High-accuracy strain sensing of frequency-scanned phase-sensitive optical time domain reflectometry based on block matching.

A strain demodulation method of frequency-scanned -OTDR based on block matching is proposed, which improves the demodulation performance under short pulse width and large strain. The method of frequency shift estimation based on image block matching improves the similarity between Rayleigh backscattered spectra and the accuracy of demodulation results by combining local frequency domain data and local spatial domain data. The image of the matching degree is denoised by a block-matching three-dimensional filter (BM3D), and the performance is further improved by three-dimensional transformation and collaborative filtering of similar image blocks.

Dispersion extension method for ultrasmall fiber probes in the chromatic confocal system.

This study proposes a method for extending the dispersion range using combined gradient refractive index (GRIN) lenses. The imaging model of the probe was established based on the self-focusing characteristics of GRIN lens. The dispersion extension of the probe can be achieved using the model to optimize the probe structure while ensuring high resolution and small size.

Nanoindentation Response of Monocrystalline Copper via Molecular Dynamics: Anisotropic Edge Effects.

In the nanoindentation testing of metallic materials, mechanical properties often decrease significantly when the indentation position shifts from the central region to the edge due to edge effects, leading to premature edge failure and potential device malfunctions. In this work, molecular dynamic (MD) simulations were conducted to investigate the anisotropic edge effects of nanoindentation on monocrystalline copper with a specific crystal orientation. The results reveal that changes in indentation position strongly influence surface collapse and lateral pile-up behaviors.

Complete model identification for measuring photodetector's data age in high-speed and high-precision interferometry.

Data age in photodetectors is a key indicator in high-speed and high-precision interferometry. Accurately measuring it is essential for ensuring timely control of high-speed movement and synchronization in dynamic calibration. Current methods for measuring photoelectric data age are limited by their inability to simultaneously account for phase shifts and time delays, primarily due to incomplete models.

Investigation on the Bending Mechanism of Single-Crystal Copper Under High Bending Rates via Molecular Dynamics.

Leaf spring-type flexible hinges serve as critical transmission components in kilogram quantization energy balance systems. Investigating their bending behavior is crucial for enhancing measurement accuracy and ensuring structural reliability. This work employs molecular dynamics simulations to analyze the mechanical properties and deformation characteristics of such hinges under varying bending rates.

Research on Forced Vibration Model of End Effector Under Low-Frequency Excitation and Vibration-Suppression Technology.

The positioning accuracy of the end effector is the core index that affects the robot's performance. However, to achieve lightweight and functional requirements, the construction of end effectors is becoming more complex. Lightweight design through slotting is becoming more common.

Dynamic laser protection window based on a topological state photonic crystal of a nonlinear LiNbO interface.

The accelerated advancement of high-energy laser technology has resulted in an increased necessity for multifunctional laser protection. Herein, we present an investigation into a static visible and dynamic 1064 nm laser protection window. Through studying the photonic crystal energy band structure and topological interface state properties, both 66.

Nanoradians level high resolution autocollimation method based on array slits.

This study developed a detailed mathematical model to elucidate array slits imaging and linear CCD acquisition. Frequency domain analysis revealed the relationship between system parameters and spot image aliasing noise. Aliasing noise was reduced through optimized array slits design and linear CCD parameter selection, improving angular measurement resolution and stability.

Pump-Wavelength Selective All-Optical Terahertz Metasurface with Independent Amplitude and Frequency Modulations.

Tunable terahertz (THz) metasurfaces based on optical control are crucial in high-speed communication, nondestructive testing, and imaging. However, realizing independent optical tunability of multiple functions in the THz band remains challenging due to limitations in control materials. Here, we experimentally demonstrate a novel THz metasurface that employs two control materials combined with an electric-field-coupled inductor capacitor microstructure to achieve all-optical independent modulations of amplitude and frequency.

Data-driven calibration of decoupling matrix for MIMO precision motion stages.

Decoupling control is a commonly employed technique for achieving high precision in multiple-input multiple-output (MIMO) motion control systems. A static decoupling matrix, which can be determined using geometric construction, is widely used due to its practicality and simplicity. However, inaccurate geometric parameters will lead to a coarse decoupling matrix, and result in interactions among the system axes and performance deterioration.

3D Shape Measurement of Aeroengine Blade Based on Fringe Projection Profilometer Improved by Multi-Layer Concentric Ring Calibration.

The precision requirements for aeroengine blade machining are exceedingly stringent. This study aims to improve the accuracy of existing aeroengine blade measurement methods while achieving comprehensive measurement. Therefore, this study proposes a new concentric ring calibration method and designs a multi-layer concentric ring calibration plate.

Adaptive Weighted Error-Correction Method Based on the Error Distribution Characteristics of Multi-Channel Alignment.

As process nodes of advanced integrated circuits continue to decrease below 10 nm, the requirement for overlay accuracy is becoming stricter. The alignment sensor measures the position of the alignment mark relative to the wafer; thus, sub-nanometer alignment position accuracy is vital. The Phase Grating Alignment (PGA) method is widely used due to its high precision and stability.

