A method based on the wavelet threshold denoising algorithm is proposed for the suppression of solar background light, so that the separation of the real signal from the noise in the Raman returned signal can be realized and the background noise in daytime can be removed. Based on all-day data measured by atmosphere water vapor Raman lidar system built in Xi’an University of Technology, influences of decomposition level, wavelet function, threshold function, and threshold selection method on the denoising results of returned signal in daytime are discussed. Signals before and after denoising are compared and denoising evaluation functions are compared. We adopt wavelet sym6, decomposition of five layers, improved threshold function, and improved threshold method to obtain the better denoising effect for water vapor Raman and Mie-Rayleigh scattering signals in daytime. Furthermore, profiles of the atmospheric water vapor mixing ratio, and the results of signal-to-noise ratio (SNR) of water vapor are discussed. Results show that SNR for lidar water vapor measurement increases by 3.4 times in the denoising process. and the water vapor detection range can be improved up to over 3 km from 1.5-2 km in daytime. Lidar continuous detection experiments and denosing process are carried out during 24 h. Variation characteristics of the atmospheric water vapor mixing ratio are obtained below boundary layer, and the results agree with data from near-surface weather stations. It is verified the feasibility and effectiveness of the wavelet denoising algorithm used in all-day atmospheric water vapor detection.

Light-induced drift velocity is an important parameter to evaluate the effect of light-induced drift, so it is important for the research of light-induced drift. In this paper, strong collision model is used to describe collision of lithium atoms and buffer gas. The effects of hyperfine structure and degeneracy of energy level on light-induced drift are also considered when establishing rate equation to express the distribution of lithium atoms in different velocities and different energy levels. In this way, light-induced drift velocity of lithium atoms is obtained. In the meantime, the influences of several parameters, like laser wavelength, laser power density, buffer gas pressure, type of buffer gas, and temperature on light-induced drift velocity of lithium are also studied. It can be seen that the relationship between light-induced drift velocity and each parameter confirms with physical principles of light-induced drift and experimental results of related literatures.

A microchannel plate (MCP) gated X-ray framing camera with three channels is developed, in which the width of the MCP microstrip line cathode is 8 mm and the gap between two neighboring photocathodes is 2.8 mm. The photocathode is driven by the gating pulse with the width of 210 ps and the amplitude of -1.9 kV. The trigger jitter of this camera is measured by the fiber bunch method. The experimental results show that the measured trigger jitter is about 94 ps, which is basically consistent with 90 ps by a high-speed oscilloscope. In addition, the measured temporal resolution of this camera is about 100 ps.

A time of flight (TOF) measurement system based on the gated microchannel plate (MCP) technology is reported. The electrons and the strobe pulse can simultaneously arrive at the MCP under a suitable MCP strobe pulse delay, and so that dynamic images can be produced. The TOF of electrons at the drift space of 50 cm is measured by using a high speed oscilloscope. When the cathode voltage of -3.5 kV is applied, it takes electrons about 15 ns to travel from cathode to MCP. The relationship between the TOF and electron energy is obtained via tuning the cathode voltage. The results show that the TOF decreases with the increase of electron energy, and the temporal resolution of the TOF measurement system is 88 ps.

By establishing the envelope model of the spectral radiation of target and the dynamic characteristic model of target attitude angle, the relationship between the target maneuvering mode and the changing rate of the attitude angle is analyzed. The model of response signal for infrared radiation is established and the key factors influencing the signal features are theoretically analyzed. The results show that the exponential terms and the high order power terms of spatial distance are the main factors which influence the overall trend of amplitude change of infrared radiation signal, and the changing rate of the target attitude angle has a significant effect on the local features of the infrared radiation response signals. The time derivative of the infrared radiation response signals is proportional to the changing rate of the target attitude angle. Three typical target maneuvering modes are chosen to perform simulation experiments, and the results show that the target infrared radiation response characteristic signals are significantly different under different maneuvering modes, which provides a feasibility to identify the target maneuvering modes and has great significance to the target maneuver tracking, maneuvering detection and situation evaluation.

To solve the problem that the traditional tracking algorithm cannot be used to effectively distinguish the image edges from the infrared dim-small targets, an improved infrared dim-small target tracking algorithm based on guided image filtering and kernelized correlation filtering (KCF) is proposed. Six groups of infrared dim-small target image array are adopted in the experiment, the obtained results are compared with that by the classical tracking algorithms. The experimental results indicate that the proposed algorithm has a better performance than the traditional algorithms on both subjective view and objective evaluating indicators, and the proposed algorithm possesses a higher tracking accuracy and a better real time performance.

