Accurate thermal conductivity measurement of low-dimensional thermoelectric materials remains challenging due to limited sensitivity and systematic errors inherent in conventional suspended MEMS devices. Existing platforms face a detection limit of 5-10 pW/K, constrained by thermometer self-heating under sub-microampere sense currents and non-isothermal conditions on sensing islands. We propose a three-island MEMS architecture introducing a reference island with mirror-symmetric geometry to cancel Joule heating effects, permitting sense current amplification without systematic bias. Finite-element simulations demonstrate a theoretical 600 & times; sensitivity enhancement, with practical realization achieving 5-10 & times; improvement. Rigorous error analysis identifies the beam-to-island thermal conductance ratio and through-thickness temperature gradients as primary accuracy limiters. Systematic optimization of silicon nitride membrane thickness (350 nm) and beam width (5 mu m) reduces measurement error below 5%, with simulated deviations of -1.4% to 0.2% across 200-500 K. This three-island design resolves the fundamental trade-off between sensitivity and accuracy, providing a robust platform for characterizing nanostructured thermoelectric materials and advancing MEMS-based thermoelectric metrology.

A dual-band multilayer structure was designed and fabricated to achieve simultaneous reflection at 17.1 nm and 19.5 nm under near-normal incidence. The initial design was based on a periodic multilayer stack, which was subsequently optimized into a non-periodic configuration using a genetic algorithm implemented in the IMD software. Theoretically, the structure exhibits reflectance of 41.5% at 17.1 nm and 42.8% at 19.5 nm. Experimentally, measured reflectance was 15.98% at 17.1 nm and 27.11% at 19.5 nm. Furthermore, proton irradiation tests were conducted on the samples, resulting in post-irradiation reflectance of 14.29% at 17.1 nm and 25.14% at 19.5 nm.

Extreme ultraviolet (EUV) imagers are key tools to monitor the space environment and forecast space weather. EUV filters are important components to block radiation in the ultraviolet (UV), visible, and near-infrared (IR) regions. In this study, various characterization methods were proposed for the nickel mesh-supported indium (In) filter, and their spectral characteristics were comprehensively studied. The material and thickness of the filter were chosen based on atomic scattering principles, determined through theoretical calculation and software simulation. The metal film was deposited using the vacuum-resistive thermal evaporation method. The measured transmission of the filter was 10.06% at 83.4 nm. The surface elements of the sample were analyzed using X-ray photoelectron spectroscopy (XPS). The surface and cross-sectional morphologies of the filter were observed using a scanning electron microscope (SEM). The impact of the oxide layer and carbon contamination on the filter’s transmittance was investigated using an ellipsometer. A multilayer “In-In2O3-C” model was established to determine the thickness of both the oxide layer and carbon contamination layer on the filter. This model introduces the filling factor based on the original model and considers the diffusion of the contamination layer, resulting in more accurate fitting results. The transmittance of the filter in the visible light range was measured using a UV-VIS spectrophotometer, and the measurement error was analyzed. This article provides preparation methods and test methods for the 83.4 nm EUV filter and conducts a detailed analysis of the spectral characteristics of the prepared optical filters, which hold significant value for space exploration applications.

The dual-wavelength extreme ultraviolet camera (EUC) for the Queqiao-2 relay satellite of the Chang’E-7 (CE-7) mission operates at 30.4 and 83.4 nm independently to simultaneously image the plasmasphere, magnetosheath, and ionospheric outflow from a lunar orbit. Each channel of the EUC is consisted of a concave multilayer mirror and a photon-counting imaging detector. This simple system achieves a large field of view (FOV), high spatial resolution, and optimized photon transmission efficiency to capture high-quality images of very weak extreme ultraviolet emissions in Earth space. Here we present the detailed design, tests, and calibrations of the EUC. Ground geometrical tests showed that the FOV was 20.2° for the 30.4 nm channel and 20.3° for the 83.4 nm channel, and the spatial resolution was 0.09° for both channels. Geometric distortion was corrected to be less than 1