Multispectral stealth multilayer etched film structure based on ultrathin silver.

Spontaneous infrared radiation dissipation is a critical factor in facilitating object cooling, which influences the thermal stability and stealth efficacy of infrared stealth devices. Furthermore, the compatibility between efficient visible, infrared, and radar stealth is challenging due to different camouflage principles in different bands. This Letter presents a five-layer etched film structure to achieve multispectral stealth, and the utilization of the high-quality ultrathin silver films enables highly efficient infrared selective emission.

Broadband High Optical Transparent Intelligent Metasurface for Adaptive Electromagnetic Wave Manipulation.

Intelligent metasurfaces have garnered widespread attention owing to their properties of sensing electromagnetic (EM) environments and multifunctional adaptive EM wave manipulation. However, intelligent metasurfaces with broadband high optical transparency have not been studied to date, and most of the previous intelligent metasurfaces lack an integrated design for their actuators and sensors, resulting in lower integration levels. This study proposes a novel intelligent metasurface with adaptive EM wave manipulation ability and high optical transparency from visible to infrared bands.

A 1064 nm laser adaptive limiter with visible light transparency based on one dimensional photonic crystals of LiNbO defects.

Herein, we present the investigation of the visible light transparency and optical limiting characteristics of one dimensional photonic crystals with LiNbO defects fabricated by the sputtering technique. Transmission spectroscopy measurements reveal a broad photonic band gap with a 1064 nm defect mode and high transmittance within the visible range. The optical energy limiting performance in the photonic crystal can be attributed to the strong confinement of the optical field surrounding the LiNbO defect layer.

A visible-near-infrared transparent miniaturized frequency-selective metasurface with a microwave transmission window.

In this work, we propose a meshed miniaturized frequency-selective metasurface (MMFSM), which is insensitive to the incidence microwave angle and has great optical imaging quality by extending the effective length of the aperture within the periodic unit and replacing large metal parts with different metallic meshes. Experimental results indicated that our MMFSM had an average normalized transmittance of 87.2% in the visible-near-infrared band, a passband loss of 1.

Quantitatively mapping local quality of super-resolution microscopy by rolling Fourier ring correlation.

In fluorescence microscopy, computational algorithms have been developed to suppress noise, enhance contrast, and even enable super-resolution (SR). However, the local quality of the images may vary on multiple scales, and these differences can lead to misconceptions. Current mapping methods fail to finely estimate the local quality, challenging to associate the SR scale content.

High-Performance Transparent Ultrabroadband Electromagnetic Radiation Shielding from Microwave toward Terahertz.

In the era of fifth-generation networks and Internet-of-Things, the use of multiband electromagnetic radiation shielding is highly desirable for next-generation electronic devices. Herein, we report a systematic exploration of optoelectronic behaviors of ultrathin-silver-based shielding prototype (USP) film structures at the nanometer scale, unlocking the transparent ultrabroadband electromagnetic interference (EMI) shielding from microwave to terahertz frequencies. A theoretical model is proposed to optimize USP structures to achieve increased transparency, whereby optical antireflection resonances are introduced in dielectrics in conjunction with remarkable EMI shielding capability.

A Method for Measuring Parameters of Defective Ellipse Based on Vision.

Ellipse detection has a very wide range of applications in the field of object detection, especially in the geometric size detection of inclined microporous parts. However, due to the processing methods applied to the parts, there are certain defects in the features. The existing ellipse detection methods do not meet the needs of rapid detection due to the problems of false detection and time consumption.

Metasurface with Electrically Tunable Microwave Transmission Amplitude and Broadband High Optical Transparency.

Metasurfaces with tunable microwave transmission amplitude and broadband high optical transparency hold great promise for the next generation of optically transparent and smart electromagnetic transmission devices. In this study, a novel and electrically tunable metasurface with high optical transparency in the visible-infrared broadband is proposed and fabricated by integrating meshed electric-LC resonators and patterned VO. Simulations and experiments demonstrate that the designed metasurface has a normalized transmittance greater than 88% over a wide wavelength range of 380-5000 nm, and the transmission amplitude can be continuously tuned from -1.

Single-shot isotropic differential interference contrast microscopy.

Differential interference contrast (DIC) microscopy allows high-contrast, low-phototoxicity, and label-free imaging of transparent biological objects, and has been applied in the field of cellular morphology, cell segmentation, particle tracking, optical measurement and others. Commercial DIC microscopy based on Nomarski or Wollaston prism resorts to the interference of two polarized waves with a lateral differential offset (shear) and axial phase shift (bias). However, the shear generated by these prisms is limited to the rectilinear direction, unfortunately resulting in anisotropic contrast imaging.

Measurement method of aero-engine rotor concentricity and perpendicularity based on deep belief neural network.

When implementing the traditional assembly method, the rotor is affected by machining errors. The morphology of the rotor is complex, and the machining error of the rotors at all levels are transmitted step by step through the stop mating surface, which affects the performance and service life of the aero-engine. The evaluation of machining error of single-stage rotor is the basis of assembly quality of multi-stage rotor.