Due to the promising applications of femtosecond laser filamentation in remote sensing, great demands exist for diagnosing the spatiotemporal dynamics of filamentation. However, until now, the rapid and accurate diagnosis of a femtosecond laser filament remains a severe challenge. Here, a novel filament diagnosing method is proposed, which can measure the longitudinal spatial distribution of the filament by a single laser shot-induced acoustic pulse. The dependences of the point-like plasma acoustic emission on the detection distance and angle are obtained experimentally. The results indicate that the temporal profile of the acoustic wave is independent of the detection distance and detection angle. Using the measured relation among the acoustic emission and the detection distance and angle, a single measurement of the acoustic emission generated by a single laser pulse can diagnose the spatial distribution of the laser filament through the Wiener filter deconvolution (WFD) algorithm. The results obtained by this method are in good agreement with those of traditional point-by-point acoustic diagnosis methods. These findings provide a new solution and idea for the rapid diagnosis of filament, thereby laying a firm foundation for femtosecond laser filament-based promising applications.

In the past thirty years, measuring laser-induced fragments generated by atoms and molecules has become a key method for exploring and understanding atomic and molecular dynamics. Nanoparticles exhibit distinct size effects and surface near-field enhancement effects compared to individual atoms, giving them unique physical and chemical properties that have created immense technological and economic value in many application fields. The exploration of interactions between femtosecond laser pulses and nanostructures has led to many breakthrough scientific technologies, significantly advancing the fields of optoelectronics, nanoelectronic devices, nanomaterial processing, photocatalysis, biotechnology, and more. Understanding the ultrafast ionization dynamics of nanostructures is crucial for comprehending the fundamental physical processes at the atomic scale when nanostructures are excited by strong laser fields. This understanding is also valuable for regulating ultrafast ionization dynamics, promoting new nanotechnologies, and developing high-performance optoelectronic materials and chips. The scientific basis for these advanced technologies and cutting-edge applications lies in understanding the microscopic physical mechanisms of interactions between laser fields and micro-nano systems. With advancements in vacuum nanobeam source technology, the interactions between laser fields and individual nanoparticles using momentum detection spectrometers can be studied. Ultrafast femtosecond lasers, with their precise control time and frequency domains, offer high peak intensities and short pulse durations. The precise control over parameters such as wavelength, polarization, pulse width, intensity, and multi-pulse delay provides unprecedented methods for accurately measuring extreme ultrafast dynamic processes in nanomaterials, exploring strong field physical effects, and developing groundbreaking disruptive technologies. Utilizing nanoparticle beam targets in velocity imaging spectrometer systems has expanded laser ionization research from atomic to larger nanoscale systems, validating numerous fundamental physical results observed in atoms and driving forward the development of practical macroscopic applications.

A monodisperse nano aerosol system has been proposed (Fig. 5). The development of a nanoparticle aerodynamic focusing system has been reported (Fig. 6). A nano velocity imaging spectrometer has been developed (Fig. 7). The physical mechanism of the M³C model has been reported (Fig. 13). The analysis of electron momentum in nanostructures influenced by carrier-envelope phase has been reported (Fig. 14). The femtosecond dynamics involved in the metallization of nanostructures have been explored (Fig. 15). The focusing effect of electrons emitted from nanoparticles has been reported (Fig. 21). Optical control of electron emission from nanostructures has been achieved (Fig. 25). A strong laser-induced minimal shock wave has been reported (Fig. 30). The synthesis of surface molecules on nanoparticles in a strong laser field has been reported (Fig. 33). Complete optical control of laser-induced dense plasma emission has been achieved (Fig. 36).

Overall, the study of strong field ionization in nanostructures remains an emerging field, with many aspects of ultrafast electron-ion dynamics still not fully understood. Future research promises to focus on the precise control of electrons and ion emission, as well as the ultrafast measurement and manipulation of surface molecular reactions. In addition, the formation of isolated nanoscale plasmas under intense laser fields provides an excellent platform for investigating the properties of small-scale plasmas. This includes exploring complex physical processes such as the expansion of dense plasmas, identifying and measuring various ion types within plasmas, generating dense ion sources, and examining the spatiotemporal phase transitions of plasmas.

