controlling the light source or the RF cavity.

[0143] 1. A method for characterizing a light beam in a charged particle column, the method comprising: directing a light beam pulse toward a sample in the charged particle column; directing a charged particle beam pulse toward the sample; detecting charged particles that have interacted with the sample based at least in part on the light beam pulse and the charged particle beam pulse; determining a time delay between the charged particle beam pulse and the light beam pulse based at least in part on the charged particles; and determining at least one characteristic of the light beam pulse based at least in part on the time delay.

[0144] 10. The machine-readable medium, method, or charged particle column of any of the preceding embodiments, wherein the charged particle beam is a charged particle beam pulse and the light beam is a light beam pulse, and determining a time delay further comprises: synchronizing the charged particle beam pulse with the light beam pulse; and determining a plurality of time steps, wherein a time step of the plurality of time steps represents a temporal offset of the charged particle beam pulse relative to the light beam pulse.

[0145] 10. The machine-readable medium, method, or charged particle column of any of the preceding embodiments, wherein the charged particle beam is a charged particle beam pulse and the light beam is a light beam pulse, and determining a time delay further comprises: synchronizing the charged particle beam pulse with the light beam pulse; and determining a plurality of time steps, wherein a time step among the plurality of time steps represents a phase delay of the charged particle beam pulse relative to the light beam pulse.

[0146] The machine-readable medium, method, or charged particle column of any of the preceding embodiments, wherein the light beam is a light beam pulse including a temporal pulse profile, and the method further comprises: directing the charged particle beam through an energy dispersive spectrometer configured to generate detector data representative of an energy distribution of the charged particle beam; generating sets of detector data representative of a plurality of energy distributions for a corresponding plurality of time steps; and generating profile data using the sets of detector data, the profile data representative of the temporal pulse profile.

[0147] The machine-readable medium, method, or charged particle column of any of the preceding embodiments, wherein generating a set of detector data includes sampling the generated detector data simultaneously with a period of interaction of the light beam and the charged particle beam, and wherein the detector data is characterized by a sampling period that is approximately one order of magnitude smaller than a pulse duration represented by the at least one characteristic, and the at least one characteristic is a temporal pulse profile of the intensity of the light beam.

[0148] The machine-readable medium, method, or charged particle column of any of the preceding embodiments, wherein the charged particle beam is a charged particle beam pulse, and generating a set of detector data includes integrating detector data for a given time step using multiple charged particle pulses.

[0149] A machine-readable medium, method, or charged particle column according to any of the preceding embodiments, wherein an operational parameter scheme corresponding to at least one characteristic is generated, the operational parameter scheme representing one or more operational parameters of the charged particle beam system, wherein the at least one characteristic includes a temporal pulse profile of the intensity of the light beam.

[0150] The machine-readable medium, method, or charged particle column of any of the preceding embodiments, wherein determining at least one characteristic of the light beam further comprises measuring an effective pulse duration of the light beam using photon-induced near-field electron microscopy (PINEM) spectroscopy.

[0151] The machine-readable storage medium, method, or charged particle column according to any of the preceding examples, further comprising characterizing the temporal intensity distribution of the light beam based at least in part on the effective pulse duration. The machine-readable storage medium, method, or charged particle column according to any of the preceding examples, further comprising characterizing the temporal intensity distribution of the light beam based at least in part on the effective pulse duration.

[0152] One or more machine-readable storage media having executable instructions stored thereon that, when executed, cause a charged particle beam system to perform operations including directing a light beam pulse toward a sample in a charged particle column; directing a charged particle beam pulse toward the sample; detecting charged particles that have interacted with the sample based at least in part on the light beam pulse and the charged particle beam pulse; determining a time delay between the charged particle beam pulse and the light beam pulse based at least in part on the charged particles; and determining at least one characteristic of the light beam pulse based at least in part on the time delay.

[0153] The machine-readable medium, method, or charged particle column of any of the preceding examples, wherein the charged particle column is a transmission electron microscope (TEM).

[0154] 10. The machine-readable medium, method, or charged particle column of any of the preceding embodiments, wherein the charged particle column includes a radio frequency (RF) cavity configured to generate charged particle beam pulses.