To realize millisecond resolution measurement of grating angular displacement, we study the design, fabrication, and spatial filtering method of gratings from the viewpoint of optics. According to the Mach-Zehnder interferometry principle, multi-beam holographic gratings are designed. At the same time, spatial filtering imaging processing of the rectangular grating and the multi-beam holographic grating is carried out. Parallel light and point light are selected as light sources of the test. Diffraction information of the gratings is collected by using area array charge coupled device (CCD) and linear array CCD. The gratings before and after spatial filtering imaging are tested from aspects of fringe quality, transmittance functions, and frequency spectra. The results show that the higher harmonic contents of the gratings are decreased with the utilization of the spatial filtering imaging processing method, and grating signal quality is significantly improved. The sine property of the gratings is effectively improved with the increase of spatial frequency of the diffraction gratings.

A micro-angle measurement method based on the two-dimensional moire fringes generated by square aperture micro-lens array and micro-graphic array is proposed. The variation principle of the moire fringe pitch formed by these arrays with different sizes is analyzed. The expression of small rotation angle is deduced. The theoretical analysis and experimental measurement are carried out on the relationship between the moire fringe pitch and the included angle of arrays. The research results show that, when the graphic element size of the micro-graphic array is shorter than the lens element size of the micro-lens array, the moire fringe pitch changes gently and is sensitive to the variation of the included angle θ between micrographics and microlens array, which is helpful for the improvement of the measurement accuracy. When the graphic element size is 0.3 mm and the lens element size is 0.4 mm, the experimental result on the relationship between the pitch and the included angle θ is basically consistent with the theoretical one.

A few-mode fiber (FMF) temperature sensor based on the interference between LP01 and LP11 modes is proposed. The sensor is fabricated with an FMF, of which one end is spliced to a lead-in single-mode fiber (SMF) with small lateral core-offsets and the other is spliced to a lead-out SMF with alignment. Firstly, the theoretical model of FMF is established with the scalar method and the characteristic equation of FMF is derived by the light field of continuous electromagnetic boundary condition. Through the numerical solution of the characteristic equation, the transmission mode of FMF is analyzed in detail. Then, the theoretical results are verified through the finite element analysis. Finally, the sensor is used for temperature sensing experiments. Through the Fourier transform of the transmission spectra at different temperatures, the two modes of interference are analyzed. According to the thermo optic effect, the temperature sensing model is established. The temperature sensitivity of the sensor is analyzed and calculated, which is consistent with the experimental results. The temperature measurement experiment is carried out with the proposed sensor, and the results show that when the temperature changes, the interference peak drifts, and the temperature sensitivity of a 16-mm-long sensor is 158.06 pm/℃ at 25.3-77.3 ℃. The temperature sensor can be widely used in industrial production, biomedical and other fields.

In order to improve transmission capacity of radio over fiber system, a photonic generation method of hybrid frequency and phase shift keying (FPSK) signal is proposed. Based on various response characteristics of polarization maintaining fiber Bragg grating (PM-FBG), the baseband signal modulated onto the optical polarization is translated to output wavelength shift. Then frequency beating is implemented at the receiver to achieve frequency modulation. Meanwhile, an optical phase modulator is employed at the transmitter to map the phase information of the optical signal to the generated microwave signal. Finally, a hybrid FPSK signal is generated. The proposed method is experimentally demonstrated through a transmission test in a radio over fiber (RoF) system. A hybrid FPSK signal with 1-Gbit/s bit rate and 12.5-GHz/9.5-GHz frequency is generated and modulated by the receiver after transmitting a 5-km fiber. The results of temporal waveform, the eye-diagram and constellation diagram after demodulation verify the effectiveness of the proposed scheme.

Chromatic dispersion and laser frequency offset have serious impact on coherent optical filter bank multicarrier systems with offset quadrature amplitude modulation (CO-FBMC/OQAM system). Preamble-based joint estimation and correction algorithm of channel and carrier frequency offset (CFO) in CO-FBMC/OQAM system is investigated. The channel transmission model of CO-FBMC/OQAM system is theoretically elaborated, and the preamble structure is deliberately designed and optimized to suppress the impact of inherent imaginary interference (IMI). In order to reduce the noise impact, an estimation method based on inter-frame averaging is proposed. In this method, the cross-correlation function within multiple frames is averaged and the laser frequency offset according to the phase of this average is estimated. Finally, we get the final channel response by averaging channel estimation results within multiple frames. The error amplitude vector and error rate of the system are numerically demonstrated through 1500 km standard single-mode fiber transmission with different CFO values. The results show that the proposed method can suppress the influence of chromatic dispersion and laser frequency offset, and significantly enhance transmission performance in the back-to-back scenario or after 1500 km optical fiber transmission.