The dual-wavelength extreme ultraviolet camera (EUC) onboard the Queqiao-2 relay satellite of the Chang’E-7 (CE-7) mission will be used to investigate the global structure and dynamics of the Earth’s magnetosheath and plasmasphere by simultaneously capturing emissions at 30.4 and 83.4 nm. In geospace, there are two emission sources at 30.4 nm: resonantly scattered emissions from plasmaspheric He+ ions and solar wind charge-exchange in the Earth’s magnetosheath. The sources of 83.4 nm emission include the ionospheric outflow O+ and the plasmaspheric O+ ions, both of which resonantly scatter sunlight at this wavelength. Global images at these wavelengths will enhance understanding of mass and energy transportation in solar wind-magnetosphere-ionosphere couplings, crucial for comprehending space weather. The Moon is an ideal platform for global imaging, allowing the EUC’s two optical heads operating at 30.4 and 83.4 nm, each with a circular field of view of 20° to capture spatial resolution of ∼0.1RE for the plasmasphere, ∼0.3RE for the magnetosheath, and ∼0.3RE for the ionospheric outflow in the meridian plane perpendicular to the Earth-Moon line. The sensitivities are as follows: 0.1 counts s−1 Rayleigh−1 at 30.4 nm channel for an angular resolution of 0.1° and 0.07 counts s−1 Rayleigh−1 at 83.4 nm channel for an angular resolution of 0.3°. Sufficient sensitivity was achieved to obtain plasmaspheric images every 10 min, magnetosheath images every 10–20 min, and ionospheric outflow images every 10 min. All of the original photon signals are transmitted to the ground, allowing for flexible processing of spatial and temporal resolutions.

Low-dimensionalization has emerged as a novel approach for thermoelectric material modification. Cu2-xTe has been proposed as promising thermoelectric material, yet its structure and properties upon lowdimensionalization remain largely unknown. Nanofilms with varying thicknesses from 20 nm to 340 nm were synthesized by RF magnetron sputtering, and their structures were characterized using high-angle annular darkfield scanning transmission electron microscopy (HAADF-STEM) and X-ray diffraction (XRD). By modulating thickness of the nanofilms, we observed a novel layered structure of Cu2-xTe and formation of three roomtemperature stable phases and their size-induced evolution. Furthermore, we demonstrate that the electrical properties of nanofilms are significantly modulated by size control. Since, we have achieved direct size-induced control over the structure and electrical properties of Cu2-xTe nanofilms.

The Lyman alpha (Lyman-α or Lyα) radiation emitted by hydrogen is the strongest ultraviolet spectral line on the corona, which can provide important coronal information that is difficult to obtain at other wavelengths and of great significance to comprehensively study the origin of the corona. In order to observe the Lyα corona and provide space weather warning in time, the stray-light suppression performance with a field-of-view (FOV) of 2.5R⊙ (R⊙ stands for the mean solar radius) for Lyα coronagraphs should be suppressed to 10-6B⊙ (B⊙ is the mean brightness of the solar disk). Since there is no Lyα light source with high brightness or Lyα detector with high sensitivity, it is difficult to measure the stray-light in Lyα wavebands directly. On the basis of the correlation between stray-light and wavelength, an evaluation method of stray-light in Lyα wavebands based on the measurement and simulation results in visible-light and ultraviolet bands is proposed. The parameters of the simulation model are modified by comparing the measurement results, and the stray-light for the internally occulted reflecting coronagraph in Lyα wavebands is analyzed with the modified model. The results show that the stray-light in Lyα wavebands can be suppressed to 10-6B⊙ at 2.5R⊙, and this method can be used to evaluate the stray-light level of all Lyα coronagraphs.

Infrared small target detection remains a subject of significant theoretical research value and practical application potential. However, the complexity of the detection environment and the interference from salt noise considerably increase the difficulty of the detection task. In scenarios involving small infrared target detection against complex backgrounds, existing methods face substantial challenges in achieving an optimal balance between superior detection capability and real-time performance. Furthermore, the influence of noise on detection efficacy is an unavoidable issue. To address these challenges, this paper proposes an anti-noise detection method that excels in both real-time performance and detection ability. Initially, energy residuals are computed to pre-assess potential target areas. Subsequently, the minimum difference between the central pixel and its local neighborhood is calculated to position the target region positioning twice, thereby enhancing targets while suppressing background noise. Finally, by defining a double gray-values descend angle and calculating its tangent quotient, further enhancement of targets is achieved alongside sup-pression of additional background interference and salt noise. Experimental evaluations were conducted on four publicly available datasets, comparing our proposed approach with seven existing algorithms. The results demonstrate that our method facilitates rapid detection of small targets affected by salt noise within complex backgrounds while exhibiting exceptional detection capabilities and real-time performance. Notably, DGDACM achieves its fastest single-frame detection time at just 0.0719 seconds—5.1% faster than the sec-ond-best average single-frame time.