[0155] The machine-readable medium, method, or charged particle column according to any of the preceding embodiments, wherein the pulse frequency of the charged particle beam pulse is between about 25 MHz and about 100 MHz.

[0156] 10. The machine-readable medium, method, or charged particle column of any preceding embodiment, wherein the operation further comprises coupling the light beam into an optically conductive material.

[0157] The machine-readable medium, method, or charged particle column of any of the preceding embodiments, wherein the operation further comprises adjusting a delay of a light beam pulse or a charged particle beam pulse directed toward the sample based at least in part on determining the at least one characteristic.

[0158] The machine-readable medium, method, or charged particle column of any of the preceding examples, wherein the operation further comprises adjusting an intensity, frequency, or phase delay of a light beam pulse directed toward the sample based, at least in part, on determining the at least one characteristic.

[0159] 1. A charged particle beam device comprising: one or more processors; and one or more machine-readable storage media operably coupled to the control circuitry, the media storing executable instructions that, when executed, cause the device to perform operations including directing a light beam pulse toward a sample within the charged particle beam device; directing a charged particle beam pulse toward the sample; detecting charged particles that have interacted with the sample based at least in part on the light beam pulse and the charged particle beam pulse; determining a time delay between the charged particle beam pulse and the light beam pulse based at least in part on the charged particles; determining at least one characteristic of the light beam pulse based at least in part on the time delay; and determining at least one characteristic of the light beam pulse based at least on the time delay.

[0160] 10. The machine-readable medium, method, or charged particle column of any of the preceding embodiments, wherein the at least one characteristic of the light beam includes characterizing temporal asymmetry of the light beam.

[0161] The machine-readable medium, method, or charged particle column of any of the preceding embodiments, wherein at least one characteristic of the light beam comprises pulse duration or laser chirp.

[0162] The machine-readable medium, method, or charged particle column of any of the preceding examples, wherein at least one characterization is used to characterize one or more optical modes within the microresonator.

[0163] The charged particle beam system may include a charged particle source, a charged particle beam column operably coupled to the charged particle source and including a plurality of charged particle optical elements arranged along a beam axis, where the charged particle optical elements may include a radio frequency (RF) cavity. In some examples, the system may include a sample section operably coupled to the charged particle beam column and defining a sample position on the beam axis, a light source optically coupled to the sample section and configured to direct a light beam toward the sample position, control circuitry operably coupled to the RF cavity and the light source, and one or more machine-readable storage media operably coupled to the control circuitry, the medium storing executable instructions that, when executed, cause the system to perform operations, including operations of methods or media according to embodiments herein.

[0164] A method for synchronizing a charged particle beam pulse with a pulsed light beam according to any of the previous embodiments. The method can include synchronizing an RF signal and an optical pulse signal. The method can include generating a composite signal using the RF signal, the optical pulse signal, and a reference signal. The method can also include synchronizing the composite signal.

[0165] The method of any of the preceding embodiments, wherein the RF signal represents a frequency generated by the action of an RF cavity on the electron beam, wherein the action of the RF cavity on the electron beam can include sweeping the electron beam across an aperture disposed in the path of the electron beam. The pulse frequency of the optical pulse signal can be between about 25 MHz and about 125 MHz.

[0166] 10. The method of claim 9, wherein the RF signal and the optical pulse signal are frequency-matched. The frequency-matched signals may correspond to a condition in which a first harmonic frequency of the RF signal is substantially equal to a first harmonic frequency of the optical pulse signal.

[0167] The method of any of the preceding embodiments further includes synchronizing the RF signal and the optical pulse signal by using a first harmonic frequency component of the RF signal and a first harmonic frequency component of the optical pulse signal to generate an error signal. Synchronizing the RF signal and the optical pulse signal can also include modifying one or more parameters of the pulsed light source as part of optimizing the error signal. Generating the error signal can include generating a vector product of the RF signal and the optical pulse signal and filtering the vector product to remove high-frequency components of the vector product. The high-frequency components can include harmonic frequencies higher than the fundamental frequency component.

