In this paper, We design a dual-channel linearly swept laser based on an electro-optic phase modulator and micro-ring filters, and constructing a long-distance coherent detection system to achieve a long range 3D imaging. This swept laser utilizes two fiber micro-ring filters to generate two independent linear scanning frequency bands, improving the system’s detection range, resolution, and anti-interference capability through dual-channel differential detection. Experimental tests indicate that the swept-source laser designed in this study has a linewidth of less than 20 kHz and a coherence length greater than 1 km; the coherent detection system based on this light source, at a fiber length of 1150 m, achieved a signal intensity of 168 dB, a suppression ratio of 48 dB, and a lateral resolution better than 0.37 m. Furthermore, through a two-dimensional scanning imaging experiment, the three-dimensional contour of a building target at a distance of 378.9 m is successfully reconstructed, with clear visibility of corner points, proving the system’s long-range three-dimensional imaging performance. The results of this paper provide new technical means and application scenarios for long-distance high-resolution laser coherent imaging.

This study proposes a standard starlight simulator with an adjustable background to improve the accuracy of ground- based tests of star sensors and space cameras. The simulator can simulate complex space light radiation environments in the simulation range of Φ300mm aperture, 0.5° field of view, and -2Mv to +6.0Mv magnitude. By optimizing the optical system design and structural design, the simulation of star points with high imaging quality and the precise control of background light irradiation uniformity has been achieved, thus ensuring the design accuracy of the equipment at the development stage.

In order to mitigate the measurement errors caused by the crosstalk in the output of the optical fiber array in the new solar radiation measurement method, this paper proposes a method that utilizes a non-spherical lens to eliminate the crosstalk and achieves effective crosstalk elimination through simulations and experiments based on relevant principles. Firstly, the analysis of the transmission principle of optical fibers is conducted to determine the causes and impacts of crosstalk in the output of the fiber array. Secondly, the imaging process of the non-spherical focusing lens is analyzed to understand its focusing effect on the divergent output beams of each individual unit. Subsequently, using Zemax, simulations are carried out to analyze the crosstalk elimination capability of the system under processing and assembly errors. Finally, based on the simulation results, a platform is constructed for testing to experimentally validate the capability of the non-spherical lens system to cleverly, simply, and real-time eliminate the output crosstalk of the fiber array, thereby enabling power calculation of any output beam.

Using the sun-sky radiometer CE318 data in 2013~2019 observed in typical dust regions including Kashgar, Zhangye and Minqin, the variation characteristics of Aerosol Optical Depth(AOD), Angstrom exponent, single scattering albedo and asymmetry factor were analyzed. The results show as follows. There are significant differences in the variability characteristics of AOD at three typical dust-type stations. The seasonal variation of AOD in Kashgar is the most obvious. The highest AOD is in spring with more dispersed KDE, and the lowest in winter with more concentrated KDE. In Zhangye and Minqin, the seasonal difference of AOD is small, with monthly means below 0.9 and more concentrated distribution in the range of 0.5~0.8. The value of Angstrom exponent in Kashgar is higher in autumn and winter than spring and summer. In spring, summer and autumn, Zhangye and Minqin have significantly higher Angstrom exponent than Kashgar. The single scattering albedo in all three stations is above 0.85, and the asymmetry factor ranges from 0.63~0.8, indicating that the aerosol scattering effects are evident throughout the year.

In this study, we focus on the temporal variation of temperature at the Fuyang station, aiming to reveal its long-term climate change trends and seasonal patterns. By collecting and analyzing temperature data from the Fuyang station over the past decades, this study utilizes time series analysis methods and the predictive effectiveness of the Prophet model to explore the periodicity, trend, and seasonal variation characteristics of temperature. Moreover, the research investigates the potential impact of climate change on temperature variations in the Fuyang area, including the influence of global warming on the long-term trend of regional temperatures. Through comparative analysis of temperature changes across different time scales, this paper aims to provide a scientific basis for the adaptation and strategy formulation of climate change in the Fuyang area. The results show that the annual average temperature at the Fuyang station has exhibited a rising trend year by year, especially with more significant temperature increases in winter, suggesting the impact of climate warming. Seasonal analysis reveals clear temperature periodicity, consistent with the specific climate characteristics of the region. The findings of this study are of great significance for understanding and predicting the climate change trends in the Fuyang area.

