The absorbing aerosol index (AAI), which can be used to characterize the proportion of absorbing aerosol components in the ultraviolet band, is one of the important data products for satellite remote sensing detection. The SCIATRAN radiative transfer model is employed to set solar zenith angle, viewing zenith angle, relative azimuth angle, surface altitude, and cloud altitude to draw up the lookup table of reflectance at the top of the atmosphere. The table is combined with the TROPOMI data to retrieve the AAI. Due to the characteristics of the satellite monitoring instrument, the directly retrieved AAI cannot fully characterize the distribution characteristics of absorbing aerosols, and the background value needs to be deducted. In this study, the background value of the AAI in the Pacific region was obtained by statistical methods. The data of the wildfire period in California, USA on September 2020 was used to study the transmission of wildfire smoke plumes. The inversion results show the distribution characteristics of aerosols, with good background correction results, and they are basically consistent with the spatial distribution of the products officially released by TROPOMI, with an average correlation coefficient of 0.963. Finally, a comparison between the aerosol optical thickness (AOT) data at ground AERONET stations and the AAI data of satellite remote sensing indicates consistent aerosol changing trends of them.

To reliably track stars and measure the transmittance of the whole-layer atmosphere at night, a two-dimensional direct-drive star-following turntable was developed using a direct-drive torque motor and a circular grating absolute encoder as servo parts. These parts offer the advantages for the turntable of high positioning accuracy, good environmental adaptability, and long-term field operation without maintenance. The turntable can realize the functions of the long-term tracking of target stars at night and automatic star change. Combined with the image acquisition system mounted on the turntable, which comprises a telescope, CCD camera, and filter wheel, the measurement experimental platform is built. The measurement experimental platform adopts the master-slave control mode. The upper computer controls the image acquisition system and provides the azimuth deviation feedback of the turntable to the lower computer. The control system of the tracking star turntable of the lower computer adopts the ARM7 digital processor loaded with the Linux system as the control core and a built-in self-developed star map. It realizes the complete function of the transmittance measurement of the whole-layer atmosphere by the collaboration of the upper and lower computer software developments. The turntable function verification experiment, the transmissivity measurement experiment of the whole-layer atmosphere, and contrast experiment using radar were conducted. Results show that the two-dimensional direct-drive star-following turntable can track the target star for a long time and automatically change the star for measurements at night. Moreover, the telescope system mounted on the turntable can reliably reverse the transmittance of the whole-layer atmosphere at night based on the image data of stars, meeting the functional requirements of measurement tests.

Additive manufacturing (AM) is a technology that makes materials into products through layer-by-layer stacking according to a digital model. Nevertheless, during the layer-by-layer stacking, the temperature change at different positions inside the model is complicated. To measure the temperature change at different positions inside the stacked structure printing model during the AM process, in this study, we embed the distributed fiber into the polylactic acid (PLA) material model by optical frequency domain reflectometry (OFDR). The temperature change at different positions inside the material model can be measured at any time during the printing process. Considering the effect of filling density on the temperature change in the model, the filling density is set as 20%, 40%, 60%, 80%, and 100%, respectively. The results show that the internal temperature variation in the model with the same density at different locations tends to be consistent during the printing process, and the temperature change range is 20--40 ℃. According to the temperature variation curves in the model at different filling densities, the printing process is divided into five typical stages, including fiber embedding, thermometer hole encapsulation, model filling encapsulation, model capping, and model temperature regression. After analyzing the temperature changes at the peak point of model filling encapsulation and at the completion point of model capping, we find that the maximum temperature at the AM core with a 100% filling density is 15 ℃ higher than that with a 20% filling density, and with the increase in the filling density of the model, the printing material further hinders temperature dissipation.