[0168]

[0013] The method of any of the preceding embodiments, wherein the pulsed light source is a pulsed laser source, and the one or more parameters can include a characteristic length of a laser oscillator of the pulsed laser source. The characteristic length can represent a path length of the oscillator between two reflectors, one or more of which are movable relative to the gain medium.

[0169] The method of any of the previous embodiments, further comprising: generating the composite signal using a vector product of a harmonic frequency component of the RF signal and a reference signal; and generating the optical composite signal using a vector product of a harmonic frequency component of the optical pulse signal and a reference signal. The harmonic frequency may refer to a harmonic order higher than the first or fundamental frequency. Generating the optical composite signal may include adding a time delay to the vector product of the harmonic frequency component of the optical pulse signal and the reference signal. The time delay may be a variable time delay.

[0170] 3. The method according to any of the preceding embodiments, wherein the reference signal has a frequency of about 5 MHz to about 50 MHz. Optionally, the frequency may be about 20 MHz.

[0171] The method of any of the preceding embodiments, further comprising: synchronizing the composite signal to generate an error signal using the composite signal. Synchronizing the composite signal can also include modifying one or more parameters of the pulsed light source as part of optimizing the error signal. Generating the error signal can include generating a vector product of the RF composite signal and the optical composite signal, and filtering the vector product to remove frequency components of the vector product outside a passband that include harmonic frequency components of the optical pulse signal and the RF composite signal.

[0172] One or more machine-readable storage media storing executable instructions that, when executed by a machine, cause the machine to perform operations, including operations of the method described in any of the preceding embodiments.

[0173] The charged particle beam system includes a charged particle source. The charged particle beam system includes a charged particle source and a charged particle beam column operatively coupled to the charged particle source and including a plurality of charged particle optical elements arranged along a beam axis, the charged particle optical elements including a radio frequency (RF) cavity. The system includes a sample section operatively coupled to the charged particle beam column and defining a sample position on the beam axis. The system includes a light source optically coupled to the sample section and configured to direct a light beam toward the sample position. The system includes control circuitry operatively coupled to the RF cavity and the light source. The system may also include one or more machine-readable storage media operatively coupled to the control circuitry, the medium storing executable instructions that, when executed, cause the system to perform operations, including operations of the method of the first aspect of one or more embodiments.

[0174] The system of any preceding embodiment, wherein the RF cavity is a dual-mode cavity. The RF cavity may include a pickup antenna. The charged particle beam system may include an electron microscope. The electron microscope may be a transmission electron microscope (TEM).

[0175] A method for synchronizing a charged particle beam pulse with a pulsed light beam, the method can include generating a trigger signal. The method can include using the trigger signal to generate a blanking signal. The method can also include using the blanking signal to modulate a beam blanker.

[0176]

[0013] The method of any of the preceding embodiments, further comprising: communicating a pulsed signal from a pulsed optical beam controller to a delay generator; generating the trigger signal can include receiving a control signal including timing information for a beam blanker and a pulsed optical beam controller; and modulating the beam blanker can include temporarily extinguishing an electromagnetic field applied by the beam blanker, wherein, in the presence of the electromagnetic field, electrons are deflected from the beam axis.

[0177] 10. The method of claim 1, further comprising: combining the trigger signal with a delay offset; and wherein generating the blanking signal comprises receiving the delay offset from a control system. The delay offset may be an element in a set of offset data. The generating the blanking signal may comprise selecting the delay offset from the set of offset data according to a process for studying the dynamic system.

[0178] The method of any of the preceding examples, wherein the trigger signal is characterized by a frequency of about 0.1 kHz to about 10 MHz. The method can include synchronizing the charged particle beam pulse and the pulsed light beam by operations including synchronizing the RF signal and the light pulse signal, generating a composite signal using the RF signal, the light pulse signal, and the reference signal, and synchronizing the composite signal.

[0179] 10. The method of any of the preceding embodiments, wherein modulating the beam blanker temporarily unblocks the charged particle beam pulses and allows one or more electron pulses to pass through the beam blanker substantially without deflection.

[0180]

[0013] The method of any of the preceding examples, further comprising generating a pulse of photons using a pulsed light source simultaneously with generating the trigger signal. The pulsed light beam may be a pulsed laser. The beam blanker may be an electrostatic beam blanker.