Gold nanoparticle-based Raman probes have the ability to significantly boost Raman spectra signals via Surface Enhanced Raman Scattering (SERS). However, accurately reflecting the precise localization and uptake of the metal probe within the intricate biological milieu becomes challenging as the probe remains within the system for an extended period. Therefore, there is a pressing need for an enhanced methodology to quantitatively assess the uptake of AuNPs in cellular environments. Flow cytometry emerges as a promising technique capable of evaluating intracellular AuNPs through efficient single-cell analysis of light scatter data obtained from a considerable population of live cells. In the conventional approach, the side scatter setting of flow cytometry is typically linked to the excitation light and employed for nanoparticle uptake detection. Nonetheless, this method presents limitations due to the suboptimal response of AuNPs to specific excitation wavelengths. To address this issue, a novel strategy is proposed. By aligning, to the fullest extent possible, the scattering absorption peak of the probe with the excitation light, achieved through the adjustment of the UV absorption peak position of the probe and selection of a red-shifted excitation light, the optical signal essential for flow cytometry based assessment of AuNPs uptake in HELA cells is markedly amplified. This innovative methodology facilitates accurate quantitative measurement of AuNPs uptake in instances where Raman molecular tracing proves inadequate. This study underlines the promising applications of flow cytometry in gauging AuNPs uptake within cancer cells and contributes valuable insights into advancing the comprehension of the mechanisms underpinning cellular uptake of AuNPs in SERS related investigations.

Effective monitoring of the spatial and temporal distribution changes of mariculture areas is of great significance for the dynamic marine supervision, ecological environment protection and disaster prevention. In this paper, the remote sensing image datas of ALOS and GF-6 are selected, and the regional network adjustment method is adopted to effectively solve the migration problem of offshore aquaculture area. The distribution information of Rongcheng raft aquaculture area is obtained through U-Net deep learning model. Moreover, the spatial and temporal change characteristics of aquaculture area and the spatial expansion mode are deeply analyzed based on the center of gravity transfer model and convex shell principle. The results show that from 2009 to 2023, the raft aquaculture area increased by 10,224.58 hm2 , and the annual average change rate of the area was 3.84%; 75% of the raft culture in the research area shifted in the south-west by 11,743.22 meters. Based on the spatial distribution of the raft aquaculture areas in2023, there occupied some port shipping areas, industrial and urban use areas, marine protection areas, special utilization areas and reserve areas.

Underwater wireless optical communication (UWOC) based on the orbital angular momentum (OAM) beam has great potential to provide a higher data rate and lower communication latency. When the OAM beam propagates underwater, due to the absorption and scattering (AS) effect, the incident light would be attenuated and diffused, causing the crosstalk between OAM modes. In this paper, the electric field Monte Carlo (EMC) method is used to simulate the AS effect by the optical transmission matrix (TM) model. The intensity and the spiral phase spectrum of the received beam at different propagation distances are studied under the coastal ocean water channel. Furthermore, the detection probability is analyzed after propagating through the coastal ocean water and turbid harbor water channels. The simulation results show that the detection probability of OAM beam propagating in an AS channel decreases linearly with the increase of propagation distance. In coastal ocean water (attenuation coefficient 0.398m^-1), the detection probability decreases to 0.5 at around 10m. In turbid harbor waters (attenuation coefficient of 2.17m^-1) the detection probability decays to 0.5 at around 2m. These results will be beneficial to the design of UWOC-OAM systems.

Differential Absorption Lidar (DIAL) is an effective approach for measuring atmospheric ozone with high precision. To solve the problem of wavelength pair selection for DIAL, numerical simulation experiments of DIAL were carried out. Within the ultraviolet band of 220nm to 360nm, tests were conducted for each wavelength with an interval of 1nm, and wavelength combinations with differences of 5nm, 10nm, 20nm, 30nm, 40nm, and 50nm were tested. The feasibility and of different wavelength combinations in the band for ozone measurement were synthesisly evaluated. The experimental results show that for DIAL systems with wavelength differences of 5 nm, 10 nm, and 20 nm, the combined error of ozone measurements in the troposphere from 0 to 6 KM below 15% if the strong absorption wavelengths (λ_on) are selected in the range of 260 nm to 283 nm, and the synthesis error of ozone measurements in the stratosphere from 15 to 30 KM below 15% if λ_on are selected in the range of 305 nm to 315 nm. For DIAL systems with wavelength differences of 30nm and 40nm, the synthesis error of ozone measurements in the troposphere from 0 to 6 KM below 15% if λ_on are selected in the range of 254 nm to 270 nm, and the synthesis error of ozone measurements in the stratosphere from 15 to 30 KM below 15% if λ_on are selected in the range of 305nm to 312nm. For DIAL systems with a wavelength difference of 50nm, the synthesis error of ozone measurement in the troposphere at 0 to 6KM is higher than 15%, and the synthesis error of ozone measurements in the stratosphere from 15 to 30 KM below 15% if λ_on are selected in the range of 305nm to 311nm. This result serves as a reference for the selection of wavelength pairs for DIAL measurements of atmospheric ozone.