The principle and design method of polymer optical fiber bundle (POFB) lens coupler with high-power light emitting diode (LED) as light source is studied. Based on energy compensation and coordinate iteration method, a free-form lens coupler with uniform energy distribution is designed. The lens coupler consists of two refraction free-form surfaces, two reflection free-form surfaces and a circular cylindrical lens surface. The small divergence angle of the modified Lambertian high-power LED beam is quasi-uniformly distributed on the end face of POFB through refractive free-form surface. The reflection free-form surface reallocates the energy of large divergence angle of LED beam as compensation to improve the target surface illumination uniformity. Lens coupler is designed and optimized for illumination uniformity and effective light utilization of the end face of the fiber bundle. The results of optical simulation show that when the 3535 LED is used as the light source, the designed coupler can make the illumination uniformity of the 20×20 polymer fiber bundle with the diameter of 0.5 mm reach 92% and effective light utilization reach 71%.

A novel fan-shaped ray-leakage-free solar concentrator is proposed. The relation of geometrical concentration ratio with parabola coefficient, posterior paraboloid width of concentration module and concentration module quantity is also explored. The proposed design method of the sawtooth ray-leakage-free lightguide can deal with the leaking situation after the coupling inlets array, which increases the optical efficiency and the concentration ratio. By the analysis of the sun tracking law, a single-axis tracker with the scrollable prism sheets is proposed instead of double-axes tracker, which can decrease the system power dissipation. The ray-tracing simulations are carried out by LightTools software considering the Fresnel loss and optical material absorption. The results show that the concentration ratio and optical efficiency are 1900 and 65.1% when the parabola coefficient is 0.019; the concentration ratio and optical efficiency are 1110 and 82.3% when the parabola coefficient is 0.032.

An adaptively-weighted blind image restoration algorithm based on energy constraint is proposed. The images are divided into several sub-images and gradients of sub-images are introduced as weights to build the estimation model of weighted optical transfer function, which can reduce the influence of image texture on the estimation of optical transfer function. Based on the energy of image signals, the constraint equation is established, and the optimal restoration result is chosen by the dichotomy to realize adaptive blind image restoration. Results of simulation and multispectral remote sensing image experiments show that the proposed algorithm can produce high peak signal-to-noise ratio and structural similarity, which will effectively restore Gaussian blurred images, enhance the image resolution, and improve subjective visual effects. The proposed algorithm can be applied to the fields requiring large data and real-time monitoring.

We propose a novel multi-source image fusion algorithm based on the improved guided image filtering and dual-channel spiking cortical model (DCSCM),in order to solve the problems that targets are not prominent, background information is easy to lose and margin information is not adequately retained. Firstly, we obtain the low frequency and high frequency sub-bands by using the nonsubsampled shearlet transform (NSST) to the two original images. Then we use the improved guided image filtering algorithm and the DCSCM model to fuse the low frequency and high frequency components respectively. Finally, we perform the inverse NSST transform on the fused high and low frequency components to obtain the final fused image. Experimental results show that the fused images of the proposed algorithm have prominent targets and rich background information. The proposed algorithm has advantages in terms of image clarity, contrast, and information entropy, compared with several other methods.

There are many problems exist in the process of registration and recognition of keypoints in 3D point cloud, such as finding matching mismatch, large number of mismatched pairs, and the decreasing of registration and recognition precision. A novel removal method of mismatching keypoints is proposed. In the stage of keypoint detection, an edge point detection algorithm is put forward based on the feature that the edge points and their neighbor points are mostly distributed on the same side. The proposed method can remove the keypoints existing in the edge to improve the repeatability and match ability, and reduce the mismatching rate in the feature matching of keypoint. In the stage of feature matching of keypoints, the initial keypoint matching pairs obtained by nearest-neighbor algorithm are matched, a lot of mismatching keypoint pairs can be removed according to the methods of Kmeans and splitting, and the matching rate of keypoints between 3D point clouds can be improved. Experimental results show that a large number of the mismatching keypoint pairs can be removed,which generated by a complete point cloud matching a complete point cloud, a complete point cloud matching a point cloud with clutter and occlusion, and a partial point cloud matching a partial point cloud, lots of mismatching keypoint pairs, and the matching effect of keypoints can be significantly improved. At the same time, the proposed algorithm is more efficient than random sample consensus algorithm in the time consumption, which is a good supplement to the nearest-neighbor algorithm.

We propose a method for face affine registration based on a single template. Firstly, in order to overcome the local deformation caused by face affine transformation, the color feature is introduced to balance the color similarity and shape mismatch rate between the template face image and the target face image, and then the face rough search algorithm is proposed based on the color feature. Secondly, the affine transformation obtained by face rough search algorithm is used as an initial constraint to establish the face shape fine registration algorithm based on the previous affine constraints. In each iteration step of the algorithm, the affine transformation obtained in the previous iteration is used to establish the correspondence of the nearest point, and the new affine transformation is solved by use of the objective function based on the previous affine constraint. The proposed algorithm successfully solves the problem that a face shape is difficult to register under the conditions of presence of rotation, scale transformation, and noise interference. Compared with the traditional face affine registration algorithm, the proposed algorithm effectively improves the robustness and accuracy of face affine registration.