[0181] One or more machine-readable storage media storing executable instructions that, when executed by a machine, cause the machine to perform operations, including operations of the method described in any of the preceding embodiments.

[0182] The charged particle beam system may include a charged particle source. The system includes a charged particle beam column operatively coupled to the charged particle source and including a plurality of charged particle optical elements arranged along a beam axis, the charged particle optical elements including a radio frequency (RF) cavity and a beam blanker. The system includes a sample section operatively coupled to the charged particle beam column and defining a sample position on the beam axis. The system includes a light source optically coupled to the sample section and configured to direct a light beam toward the sample position. The system includes control circuitry operatively coupled to the RF cavity and the light source. The system may also include one or more machine-readable storage media operatively coupled to the control circuitry, the medium storing executable instructions that, when executed, cause the system to perform operations, including operations of the method of the fourth aspect of one or more embodiments.

[0183] The system of any of the previous examples, wherein the charged particle beam system is an electron microscope. The electron microscope may be a transmission electron microscope (TEM). The beam blanker may be an electrostatic beam blanker.

[0184] A method for sampling a pulsed light beam, comprising directing a light beam across a beam axis of a charged particle beam system. The method can include generating a charged particle beam substantially aligned with the beam axis. The method can include directing the charged particle beam through an energy dispersive spectrometer configured to generate detector data representative of an energy distribution of the charged particle beam. The method can also include generating sets of detector data representative of a plurality of energy distributions for a corresponding plurality of time steps.

[0185]

[0013] The method of any of the preceding examples, wherein the charged particle beam is a pulsed beam and the light beam is a pulsed beam. The method can include synchronizing the charged particle beam with the light beam. The method can also include defining a plurality of time steps, wherein a time step of the plurality of time steps can represent a temporal offset or phase delay of the charged particle beam relative to the light beam.

[0186] The method of any of the preceding embodiments, wherein the light beam includes pulses of photons defining a temporal profile. The method can include generating profile data using a set of detector data, the profile data representing the temporal profile. Generating the set of detector data can include sampling the generated detector data coincident with a period of interaction between the pulse of photons and the charged particle beam. The detector data can be characterized by a sampling period that is approximately one order of magnitude smaller than the pulse duration represented by the temporal profile. The method can include generating an operational parameter scheme corresponding to the temporal profile, the operational parameter scheme representing one or more operational parameters of the charged particle beam system.

[0187] The method of any of the preceding examples, wherein the charged particle beam includes pulses of charged particles. Generating the set of detector data can include integrating detector data for a given time step using multiple pulses of charged particles. The charged particles can be electrons. Directing the light beam across the beam axis can include coupling the light beam into an optically conductive material, the material being at least partially transparent to the charged particles. The material can be at least partially disposed on the beam axis. The optically conductive material can include a photonic nanostructure, a microresonator, or a photonic metamaterial.

[0188] The method of any of the preceding examples, wherein the charged particle beam system is an electron microscope. The electron microscope may be a transmission electron microscope (TEM). The electron microscope may include a radio frequency (RF) cavity configured to generate charged particle beam pulses having a pulse frequency of about 25 MHz to about 100 MHz. Optionally, the pulse frequency may be about 75 MHz.

[0189] One or more machine-readable storage media storing executable instructions that, when executed by a machine, cause the machine to perform operations, including operations of the method described in any of the preceding embodiments.

[0190] The charged particle beam system includes a charged particle source. The system includes a charged particle beam column operatively coupled to the charged particle source and including a plurality of charged particle optical elements arranged along a beam axis, the charged particle optical elements including a radio frequency (RF) cavity and a beam blanker. The system includes a sample section operatively coupled to the charged particle beam column and defining a sample position on the beam axis. The system includes a light source optically coupled to the sample section and configured to direct a light beam toward the sample position. The system includes control circuitry operatively coupled to the RF cavity and the light source. The system may also include one or more machine-readable storage media operatively coupled to the control circuitry, the medium storing executable instructions that, when executed, cause the system to perform operations, including operations of the method of the seventh aspect of one or more embodiments.