The new generation of ocean color observation satellites in China has many moving mechanism components, and the impact of micro-vibration generated by the satellite on the imaging quality of the high-resolution new generation coastal zone imager cannot be ignored. This article provides a testing method for the impact of micro-vibration on the imaging quality of coastal zone imager. Through imaging based on resolution target, the uniform illumination of integrating sphere radiation source is on the black and white stripe resolution plate, and the imaging of resolution plate is on the measured device through optical system. The image acquisition equipment collects black and white stripe image signals output from the coastal zone imager. According to various mechanism components on the whole satellite, this article divides into multiple working modes, and image data corresponding to each working mode is collected separately. Then, image centroid calculation analysis, MTF test image calculation analysis, and pixel DN value calculation analysis are carried out respectively. It is concluded that the refrigerator micro-vibration has the greatest impact on the imaging quality of coastal zone imager. Through image data calculation analysis and comparison under two different scenarios of satellite installation vibration reduction device and installation process support, the effectiveness of satellite vibration reduction and isolation system design is verified. The research example proves the feasibility of this testing method, providing a basis for improving the imaging quality of satellite, and the research results can provide reference for vibration isolation and suppression design of satellite.

This paper illustrates an adaptive mesh grid scaling algorithm, which can be applied in the simulation of laser propagation. The algorithm can effectively improve the far-filed laser spot resolution in the simulation of focused laser propagation. And the algorithm’s effectiveness is verified by the simulation of various laser beam type’s diffraction. The phenomenon of diffraction exits in all the laser beam propagation, in which the divergence angle is directly proportional to the laser wavelength, and inversely proportional to the laser aperture. The proportion coefficients will vary depending on the type of laser beam, such as gaussian beam and flat-topped beam with different obscuration, which have accurately theoretical value. Moreover, the simulation results of adaptive mesh scaling algorithm agree well with theoretical values, which effectively checked the algorithm’s feasibility and accuracy.

In recent years, with the rapid development of military combat technology worldwide, research on target detection and identification has deepened, integrating polarization characteristics with the intensity information of plumes to enhance the detection and identification performance of aerial targets from multiple dimensions. This article studies the spatial distribution characteristics of ultraviolet polarized radiation in gas-solid two-phase flow plumes through the improved Spherical Harmonic Discrete Ordinate Method (SHDOM). Adjustments were made to SHDOM to suit the complex environment of plumes, and the spatial distribution cloud diagram of Stokes parameters in solid rocket motor plumes was analyzed through simulation. Simulation results indicate that the overall spatial distribution of polarized radiation components in two-phase flow plumes is similar, but the positions of the internal peaks differ; the detection zenith angle directly impacts the distribution characteristics of polarized radiation in the plume, with all polarized radiation components in the plume increasing as the detection angle increases. These improvements and studies deepen the understanding of the polarization radiation characteristics of vehicle plumes, providing an important theoretical basis for enhancing the precision of plume detection and analysis.

With the rapid advancement of hypersonic flight technology, the high-precision measurement of hypersonic flow field parameters has become an urgent issue. The computational fluid dynamics (CFD) method for obtaining high-resolution flow field data requires high grid quality and involves complex numerical solving processes, leading to significant computational costs. There is a growing need to quickly obtain high-resolution flow field data with less effort. Leveraging the powerful nonlinear fitting capabilities of neural networks, it is possible to perform fine super-resolution reconstruction of low-resolution flow field data in a data-driven manner. In this study, we propose an improved Enhanced Super-resolution Convolutional Neutral Network (ESRCNN) model tailored for hypersonic target flow fields. This enhanced model is applied to the super-resolution reconstruction of low-resolution flow fields of blunt body aircraft targets and compared with interpolation methods and traditional deep learning methods. Peak Signal-to-Noise Ratio (PSNR) and Structural Similarity Index (SSIM) are used as evaluation metrics. The results validate the accuracy and superiority of this model in reconstructing hypersonic target flow fields. This method provides an effective approach for the precise measurement and reconstruction of hypersonic flow fields, thereby contributing to the advancement of hypersonic flight technology.

The primary purpose of this research is to analyze the impact of different chemical reaction models on the characteristics of NO ultraviolet spectral radiation in the shock layer of hypersonic vehicles. The study is conducted from two main aspects. Firstly, three different non-equilibrium chemical reaction models—Gupta, Park, and the modified Ozawa model—were used to simulate the non-equilibrium flow field in the shock layer of the vehicle. Secondly, we further analyzed the effects of different chemical reaction models on the formation of substances in the shock layer and the characteristics of NO ultraviolet spectral radiation. In this paper, we conducted an in-depth study and analysis using the typical flight case of the BSUV (Bow-shock Ultraviolet) flight experiment, which revealed that the non-equilibrium chemical reaction models in the shock layer significantly influence the concentration and distribution of substances, thereby affecting the ultraviolet spectral radiation. By comparing the computational results with the experimental detection spectra, the Park model showed better agreement with the experimental data, with a weighted error below 10%, outperforming the Gupta chemical reaction model. The Park model exhibits comprehensive performance in the current computational cases.