The organ shape is an important factor that affects the propagation of modeling light in vivo. It can directly affect the reconstruction process of fluorescence molecular tomography (FMT). Manual segmentation of organs is complex and requires high-quality images, while automatic segmentation methods such as edge detection, region growing and active contour models have great limitations in dealing with complex medical images. We propose an automatic segmentation method based on active shape models (ASM) to accurately segment the images of mouse organs. Moreover, the light source reconstruction is realized based on L1 norm optimization. We carry out an experiment with the computed tomography (CT) data of a real mouse to explore the relation between organ image segmentation accuracy based on ASM and reconstruction accuracy. The experimental results show that the ASM method can replace manual segmentation without affecting the position reconstruction of light source, when compared with the popular Snake model-based segmentation algorithm.

The large-caliber Fresnel diffraction lens can be produced by the multiple segmented lens splicing method, yet the splicing error has effects on the image quality of the optical system. The database of piston and tip-tilt error and corresponding wavefront error Zernike coefficient of the segmented lens along its own x' axis tilt, y' axis tilt, z'-axis piston is obtained by means of diffractive ray tracing and wavefront reconstruction method. The nonlinear coupling mapping model of the Zernike coefficient and the corresponding piston and tip-tilt error is established with the database based on back-propagation neural network optimization algorithm. We can accomplish the quick solution to the piston and tip-tilt error coupling disturbance by inputting the Zernike coefficients, and determine the magnitude and direction of the piston and tip-tilt error by the symbol of values. The model is simulated numerically, the accuracy and reliability of the analytical method are verified. This work provides theoretical basis for the coplanar detection and adjustment of the segmented diffractive lens.

A wavefront aberration measurement method for freeform spectacle lenses in real viewing condition is proposed based on the human eye-spectacle lens model. The method is different from the existing focimeter and the Hartmann-Shack wavefront aberration measurement method in which the wavefront aberration on the back surface of spectacle lenses is measured. The principle of wavefront aberration measurement for spectacle lenses on its vertex sphere in real viewing condition is demonstrated. Based on the principle, the corresponding experimental measurement apparatus is designed and built. Experiments of scanning and measuring spectacle lenses are carried out to obtain the wavefront aberration and wearer power on the vertex sphere. The measurement results verify that wavefront aberration measurement for freeform spectacle lenses in real viewing condition can be achieved by the proposed method. The findings assist in evaluating the manufacturing and image qualities of freeform spectacle lenses. The results also guide design and optimization of the lenses.

Wavefront aberration can well reflect the performances of optical system. The test result of wavefront is usually expressed in a linear combination of Zernike polynomials. The wavefront of the transmission optical system needs to be tested at specific wavelengths. From now on, only a few wavelength wavefronts can be accurately tested because of the limitation of detection instrument. A new idea is put forward in this paper, the wavefront can be tested at any wavelength by analyzing the functional relationship between transmitted wavefront Zernike coefficients and wavelength, which can indirectly reflect the variation of the wavefront with the wavelength. The optical system is modeled by Zemax. The wavefront Zernike coefficients of the optical system at different wavelengths are collected. Then the possible function form of the curve of the Zernike coefficients and the wavelength are fitted by Matlab curve fitting tool. Finally, the Conrady-Zernike formula is determined. The maximum error of the calculated Zernike coefficients is within 1%, which is calculated by the Conrady-Zernike formula in the simulated optical system. The results show that the wavefront Zernike coefficients and the wavelength of transmitted optical system are basically consistent with the Conrady-Zernike formula.

Snow targets of Dome C and Greenland in the south and north poles are the calibration tracking targets, which are internationally applied. However, due to the existence of polar night phenomenon, it is difficult to continuously calibrate and track remote sensing instruments in a single polar ice and snow target. In response to this problem, a method of continuous tracking and monitoring of the radiation performance of the FY-3A/medium resolution spectral imager (MERSI) solar reflectance band using a combination of two polar ice targets is proposed. Firstly, using the relatively stable observation data of FY-3A/MERSI in late life stage, two bidirectional distribution function models of apparent reflectivity of ice and snow target are established. Then, the model is used to normalize the apparent reflectivity sequence of ice and snow target, eliminate the change information caused by the target non-Lambertian, obtain the parameters that reflect the change of the radiation performance of the remote sensor, and achieve the fusion of different ice and snow target data series. Finally, using the quadratic polynomial fitting model, the trend of the data after the fusion is analyzed, and it is compared with other related research results. The results show that the uncertainty of the tracking model is better than 3%, especially for the short wavelength of less than 550 nm, in which the uncertainty is better than 2%. Attenuation rate results show that the blue band attenuation is significant, especially in the band 8 (413 nm), the annual average attenuation rate is close to 7%. The red and the near infrared band (excluding the water vapor channel) are the most stable wave bands, and the annual average attenuation rate is within ±0.5%. The verification results show that the proposed method is in good agreement with other methods, and the deviation of the total attenuation rate of many years in most bands is less than 3%.