[0191] In the foregoing description, various embodiments have been described. For purposes of explanation, specific configurations and details have been set forth to provide a thorough understanding of the embodiments. However, it will be apparent to those skilled in the art that the embodiments may be practiced without the specific details. Furthermore, well-known features may be omitted or simplified so as not to obscure the described embodiments. While the exemplary embodiments described herein focus on ultrafast charged particle beam systems, and in particular ultrafast TEM (or UTEM) systems, these are intended as non-limiting exemplary embodiments. Embodiments of the present disclosure are not limited to such embodiments, but rather are intended to address analytical instrument systems capable of analyzing a wide range of material samples to determine chemical, biological, physical, structural, or other properties, including, but not limited to, chemical structure, trace element composition, and the like, that exhibit temporal dynamics on sub-microsecond timescales, among other aspects.

[0192] In the foregoing description, various embodiments have been described. For purposes of explanation, specific configurations and details have been set forth to provide a thorough understanding of the embodiments. However, it will be apparent to those skilled in the art that the embodiments may be practiced without the specific details. Additionally, well-known features may be omitted or simplified so as not to obscure the described embodiments. While the exemplary embodiments described herein focus on electron microscopy systems, these are intended as non-limiting exemplary embodiments. Embodiments of the present disclosure are not limited to such materials, but rather are intended to address electron beam systems applicable to atomic-scale imaging, microanalysis, and / or processing of a wide range of particles. Such particles may include, but are not limited to, electrons, ions, or photons in TEM systems, SEM systems, STEM systems, UFTEM systems, EFTEM systems, ion beam systems, and / or particle accelerator systems.

[0193] Some embodiments of the present disclosure include a system including one or more data processors and / or logic circuitry. In some embodiments, the system includes a non-transitory computer-readable storage medium including instructions that, when executed on one or more data processors, cause the one or more data processors to perform some or all of one or more methods and / or some or all of one or more processes and workflows disclosed herein. Some embodiments of the present disclosure include a computer program product tangibly embodied in a non-transitory machine-readable storage medium including instructions configured to cause one or more data processors to perform some or all of one or more methods and / or some or all of one or more processes disclosed herein, including, for example, the methods, operations, and processes of FIGS. 5, 7-10, 13-15, and 20-25.

[0194] The terms and expressions which have been employed are used as terms of description and not of limitation, and in the use of such terms and expressions there is no intention to exclude any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the claims. Thus, while the present disclosure includes specific embodiments and optional features, it should be understood that modifications and variations of the concepts disclosed herein may be adopted by those skilled in the art, and that such modifications and variations are considered to be within the scope of the appended claims.

[0195] As used in this application and claims, the singular forms "a," "an," and "the" include the plural forms unless the context clearly dictates otherwise. Additionally, the term "includes" means "comprises." Furthermore, the term "coupled" does not exclude the presence of intermediate elements between the coupled items.

[0196] The systems, devices, and methods described herein should not be construed as limiting in any way. Instead, the present disclosure is directed to all novel and non-obvious features and aspects of the various disclosed embodiments, alone and in various combinations or subcombinations with one another. The disclosed systems, methods, and devices are not limited to any specific aspect or feature or combination thereof, nor do the disclosed systems, methods, and devices require that one or more specific advantages exist or problems be solved. While theories of operation are for ease of explanation, the disclosed systems, methods, and devices are not limited to such theories of operation.

[0197] Although some operations of the disclosed methods are described in a particular order for convenient presentation, it should be understood that the described methods encompass rearrangements unless a specific order is required by specific language. For example, operations described sequentially may in some cases be rearranged or performed simultaneously. Moreover, for simplicity, the accompanying figures may not show the various ways in which the disclosed systems, methods, and apparatuses can be used in conjunction with other systems, methods, and apparatuses. Also, the description may use terms such as "produce" and "provide" to describe the disclosed methods. These terms are high-level abstractions of actual operations that are performed. The actual operations corresponding to these terms will vary depending on the particular embodiment and will be readily discernible to those skilled in the art.

[0198] In some instances, values, procedures, or devices are referred to as "lowest," "best," "minimum," "greater than," "less than," "equal to," etc. Such descriptions are intended to indicate that a selection may be made from among many functional alternatives used, with the understanding that such a selection is not necessarily better, less, or otherwise preferred than other selections.