In this paper, an encryption algorithm based on three-dimensional Arnold transform and chaotic Frank sequence is proposed, which is used to deal with low data security and excessive peak-to-average power ratio (PAPR) in orthogonal frequency division multiplexing passive optical network (OFDM-PON) systems. The algorithm uses the chaotic sequence generated by the conservative digital chaotic system based on the principal component analysis to encrypt, which can solve the degradation problem caused by the chaotic sequence structure and calculation accuracy. First, the OFDM signal is converted into a three-dimensional signal matrix, and the three-dimensional Arnold transform is used to perform scrambling transformation to realize the encryption of the data; then, the encrypted data is passed through the Frank sequence randomly selected by the chaotic sequence to reduce the PAPR of the OFDM signal. The simulation experiment results show that, compared with the traditional OFDM-PON algorithm, When the probability in the complementary cumulative distribution function is 10 -3, the algorithm can reduce the PAPR of the signal by about 2.1 dB, and when the bit error rate is 3.8×10 -3, the received optical power can be reduced by about 1 dB.

A remote optical information authentication system based on visual cryptography is proposed in this paper. The system can pair distant visual key with visual key in the system by telescope system to achieve incoherent superposition for authentication operation, which not only reduces the manual transfer process of the shared keys, but also solves the problem of inconvenient transport of the keys in practical applications. Moreover, the field of view is limited by the system during the entire extraction process, only the operator can see the authentication information in the system, and others cannot view it even if they are nearby, which strengthens the security of the information display and reproduction. The authentication process only requires the operator to align the two shared keys carefully, without mastering other optical and cryptographic knowledge, and the whole process is simple and efficient. In addition, optical experiments also prove that the system can be used in practice and has high security.

Optical diffusers are key components in liquid crystal displays (LCDs). Diffusers with wide angles, high transmittance, and great uniformity have always been an important research goal in the LCD field. Based on the Helmholtz-Kirchhoff theory, the spectral distribution of speckle intensity for laser passing through a rough surface is derived. A design method for holographic diffusers is proposed, which is based on the superposition exposure of scattering fields formed by multiple beams at specific incident angles irradiating a rough surface in turn. This method broadens the scattering angle of holographic diffusers and improves the uniformity of scattering intensity. The fabrication path to holographic diffusers is made and holographic diffusers are fabricated by the proposed method. The far-field intensity distribution measured by this method is in good agreement with the simulation results. The full width at half maximum (FWHM) of scattering angles reaches 130°; the light transmittance is more than 90%, and the diffusion coefficient is as high as 92%. In addition, wide angles, high transmittance, and great brightness uniformity are realized. This method has potential application prospects in LCDs.

Star identification algorithm is the key technology of star sensor. Through the identification of observed stars, the high-precision attitude calculation of spacecraft is realized. The existing star identification algorithms usually need to select the nearest neighbor star as the starting star, which results in poor recognition accuracy due to over reliance on the selection of the starting star. In this paper, a star identification algorithm based on dynamic angle matching is proposed. The angles between neighbor stars, and the distances between neighbor stars and observation star are used as the dynamic angle features. With the help of the features, the matching score between observation star and each navigation star is calculated. Finally, the navigation star with the highest matching score is taken as the recognition result. The simulation results show that the method has high recognition rate and good robustness to noise. In the simulation experiment of 16200 simulated star images, the recognition rate of this method can reach 99.80%, and it can maintain above 97.00% under the influence of position noise, false stars and magnitude noise.

In this paper, we extract visual features from the spatial, angular, coupling, and projection domains considering the spatial-angular coupling of the plenoptic function to propose a nonreference method for assessing light-field image quality. Natural scene statistics (NSS) features of the central subaperture image are extracted in the spatial domain. In addition, macropixel and grayscale co-occurrence matrix (GLCM) features on epipolar plane images (EPI) are extracted in the angular and spatial-angular coupling domains, respectively, and local entropy statistical distribution characteristics of the refocusing maps are extracted in the projection domain. Then, multiple visual features are fused to form the visual feature vector of the light field, and support vector regression (SVR) is applied to train a scoring model. Thus, the light-field image quality assessment method based on multiple visual feature aggregation is established. Experimental results show that the proposed method shows consistency between the light-field score and subjective score.