In recent decades, polarization imaging has garnered much interest and research focus, due to its wide range of applications in the fields of atmospheric remote sensing, astronomy, biomedical and target detection, etc. Linear division-of-focal plane (DoFP) polarimeters deploying metal wire grid micro-polarization array as the polarization state analyzer (PSA) possess the capacity to capture polarization properties of the scene target during a single snapshot and benefit from their rugged and compact designs. However, these systems acquire the polarization measurements through spatial modulation and inevitably lead to spatial resolution loss, which cause instantaneous field of view (IFOV) errors and degradation of polarimetric accuracy. In response to this challenge, various interpolation/demosaicking methods tailored to DoFP imaging to fill the missing polarization information have emerged in recent years. This survey aims to explore these methods and briefly describe their effectiveness in enhancing the image restoration performance, highlighting their advantages and disadvantages. Lastly, according to current progress, some suggestions are made for high accuracy polarimetric measurements, especially for polarization remote sensing applications at different scales.

Traditional Monte Carlo method lacks the capability to trace and record polarization and phase information when simulating the transmission of photons. In this paper, based on Mie scattering theory and Electric Field Monte Carlo(EMC) method, we simulates the multiple scattering between photons and smoke particles and obtains the intensity and electric field information of backscattered photons, by calculating the rotation rules of local coordinate system and amplitude scattering matrix of photon. Simulations reveal that with an idealized point light source, backscattered photons concentrate into a speckle on the receiving surface, which expands as the scattering media thickens. The number of backscattered photons rapidly decreases over time, while their degree of polarization stabilizes within a specific range, forming a cross pattern that rotates based on the light's initial polarization. These findings offer valuable insights for developing anti-smoke interference imaging techniques.

To meet the observation requirements of atmospheric environmental, water environmental and ecosystems etc., China has planned a number of comprehensive environmental observation satellites, including the Gaofen-5 satellite, the hyperspectral observation satellite, the atmospheric environment monitoring satellite, the high-precision greenhouse gas monitoring satellite and the hyperspectral integrated observation satellites. The spectrum of the comprehensive environmental observation satellites covers from ultraviolet to longwave infrared, and the observation means of the satellites include multi-spectral, hyperspectral, polarization, multi-angle, active lidar etc. The satellites are characterized by hyperspectral, high quantitative, high accuracy and multi-detection methods, and becoming the symbol of China's hyperspectral remote sensing capability. In this paper, the development status of China's comprehensive environmental observation satellites is summarized. The detection capability is analyzed from two aspects: the integrated terrestrial observation capability and the integrated atmospheric observation capability. The comprehensive application examples and efficiency under the existing system is given. The shortcomings of the existing environmental observation system are analyzed from the aspect of observation timeliness, spatial resolution, detection elements, etc., and the development suggestions are given for the subsequent development of environmental comprehensive satellites.

Tunable diode laser absorption spectroscopy (TDLAS) has emerged as a paramount technology for high-precision gas concentration measurement. However, due to the significant influence of temperature changes on the gas absorption spectrum, the system's detection accuracy is substantially compromised. This paper explores a temperature-independent calibration concentration compensation method for TDLAS technology, aiming to mitigate measurement errors in gas concentration under unknown temperature conditions. Initially, the paper introduces the basic principles of the gas detection based on TDLAS technology. Subsequently, the theory of temperature-independent calibration concentration compensation method based on TDLAS is emphasized. Lastly, taking methane gas as an example, based on the HITRAN database, the absorption spectra of trace methane gas with a concentration of 10×10^-6 is simulated at temperatures ranging from 243K to 323K. Two relationship equations are fitted for absorption intensity and the HWHM (half-width at halfmaximum) at different temperatures, yielding determination coefficients (R²) of 0.9999 and 0.9995, respectively. Therefore, we verify the rationality of the method. The results show that the gas concentration can be inverted and compensated by calculating the absorption degree and temperature of the gas absorption spectrum and combining the relationship between temperature and the HWHM of the absorption spectrum. Compared to traditional temperature calibration compensation methods, the novel method not only reduces the costs and complexity of the gas detection system, but also has certain reference significance for improving the accuracy of TDLAS gas detection and system miniaturization.