Currently, the rapid development of artificial intelligence (AI), cloud computing, mobile communications, the Internet of Things, and other fields has created a significant demand for advanced chips. Lithography is a core step in the manufacture of these chips, as its level directly determines the process and performance of the chip. The most advanced extreme ultraviolet (EUV) lithography machines currently use 13.5 nm light and are employed in high-volume manufacturing (HVM) of chips at 5 nm node and below. Throughout the production process, each step must be quantitatively measured to ensure that key parameters meet the process targets. While optical technology is predominant in semiconductor inspection and metrology, the sensitivity of traditional optical methods is gradually diminishing. Due to the substantial wavelength shift from 193 nm to 13.5 nm, EUV lithography necessitates new components and materials. Consequently, the detection of these components and research into material interactions need to be conducted anew under EUV light sources. Presently, EUV optical equipment mainly uses discharged produced plasma (DPP) and laser produced plasma (LPP) light sources. However, these plasma light sources have several drawbacks. They produce significant contamination, as plasma fragments can affect devices from the collection mirror to the sample, impacting their lifespan and operating environment. In addition, although plasma EUV light sources offer high power, its radiation of 4π solid angle leads to its low brightness, which will affect its application in high-resolution detection. Therefore, exploring new EUV light sources for quantitative detection is crucial. Since the first discovery of high-order harmonics (HHG) in 1987, extreme ultraviolet high-order harmonics (HHG-EUV) have been widely used in electron dynamics research and various spectroscopy and imaging studies due to its high coherence, short pulses, and high photon energy. High-order harmonics exhibit unique properties, such as good directionality, excellent temporal and spatial coherence, and a broadband spectrum ranging from extreme ultraviolet (XUV) to soft X-ray bands. This makes it feasible to use Table-top-terawatt (T³) lasers to obtain tunable coherent XUV and soft X-ray sources, which have become an important research tool in EUV lithography technology. Concurrently, research on the application of these ultrafast EUV light sources in lithography and semiconductor metrology is advancing rapidly.

Our study reviews the development of high-repetition-rate and high-brightness ultrafast EUV light sources in recent years and their applications in semiconductor metrology. The high-order harmonic method can generate a single harmonic with a power of up to 12.9 mW in the EUV region, significantly expanding its application range. In the lithography process, the exposure step transfers patterns from the mask to the photoresist. During exposure, tiny mask defects can cause substantial changes in the critical dimension (CD) on the wafer. Defects above a certain size on the mask must be detected and repaired. Due to the high brightness, broad spectrum, and broad coherence of high-order harmonics, they currently have prospects in coherent diffraction imaging and coherent scattering imaging. Samsung has developed an EMDRS (extreme ultraviolet lithography mask defect review system) device to meet the review needs of EUV mask defects. Hyogo and RIKEN have jointly developed the HHG-CSM (HHG-coherent scatterometry microscope) device based on coherent scattering microscopy, which can observe line defects as small as 2 nm in mask inspection. Huazhong University of Science and Technology has proposed a new high-resolution mask defect detection method that can detect defects with high sensitivity and accurately inspect defects with higher resolution. In wafer inspection and metrology, inspection refers to detecting heterogeneities on the wafer surface or within the circuit structure, while metrology involves the quantitative description of structural dimensions and material properties on the observed wafer. KMlabs can perform interface detection within a certain depth range beneath the surface using coherent diffraction imaging. Researchers from ASML and Intel use 10-20 nm wavelength EUV scattering measurements to offer a promising next-generation metrology technology, expected to enable 3D nanometer-size measurements of transistors.

The application of high-repetition-rate and high-brightness high-harmonic EUV light sources in semiconductor nanostructure detection has gradually emerged, with significant research results obtained in the actinic detection of mask defects and wafer metrology. The EUV light source generated by the high-harmonic process features a wide spectrum and high brightness, providing unique advantages in inspection and metrology. High-brightness EUV light sources enhance the detection resolution of EUV masks and wafer patterns, while multi-wavelength broadband spectra improve the accuracy of critical dimension measurement, overlay measurements, and complex three-dimensional transistor structures. This advancement is crucial for the development of future semiconductor processes.