[0199] The term "image" is intended to include a two-dimensional grid, which can include at least one or more portions. Each portion is characterized by its coordinates and its value (color and / or intensity). Thus, an image can refer to a visual representation of a sample in varying gray levels and / or varying colors and / or varying intensities. Furthermore, each portion in an image can correspond to a point (e.g., location) on a target or a portion location on a target, or the like.

[0200] Some embodiments of the present disclosure include a system including one or more data processors and / or logic circuitry. In some embodiments, the system includes a non-transitory computer-readable storage medium including instructions that, when executed on the one or more data processors and / or logic circuitry, cause the one or more data processors and / or logic circuitry to perform some or all of one or more methods and / or some or all of one or more processes and workflows disclosed herein. Some embodiments of the present disclosure include a computer program product tangibly embodied in a non-transitory machine-readable storage medium including instructions configured to cause one or more data processors and / or logic circuitry to perform some or all of one or more methods and / or some or all of one or more processes disclosed herein.

[0201] The terms and expressions which have been employed are used as terms of description and not of limitation, and in the use of such terms and expressions there is no intention to exclude any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the claims. Thus, while the present disclosure includes specific embodiments and optional features, it should be understood that modifications and variations of the concepts disclosed herein may be adopted by those skilled in the art, and that such modifications and variations are considered to be within the scope of the appended claims.

[0202] When terms are used without explicit definition, it is understood that the ordinary meaning of the word is intended unless the term has a special and / or specific meaning in charged particle microscopy systems or other related fields. The terms “about,” “substantially,” or “substantially” are used to indicate deviations from a described characteristic to the extent that the deviation has little or no effect on the corresponding function, characteristic, or attribute of the described structure. In illustrated examples where a dimensional parameter is described as “substantially equal” to another dimensional parameter, the term “substantially” is intended to reflect that the two parameters being compared may be unequal within acceptable limits, such as manufacturing tolerances or confidence intervals inherent in the operation of the system. Similarly, when a geometric parameter such as alignment or angular orientation is described as “nearly” perpendicular, “substantially” perpendicular, or “substantially” parallel, the terms “about” or “substantially” are intended to reflect that the alignment or angular orientation may differ from the exact described condition (e.g., not exactly perpendicular) within acceptable limits. For numerical values ​​such as diameter, length, and width, the term “about” can be understood to represent a deviation of up to ±20% from the stated value. For example, a dimension of "approximately 20 mm" can represent a dimension between 15 mm and 25 mm.

[0203] The description provides exemplary embodiments and is not intended to limit the scope, applicability, or configuration of the present disclosure. Rather, the following description of exemplary embodiments will provide those skilled in the art with an effective description for implementing various embodiments. It will be understood that various changes can be made in the function and arrangement of elements without departing from the spirit and scope as set forth in the appended claims. Specific details are given in the description to provide a thorough understanding of the embodiments. However, it will be understood that the embodiments may be practiced without these specific details. For example, specific system components, systems, processes, and other elements of the disclosure may be shown in schematic form or omitted from illustrations so as not to obscure the embodiments in unnecessary detail. In other instances, well-known circuits, processes, components, structures, and / or techniques may be shown without unnecessary detail.

Claims

1. 1. A method for characterization of a light beam in a charged particle column, comprising: directing a light beam pulse toward a sample within the charged particle column; directing a charged particle beam pulse towards the sample; detecting charged particles that have interacted with the sample based at least in part on the light beam pulses and the charged particle beam pulses; determining a time delay between the charged particle beam pulse and the light beam pulse based at least in part on the charged particles; and determining at least one characteristic of the light beam pulse based at least in part on the time delay.

2. The charged particle beam pulse is a charged particle beam pulse, the light beam is a light beam pulse, and determining the time delay includes: synchronizing the charged particle beam pulse with the light beam pulse; 2. The method of claim 1, further comprising: determining a plurality of time steps, wherein a time step of the plurality of time steps represents a temporal offset of the charged particle beam pulse relative to the light beam pulse.