In the design of optical systems for consumer-grade optical products, achieving a balance between imaging performance and systems cost is crucial for enhancing product competitiveness. As a significant component of system cost, the selection and optimization of optical materials directly affect the system configuration, performance, and economic efficiency. This paper proposes a design method based on glass materials cost, which comprehensively considers the materials relative price, tolerance grade, and volume. The method quantitatively evaluates the trade-off between image quality and material cost at the design phase. The simulation results indicate that under the precondition of less than 5% variation in system image quality, the cost reduction of the optimal design solution reaches 37%. This study provides what we believe to be a novel and practical design approach to improving the cost-performance ratio of optical systems.

Until now, only the Sc-based multilayer has been developed for solar transition observation at 46.5 nm, which has a high reflectivity and a narrow bandwidth. However, Sc is chemically reactive, which poses a potential threat to the mirror's stability. Here, a Ge/Mo2C multilayer for 46.5 nm was proposed for high stability, long lifetime payloads. The generation and impact of Mo2C nanocrystals were discussed. Experimental results showed that the multilayer structure with a Ge seed layer, owing to the wetting properties of Ge, achieved an interface diffusion of 0.8 nm and an RMS surface roughness of 0.18 nm, which resulted in a high reflectivity of 30.3% at 46.5 nm. Our job provides a good candidate material pair for the EUV optical system at 46.5 nm.

Significance With the development of aerospace technologies and the widespread adoption of communication and navigation systems, accurate and timely space weather forecasting has become increasingly urgent to mitigate the influence of catastrophic space weather events on human activities. Since the 1970s, space weather has been actively studied and applied. Many observational instruments have been developed to monitor solar activity and space environment variations. In particular, a series of space payloads have been developed for the extremely sensitive wavebands of X-ray, extreme ultraviolet (EUV), and far ultraviolet (FUV) to monitor changes in the Sun and the terrestrial space environment. Since the 1980s, several key technological breakthroughs have been achieved at Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences (CIOMP), including optical elements, single- photon- counting imaging detectors, and radiometry for X-ray, EUV, and FUV regions. A number of optical elements and detectors have been fabricated, and calibrations are applied to space payloads. Progress EUV multilayer mirrors have been fabricated with working wavelengths including 9.4, 17.1, 19.5, 21.1, and 30.4 nm, with reflectance of 28 degrees o, 45 degrees o, 35 degrees o, 38 degrees o, and 38 degrees o, respectively [Fig. 1(a)]. Broadband, aperiodic FUV LaF3/MgF2 multilayer mirrors have also been prepared, with a working wavelength range of 140-180 nm and an in- band average reflectance of 45 degrees o. These mirrors also exhibit good out- of- band reflectance suppression [Fig. 1(b)]. For observing weak EUV and FUV targets, a single- photon- counting imaging detector with a spherical photosensitive surface and excellent adaptability to space environments has been developed. This includes key technological advancements such as the fabrication of spherical microchannel plates, the carving of micro- strip anodes, and the processing of weak optoelectronic pulse signals. The detector has an equivalent pixel size of 45 mu m, a counting rate of 3.5x105 s-1, an effective aperture of & Fcy; 75 mm, and approximately 1600x1600 equivalent pixels. Test and calibration devices for optical element measurements in X-ray, EUV, and FUV regions have been established. These devices are equipped with a hollow cathode source, a laser- produced plasma source, and an X-ray tube. The device's working wavelength range is from 0.1 nm to 200 nm, with a spectral resolution of 0.1 nm, a test repeatability of 1 degrees o, and a wavelength precision of 0.2 nm. These have been used to measure the reflectance and transmittance of optical elements and grating efficiencies. To obtain high- resolution solar images, a high- precision pointing and imaging stabilization technology has been developed. A solar guide telescope (GT) has been developed at CIOMP, achieving a pointing accuracy of 0.1 '' and a data update speed of 1 kHz. The GT is used in payloads onboard FengYun meteorological satellites and the Kua Fu advanced space- based solar observatory satellite (ASO-S). Based on the breakthroughs in the above key technologies, four payloads have been developed at CIOMP and are employed in space weather forecasting, warning, and scientific research. An innovative X-ray and EUV double- wavelength solar imager is developed, which combines an EUV multilayer of normal- incidence optics in the central part of an X-ray grazing- incidence imaging optics for the FY- 3E satellite. This imager covers the 0.6-8.0 nm X-ray waveband and 19.5 nm EUV dual wavelengths. The instrument serves the function of two separate instruments. The imager is also equipped with a sensor for the same wavelengths which measures solar irradiance and regularly calibrates the X-ray and EUV solar images. Figure 9 shows solar images with absolute brightness. A Lyman alpha solar telescope (LST) has been developed for solar flare and coronal mass ejection (CME) observations, including a solar corona imager (SCI), a solar disk imager (SDI), and a white light solar telescope (WST). SCI utilizes a special design combining off- axis reflective optics and an FUV beam splitter to achieve inner corona imaging in dual wavebands of 121.6 and 700 nm. On- orbit test results indicate SCI achieves an angular resolution of 4.8 '', which is about one- eighth that of METIS/Solar Orbiter. The SDI's field of view (FOV) is 38.5 ' , allowing for full solar disk observation. The solar observation area of the SDI is approximately four times larger than that of EUI/Solar Orbiter. LST is the first to achieve imaging observation of all regions, from the full solar disk to the inner corona, at Lyman-alpha, monitoring the real-time process of fine corona and prominence. These observations have been used for space weather forecasting and scientific research. The AEUV camera onboard Chang'e-3, as part of the mission's payload, is the first EUV instrument to be used for observing Earth's plasmasphere from lunar orbit. These Earth plasma images are released by the Lunar Exploration and Space Program Center of China National Space Administration in January 2014. Figure 16 shows the panorama image of Earth's plasmasphere captured from the lunar surface. The wide- field auroral imager onboard FY- 3D has been developed to monitor aurora in the 140-180 nm waveband and can image the entire polar region (5000 kmx 5000 km) in two minutes. Compared with DMSP/SSUSI and TIMED/GUVI, it has a higher temporal resolution, offering an advantage for forecasting and scientific research. Conclusions and Prospects A series of core space optical technologies in the X-ray, EUV, and FUV wavebands have been mastered, including the manufacture, testing, and calibration of instruments. A research system has been established at CIOMP. Several payloads in these wavebands have been developed and launched into lunar orbit, polar orbit, and sun- synchronous orbit. These payloads play an important role in space weather forecasting and scientific research.

