10675 results about "Particle physics" patented technology

The technology relates to enhancing performance of quantum sensor operation in a noisy environment. Quantum neural networks are used to pre- and post-process analog signals to which qubits of a quantum sensor are exposed. Intra-processing using additional quantum neural networks may also be employed. This approach filters out noise from both the input analog signal and the system itself to achieve a very high signal to noise ratio. This permits the system to detect induced dynamics associated during exposure of the qubits to the analog signals. This enables the quantum sensor to sense a change in a state of a system under test, which can be beneficial for areas such as imaging, magnetometry, sensing electric fields, optomechanical sensors, quantum radar and other areas where enhanced signal to noise ratios are desired.

The invention relates to the technical field of optical detection and calibration, in particular to an optical detection and calibration method based on a laser cross calibration method, which comprises the following steps of: 1, suppressing dynamic ambient light and adjusting laser parameters; step 2, extracting anti-distortion feature points; 3, multi-view error collaborative optimization: inputting the corrected coordinates output in the step 2 and mechanical motion parameters of a rotating shaft encoder into a splicing optimization model, constructing a coordinate transformation matrix with curvature constraint, and obtaining a three-dimensional calibration point cloud under a global coordinate system through iterative optimization; and 4, dynamic closed-loop compensation: dynamically correcting the laser power compensation coefficient in the step 1 and the distortion correction parameter in the step 2. Through close cooperation of multiple steps, high-precision, stable and self-adaptive laser calibration is realized, and reliable optical detection and calibration results can be provided in various environments and working conditions.

The invention discloses a single-coil winding type four-eight-pole composite iron system for beam homogenization. The composite iron system comprises a composite magnet current control device, a composite magnet main power supply and four-pole / eight-pole composite iron, the quadrupole / octupole composite iron has eight pole heads, and only one type of excitation coil is wound on each pole head; the current value of the A-type excitation coil is an absolute value of a quadrupole magnetic field excitation current value plus an octupole magnetic field excitation current value; the current value of the B-type excitation coil is an absolute value obtained by subtracting an octupole magnetic field excitation current value from a quadrupole magnetic field excitation current value; the quadrupole / octupole composite iron is used for simultaneously generating a dominant quadrupole magnetic field and an octupole magnetic field, so that the effects of quadrupole iron and octupole iron can be simultaneously realized by only installing one transmission element; the excitation coil structure of the quadrupole / octupole composite iron composite magnet is improved, and only one excitation coil is wound on each pole head, so that the size of the coil structure can be reduced, and the construction cost is reduced.

The invention discloses a high-speed multi-photon detection system and method. The system comprises a detector and a signal processing circuit, wherein the detector is composed of a window plated with a photoelectric cathode, a micro-channel plate stack and an anode; a plurality of incident photons are converted into a plurality of photoelectrons by the photoelectric cathode, and the photoelectrons are converted into electron cloud by the micro-channel plate stack; the incident electron cloud is divided into multiple paths by three layers of staggered metal strip electrodes of the anode, and charge collection is carried out to obtain charge short pulses of each layer of electrode; the signal processing circuit converts the charge short pulses transmitted by the three layers of electrodes into digital pulse signals, obtains the centroid coordinates of the electron cloud from the digital pulse signals as the abscissa value, the ordinate value and the verification value of the incident photon position, combines the abscissa value, the ordinate value and the verification value based on the screening condition to obtain the target two-dimensional coordinates, and finally obtains the target two-dimensional coordinates. And transmitting to a terminal for imaging display. According to the invention, a plurality of synchronous photons can be detected, the overall counting rate of the detector is greatly improved, and the detection efficiency is improved.

In a general aspect, a quantum program can be automatically synthesized or compiled. In some implementations, a discretized state space is obtained. The discretized state space includes a plurality of states for one or more qubits of a quantum processor. A discrete action space is obtained. The discrete action space includes a plurality of unitary operations for the one or more qubits of the quantum processor. A policy that uses the discretized state space and the discrete action space to generate quantum programs for quantum state preparation is defined. A dynamic programming process is used to improve the policy. An initial state and a target state of the one or more qubits is identified. The policy is used to generate a quantum program to produce the target state from the initial state. The quantum program include a subset of the unitary operations in the discrete action space.