The rotating double-prism system allows the expansion of the imaging field of view and increase of apex angle of prisms through beam control, therefore increasing the magnification of the field of view but aggravating imaging distortion. This paper proposes a fast distortion correction and video mosaic method for large-apex-angle double-prism systems to achieve real-time imaging with a large field of view. The real-time distortion correction and video mosaic of a two-way rotational double-prism imaging system are performed by multiple camera pre-calibrations, the construction of a table-lookup-based interpolation re-projection algorithm, and the application of a multi-resolution fusion algorithm with image scale transform based on the search for the optimal seam. For the expansion of the field of view, we propose an evaluation method of the expanded field of view based on the law of refraction in the vector form, and the field angle expansion factor is used as the evaluation index. The simulation results show that the horizontal and vertical field angle expansion factors of the mosaic field of view can reach 1.50 and 1.30, respectively. The experimental results verify the feasibility of the proposed method and achieve real-time distortion correction and video mosaic at 30 frame/s.

This paper introduces the evaluation results of nondestructive detection of the wall paintings in the Yuan Dynasty tombs in Pucheng, Shaanxi Province using the square-heating thermograph. For this purpose, a three-dimensional thermal tomography quantitative evaluation method for reconstructing the heat storage coefficient of the material is proposed, and the results are compared with the post-processing results of pulse phase thermal imaging and principal component thermal imaging. The experimental results show that the three methods can improve the defect detection ability, but the three-dimensional thermal tomography method can realize the quantitative three-dimensional assessment of the internal disease distribution of the mural. Finally, three-dimensional thermal tomography is performed on one of the entire murals. The proposed method can realize the detection and evaluation of hollow drums, cracks, and wall support structures, and can provide useful evaluation methods and reference information for mural removal, restoration and protection, and mural research.

Computed tomography (CT) is one of the important technical means in the field of security inspection. It is of great theoretical and practical value to study new CT imaging methods for security inspection. In this paper, a triple-source swinging spiral CT (TS-SCT) imaging method is proposed, which can be used for the safety inspection of passenger luggage and express parcels. Three groups of X-ray source-detector uniformly distributed in the circumference are used to swing around the rotation center in the range of 120°, the detected object moves along the axial direction in the scanning field of view, and the swing spiral scanning is realized. Compared with spiral CT, the proposed method does not need the whole rotation, and can use the rotating parts which are easier to manufacture, maintain, and are more wear-resistant than the slip-ring. Moreover, the cable is used to transmit data and power, breaking the limitation of a slip-ring on data and power transmission capacity. The imaging model of TS-SCT is established, the effects of scanning mode, scanning parameters, and ratio r between pitch h and projection height T of a cone-beam near the source in z-direction on imaging efficiency and results are analyzed, and the FDK reconstruction algorithm for TS-SCT is derived. The simulated and experimental results show that the TS-SCT FDK reconstruction algorithm is correct and effective, and the TS-SCT method can be used to realize the 3D imaging of detected objects. On the premise of ensuring imaging quality, r≤1/2 is suggested.

The neural network based on attention mechanism can focus on extracting the feature information from the key areas. The application of this characteristic in the polarimetric imaging target classification can help us to obtain the relationships among different polarimetric images and to extract more feature information from critical areas. To solve the difficulty of target recognition in cluttered natural backgrounds, this paper presents a polarimetric imaging target classification method based on an attention mechanism. Firstly, the attention mechanism and the convolutional neural network are combined to construct a polarimetric feature extraction model suitable for limited samples. Then, proper polarimetric images are selected as the input model for training so that the attention module can give more weights to the channel domain and spatial domain feature information that is easily classified to obtain higher classification accuracy. The experimental results show that the classification accuracy of the proposed method can be further improved in different natural backgrounds and reach more than 95% in the self-built polarimetric target database, which is obviously improved to compare with that of the traditional deep learning classification method. Thus, our method is more suitable for target classification in cluttered backgrounds.