The design of optical systems not only considers the imaging performance but also the manufacturing difficulty and feasibility of the system. In practice, errors in the manufacturing process of glass materials and deviations in glass material parameters introduced in complex environments can both lead to degradation in the imaging quality of optical systems. Optical systems that are sensitive to glass material errors face increased manufacturing difficulty and reduced stability. This paper, based on geometrical optics theory, establishes an evaluation function for refractive index error sensitivity and analyzes its relationship with optical parameters and glass materials. It proposes a design method to reduce the refractive index sensitivity of optical systems. Through simulation verification and analysis using examples, the validity of the desensitization design method is confirmed.

Infrared small target detection is widely used in the military field, and robust infrared small target detection has significant significance. Inspired by plants, an infrared small target detection method based on the four-leaf model is proposed. This model has both macro and micro attributes, with macro attributes referred to as the background suppressor (BS) and micro attributes referred to as the texture collector (TC). BS is a four-neighborhood model that can achieve background suppression while reducing the interference of bright background clutter in the target neighborhood to a certain extent. TC can collect texture information of small targets and improve the enhancement effect of small targets. The fusion of TC and BS can effectively suppress background clutter and improve the detection performance of infrared small targets. The experiment is carried out on five real infrared image sequences. The results show that the proposed infrared small target detection method can improve the detection rate and reduce the false alarm rate in the face of infrared images with complex backgrounds. Compared to existing algorithms, the algorithm has high robustness.

Rippling in graphene, which is an out-of-plane corrugation induced by thermal fluctuations, plays a fundamental role in supporting the material’s stable existence. These ripples have also been instrumental in explaining various unconventional electronic and chemical properties of graphene. Previous experimental findings have indicated that graphene exhibits smoothing effects on underlying substrates in the high-spatial-frequency regime. To explain this phenomenon, we employed a force balance model that considered both van der Waals forces and strain forces. By utilizing traditional film-growth theory, our model successfully predicted experimental results.

Metal sulfide has become an important anode electrode material for lithium-ion batteries due to its high theoretical specific capacity and low cost. In this work, nano-SnS/ZnS grown on a honeycomb substrate carbon were coated with nitrogen-doped carbon (EG@SnS@ZnS@N-C) by solvothermal and in situ thermal decomposition/sulfide reactions. Honeycomb carbon with good electrical conductivity and mechanical mechanism is loaded with SnS and ZnS with synergistic effects, combined with nitrogen-doped porous carbon with enhanced ion transport. These unique designs enable EG@SnS@ZnS@N-C to exhibit excellent lithium storage performance with a specific capacity of 880 mAh/g at 0.1 A/g and capacity retention of 98% after 100 cycles.