In this paper, a new method of full Stokes polarization imaging based on liquid crystal polarization grating is proposed. Firstly, the theory of polarization detection module based on quarter-wave plate liquid crystal polarization grating is deeply explored by using Stokes calculus and Jones matrix method. The relationship between incident deflection state and diffraction efficiency is deduced in detail; furthermore, the performance of polarization detection module is optimized. The Stokes polarimeter designed in this paper has the advantages of compact structure, high flexibility and convenience in practical application. Moreover, it can be installed in various optical systems for correlation detection. Compared with the traditional measuring device, the polarizer can directly obtain the image from the CCD camera, which simplifies the data processing process and improves the detection efficiency. This innovative design makes the Stokes Polarimeter a significant advantage in a variety of polarization detection scenarios, providing support for underwater imaging and detecting the polarization information of underwater materials. In addition, the performance of the Stokes polarimeter was evaluated and optimized in detail. Meanwhile, the stability and accuracy of the instrument under various working conditions were verified by the detection of incident light with different polarization states. The experimental results show that Stokes polarimeter has high detection efficiency in polarization detection. This technology finds extensive applications in optical experiments, scientific research, and engineering disciplines.

Feature extraction and attribute recognition of particulate light scattering signals are important in the fields of environmental monitoring, atmospheric science and industrial process control. However, due to the complexity of particles, it remains a challenge to accurately extract features from light scattering signals and perform attribute recognition. In this study, a deep learning-based feature extraction and attribute classification model for particulate light scattering signals is proposed. Firstly, the acquisition of particulate light scattering signal is accomplished by the multi-angle detection of light scattering signal experimental flat, secondly, a total of 20 statistical features in time domain, frequency domain and information entropy features of the signal are extracted to describe the local details of the signal at different frequencies and the feature weights of the signal are obtained by the ReliefF algorithm, so as to find the optimal feature vectors of the signal. Finally, the GRNN and PNN neural network algorithms are used to construct the particle attribute classification model, and the acquired optimal feature vectors are input into the model for attribute classification and recognition. The results show that the recognition accuracy of GRNN reaches 86.7%, while that of PNN reaches 91.67%. It is verified that the GRNN and PNN methods are able to effectively distinguish the above six particles with different attributes.

With the development of industrialization, the problem of aerosol pollution has become increasingly prominent, which has a significant impact on public health. In this paper, the variation of Stokes vector of scattered light of aerosol particles under 45° incident polarized light is analyzed by T-matrix method, and the effects of complex refractive index, shape and particle size on Stokes vector are discussed. The results show that the variation trend and numerical difference of normalized S1, S2 and S3 can realize the morphological recognition of spherical and ellipsoidal particles. These parameters are sensitive to real and imaginary parts of different complex refractive indices in different detection ranges. This shows that the scattering Stokes vector obtained by 45° linearly polarized light shows great potential in identifying the morphology, complex refractive index and particle size of aerosol particles, and provides a new method and idea for the accurate identification of aerosol particle properties.

Atmospheric particulate matter has complex components and a wide range of sources. It not only frequently occurs in bad weather such as haze, but also aggravates environmental pollution as a carrier of pollutants, posing a potential threat to human health. In order to identify its composition characteristics and sort particles with different particle sizes, this study designed a particle sorting structure based on microfluidic technology, in order to provide scientific guidance for solving the problem of atmospheric particulate matter pollution. Based on the principle of microfluidic particle optical sorting, a particle sorting structure of microfluidic technology was designed to achieve continuous sorting of particles with different particle sizes. The results show that the use of optical radiation force and fluid resistance can effectively achieve the separation of particles with different particle sizes, so as to effectively sort the atmospheric particles according to the particle size.

To address the issue of limited detection of water vapor in the near-surface area by existing Lidar technology, a side-scanning continuous light method is proposed. This method uses a high-power continuous light laser as the detection source and obtains the water vapor concentration contour by side-scanning the light scattering and absorption signals on the detection path. The water vapor concentration contour is then obtained through inversion based on the differential absorption method. The model establishes the detection of water vapor concentration using side-scanning continuous light. The validity of the method is verified through simulation, which shows that semiconductor continuous-wave lasers with detection wavelength pairs of 880 nm and 940 nm and energy of 5 W can effectively detect water vapor within 500 m near the ground. This method does not require expensive narrow-pulse lidar as the detection light source. It has the advantages of being easy to implement and cost-effective. It can be a useful supplement to existing water vapor detection technology for near-surface detection.