In order to improve the measurement speed and accuracy of fringe projection three-dimensional (3D) measurement system, an approved phase-to-height mapping model is proposed. By building a virtual camera coordinate system and analyzing the conversion relation of fringe patterns between projector coordinate system and camera coordinate system, a one-to-one mapping relationship from phase to height in the camera corrected system is built and the lens distortion of the camera is included in the mapping model. Due to its simple expression, this model is suited for combining with look-up-table (LUT) method. With LUT method, this model can be used in high speed measurement because of its low algorithm complexity. Meanwhile, a calibration method for this model is proposed, and back-projection process is used to optimize the parameters of the camera in calibration process. The calibration method is easy to operate and no reference plane is needed. Also, the relative postures of the camera and the projector in fringe projection system can be arbitrarily arranged. Experimental results indicate that the proposed mapping model and its calibration method can achieve 3D measurement rapidly and accurately.

The concentration of water vapor is one of the important indices during semiconductor sealing element manufacturing process, and excessive water vapor has seriously influence on the quality of semiconductor. Therefore, a real-time water vapor measurement technique with high sensitivity and high precision is crucial. In the work, a low-concentration water vapor measurement system based on off-axis integrated cavity absorption spectroscopy is developed, the reflectivity of the mirror is 0.99920, effective optical path length is 250 m, and measurement time is 0.025 s. The mode density of the resonant cavity can be improved when the light is off-axis transmitted into the laser resonant cavity, thus the signal-to-noise ratio is significantly increased. The system is utilized to investigate the absorption line of water vapor near 7036.5 cm-1, it is found that the sensitivity of the system is 7.07×10-6 cm-1, and measurement error is less than 5%. By injecting different concentrations of water vapor into the cavity, the on-line continuous measurement performance of the system is tested, the result reveals that the system can meet the process requirement.

A graphene-based plasmonic XNOR/XOR logic gate where the add-drop-channel micro-ring resonators are used as the basic unit is designed. The transmission states of graphene-based surface plasmonics can be controlled by tuning the chemical potential of graphene, and so that the XNOR and XOR operation results can be obtained simultaneously at the two output ports of this device. The simulation results show that the opening and closing of the add-drop-channel micro-ring resonators of graphene-based plasmonic waveguide can be realized when the chemical potentials are 0.677 eV and 0.95 eV, and the working frequency is 30 THz. In addition, the minimum crosstalk of the designed XNOR/XOR logic gates is -10.60 dB when the input logic states are ‘00’, ‘01’, ‘10’ and ‘11’.

The flow field and pressure loss coefficient of rectangular inner channel at right-angled bend are studied by the finite volume method. Specifically, the influence of channel size, coolant flow rate and coolant volume fraction on the local flow field and pressure loss coefficient is analyzed. The result shows that the pressure loss coefficient decreases gradually with the increases of the channel width a and the channel height b, and decreases and then increases slightly with the channel interval e. The change of bend width c causes the change of local flow field in bend and the pressure loss coefficient. The greater the flow velocity is, the smaller the pressure loss coefficient is. The greater the volume fraction of the cooling fluid is, the larger the pressure loss coefficient is.

Combined with the visual attention mechanism, the influence of contrast factor on visual comfort of stereo image is studied quantitatively through a large number of subjective experiments. First, a stereo salient degree map is derived from stereo disparity map and planar salient map. It is optimized through fuzzy membership degree and mask, and the salient stereoscopic images can be obtained. An eye tracker is used to verify its rationality. Then, a series of subjective experiments are conducted after contrast conversion of left and right views. Finally, the comfortable contrast matching map and difference map are obtained after data screening. The experimental results show that the contrast difference thresholds of left and right view change with different left view contrasts, and the contrast difference should not be too large. The maximum and minimum difference values are 1.97 and -2.40, respectively. The obtained comfortable contrast ranges reflect the comfort of stereo image better, and the correct rate reaches 95%, which provides more reasonable and feasible quantitative standards for the making of stereo contents.