The invention discloses a wavefront reconstruction method for improving the dynamic range of a Shack-Hartmann wavefront sensor. Belongs to the technical field of wavefront detection. According to the method, a new Shack-Hartmann wavefront detection method is needed, the effective dynamic range of a Shack-Hartmann sensor can be expanded on the premise that the hardware complexity is not remarkably increased, local mismatching accumulation can be avoided through a reasonable matching strategy, and the detection accuracy is improved. Therefore, high-precision and high-reliability wavefront reconstruction can be realized in a large-amplitude wavefront distortion scene. Comprising the following steps: S1, detecting by a Shack-Hartmann wavefront sensor to obtain a light spot distribution diagram H (x, y); s2, extracting a light spot centroid pixel-level position through a matched filtering algorithm; s3, calculating the sub-pixel-level position of the mass center of the light spot through Gaussian interpolation; s4, a mass center-subaperture matching relation is established through a Kuhn-Munkres algorithm; and S5, calculating the wavefront slope according to the corresponding relationship between the centroid and the sub-aperture, and then recovering the wavefront according to the wavefront slope.

The invention discloses a self-adaptive full-band efficiency correction method for an LIBS (laser-induced breakdown spectroscopy). The method comprises the following steps: for each laser pulse, inputting collected spectral data into a trained physical information deep network to obtain a current plasma temperature; when the current plasma temperature is not in a preset ideal temperature interval, predicting by using a physical information deep network to obtain an optimal laser energy adjustment sequence; wherein energy adjustment is performed according to the optimal laser energy adjustment sequence, so that a future temperature sequence can be converged to a preset ideal temperature interval; controlling an energy controller of the laser to emit a next laser pulse according to the optimal laser energy adjustment sequence to obtain a stable plasma; and after the stable plasma is obtained, collecting target spectral data, and outputting a full-band efficiency calibration curve according to the target spectral data. And high-precision and high-robustness full-band efficiency correction can be realized in a complex and changeable real environment.

The present disclosure relates to an active graded magnetic compensation system and method for an unshielded SERF magnetometer. The system comprises: a detection laser, a half-wave plate, a magnetic field compensation coil, a magnetic field modulation coil, a non-magnetic heating assembly, an alkali-metal atomic vapor cell, a polarizing beam splitter prism, a balanced photodetector, a graded feedback control module, a pump laser, a quarter-wave plate, a focusing lens and a photodetector. By means of the present disclosure, a graded compensation system is used to realize high-precision compensation for a magnetic field within a large dynamic range in a geomagnetic environment, thereby ensuring that an instrument carries out high-sensitivity magnetic field measurement under geomagnetic conditions.

The invention relates to a partial discharge detection system based on Rydberg atoms in the field of partial discharge detection of electrical equipment, the system comprises an optical path frequency stabilization module, an atom probe, a photoelectric detection module, a controller module and a power frequency synchronous trigger signal circuit, the optical path frequency stabilization module locks 852.35 nm probe light and pump light frequency less than 509.53 nm through SAS and EIT technologies, and the atomic probe is used for detecting the frequency of the probe light. Inducing transition from a cesium atom ground state to a first excited state to a Rydberg state; under the effect of partial discharge pulse, the atomic probe outputs a modulated EIT transmission spectrum signal, after photoelectric conversion and filtering, the controller module analyzes the amplitude and phase information of the pulse in combination with a power frequency synchronizing signal, the upper computer generates a PRPD diagram to analyze the discharge correlation, the detection sensitivity of the system reaches-50dBm, the frequency band of 300MHz-2GHz is covered, the dynamic range is greater than or equal to 50dB, the equivalent height is greater than or equal to 20mm, and the discharge correlation is greater than or equal to 20mm. Broadband and high-resolution detection is achieved, the problem of phase synchronization is solved, and the device is suitable for high-voltage environment on-line monitoring.

The invention provides a method and a system for measuring plasma current in a quasi-ring symmetrical star simulator, and relates to the technical field of star simulators, and the method comprises the steps: determining a sensor design index according to a bootstrap current simulation calculation result, and converting the design index into an actual arrangement scheme according to an installation environment constraint; all the magnet coils are independently excited in a plasma-free state, wall eddy current interference signals generated by the magnet coils are calibrated, and thus wall eddy current calibration voltage signals are output; a sensor in an actual arrangement scheme is used for synchronously collecting a total original induced voltage signal including plasma current and wall eddy current; an integral voltage signal representing the total current is output; and compensating the integral voltage signal by using the wall eddy current calibration voltage signal, and inverting the final measurement value of the plasma current in the quasi-ring symmetric star simulator. The device and the method have the beneficial effects that the interference of a stray field on a measurement result is weakened, and a high-precision diagnostic tool is provided for the plasma physical research of the star simulator.