In coal mining regions, extensive coal dust is generated during mining, transportation, and storage, coupled with substantial black carbon produced resulting from incomplete coal combustion in the industry chain. Over time, these materials form absorbable substances, evolving into core-shell aerosols with inorganic salt shells. These aerosols, including sulfate, nitrate, and water, exert significant climate impacts through direct and indirect radiation effects. The environmental and radiative forcing effects are substantial. Absorbing aerosol demonstrates strong solar radiation absorption across the ultraviolet to infrared spectrum. However, past studies primarily focus on their optical properties in visible and infrared bands, overlooking ultraviolet band absorption. Current research often assumes a lognormal particle size distribution for absorbing aerosols, neglecting variations in distribution and optical properties resulting from diverse emission scenarios. Therefore, a thorough analysis of absorbing aerosol optical properties at local scales is crucial. Quantitative assessments of particle size distribution, mixing state, and spatio-temporal variations are vital for elucidating the intricate interactions with boundary layer development, radiative forcing changes, and air pollution.

In our study conducted in the coal mining area of Changzhi City, Shanxi Province, various datasets are collected, including surface black carbon concentration, particle size distribution, and columnar aerosol optical depth (AOD). The investigation commenced with the utilization of the variance maximization method to categorize AOD data into distinct pollution events. Subsequent analysis involved evaluating the particle size distribution corresponding to different pollution degrees through probability density functions. The uncertainty of particle size for the desorption aerosol core and shell is then determined by integrating black carbon mass concentration data and particle size distribution information. These uncertainties are then used as input parameters to run the Mie scattering model based on the “core-shell” structure. This process results in the inversion of the multi-band optical characteristic parameters of absorbing aerosol in the coal mining area. The computations are carried out under both the assumption of a uniform distribution and a non-uniform distribution, representing different mixing degrees of aerosols. To complete the picture, the uncertainty interval for the single scattering albedo (SSA) of absorbing aerosol was constrained through the application of absorption ?ngstr?m exponent (AAE) theory. This comprehensive approach provides a nuanced understanding of the complex dynamics of absorbing aerosol in the specific context of coal mining environments.

In the coal mining area, absorbing aerosols are influenced by emission sources, manifesting a particle size distribution divergent from the lognormal model. Under various pollution conditions, robust peaks are discernible in smaller particle size ranges (0.28-0.3 μm), with weaker peaks present around 0.58-0.65 μm. The relative proportion between the two peaks fluctuates in tandem with the pollution severity (Fig. 3). Using the Mie scattering model, the optical characteristics of absorbing aerosol are inverted based on AOD information, black carbon mass concentration, and particle number concentration. Results indicate that under the assumption of a uniform distribution (Fig. 4), the average size of the “core” particles at 0.28, 0.58, and 0.7 μm is relatively low, leading to corresponding patterns in SSA with changes in “core” particle size. Additionally, the average “core” particle size shows no significant variation with changes in wavelength in different size ranges. SSA decreases with increasing wavelength, with greater fluctuations in the smaller particle size range (0.25-0.58 μm) and more stable changes in the larger particle size range (0.58-1.6 μm). Under this assumption, the AAE theory is found to be inapplicable. In the case of a non-uniform distribution (Fig. 5), SSA values exhibit a slow, followed by a gradual and then rapid increase in the shortwave region, while in the longwave region, SSA first rapidly increases and then gradually levels off. For shorter wavelengths (500 nm and above), AAE theory proves effective for absorbing aerosol with smaller particle sizes. For longer wavelengths (675 nm and above), AAE theory is applicable to absorbing aerosol with moderate particle sizes. However, for larger particles such as coal dust, AAE theory is not suitable. It is noteworthy that, under both assumptions, the inversion results of SSA values in the longwave spectrum (such as 870 and 936 nm) are relatively lower compared to the shortwave spectrum (such as 440 and 500 nm). This discrepancy will lead to an underestimation of emission quantities.

We conduct on-site observations in the coal mining area of Changzhi City, Shanxi Province, aiming to capture the variation characteristics of AOD, particle concentration, and black carbon mass concentration. Utilizing the Mie scattering model based on the “core-shell” hypothesis, we simulate the SSA of absorbing aerosol under two different mixing states. Additionally, we calculate the optical variations of absorbing aerosol constrained by the AAE. The research findings reveal the following:

1) The particle size distribution of absorbing aerosol in the coal mining area deviates from the assumptions made in previous studies, which typically assumed single or double-peaked distributions. Influenced by emission sources, the characteristics vary under different pollution conditions. Smaller particles predominantly originate from the incomplete combustion of coal in local power plants and coking factories, producing black carbon. Larger particles stem from the aging processes of black carbon in the atmospheric environment and coal dust generated during coal transportation.