With the rapid development of industry, the content of greenhouse gases such as CH4 in the atmosphere is increasing, which has a certain impact on human production and life. Therefore, high-precision gas detection has been a research hotspot in the field of gas sensing, but the temperature and pressure changes in the environment will affect the line shape of the gas absorption spectra, resulting in errors in gas concentration monitoring. This paper presents a temperature-pressure compensation algorithm. Firstly, the temperature and pressure compensation coefficients under different ambient temperatures and pressures are obtained by simulation. Then, the temperature and pressure of the ambient gas are monitored, and the detection signal is compensated in real time. Finally, the monitored gas concentration is calculated according to the linear relationship between the detection signal amplitude and the gas concentration. The experimental results show that the detection accuracy of the gas detection system is significantly improved after using the compensation algorithm to compensate for the signal amplitude. Taking the measurement of 2 ppm CH₄ concentration as an example, the maximum error of CH₄ concentration obtained after using the temperature-pressure compensation algorithm is 5%, while the maximum error of CH₄ concentration obtained without using the temperature-pressure compensation algorithm is 9.5%. The system was also utilized for long-term stability monitoring of 2 ppm CH₄, and the concentration fluctuation of the system was only 0.04 ppm. According to theoretical and experimental proofs, the monitoring stability of the TDLAS gas sensing system can be effectively improved and the monitoring error can be reduced by this temperature-pressure compensation algorithm.

When space infrared detection system is detecting weak targets in low Earth orbit, the complex and intense out-of-field stray radiation from Earth, Sun and Moon is several orders of magnitude higher than the target energy, which has a serious impact on detection. Therefore, modeling and analysis of out-of-field stray radiation are needed. In this paper, the observation hemisphere at the entrance of the system is divided into regional grids, and then the stray radiation model in any time and space is established according to the detection geometry, combining the characteristics of the stray radiation from different sources. Taking the long-wave infrared spectrum of a detection system as an example, the energy of stray radiation reaching the focal plane is calculated, and the stray radiation is analyzed in typical space and time state. The out of-field stray radiation accounted for 39.1% of the total radiation, and the out-of-field stray radiation from the incident off axis angle less than 20° accounted for 95.3% of the total radiation. When the observation hemisphere is illuminated by the Sun, the maximum out-of-field stray radiation from the Earth's surface region and the Earth's atmosphere region increases by 16.7% and 10.9%, respectively. The out-of-field stray radiation model established in this study can be used as the support and basis for the design of stray radiation suppression in space infrared detection systems.

Surface enhanced Raman spectroscopy is a vibrational spectroscopy technique that enhances molecular Raman signals through noble metal nanostructures, commonly used in biological or chemical analysis in the fields of food, environment, and medicine. The controllable, repeatable preparation of nano periodic structures with high-density hotspots is currently the research highlights. This article introduces the method of using ion beam evaporation deposition and ultra-thin dual pass anodized aluminum oxide (AAO) template to prepare low-cost, large-area periodic nanodots array SERS substrates, and simulates the absorption rates of gold nanodots array with different diameters. The surface enhanced Raman spectroscopy characteristics of the SERS substrates were tested and analyzed using Rhodamine 6G as the probe molecule. The results showed that the SERS substrate of gold nanodots with a diameter of 260nm and a thickness of 35nm prepared on Si substrate can detect 10^-7mol/L of Rhodamine 6G. The enhancement effect of the periodic structure of the gold nanodots at 1361.555 cm^-1 is 22 times that of ordinary gold films of the same thickness.

The present study utilizes a turbulence radiosonde to obtain profiles of atmospheric temperature, pressure, wind field, and optical turbulence at different time periods in the northwest region of China. Three turbulence parametric models based on Tatarski theory (Dewan model, Kondo model, and HMNSP99 model) are selected for comparison and validation with measured turbulence profiles. According to the radiosonde data, wind shear, potential temperature gradient and Richardson number are calculated, and the corresponding relationship between them and the measured C²_n (atmospheric refractive index structure constant) profile is analyzed, which confirms the feasibility of Tatarski theory in the local area. The C²_n profiles calculated by the three models were compared with the measured C²_n profiles at different time periods. The results show that Tatarski theory has a large error in the estimation of nearsurface layer and boundary layer turbulence, but has a better estimation effect on the free atmosphere turbulence dominated by wind shear. We also analyze the applicability and limitations of the three models, and the results of root mean squared error (RMSE) and correlation coefficient (R_xy) show that the HMNSP99 model has the best application effect in this area, which provides method verification for the application research of atmospheric optical turbulence model in typical region.

