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Abstract:This paper introduces the fundamental working principles of scanning tunneling microscope (STM), addresses how it comprehensively fulfills the three core requirements of atomic-scale manufacturing —— "visualization", "precision measurement" and "fabrication feasibility"， and examines its pivotal role in revealing quantum phenomena and constructing artificial atomic structures. Studies highlight that STM's environmental adaptability, ultra-high spatial resolution, and ultra-high temporal resolution provide key experimental evidence for revealing novel mechanisms and effects in atomically precise manufacturing. STM, based on the unique quantum tunneling effect, performs precise measurements of physical properties (e.g., electronic and magnetic) in fabricated structures, and establishes quantitative structure-property relationships between fabrication parameters and device performance, thereby providing a critical basis for process optimization and quality assessment. The deep integration of STM atomic-scale manipulation capabilities with automated and high-throughput modules represents a critical strategy for breaking-through its efficiency bottleneck and propelling it into industrial applications. This technological convergence will propel atomic manufacturing from the precise fabrication of individual structures to the efficient and controllable manufacturing of complex functional devices. Future research needs to focus on developing in-situ STM measurement techniques that can simultaneously achieve femtosecond-level temporal resolution and sub-angstrom spatial resolution, as well as expanding the comprehensive physical property characterization capabilities of STM systems under complex multi-physical field coupling conditions, so as to provide technical support for the development of next-generation quantum materials and information devices.

Abstract:This study addresses the photon count distortion under high count rates and difficult positioning under low Signal-to-Noise Ratio (SNR) condition in Four-Quadrant Superconducting Nanowire Single-Photon Detectors (QD-SNSPD) The nonlinear correction mechanism for photon counts is introduced and an analytical solution for Gaussian spot localization problem after correction is derived. A differential localization method using non-integer power operations is proposed, which increase signal differentiation between positive and negative semi-axes through an exponent n>1 to improve positioning accuracy. Results demonstrate that count correction improves spot localization accuracy under high count rates. Non-integer power operations effectively reduce the positioning errors under low SNR conditions. Compared with classical differential localization methods, the 1.4-power operation reduces the positioning errors by 27% when SNR < 10, and the corrected Gaussian model reduces the errors by 70% when SNR > 50. When photon counts exceed 104, both the corrected Gaussian model and power operation methods (0.8≤n≤2) achieve a positioning standard deviation below 0.01 times the spot radius. These findings provide substantial support for high-precision spot localization using QD-SNSPDs.

Abstract:This paper introduces the fundamental principles and classifications of optical frequency combs, reviews the generation mechanisms and representative architectures of electro-optic frequency combs (EOFCs), and systematically summarizes implementation approaches and performance characteristics of EOFCs on emerging material platforms, including thin-film lithium niobate (TFLN) and silicon nitride (SiN), covering schemes based on Mach-Zehnder modulators, phase modulators and micro-resonator modulator. Methods for spectral extension of EOFCs are discussed, followed by an overview of EOFC applications in spectroscopy, precision ranging, and optical communications. Finally, future development directions are outlined, emphasizing that interdisciplinary integration and co-design can further reduce control complexity, noise sensitivity, and thermal drift, while improving accuracy, environmental robustness, and frequency-stabilization performance, thereby accelerating the practical deployment of EOFCs in precision ranging and coherent communications.

Abstract:In the process of ultra long span fiber frequency transmission, factors such as power attenuation and additional noise of active devices lead to weak frequency signal at the receiving end, which limits the signal detection resolution and sensitivity. To solve this problem, the research team proposed a dual-mixing time-delay detection of weak frequency signals enabled by local-oscillator optical enhancement. The weak carrier signal power was enhanced by a coherent laser, and the dual-mixing time-delay detection structure was used to improve the receiving sensitivity. At the same time, the high signal-to-noise ratio signal extraction was realized by combining with the balanced detection technology. The experimental results show that compared with the traditional intensity modulation / direct detection method, the dual-mixing time-delay detection of weak frequency signals enabled by local-oscillator optical enhancement can effectively improve the sensitivity of the receiver by about 10 dB, the RF power is increased by 25 dB under the same input power condition, and this method achieves excellent frequency stability, with Allen deviation of 2 × 10^-13@1 s and 2.1 × 10^-15@10 000 s, and stability of 3 × 10^-17@1 s and 3 × 10^-19@10 000 s under the condition of difference frequency of 10 kHz, which verifies the feasibility and significant advantages of the proposed method in high-precision optical fiber frequency transmission.