2) Comparison of the SSA variations under different mixing states simulated by the two hypotheses indicates that particle size, mixing state, and spectral range significantly impact the SSA of absorbing. In contrast to previous studies using the infrared spectrum, the present investigation reveals higher SSA values in the ultraviolet and visible light spectrum, suggesting a potential underestimation of black carbon emissions.

3) The AAE theory is applicable only to certain particle size ranges in different spectral bands. For large-sized absorbing aerosol in the coal mining area, using the AAE theory to estimate SSA introduces uncertainty, and applying the AAE assumption across all particle size ranges leads to an underestimation of emissions. These findings underscore that the distribution characteristics of SSA in absorbing aerosol do not strictly adhere to the power-law relationship of the AAE index but are collectively determined by particle size distribution, mixing state, and spectral range.

The Moon has emerged as a global hotspot for deep space exploration. Since the former Soviet Union launched the first lunar probe satellite in 1959, human understanding of the Moon has been gradually deepened. China launched its first lunar satellite, Chang’e-1, in 2007, and by 2020, the Chang’e-5 mission successfully returned lunar samples to Earth, marking the successful completion of the first three phases of the lunar exploration project (orbiting, landing, and returning). Today's lunar exploration is shifting from a focus solely on mastering technology to a comprehensive development of technology, science, and application. Currently, the International Lunar Research Station (ILRS) planned by China will be the first scientific research facility on the moon. A large number of facilities including orbiters, landers, rovers, power stations, network communication stations, scientific equipment, and various robots will collaborate in near-lunar space and on the Moon. Comprehensive planning of various types of optical cameras to form an optical monitoring network is of significant importance for the construction and operation of the ILRS. The ILRS constitutes a long-term and intricate space infrastructure construction initiative, entailing multiple launches, each comprising several modules. These missions necessitate engineering payloads endowed with continuity, universality, and reliability across various tasks. Among them, optical imaging payloads, serving as the eyes of lunar exploration, play a vital role in facilitating both scientific investigations and engineering tasks. In the future, on the lunar research station, a substantial array of equipment and facilities will operate in concert across the lunar surface and in cislunar space. Strategically planning the various optical cameras in these facilities to form an integrated optical imaging surveillance network system holds paramount importance. This endeavor will collectively realize scientific and application objectives, and it is of great significance for the engineering construction and safe operation of the future International Lunar Research Station, as well as for showcasing the station’s distinctive features to the world. Over the past few years, the field of optical surveillance has witnessed the development of a variety of key technologies, including the optimization of network architectures for surveillance systems, camera systems with multiple optical modules, embedded intelligent image processing technologies, ultra-lightweight camera mounting technologies, and risk mitigation technology. These key technologies complement each other and have shown promising application prospects in major scientific and technological areas. However, there are still a series of challenges in terms of engineering feasibility and performance stability in the field of deep space exploration. Therefore, organizing the technology tree and addressing the direction of key technologies are very important and necessary for more rationally guiding the future development of this field.

First, the concept and overall plan of China’s lunar research station are briefly introduced. Second, a detailed survey has been conducted on the current state of optical surveillance systems in domestic and international deep space exploration missions, summarizing the technical characteristics of optical surveillance cameras used in these missions. Third, based on the overall requirements of the optical surveillance system for the lunar research station, we propose the overarching goals of the ILRS optical surveillance system, which are summarized as system perception, collaborative cooperation, and resource optimization. Moreover, the specific requirements of the ILRS optical surveillance system are proposed as comprehensive functionality, network intelligence, lightweight and reliable, and upgradable iterations. Finally, a preliminary concept for the ILRS optical surveillance system is constructed, and on this basis, key technologies that require significant breakthroughs are identified, such as network architecture optimization, multi-optical module technology, intelligent image processing, lightweight carrying technology, and reliability analysis techniques.

By analyzing the composition of the optical surveillance system network and features of various optical camera imaging systems at the front end, a general construction concept for the system, the outlines of the technology tree, and key technologies that need to be tackled are proposed. There is an urgent need to combine the overall plan of the ILRS with the top-level design of the surveillance system and to tackle the key technologies, conducting timely onboard test verifications as necessary. The purpose of our analyses and organization is to call upon experts and scholars in the field of space optics and surveillance, both domestically and internationally, to actively participate and contribute their knowledge and strength to the construction of the ILRS.