A wide-field dynamic magnetic imaging device and method. The wide-field dynamic magnetic imaging device comprises: a probe assembly (1), comprising a diamond (101) containing NV centers; a microwave magnetic field assembly (2) configured to generate a uniform microwave field and a uniform bias magnetic field in the vicinity of the diamond (101), so as to regulate the spin energy level of the diamond (101) and the quantum state evolution process; a laser modulation assembly (3) configured to output an initial uniform pulsed laser to excite the diamond (101) to emit fluorescence; a fringe light modulation assembly (4) configured to modulate the initial uniform pulsed laser to output a fringe pulsed laser, causing the fluorescence emitted by the diamond (101) to be fringe fluorescence, or to modulate the fluorescence emitted by the diamond (101) into fringe fluorescence; a fluorescence detection assembly (5) configured to perform spatial imaging on the fringe fluorescence to obtain magnetic field information of a sample under test (7), thereby obtaining an initial magnetic image of said sample (7); and a data processing assembly (6) configured to perform Fourier transform and inverse Fourier transform on the initial magnetic image to obtain a first magnetic image.

The invention provides an active regulation and control device for a microwave resonant cavity based on Rydberg atoms. The microwave resonant cavity comprises a protective shell, an atomic gas chamber and a photoelectric detector, the active regulation and control device comprises a PID control module and piezoelectric ceramics, the PID control module is used for processing a received EIT transmission spectrum signal after generating a modulation signal to carry out atomic resonant frequency scanning on the atomic gas chamber, obtaining a target resonant frequency through a current feedback zero crossing point corresponding to an EIT transmission spectrum valley bottom value, and generating a deviation correction signal; and the piezoelectric ceramic is used for adjusting the length of a protective shell of the microwave resonant cavity according to the received correction signal, so that the atomic resonant frequency is locked as the target resonant frequency. The invention further provides an active regulation and control method for the microwave resonant cavity based on the Rydberg atoms. According to the invention, the resonant frequency of the microwave resonant cavity can be rectified in real time, and the optimal and most stable resonant mode of the local oscillation microwave frequency responding to atoms is kept.

The invention relates to the technical field of quantum computing, and provides a polariton quantum computing simulation method and related device.The method comprises the steps that parameterized quantum circuits are generated based on micromodels used for describing polaritons for all to-be-computed excitation states respectively, and the parameterized quantum circuits are generated based on initial Hamiltonian of polaritons in a ground state; the target Hamiltonian amount of the polariton in the current excitation state is obtained, then the value of each parameter is adjusted at least once, and the target energy of the corresponding excitation state is obtained. In the primary adjustment process, parameter updating is carried out on the quantum circuit, a reference quantum state of the corresponding excitation state is obtained by utilizing the updated quantum circuit, reference energy of the corresponding excitation state is obtained based on the reference quantum state and in combination with the target Hamiltonian, and then when a set convergence condition is met, the target Hamiltonian is obtained. And taking the reference energy as target energy of the corresponding excited state. The polaritons are simulated through the quantum computer, and the simulation efficiency is improved.

A quantum computing service provides a quantum algorithm development kit that enables a customer to define a quantum task, a quantum algorithm, or a quantum circuit using an intermediate representation. The quantum computing service is then configured to automatically translate the quantum task, quantum algorithm, or quantum circuit into a specific representation specific to a particular quantum computing technology selected by the customer to be used to execute the customer's quantum task, quantum algorithm, or quantum circuit.