3. The charged particle beam pulse is a charged particle beam pulse, the light beam is a light beam pulse, and determining the time delay includes: synchronizing the charged particle beam pulse with the light beam pulse; 10. The method of claim 1, further comprising: determining a plurality of time steps, wherein a time step of the plurality of time steps represents a phase delay of the charged particle beam pulse relative to the light beam pulse.

4. the light beam is a light beam pulse having a temporal pulse profile, and the method comprises: directing the charged particle beam through an energy dispersive spectrometer configured to generate detector data representative of an energy distribution of the charged particle beam pulse; generating sets of detector data representing a plurality of energy distributions for a corresponding plurality of time steps; The method of claim 1 , further comprising: generating profile data using the set of detector data, the profile data representing a temporal pulse profile.

5. 5. The method of claim 4, wherein generating the set of detector data comprises sampling detector data generated concurrently with a period of interaction of the light beam and the charged particle beam, the detector data characterized by a sampling period that is approximately an order of magnitude smaller than a pulse duration represented by at least one characteristic, the at least one characteristic being the temporal pulse profile of the intensity of the light beam.

6. 5. The method of claim 4, wherein the charged particle beam is a charged particle beam pulse, and generating the set of detector data comprises integrating detector data for a given time step using a plurality of charged particle pulses.

7. 10. The method of claim 1, further comprising generating an operational parameter scheme corresponding to the at least one characteristic, the operational parameter scheme representing one or more operational parameters of a charged particle beam system, and the at least one characteristic comprising a temporal pulse profile of an intensity of the light beam.

8. Determining the at least one characteristic of the light beam The method of claim 1 , further comprising measuring an effective pulse duration of the light beam using photon-induced near-field electron microscopy (PINEM) spectroscopy.

9. The method of claim 8 , further comprising characterizing a temporal intensity distribution of the light beam based at least in part on the effective pulse duration.

10. One or more machine-readable storage media storing executable instructions that, when executed, cause a charged particle beam system to: directing a light beam pulse towards a sample within the charged particle column; directing a charged particle beam pulse towards the sample; detecting charged particles that have interacted with the sample based at least in part on the light beam pulses and the charged particle beam pulses; determining a time delay between the charged particle beam pulse and the light beam pulse based at least in part on the charged particles; and determining at least one characteristic of the light beam pulse based at least in part on the time delay.

11. The one or more machine-readable storage media of claim 10 , wherein the charged particle column is a transmission electron microscope (TEM).

12. The one or more machine-readable storage media of claim 10 , wherein the charged particle column includes a radio frequency (RF) cavity configured to generate charged particle beam pulses.

13. 11. The one or more machine-readable storage media of claim 10, wherein the pulse frequency of the charged particle beam pulses is between about 25 MHz and about 100 MHz.

14. The operation is The one or more machine-readable storage media of claim 10 , further comprising coupling the light beam pulse into an optically conductive material.

15. The operation is 11. The one or more machine-readable storage media of claim 10, further comprising adjusting a delay of a light beam pulse or a charged particle beam pulse directed toward the sample based at least in part on determining the at least one characteristic.

16. The operation is 16. The one or more machine-readable storage media of claim 15, further comprising adjusting an intensity, frequency, or phase delay of the light beam pulses directed at the sample based at least in part on determining the at least one characteristic.

17. 1. A charged particle beam device, comprising: one or more processors; one or more machine-readable storage media operably coupled to the control circuitry and storing executable instructions that, when executed, directing a light beam pulse towards a sample within the charged particle beam device; directing a charged particle beam pulse towards the sample; detecting charged particles that have interacted with the sample based at least in part on the light beam pulses and the charged particle beam pulses; determining a time delay between the charged particle beam pulse and the light beam pulse based at least in part on the charged particles; and determining at least one characteristic of the light beam pulse based at least in part on the time delay.

18. 20. The charged particle beam device of claim 17, wherein the at least one characteristic of the light beam pulse comprises a characterization of a temporal asymmetry of the light beam pulse.

19. 18. The charged particle beam device of claim 17, wherein the at least one characteristic of the light beam pulse comprises pulse duration or laser chirp.

20. 20. The charged particle beam device of claim 17, wherein the evaluation of the at least one property is used to characterize one or more optical modes within a microresonator.

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