A T-type microfluidic chip for particulate matter sorting and collection is theoretically established based on optical methods, and an analytical solution for the offset distance of particles is also derived. On this basis, a dimensionless parameter S is proposed in combination with the characteristic parameters of the microfluidic chip. The trajectories of the particles under different conditions are calculated by means of numerical simulations, and the numerical simulations are compared with the theoretical calculations to verify the validity of the calculations and models. At the same time, an experimental platform was constructed, and the final experimental results show that the errors of the particle offset distances are 4.2 μm and 1.4 μm compared with the results of theoretical calculations and numerical simulations, respectively. Meanwhile, the particle sorting efficiency was counted according to the experimental results, and the experimental results and the numerical simulations are sufficient to attain satisfactory agreements.

This paper proposes the implementation of a self-deformation estimation strategy for an active mirror within a framework of mechanoelectrical sensing. This architecture can collaborate with conventional optical wavefront sensors in a complementary manner, integrating information from various working bands and noise levels. The aim is to enhance the shape maintenance of the Active Optics mirror and improve its capability to reject disturbances from external sources. The paper firstly discusses the theoretical background of relative shape detection, providing examples such as voice coil Deformable Mirrors with an out-of-plane actuator/sensing architecture. Then, it illustrates the transverse sensing of the mirror surface in modal coordinates, with applications on stacked piezoelectric mirrors and unimorph Deformable Mirrors. Finally, a design of the active mirror for space Active Optics with internal actuator/sensor units is proposed.

This paper presents a study on the excitation method for a thin-shell active reflector with an electric actuation source. The actuators are considered with very small dimensions. We discuss two main topics: the distinguishable mechanical behavior of the quasi-static response of unimorph composite charging by a distributed field, focusing on reduced morphing amplitudes and limited influencing areas. Then, we investigate the method of computing the distributed electric field for adjusting the shape using an equivalent mechanical model with various load sets of self-equilibrium forces and moments. The correction process can be iterative, and the potential update to change the shape is linearly related to the distribution of the mean curvature. Finally, we discuss downsampling issues and present some initial numerical results. Additionally, we propose a framework of hierarchically iterative charging strategy.

Currently, the construction of low-orbit satellite constellation is booming in the world. To make full use of carrier resources and improve launch efficiency, the extra-vehicular launch envelope size of spaceborne laser communication payload need to be smaller and flatter. Tracking mirror is the decisive factor of launch size because its rotating mechanism of external load and itself cannot be packed in to the cabin. . Therefore, we propose the design architecture of the tracking mirror with eccentric rotation axis and independent temperature control. the scanning space of the short side during the movement is reduced by tilting the rotation axis of the pendulum mirror to one side,. To decrease the height of the support axis for the pendulum mirror and minimize the overall launch envelope, the mirror is positioned horizontally during the launch stage. The design of the eccentric pendulum mirror utilizes rigid body isolation and radiation temperature control. It considers various factors including material properties, adhesive layers, and film layers. Additionally, it implements multi-point flexible installation and lens radiation temperature control techniques, while fine-tuning parameters through finite element analysis. The design achieved a 67.5mm reduction in the size of the transmitting envelope, accounting for 43% of the total height of the original mechanism. In the temperature range of 23~33℃, the RMS value of the pendulum mirror type changes to (1/166λ)/℃, which shows a linear trend. Lab test results show that the surface RMS value changes to (1/161λ)/℃ in the range of 21~32℃, which aligns well with the simulation value. The pendulum mirror has passed the mechanical and thermal vacuum environment test and achieved the design requirements, ensuring the smooth delivery of loads and on-orbit operation. Additionally, it introduces an innovative design optimization method for space eccentric tracking pendulum mirrors.

The polarization payload onboard Fengyun-3 precipitation satellite (FY-3G) is the first Polarization and Multi-Angle Imager (PMAI) with a shortwave infrared channel in China. Three spectral bands are equipped with polarizers : 1030 nm, 1370 nm and 1640 nm. For each of these wavelengths, three similar spectral filters are associated with three polarizers, the direction of the first and the third one being at +60° and -60° from the direction of the central one. The three polarization image of the band are obtained from the subsequent detector response. To compensate for the flight lag, the design uses the wedge prism to register the three images together. The satellite adopts an autonomous 180° yaw maneuver control scheme to guarantee the on-orbital performance. In order to solve the problem of polarization channel registration of imager during satellite inverted flight, we developed a set of on-orbit registration algorithms. In order to verify the effect of the registration algorithm during the inverted flight, we used a typical observation scence to perform pre- and post-calibration tests. During the forward flight of the satellite, the cloudbow from polarization channel was obtained by PMAI. However, during the backward flight due to the wrong channel registration between sub-pixels, the rainbow is drowned in noise. After calibrated by the on-orbit registration algorithms in backward flight, the cloudbow come to appear in the 140° scattering angle. Results show that during inverted flight the registration effect is greatly improved, and the accuracy of polarization observation is dramatically enhanced.