Abstract:This paper introduces the characteristics of structured-light-based three-dimensional (3D) measurement technology, including its non-contact nature, high accuracy, and high flexibility. It reviews the principles and recent research progress of fringe structured-light illumination techniques for 3D surface measurement in complex scenes, with particular emphasis on a series of studies conducted by our research group to improve measurement accuracy and efficiency. Application cases of fringe structured-light-based 3D measurement are analyzed in the areas such as large-scale fossil fault planes, high-dynamic-range workpieces, high-speed kinematic processes, and large-aperture and smooth optical components. The challenges faced by 3D surface measurement technology based on structured-light illumination are further discussed. It is pointed out that future advancements can be achieved through deep interdisciplinary integration, thereby further enhancing the accuracy and efficiency of fringe structured-light-based 3D measurement, overcoming existing technical bottlenecks, and enabling highly reliable and digitized 3D measurement in a wide range of extreme and complex environments.

Abstract:This paper reviews the principles and distinctive features of optical frequency combs, and introduces the advantages of optical-frequency-comb-enabled laser ranging, including high accuracy, high measurement speed, and large detection range. The recent research progress of comb-based laser ranging methods is analyzed, covering time-of-flight method, dispersive interferometry method, frequency-modulated continuous wave method, and random-modulated continuous wave method. Finally, future prospects for optical-frequency-comb-based laser ranging are discussed. It is pointed out that by exploring new physical mechanisms for comb-based ranging we may further extend the measurement range, increase the update rate, and reduce system complexity; by developing new schemes for comb stabilization and flexible parameter control we can suppress noise and thus further improve measurement accuracy; and we can enhance practicality by establishing drift error monitoring and automatic calibration mechanisms across multiple time scales, as well as by integrating multi-parameter environmental sensing and an online refractive-index compensation chain.

Abstract:This paper introduces the advantages of white light interferometry, including non-contact operation, high precision, and strong adaptability. However, in practical measurements, interference signals are affected by light source instability, scanning nonlinearity, and environmental disturbances, leading to a significant increase in phase noise. The recent progress in the analysis and suppression of phase noise in white light interference signals is reviewed. Particular attention is given to a series of studies carried out by our research group, including the establishment of a multi-source noise analysis framework that incorporates random perturbations, dispersion errors, and vibrations, as well as noise suppression strategies. Finally, future research directions are discussed, emphasizing the need for deeper investigations into the formation mechanisms of phase noise, phase response characteristics, and coupling with system parameters. Multi-source noise modeling, adaptive optimization, and deep learning techniques can be applied to the analysis and suppression of phase noise in white-light interference signals, thereby advancing precision measurement technologies.

Abstract:Traditional frequency modulated continuous wave (FMCW) laser ranging techniques are mostly implemented using tunable lasers or dual-light-source architectures. These systems are complex and difficult to engineer, and they suffer from error amplification in dynamic scenarios. To address these limitations, our research team proposed an FMCW laser ranging method based on electro-optic double-sideband (DSB) modulation. A frequency-stabilized laser and an electro-optic modulator are used to generate two oppositely swept frequency signals, which reduces the system size and mitigates dynamic errors. An all-phase fast Fourier transform (APFFT) algorithm was designed to achieve stable and reliable phase retrieval under highly dynamic and high-noise conditions. In addition, Kalman filtering was introduced to optimize dynamic state estimation and improve ranging stability. Experimental results show that, with a 20 m fiber link, the absolute distance measurement error of the proposed method does not exceed ± 20 μm. For a sinusoidally vibrating target with amplitude ≤ 500 nm and frequency ≤ 200 Hz, the relative displacement measurement error does not exceed ± 25 nm. These results verify the high reliability of the proposed method and provide strong support for promoting the engineering deployment of FMCW laser ranging technology.