A precise structured laser model is the basis of three-dimensional optical measurement, in which the intersection model of distributed spatial measurement positioning system is based on the ideal plane model of the line-structured laser surface. However, the line-structured laser surface in large-scale space has complex deformation which is difficult to be accurately fitted by any mathematical model. Therefore, this paper studies a nonparametric model calibration method for the laser surface based on a high-precision rotary table. This method constructs a precise mapping table between the rotation time of laser surface and the space angle to replace the surface fitting parameter model. Based on the nonparametric calibration results of laser surface, the intersection model is optimized. Taking workshop measurement positioning system as the verification platform, the experimental results show that the calibration method can effectively overcome the complex deformation of laser surface and reduce coordinate measurement error of the areas with obvious deformation to approximately 50% within a measuring range of 12 m.

Photoacoustic spectroscopy has been widely used in gas detection because of its high sensitivity, strong reliability, and fast response. Because the high-reflectivity coating on the inner walls of integrating spheres can greatly increase the optical path, integrating spheres are often adopted in absorption spectroscopy to improve detection sensitivity. In this paper, an integrating sphere is applied to gas detection by photoacoustic spectroscopy. With the integrating sphere gas cell as the absorption pool, an aluminum tube is attached to the sphere as a resonant cavity to form a coupled acoustic system. The actual resonance frequency of the system is obtained through simulations and experiments. At this frequency, the LED light source is modulated, and the gas is stimulated to generate photoacoustic signals. Embedded technology is integrated to collect the signals of the two microphones on the ball and at the end of the aluminum tube for data processing, analysis, uploading and display. NO2 gas is employed in the experiments and the experimental results show that the signal values at the end of the aluminum tube can effectively invert the NO2 gas concentration, and the minimum detection concentration (volume fraction) is 3×10 -6.

In order to expand the detection range of the piston error in the fine common phase stage, reduce the detection process and reduce the installation and calibration requirements in the multi-method detection connection process, this paper proposes a segmented mirror common phase detection method based on multi-wavelength interference technology. In the coarse common phase, monochromatic laser interferometry and white light interferometry are used to achieve the calibration requirements of 100 micron-level and micron-level piston errors respectively; in the fine common phase, dual-wavelength laser interferometry is used to achieve high-precision detection of micron-level piston error. Taking the two hexagonal spherical sub-mirrors cut out of the whole mirror as the test object, the red and green laser dual-wavelength phase shifting interferometer and the white light micro-interferometer are used to experimentally verify the proposed technical scheme, and the proposed technique is based on the segmented mirror shape. A relative piston error calculation algorithm based on the segmented mirror shape detection data is proposed, and a set of segmented mirror co-phasing assembly and calibration system is designed and constructed. After the calibrated piston error of the coarse common phase is on the order of micrometers, the piston error between the sub-mirrors in the fine common phase can be compensated from 601.6 nm to 16.0 nm.

This paper presents a three-dimensional (3D) measurement method for discontinuous specular objects based on feature matching, which can not only avoid the integration errors between discontinuous surfaces, but ensure the high accuracy. First, the image segmentation method and stereo deflectometry technique are applied to separate the discontinuous specular object into several continuous surfaces and calculate the 3D shape of each area independently by slope integration. Then, the binocular vision technology is utilized to obtain the absolute spatial coordinates of the feature points to accurately evaluate the relative positions between continuous surfaces. Meanwhile, a feature matching method combining epipolar constraint and feature descriptor is proposed to overcome the problem of poor matching rate of non-texture specular objects. Finally, the 3D shape of the measured object is reconstructed by combing the topography and absolute spatial position of each surface. Experimental results show that the method can obtain better results without texture matching and can achieve high precision measurement of discontinuous specular object.

The detection technology for camouflage objects plays an important role in agricultural management, field search and rescue, military detection, and other fields. However, this technology usually requires complex operational models and massive data experiments, which is not conducive to high-speed online detection. In this paper, a detection method for camouflage objects with binary fringe projection is proposed. Three binary fringe images are projected onto the surface of the detection area and the camouflage object intrusion area, respectively, and the edge image is acquired. After the background shadow is eliminated by the mask extraction algorithm and the misplaced fringe is eliminated by the dilation operation, the complete real information of the camouflage object is finally obtained. The simulation and experimental results show that the proposed technology can quickly and accurately attain the real information about the position and contour of camouflage objects in complex environments, which verifies the effectiveness of the proposed method.