The invention provides an intrinsic solid-state ion diffusion coefficient test method and device based on optical imaging, and relates to the technical field of solid-state ion test.The method comprises the steps that a test sample is pretreated; carrying out a photoelectric test on the test sample; placing the electrochemical cell in an optical imaging system, connecting the electrochemical cell with an electrical testing system, applying a constant voltage deviating from a steady state to the monodisperse electrode plate, collecting the real-time change condition of the material under the modulation of the constant voltage in real time through an industrial camera, and outputting relational data of optical intensity and time; analyzing the diffusion path through in-situ characterization equipment, and obtaining an ion diffusion path corresponding to the to-be-detected ion battery electrode material particles in combination with dynamic information provided by an optical imaging system; and determining the characteristic time according to the relational data of the optical intensity and the time, and determining the intrinsic solid ion diffusion coefficient corresponding to the test sample by combining the characteristic time and the ion diffusion path corresponding to the to-be-tested ion battery electrode material particles.

The invention provides a quasi-continuous thulium-doped fiber laser capable of synchronously suppressing relaxation oscillation and self-pulse, relates to the technical field of fiber laser, and is used for simultaneously realizing suppression of a self-pulse effect and a relaxation oscillation peak. Comprising a continuous driving module, a pulse driving module, a semiconductor laser pumping source, a high-reflectivity fiber bragg grating, a low-reflectivity fiber bragg grating, a beam combiner, a thulium-doped gain fiber, a passive fiber, a cladding pumping stripper and a laser output port, the continuous pump light and the pulse pump light are respectively driven by the continuous driving module and the pulse driving module to output continuous pump light and pulse pump light; the high-reflectivity fiber bragg grating and the low-reflectivity fiber bragg grating form a resonant cavity structure, the thulium-doped gain fiber serves as a gain medium of the thulium-doped fiber laser and absorbs pump light to generate population inversion, laser oscillation is formed by combining the resonant cavity of the laser, relaxation oscillation suppression is achieved, and meanwhile longitudinal mode distribution of the laser is effectively disrupted.

The invention discloses a point light source electron accelerator which comprises a sealing box body, a cathode, a laser emitter, a reflecting cover, a grid plate and a mounting plate, the mounting plate is erected in the sealing box body, a mounting hole is formed in the mounting plate, the cathode is mounted in the mounting hole, and the laser emitter is arranged in the sealing box body. The reflecting cover is arranged at the top of the mounting hole; the reflecting cover is a semi-spherical surface, a laser through hole is formed in the top of the semi-spherical surface, and the laser through hole is coaxial with the cathode; the transmitting end of the laser transmitter is aligned with the cathode; the grid plate is mounted below the mounting plate and is aligned with the mounting holes; and an electron outlet is formed below the grid plate. The invention provides a point light source electron accelerator, and the point light source electron accelerator provides a light and miniaturized electron accelerator design, so that the application field of the accelerator is wider.

The invention provides a nonlinear data generation and processing method based on light quantum and a light quantum computer, and the method comprises the steps: obtaining a nonlinear function and attribute information of a nonlinear layer; according to the frequency spectrum number and the attribute information of the nonlinear function, constructing an initial light quantum circuit; measuring the initial light quantum circuit, and determining a target function corresponding to the initial light quantum circuit according to a measurement result; loss information of the target function is determined, whether the initial light quantum circuit is applied or not is determined according to the loss information, and if yes, the initial light quantum circuit serves as a target light quantum circuit; and performing operation on input data of the nonlinear layer based on the target light quantum circuit. According to the method, the low-energy-consumption characteristic of photon calculation, the nonlinear characteristic of light quantum calculation and the general programmable capability of electronic calculation can be fused, and high-energy-efficiency calculation can be carried out on input data of a nonlinear layer. In addition, the method also has the advantages that the complexity of a quantum circuit is smaller, and the participation of a nonlinear optical device is not needed.

A Rydberg sensor may include a probe laser source and a quantum radio frequency (QRF) cavity downstream from the probe laser source and configured to define a path for a plurality of probe laser beam passes within the QRF cavity. A Rydberg sensing region may be within the QRF cavity and in the path of the probe laser beam passes. An optical amplifier may be within the QRF cavity and in the path of the probe laser beam passes. A detector may be downstream from the QRF cavity.

The invention provides a chiral super-structure surface and a dynamic regulation and control method for circular dichroism of the chiral super-structure surface, and belongs to the technical field of micro-nano optics. The chiral metasurface can perform differential absorption on vertically incident left-handed circularly polarized light and right-handed circularly polarized light. The chiral metasurface comprises: a substrate layer; the optical waveguide layer is arranged on the substrate layer; the nano structure layer is arranged on the optical waveguide layer and comprises a plurality of Z-shaped nano units which are periodically arranged in a square shape; and the hydrogel layer is arranged on the optical waveguide layer and the plurality of Z-shaped nano units and is used for dynamically regulating and controlling the circular dichroism of the chiral super-structure surface when the environment humidity changes. Under the condition that high circular dichroism of the chiral super-structure surface is achieved, the circular dichroism of the chiral super-structure surface is made to move when the environment humidity changes, and therefore the circular dichroism of the chiral super-structure surface is dynamically regulated and controlled.