In correlation filter tracking, occlusion and object scale change can lead to tracking failure easily. To deal with this problem, a correlation filter tracking algorithm based on online detection and scale-adaption is proposed. The target is initially located through a correlation filter tracker fusing histogram features of oriented gradient, color attribute features and illumination invariant features. The reconstruction residual of local sparse representation model is used for occlusion discrimination. If occlusion occurs, online support vector machine detection will be carried out and target relocating will be realized. Scale estimation from coarse to precise is carried out, and precise scale of target is obtained by scale pre-estimation and Newton iterative method. A balanced model updating strategy is used to update correlation filter regularly and update sparse representation model and support vector machine conservatively. Experimental results show that, compared with existing tracking algorithms, the proposed algorithm can effectively reduce the occlusion, target scale change and other complicated factors, and can gain higher distance precision and success rate on 50 groups of test sequences. The overall performance of the proposed algorithm is better than other contrast algorithms.

A line tracking method of arm vein is proposed based on Bayesian theory, and the method can detect vascular boundary. The method can automatically select initial seed points, avoiding artificial disturbance. In the vessel tracking, the vessel structures are divided into normal, bifurcation and crossing types. For each iteration, the algorithm takes longitudinal and horizontal characteristics of vessels into account. Because blood vessels within a short distance are approximately a straight line, a multi-scale line template is applied on the image filtering to obtain line strength of each pixel. A Gaussian model is used to fit the gray distribution of vessel along the cross section. The most possible vessel structure is determined based on Bayesian maximum posteriori probability criterion. Therefore, the edge points, central points, diameter and direction of local vessel can be acquired. The experiment results show that, compared with traditional threshold segmentation method and repeated line tracking method, the proposed method performs better in identification accuracy, comprehensiveness, and robustness to noise.

A novel palm print and palm vein joint recognition system based video is built. First of all, a novel registration and identification approach is proposed, and we can obtain the palm motion video by proposed system instead of static image obtained by traditional collection method. The approach allows the users simply sweep their palms across the acquisition platform without having to stop, which effectively enhances the affinity of authentication. A new strategy of fusing rotating videos with sweep videos to generate the registration feature set is proposed, which ensures the abundance and integrality of the register feature and enhances the robustness of the system for various palm postures in authentication. A cascaded fusion strategy is presented to improve the recognition speed of the registered users. We construct a palm print and palm vein database containing 1200 videos with motion blur from 100 palms and carry out a series simulations. The results show that the proposed system can achieve a low equal error rate of 1.51% within the expected time consumption of 915 ms, which desmonstrates the effectiveness and practicality of the new system.

Aiming at the problems of noise-sensitive, easy distortion and with high false matching ratio in the disparity discontinuity region and weak texture region of the existing local matching algorithm, a multi-scale stereo matching algorithm for improved Census transform and gradient fusion is proposed. The weighted average gray value of all the pixels in the support window is used as the reference value of the Census transform. The Census cost is weighted combined with the gradient cost normalized by the horizontal and vertical directions, and a stable cost is obtained when the noise margin is set. Therefore, the reliability of the single pixel matching cost is obtained. Under the multi-scale, the improved guided filtering algorithm is used to complete the aggregation of the matching cost. The disparity map is obtained by parallax extraction. The experimental results demonstrate that the average false matching ratio of standard stereo image pairs obtained by the proposed algorithm is 4.74% on the Middlebury testing benchmark, and the average false matching ratio of the 27 extended stereo image pairs is 8.67%. In the parallax discontinuity region and the weak texture region, the false matching ratio is further reduced by the proposed algorithm, and it shows better robustness for noise and light.

A frequency-reconfigurable graphene patch antenna working in the terahertz band is designed on a polyimide substrate. The resonance frequency points of this antenna can be tuned dynamically by the bias electrical field rather than any electronic switch, meanwhile its radiation performance is kept. The main characteristics of graphene are studied, the input impedance of the graphene patch antenna is calculated based on the equivalent circuit model, and the reason of frequency-tuning is explained theoretically. The designed graphene antenna achieves five resonance frequency points in the terahertz band, which covers the frequency bands ranging from 678.25 GHz to 721.75 GHz. The radiation gain peak can reach 6.92 dB, and the radiation efficiency can reach 86.48%.

The WO3 films are prepared on the substrate of FTO conductive glass by using the ammonium metatungstate as the tungsten source and Pluronic F127 as the coordination polymer. The influence of the coordination polymer on the electrochromic performance of WO3 films is investigated. The experimental results show that the WO3 films have a cubic crystal structure. With the increase of the Pluronic F127 content, the WO3 film roughness increases, and the charge capacity increases first and then decreases. When the Pluronic F127 content is 26%, the charge capacity of the WO3 thin films is the largest, and the electrochromic performance is the best. The optical modulation range is up to 62.68% and the optical density difference is up to 0.864 in the visible region. Meanwhile, the total solar energy transmittance in the colored state is lower than that in the bleached state. The prepared thin films have a good energy saving effect.