Aiming at the problem of locking the long-term frequency drift of a laser, a digital laser frequency stabilization system is achieved with reference to an optical frequency comb. In this system, the heterodyne interference between the slave laser and the optical frequency comb is first performed to obtain the beat signal which represents the laser frequency drift. Then, the frequency of the beat signal is measured by a self-developed digital-counting-based frequency to voltage conversion circuit, and the value of the measured frequency is converted to an error voltage signal. At last, the slave laser is controlled through the feedback control of the master program. In the long-term frequency stabilization experiment of a 760 nm narrow linewidth semiconductor laser, the system improves the long-term stability of the laser frequency by two orders of magnitude, and the stability of the laser reaches 4.4×10 -10(τ=262 s). Experimental result shows that the proposed system can achieve a long-term frequency drift locking for lasers with wavelength locating in the spectrum range of the optical frequency comb. This system can provide a basis for further fine-locking of the frequency and phase of the laser.

The optical microcavity based optical frequency comb (OFC) has the advantages of low threshold, compact structure, and easy chip integration, and has very good application prospects in the research fields of precision spectroscopy and atomic clocks. Although the research on OFC has achieved rich results, most OFCs have a sparse comb-tooth pattern, which is not conducive to the tuning of OFC. In view of this, the ohmic heat of the high quality factor optical microbubble resonant cavity is used to realize the tuning of the OFC. First, we theoretically analyze the principle of microcavity dispersion, and calculate the relationship between the microcavity dispersion parameter and the size of the microbubble cavity. Then, a microbubble resonator with a diameter of 275 μm and a quality factor of 1.2×10 8 is prepared, a broadband OFC is obtained by continuous laser pumping in the anomalous dispersion region. Finally, the Au microwire is integrated into the empty channel in the microbubble resonant cavity with a diameter of 297.5 μm and placed in the circuit. The current controller is used to apply current to the Au microwire to generate ohmic heat to realize the tuning of the OFC. The range reaches 0.21 nm.

Since the spliced sub-mirror of the primary mirror of the large-aperture telescope is off-axis aspherical, it increases the difficulty of mirror processing and inspection. In order to further improve the processing efficiency of the off-axis aspheric sub-mirror and shorten the manufacture cycle, the stressing loading method and the bluetooth-based contact two-dimensional displacement sensor array detection method and related devices are used to complete the lapping experiment on an off-axis aspheric segment with a diameter of 380 mm. First, we introduce the principle of stressed mirror processing. Then, we introduce the test method on stressing lapping and loading experimental results on the Φ380 mm glass-ceramic mirror. Second, we introduce the convergence property of the stressed grinding processing. Finally, three coordinate measuring machine and contact two-dimensional displacement sensor array are used to cross check eventually surface shape of lapped mirror. The experimental results show that the stressed grinding method is feasible and high processing efficiency.

During irradiance regulation with solar simulators, narrow regulation range, discontinuous values, and other defects seriously affect irradiation instability and spectral matching. Therefore, a method based on the theories of ring concentrated light and symmetric uniform light is proposed for solar irradiation modulation. Firstly, the energy distribution of the irradiated surface formed by the light distribution with an ellipsoidal mirror is studied. Subsequently, the energy modulation method based on through holes is proposed by studying the uniform light mechanism of optical integrators. The irradiance distribution function is combined to obtain a uniform irradiance distribution. Finally, the irradiation regulation system is designed, which continuously adjusts the irradiance by changing the aperture size of the irradiation regulation plate, and the irradiance is simulated with Lighttools. The simulation results show that the irradiance of the solar simulator is continuously adjustable in the range of 490.38--1473.78 W/m 2, and the nonuniformities under different irradiances are better than 1.76% (meeting the requirements of Class A in the calibration specification of solar simulators) when slope error of ellipsoidal mirror is σ=2 mrad. In conclusion, the wide-range irradiance regulation of solar simulators is realized, without changing the irradiance instability and spectral matching.