The invention provides a space measurement and analysis method and system for a neutron diffraction rocking curve of a single crystal material, and the method comprises the steps: S1, building a laboratory coordinate system and a sample coordinate system, and setting a test point grid; s2, collecting a two-dimensional diffraction image of each test point to obtain angle information of the test point; s3, integrating the angle information of the test points based on the test point grid, and preprocessing the two-dimensional diffraction image; s4, extracting key structure parameters of each test point based on the preprocessed two-dimensional diffraction image; s5, constructing a stress field according to the key structure parameters; and S6, constructing a distribution map of crystal internal lattice parameters in a three-dimensional space according to the stress field. The method provided by the invention effectively improves the capability of identifying the non-uniformity and local distortion of the crystal structure, can be widely applied to the fields of residual stress evaluation, defect evolution monitoring, material quality control and the like, and has a remarkable engineering application value.

The invention relates to the technical field of signal detection, in particular to a weak electric field signal detection method and system. According to the invention, complete information of frequency, amplitude and phase of a to-be-measured electric field signal is obtained at the same time in one measurement of the injection locking phonon laser, a to-be-measured laser amplitude spectrum and a to-be-measured laser phase spectrum are generated by the same injection locking phonon laser, and the amplitude signal and the phase signal which are measured and received must arrive at the same time. The two are simultaneous in time and have natural orthogonality in physics; therefore, compared with a traditional double-phase lock amplifier for analyzing two asynchronous signals to be measured received by two frequency mixers, the method for analyzing the laser amplitude spectrum and the laser phase spectrum to be measured to obtain the electric field information to be measured has the advantages that the accuracy is higher; the double-phase lock amplifier solves the technical problem of measurement errors caused by deviation of to-be-measured signals received by two frequency mixers in a traditional double-phase lock amplifier.

The invention relates to the technical field of semiconductor devices, in particular to a low-working-current-density green light Micro-LED epitaxial structure and a preparation method thereof. The epitaxial structure comprises a substrate, a buffer layer, an N-type semiconductor layer, a low-temperature stress release layer, a multi-quantum well light-emitting layer and a P-type semiconductor layer. The electron blocking layer is not arranged on the multi-quantum-well light-emitting layer, the multi-quantum-well light-emitting layer comprises four sub-layers including a first light blue light multi-quantum-well layer, a second blue light multi-quantum-well layer, a third green light multi-quantum-well layer and a fourth light blue light multi-quantum-well layer, and the In component content in the third green light multi-quantum-well layer is larger than that in other layers. The third cyan light multi-quantum well layer is a main light-emitting unit and is not provided with an electron blocking layer, so that the blocking effect on hole injection can be eliminated, the hole injection efficiency of the P-type semiconductor layer is remarkably improved, and the matching degree of electron hole concentration in a multi-quantum well light-emitting layer region is improved.

The invention belongs to the technical field of terahertz detection, and discloses a terahertz metamaterial enhanced spectrum detection system. Comprising the following steps: constructing a metamaterial enhancement factor tensor matrix according to the interaction between terahertz waves and a metamaterial; performing local field enhancement and surface plasma resonance optimization on the target sample based on the metamaterial enhancement factor tensor matrix to obtain a feature enhancement spectroscopy mapping function; constructing a multi-dimensional detection feature space based on a feature enhancement spectroscopy mapping function; a spectral signal enhancement topology network is formed based on the multi-dimensional detection feature space; enhancing the topological network based on the spectral signal, and generating an enhanced spectral feature discrimination function; obtaining a high-precision terahertz spectrum detection result based on the enhanced spectrum characteristic discrimination function; according to the invention, internal correlation between spectral characteristics can be mined, and comprehensive description of sample information is enhanced, so that high-precision terahertz spectrum detection is realized.