Abstract:Current full-field spectral-domain interferometry relies on wavelength or galvanometer scanning, which limits its ability to acquire full-field information in a single detection. To address this issue, this paper proposes a full-field spectral-domain interferometry technique based on a Digital Micromirror Device (DMD). By encoding the spatial light field distribution via the DMD, time-varying spectral signals corresponding to sequentially loaded masks are acquired, which are further decoded to obtain the amplitude response at each spatial pixel. Combined with the measurement algorithm, full-field information retrieval is achieved. Experimental results demonstrate that the proposed technique enables high-precision spectral interferometric distance measurement and spectroscopic ellipsometric film thickness measurement, while significantly improving full-field measurement efficiency. The DMD-based full-field spectral interferometry technique is suitable for rapid three-dimensional structure recovery and reconstruction of sparse surfaces, providing strong support for efficient thickness and topography characterization of polished wafers, Silicon-On-Insulator (SOI) substrates, and bonded interfaces.

Abstract:Current domestic and international calibration specifications for structured light 3D measurement systems do not specify calibration methods for scenarios where the surfaces of measured objects are various non-diffuse reflective surfaces, and thus cannot fully meet the actual calibration needs. To address this issue, our research team analyzed the actual calibration scenarios of structured light 3D measurement systems, defined translucent surfaces, highly reflective surfaces and high dynamic range reflectivity surfaces from the perspective of optical properties, and designed standards applicable to different surfaces. In accordance with actual requirements, we formulated specific calibration methods, realizing the calibration of the capability of structured light 3D measurement systems to measure the geometric parameters of various non-diffuse reflective surfaces. The calibration method for structured light 3D measurement systems for various non-diffuse reflective surfaces proposed by our research team supplements and perfects the existing calibration methods for structured light 3D measurement systems, and plays an important role in promoting the development of structured light 3D measurement technology toward precision and standardization.

Abstract:There is a lack of a universal and readily integrable online measurement and compensation scheme for six-degree-of-freedom (6-DOF) errors along the Z-axis of micro-nano coordinate measuring machines (CMMs). To address this challenge, this study introduces a synchronous measurement method for the axis of micro Z-axis linear and angular errors based on laser interferometry and autocollimation principles，and establishes a spatial error compensation model under Z-axis 6-DOF influence based on the Abbe principle and the Bryan principle. An in-situ and on-line Z-axis 6-DOF error measurement system based on the measurement method was developed and applied to a micro-nano CMM. Measurements were performed along the Z-axis on a grade 0 gauge block with a nominal thickness of 8 mm using the CMM. The results show that the measurement standard deviation and indication error are reduced by 54.6% and 54.3%, respectively, after compensation. This method, compensation model and the system provide a reliable solution for improving the measurement and machining accuracy of coordinate measuring machine(CMM) and other precision equipment.

Abstract:Changes in the beam incidence angle caused by variations in receiver orientation in a rotating laser scanning angle measurement system can introduce systematic angular measurement errors that affect the system's precision and robustness. To address this issue, a local projection model and a Gaussian light-strip distribution model were established based on beam propagation geometry and receiver structure characteristics, and differences in photoelectric response under different incidence conditions were analyzed. Furthermore, by incorporating attitude information provided by an Inertial Measurement Unit (IMU), an effective receiving surface model was constructed in the receiver coordinate system, and an error compensation method considering receiver structure features was proposed. Simulation results show that as the incidence angle increases, the photoelectric response waveform of the receiver becomes significantly asymmetric, with angular measurement errors reaching several tens of arcseconds. The proposed compensation method effectively corrected these errors, reducing the root-mean-square (RMS) error by approximately 90%. In precision turntable experiments, the roundness error of the receiver trajectory decreased from 0.81 mm before compensation to 0.17 mm after compensation, confirming the effectiveness of the compensation model. The study enriches the error modeling framework of rotational laser scanning systems, and provides an effective approach to enhance measurement accuracy and robustness under varying receiver attitudes.