SIF is closely related to gross primary productivity (GPP) at ecosystem scale, but low spatial resolution of existing satellite limits the understanding of the relationship between SIF and GPP at different spatial and temporal scales. A new generation of terrestrial and airborne observation systems with high spatial and spectral resolution has been widely used. The future satellite FLEX has 300 m spatial resolution, but SIF signal is less than 5% of the background signal, so strict instrument characterization is necessary for reducing SIF retrieval error. In this study, satellite radiance products were simulated using airborne hyperspectral imaging spectrometer data of the HyPlant, and then the pixel of satellite image were aggregated to 10m, 30m, 50m respectively, and SIF of the merged images was retrieved and analyzed. The results show that SIF signal can be retrieved from simulated satellite images with different spatial resolutions, and the retrieval SIF has a good correlation with that retrieved from the original HyPlant image. We also find that the detail of SIF in image gradually smoothed out with the decrease of spatial resolution, and the SIF retrieval error decreased simultaneously. The results of this study also reveal the importance of high spatial resolution satellite imaging spectrometer to detect and quantify SIF.

To analyze the changes in the polarization characteristics of the ocean surface caused by foam scattering, we propose a novel approach utilizing geometric optics approximation theory and Fraunhofer diffraction theory to characterize the scattering properties of bubbles composing foam. Assuming that the bubbles are spherical particles coated with a uniformly thick layer of material exhibiting absorption-scattering feature. The polarized Monte Carlo method is employed to simulate the propagation of lights carrying Stokes vectors within bubbles. Counting all the lights leaving the outer surface of bubble and calculating the scattering properties of bubble, including scattering/absorption efficiency factors and scattering phase function matrix. Validity of the proposed method in this paper is confirmed through comparison with the results calculated by Mie scattering methods under identical computing conditions. As an application, the method proposed in this paper is utilized to compute the scattering properties of bubbles under various conditions. On this basis, an analysis was conducted to investigate the influence of bubble diameter, void fraction, and wavelength on the scattering properties of bubbles. The results indicate that: when the absorbability of the water film is not considered, the scattering phase function of the bubble is greatly influenced by its internal structure, and as the inner and outer diameter ratio of the bubble gradually increases, the scattering phase function gradually flattens as the scattering angle increases, and the linear polarization ratio also exhibits a similar change rule; when the absorbability of the water film cannot be ignored, the scattering phase function and linear polarization ratio are hardly affected by the internal structure of the bubble. The scattering phase function of the bubble is extremely sensitive to the change of the particle diameter only when the scattering angle is 0°, but under other scattering angle conditions, the scattering phase function and linear polarization ratio are hardly affected by the particle diameter.

Recent advancements in wavefront sensorless Adaptive Optics (AO) systems have attracted significant scholarly attention, primarily attributed to their free of wavefront detection, streamlined architectures, and enhanced functional capabilities. The control algorithm determines the correction performance of the wavefront sensorless AO system. Among the existing algorithms, certain algorithms demonstrate robust global convergence properties despite their relatively slow convergence rates. Some algorithms exhibit limited global optimization capabilities but converge more rapidly. Others achieve rapid convergence but require extensive preprocessing. The African Vulture Optimization Algorithm (AVOA) is introduced to control the wavefront sensorless AO system in this paper, which is inspired by the observation of the hunting and flight behaviors of African vulture populations. In the Matlab programming environment, an adaptive optics system based on AVOA is built, which mainly includes a 61-element deformable mirror (DM) element and an imaging sensor device. Based on this AO system model, we studied the correction performance, convergence speed, and local convergence behavior of the AVOA control algorithm. For comparison, the correction performance of the adaptive optics system based on particle swarm optimization (PSO) and genetic algorithm (GA) is provided, respectively. The results show that AVOA can significantly improve the convergence speed of the adaptive optics system while ensuring global convergence. These results provide a new method for the control of wavefront sensorless AO systems, which can be applied in fields such as free-space optical communication, biological microscopy imaging, retinal imaging in the human eye, and environmental monitoring.

Baffles with multi-vane structure are most commonly used in heliospheric imaging instruments to attenuate the sunlight. In former works, a semi-empirical model based on Fresnel integral was employed to evaluate the attenuation factor while neglecting the non-uniform field on the subsequent vane planes. In this paper, we for the first time proposed a rigorous theoretical analysis on the diffraction effects of multi-vane baffle system, based on the uniform boundary wave diffraction theory. We proved analytically that the Fresnel integral is a paraxial approximation of boundary diffraction and it has sufficient accuracy in engineering usage. We analyze the diffraction effect of non-uniform fields caused by the previous vane diffraction and express it as the gradient diffraction term. It is proved numerically that this term is much smaller than the boundary diffraction term and can be neglected in engineering case.