The invention discloses a scanning electron microscope. The scanning electron microscope comprises a scanning electron microscope main body and a sample table located in a sample cavity, the scanning electron microscope main body is fixedly connected with the upper cover of the sample cavity, so that a closed space is formed in the sample cavity; a closed-loop groove is formed in an upper cover of the sample cavity; wherein the groove is located outside the connection position of the upper cover of the sample cavity and the scanning electron microscope main body, and the bottom of the groove is not higher than the supporting surface of the sample table; a magnetic shielding layer is arranged in the groove; wherein the length of the magnetic shielding layer is not less than the distance from the objective lens of the scanning electron microscope main body to the supporting surface of the sample stage.

A method for secure quantum communication includes generating a photon. The method includes modulating at least two quantum state dimensions selected from the group consisting of orbital angular momentum (OAM), polarization, and phase of the photon to form a composite quantum state. The method includes directing the photon to an emission point on a helical structure having a defined spatial coordinate corresponding to classical data. The method includes emitting the photon from the emission point into a quantum channel. The composite quantum state and spatial coordinate together encode secure information.

The invention relates to the technical field of X-ray tube control, and discloses a control method and device for a controllable flying focus X-ray tube, and the method comprises the steps: building an orthogonal electromagnetic deflection system based on an electron beam flight path of the X-ray tube, and the orthogonal electromagnetic deflection system comprises an X-direction electromagnetic coil and a Y-direction electromagnetic coil; creating a conversion relation for converting the target focus position function into an electromagnetic coil current value; executing nonlinear magnetic field response compensation to obtain high-speed switching control signals of the X-direction electromagnetic coil and the Y-direction electromagnetic coil; and performing focus trajectory prediction based on the high-speed switching control signal to obtain a focus motion trajectory formed by the electron beam on the target material, and performing thermal load distribution optimization on the focus motion trajectory to obtain a focus position control scheme for uniform distribution of the surface temperature of the target material. Accurate positioning control of the electron beam on the target material is achieved, and the X-ray imaging quality is improved.

The invention relates to the technical field of space electric propulsion, in particular to an ion thruster discharge chamber magnetic pole optimization method, which obtains an optimized discharge chamber magnetic pole structure by researching plasma generation and evolution behaviors under a specific magnetic pole structure based on a plasma numerical simulation process. On one hand, plasma characteristic parameters which cannot be tested by a test are obtained by using a numerical simulation means and a basic discharge principle of a discharge chamber, and on the other hand, change relationships between electron motion behaviors and the magnetic field intensity of a cathode magnetic pole and the magnetic field intensity of a conical section magnetic field are established; the working process and the working mechanism in the discharge chamber when the ion thruster works are understood more deeply, and data support and technical support are provided for optimization design of the discharge chamber of the ion thruster.

The invention discloses a battery internal defect detection method, system, medium and equipment, and the method comprises the steps: preparing battery samples with different defects; performing an electrochemical impedance spectroscopy test on the battery sample under the same temperature environment, and establishing an impedance spectroscopy database of the battery in a normal state and a defect full charge state under a normal temperature working condition; calculating charge transfer impedance, solid electrolyte interfacial film impedance and relaxation time of a corresponding characteristic peak in the impedance spectrum data through the relaxation time distribution curve area, and analyzing the charge transfer impedance, the solid electrolyte interfacial film impedance and the relaxation time of the corresponding characteristic peak; constructing a battery internal defect identification model to accurately identify whether the battery has internal defects or not; performing relaxation time distribution quantification at a constant temperature to obtain charge transfer impedance, solid electrolyte interfacial film impedance and relaxation time of a corresponding characteristic peak; and importing the charge transfer impedance, the solid electrolyte interfacial film impedance and the relaxation time of the corresponding characteristic peak into the battery internal defect identification model to obtain a diagnosis result of whether the defect exists in the single battery or not.

An electron-optical projection device for projecting a plurality of charged particle beams towards a sample, the device comprising a stack of plates comprising beam directing elements configured to project the plurality of charged particle beams towards a sample location on the sample, wherein at least one plate of the stack comprises a planar optical member configured to direct stimulation light towards the sample location so that the stimulation light is coincident with the plurality of charged particle beams, desirably coincident with the paths of the plurality of charged particle beams towards the sample location, desirably in the at least one plate comprising an optical member is defined a plurality of apertures for respective paths of a plurality charged particle beams.