Change detection (CD) in high-resolution remote sensing imagery remains challenging due to the complex nature of objects and varying spectral characteristics across different times and locations. Convolutional neural networks (CNNs) have shown promising performance in CD tasks by extracting meaningful semantic features. However, traditional 2D-CNNs may struggle to accurately integrate deep features from multi-temporal images, limiting their ability to improve CD accuracy. This study proposes a Multi-level Feature Cross-Fusion (MFCF) network with 3D-CNNs for remote sensing image change detection. The network aims to effectively extract and fuse deep features from multi-temporal images to identify surface changes. To bridge the semantic gap between high-level and low-level features, a MFCF module is introduced. A channel attention mechanism (CAM) is also integrated to enhance model performance, interpretability, and generalization capabilities. The proposed methodology is validated on the LEVIR construction dataset (LEVIR-CD). The experimental results demonstrate superior performance compared to the current state-of-the-art in evaluation metrics including recall, F1 score, and IOU. The MFCF network, which combines 3D-CNNs and a CAM, effectively utilizes multi-temporal information and deep feature fusion, resulting in precise and reliable change detection in remote sensing imagery. This study significantly contributes to the advancement of change detection methods, facilitating more efficient management and decision making across various domains such as urban planning, natural resource management, and environmental monitoring.

Real-time detection of infrared small targets is of great significance for practical engineering projects. The existing algorithms mainly focus on single-frame detection (SFD) and multi-frame detection (MFD), which have a certain degree of latency. This paper proposes a novel single-row detection (SRD) method based on a one-dimensional bidirectional vector feature measure (1BVFM). A one-dimensional bidirectional vector (1BV) model is defined, and based on this, a one-dimensional bidirectional vector contrast (1BVC) operator is established to suppress the background. At the same time, a one-dimensional bidirectional vector gradient (1BVG) operator is established to enhance the target. By integrating 1BVC and 1BVG, the background suppression effect is enhanced and the target saliency is improved. The experimental results show that compared with the single frame detection method, the algorithm proposed in this paper still has certain advantages. It is a robust infrared small target detection method that can be used for optoelectronic detection equipment.

To protect the security of image information in storage or transmission. We present a color image encryption algorithm based on the image features, which are unique to each other. Firstly, 12 pseudo-random sequences are generated based on The Logistic Sine (LSS) coupled mapped lattice. One group of pseudo-random sequences is selected to group the remaining 11 groups of sequences randomly, of which eight groups of sequence data realize the scrambling operation of the bit-level image, and the other three groups learn the image diffusion operation to obtain the encrypted image. The experimental results show that the image encryption algorithm proposed in this paper has ample key space. The number of pixel change rates (NPCR) and unified average change intensity (UACI) are 99.62% and 33.57%, respectively, close to the ideal value. The proposed algorithm effectively resists standard data statistics, cutting, and noise attacks.

The Ly α Solar Telescope (LST) is the first instrument to achieve imaging of the full solar disk and the coronal region in both white light (WL) and ultraviolet (UV) H i Ly α , extending up to 2.5 solar radii (Rs), contributing to solar physics research and space weather forecasting. Since its launch on 9 October 2022, LST has captured various significant solar activity phenomena, including flares, filaments, prominences, and coronal mass ejections (CMEs). On-orbit observation and test results show that LST covers a continuous spatial range and the wavelengths of 121.6, 360, and 700 nm. The Ly α Solar Disk Imager (SDI) has a field of view (FOV) of 38.4′ and a spatial resolution of around 9.5″, while the White-Light Solar Telescope (WST) has an FOV of 38.43′ and a spatial resolution of around 3.0″. The FOV of the Ly α Solar Corona Imager (SCI) reaches 81.1′ and its spatial resolution is 4.3″. The stray-light level in the 700 nm waveband is about 7.8 × 10−6 MSB at 1.1 Rs and 7.6 × 10−7 MSB at 2.5 Rs, and in Ly α waveband it is around 4.3 × 10−3 MSB at 1.1 Rs and 4.1 × 10−4 MSB at 2.5 Rs (MSB: mean solar brightness). This article will detail the results from on-orbit tests and calibrations.