In this study, a three-dimensional (3D) Cu(OH)2-Ag substrate with abundant “hotspots” is developed. First, the 3D Cu(OH)2 nanotubes (NTs) are developed on the surface of copper sheets through chemical etching. Then, silver nanoparticles (NPs) are adsorbed onto the surface of Cu(OH)2 NTs using self-assembly technique. The prepared Cu(OH)2-Ag substrate has a high Raman sensitivity with a mass concentration limit of detection (LOD) of 8.9×10 -10 g/L for probe molecule rhodamine 6G (R6G). Additionally, it has high uniformity and reproducibility with a relative standard deviation (RSD) of 8.79% and 3.49%, respectively. Simultaneously, the substrate has excellent sensitivity to malachite green (MG), and the mass concentration LOD of MG in river water is 2.13×10 -8 g/L. The 3D substrate is easy to fabricate and has excellent surface-enhanced Raman spectroscopy (SERS) performances. It shows that the substrate has great application prospects in detecting illegal fishery drugs in water.

In order to obtain high-quality multi-wavelength coherent Airy beams without chromatic aberration, we propose a method for generating multi-wavelength Airy beams based on deformable mirrors, and through simulation and experiment, the generation and propagation characteristics of multi-wavelength Airy beams are studied. The experimental results show that the deformable mirrors can effectively eliminate the influence of chromatic aberration on the beam and generate a high-quality multi-wavelength Airy beam, and the main lobe does not undergo chromatic aberration separation and diffraction during propagation. In addition, the main lobe of the generated multi-wavelength Airy beam can heal itself after propagating for a certain distance when it is blocked by an opaque obstacle. This research provides a basis for the potential applications of multi-wavelength Airy beams in the fields of multispectral imaging and optical micromanipulation.

This paper studies a measurement-device-independent quantum key distribution protocol based on a multiple crystal heralded source and pulse position modulation to improve its performance. The performances of the protocols with or without pulse position modulation are compared under the multiple crystal heralded source. The simulation results show that the application of pulse position modulation can further improve the key generation rate and increase secure transmission distance of the protocol. Moreover, as the time slot increases, the key generation rate and the secure transmission distance gradually rise. Furthermore, we analyze the relationship between the secure transmission distance and the key generation rate under different detection efficiencies of the detector. The results show that the higher detection efficiency of the detector leads to the greater key generation rate and the longer secure transmission distance.

The information manipulation relevance among different users has profound significance in secure quantum communication. EPR steering, which means that one party can steer the state of a distant party by exploiting shared entanglement, is an important resource in a secure quantum network. In this work, we present a quantum switch scheme based on entanglement swapping, in which a tunable beam splitter is set as a control switch during the swapping of two space-separated EPR entangled states. The dependence of the EPR steering direction on the reflectivity of tunable beam splitter is observed, and the control of steering direction among different users is investigated. The proposed scheme has reference value for secure quantum communication.

Current remote sensing target detection methods based on deep learning can only identify the type and location of remote sensing targets, but cannot detect the spatial relationship between remote sensing targets. Aiming at this problem, a method for detecting the spatial relationship of remote sensing targets is proposed. First, a convolutional neural network is used to construct a vision module to extract the visual features in the remote sensing image. Second, a semantic module is constructed to map the extracted visual features to the semantic embedding space to achieve the deep fusion of the visual features and semantic features of the remote sensing target. Finally, the Softmax function and the visual consistency loss function are introduced into the traditional triplet loss function, and an improved triplet loss function is designed. The proposed method is used to conduct experiments on the self-made remote sensing target spatial relationship detection dataset. The experimental results show that among the top 20, 50 and 100 prediction results, the recall rates of the proposed method are 76.32%, 78.54% and 81.47%, respectively, indicating that the proposed method has good spatial relationship detection performance and can accurately detect remote sensing objects and their spatial relationships in remote sensing images.