The coupling properties of defect modes between the double-defect microcavities in the octagonal quasi-photonic-crystals are investigated under a low-refractive-index contrast based on the organic semiconductor luminescent materials. The study results show that, in the quasicrystal structure with double nine-air-hole-missing microcavities, it is observed that not only the modes split, but also a new mode in the composite cavity constructed by the double-defect microcavities and the intermediate scatterers. Based on this, by using the three-dimensional field distribution and the phase relationship among the defect modes, the physical mechanism of mode-coupling is disclosed. These results provides a theoretical foundation for the future design and fabrication of organic semiconductor photonic crystal devices in visible light band.

Ultraviolet (UV) imaging spectrometer is one of the most important parts of remote sensing instruments. In the field of airborne and satellite-borne, remote sensing platforms are increasingly requiring that spectrometers be lightweight and miniaturized while achieving high resolution. Aiming at the characteristics of high spectral resolution, light weight and miniaturization of UV imaging spectrometer, the UV imaging spectroscopy system based on Offner structure is studied. The high-resolution UV imaging spectrometer with operating wavelength range of 250-400 nm, the slit length of 40 mm, the spectral resolution of 0.3 nm is designed, and the design results are analyzed and evaluated. The results show that this UV imaging spectrometer achieves a modulation transfer function above 0.76 at 38.5 lp/mm, and it realizes excellent image quality near the diffraction limit. Keystone and smile are within 10% of pixel size. In addition, the structure greatly reduces the system volume based on the original Offner structure, which realizes the miniaturization and weight reduction of the ultraviolet remote sensing instrument. It is easy to be processed and adjusted, which meets the design requirements. And it is suitable for airborne and spaceborne remote sensing applications.

In order to increase the valid view of field, make it easy for using, and save cost, it's necessary to improve the performance of the existing rigid endoscope. Firstly, the development status and main problems of rigid endoscopes at home and abroad are analyzed. And the design requirement is proposed by comparing related product. Next, a design method of 30° viewing angle rigid endoscope is proposed. Then, on the basis of the analysis of the current steering system structure of all kinds of rigid endoscope on the market, a method of designing the 30° viewing angle endoscope with total reflection prism is proposed. Finally, the tolerance analysis and image quality evaluation are carried out according to the corresponding standard. The design results show that the total length of the designed endoscope is 365 mm. The diameter is less than 6 mm. The angle of the field of view is ±40°. And the object space resolution is 12 lp/mm, which is close to the diffraction limit. The energy distribution is uniform as well. Considering the processing and assembly error, the results show that the image quality can still meet the user needs after the tolerance analysis. The design results can basically meet the actual use needs and the design requirements, which have engineering application significance for the localization of high quality medical rigid endoscope.

In order to meet the needs of miniaturization and large field-of-view (FOV) of endoscopes in modern medical field, by using the retrofocus optical structure as initial structure, a high definition electronic endoscope objective optical system with 5×5 microlens array in the visible spectrum designed by Zemax software is presented. The optical system has a FOV of 110°, a focal length of 1.55 mm, F number of 4.2, a maxium clear aperture of 3.15 mm and a total length of system of 7.99 mm. The optical system is composed of 6 pieces of lens, which are divided into the front lens group and the rear lens group. The front lens group includes one lens with two-array surfaces. The rear lens group includes one double cemented lens. The modulation transfer function value of the whole system is 0.36 at the spatial frequency of 120 lp/mm, which is approaching to the diffraction limit, and meets the use of medical treatment. The design results show that the microlens array has obvious advantages in increasing the field of view of the endoscopic optical system without changing the aperture, and has a wide application prospect in medical treatment.

Most existing life prediction models for photoelectric products have many problems such as time consuming and low precision in processing test data. In order to accurately predict the life of optoelectronic products in a short time, two-parameter Weibull function is used to fit luminance degradation data under multigroup stresses to obtain accelerated life, and Power function determined by the parameters of goodness-of-fit test is employed to extrapolate conventional life. Thereby, a novel model of life prediction, named accelerated life extrapolation model (ALEM), is established. The model is applied to rapidly predict the life of vacuum fluorescent display (VFD), accelerated degradation tests under four groups of constant stresses are carried out, and then the evaluation of the model precision is achieved. The results show that VFD test design scheme is correct and feasible, and the collected test data objectively reflect the characteristics of VFD luminance degradation. The ALEM exactly describes the change trajectory of luminance under each accelerated stress, well reveals the variation law of stress with life, and precisely extrapolates the product life without conducing conventional life test. Which can open up a new method and approach for the life estimation of modern optoelectronic products.