Lidar can accurately and quickly obtain the three-dimensional(3D) spatial information of the target, which is a commonly used high-resolution imaging technology. Combined with high frequency pulse laser, streak camera and signal processing technology, a 3D imaging system of lidar is designed in this paper. Among them, the pulsed laser has the characteristics of high peak power, which can effectively detect long-distance targets. Compared with high frequency microwave modulated laser pulse, high energy laser pulses can be obtained by combining pulse compression and Fabry-Perot oscillation cavity. The streak camera is a kind of high-speed camera with the ability of fast weak light detection, which can detect long-distance targets. Mean filter and neighborhood mean filter are used to suppress the background noise of streak camera. Band pass filter and matched filter are used to suppress low-frequency noise and increase signal-to-noise ratio. According to the intensity distribution of noise, threshold filter is used to filter the residual noise, and finally high-precision 3D target image is obtained. The experimental results of 3D target imaging in air and smoke show that the system has high range resolution and strong ability to capture target details.

Aiming at the problem that the existing remote sensing image restoration effect is poor due to the mismatch between the point spread function (PSF) model and the actual blur kernel, an image restoration method based on a Lorentz fitted PSF is proposed to fully fit the estimated PSF of a remote sensing image and to improve the restoration accuracy. Firstly, considering the matching error between the existing model and the actual degradation process, the blurred kernel is modeled as a linear combination of basic two-dimensional models, and a Lorentz function is used as the basis function to model the blurred effect caused by actual degradation. Then, while selecting the ground object with edge characteristics to estimate the degradation function of the remote sensing imaging system, the established mathematical model is used for fitting correction of the estimated point spread function. After fitting correction, the point spread function is applied to the remote sensing image restoration and to reduce the interference of the degradation ambiguity of the imaging system. Finally, the corrected point spread function and the Richardson-Lucy restoration algorithm are used to restore the remote sensing image. The experimental results show that compared with those of the existing remote sensing image restoration methods based on other point spread function models, the effectiveness of the proposed method is significantly enhanced.

Color stimuli with different primary colors will arouse different color perceptions, and color matching accuracies calculated by different color matching functions are also different. To investigate the influences of the peak wavelength location of primary colors from self-illuminating equipment on such differences, we selected one 3-channel LED panel (R1G2B1) and one 6-channel LED panel (R1R2G1G2B1B2). The color displayed by the 636 nm-524 nm-452 nm combination in the 3-channel LED panel was defined as the target color, and seven corresponding combinations (including one combination of the same spectrum) were generated after the RGB single channel and double channel of the 6-channel LED panel were changed. Thirty-nine observers (aged from 19 to 24) with normal color vision were organized for the color matching experiments of white color, and 357 sets of data were collected in the visual experiments. Four sets of color matching functions were employed, including CIE1964, CIE2006, Sarkar2, and BIGC17 (the latter two are based on reflective color sample pairs and suitable for young observers). Their performances were evaluated with Δ(u', v') calculated by CIE1976-u'v' chromaticity. The results indicated that regarding the color matching accuracy and the observer variation calculated by CIE1964 and CIE2006, the peak wavelength positions of the red channel, blue channel, and green channel had increasing influences, and the differences from the same-spectrum combination results were also in an ascending order. Sarkar2 and BIGC17 outperformed CIE1964 and CIE2006 in some combinations.

In this paper, a new spectral characterization method for displays is developed. Firstly, after singular value decomposition, the k most important basis vectors can be obtained for each of the three channels, so that for any given driving signal, its corresponding spectral radiance on each channel can be the linear combinations of these basis vectors and the datum coordinates can be acquired through orthogonality. Then, a lookup table is compiled. Thus, for any driving single in an individual channel, the corresponding spectral radiance can be linearly expressed by basis vectors and the combination coefficients can be got by the lookup table and the interpretation technique. Finally, for any set of driving signals R, G, and B, the overall spectral radiance can be predicted by the summation of the spectral radiances on the three individual channels. When k=1, the proposed method becomes the traditional piecewise linear interpolation assuming constant chromaticity (PLCC) method. The inverse model for the proposed method is also given. Comparison results in terms of the color difference and spectral root mean square error show that the proposed forward model is better not only than the traditional Gain-Offset-Gamma and PLCC methods but also than the newly developed spectral radiance model based on wavelength partition and spectral radiance piecewise partition model.