Mode properties of parallel dielectric nanowires coated with graphene are analyzed by using the multipole method. The effects of the operating frequency, the geometrical parameters of the dielectric nanowires, and the Fermi energy of the graphene on the effective refractive index and the propagation length are investigated in detail. The results show that mode properties can be easily adjusted by changing the operating frequency and the Fermi energy of graphene. In addition, the radius or the spacing can be used to adjust mode properties within the range of 50 nm. However, the effects of the two parameters decrease gradually when their values continue to increase. The comparison shows that the analytical results of the multipole method are in good agreement with the numerical results of the finite element method.

The metal circular arc hole array structure consisting of two symmetrical large and small circular arcs, at the positions of up and down, left and right, is proposed. In order to obtain an extraordinary optical transmission phenomenon, we use Fabry-Perot cavity formed by the structure to enhance the coupling of surface plasmon polariton (SPP). At the same time, a refractive index sensing property is investigated based on the phenomenon. The effects of the radiuses of big and small circular arc holes, the center distance of two circular arcs and the array period on extraordinary optical transmission phenomenon are investigated with the utilization of finite-difference time-domain (FDTD) method. It is found that when the radius of the big and small circular arcs are 95 nm and 70 nm, respectively, the center distance of the two circular arcs is 100 nm and the period is 425 nm, this structure has an extraordinary optical transmission phenomenon and its sensitivity is 279 nm/RIU. These results serve as a theory reference for the design of next-generation high-performance micro-nano plasmonics sensors.

In process of phase retrieval, the image reconstruction quality can be improved when we use the image sparsity as the prior knowledge. By combining the group sparsity of image in wavelet domain with the gradient sparsity of the image itself, we propose a phase retrieval algorithm fusing orthogonal wavelet db10, sym4 group sparsity and total variation regularization for the coded diffraction pattern model. Aiming at the problem that reconfiguration time of the current phase retrieval algorithm is long, we use composite splitting algorithm to decompose nonconvex optimization problem into several sub-problems (including two group hard threshold operators and total variation minimization) that can be solved easily, which reduces the image reconstruction time. Experimental results show that the peak signal-to-noise ratio of the reconstructed image obtained by the proposed algorithm is improved by about 0.8 dB compared with that of BM3D-PRGAMP algorithm under Gaussian noise, and the reconstruction time is reduced by 90%. In Poisson model, the proposed algorithm also has a great advantage, which fully demonstrates that the algorithm is robust to noise.

We obtain vector wave function expansion coefficients of the circularly-symmetric vector Bessel vortex beam based on the expansion of electromagnetic field in terms of vector wave function and the transformation of vector wave functions in different coordinate systems. Then, we obtain the expansion coefficients of reflection field, transmission field, and internal field of homogeneous uniaxial anisotropic media, which is illuminated by a circularly-symmetric vector Bessel vortex beam in any direction under the electromagnetic field boundary conditions. At last, we simulate the electric field distributions of reflection field, transmission field, and internal field in the cross sections and the total electric field distribution in xOz plane. The simulated results show that for a circularly-symmetric Bessel vortex beam incidence to uniaxial anisotropic media, the reflection field contour keeps a concentric ring structure, whereas the reflection field intensity distribution is asymmetric; there are two refracted rays in the transmission field, which brings about the distortion of the electric field intensity contour.

The balanced homodyne detector for continuous-variable quantum memory is improved, and a fast response balanced homodyne detector for real-time measurement of amplitude and phase quadrature components of short pulsed optical signals is obtained. By using the circuits without capacitors and the photodiodes with a high quantum efficiency and a low capacitance, the response time of 65 ns for this balanced homodyne detector is obtained. The signal-to-noise ratio is higher than 12 dB at 2.5 MHz when a laser with a power of more than 100 μW and a wavelength of 795 nm is incident, and the corresponding saturation power is 6.8 mW. This balanced homodyne detector can be applied in the continuous-variable quantum memory and the quantum network, and so on.

With the great increase of resolution capability of modern sensors, the object is regarded as an extended one with object extension, instead of a point target. Thus, conventional point target modeling and state estimation approaches are no longer suitable for many current tracking scenarios. An extended object's motion and extension (i.e., shape and orientation) undergo an abrupt change when it maneuvers, and both of them are usually highly coupled. In view of this problem, the uncertainties of the extended object maneuvers, the evolution of the kinematic state and object extension, and their close coupling are researched. A general hybrid system modeling framework of the maneuvering extended objects is established. The results show that a joint kinematic state and object extension estimation algorithm can be derived easily owning to the concise linear form of the proposed model. Simulation results and performance comparison demonstrate the effectiveness of the proposed modeling and tracking approaches.

Au-Ag alloy films of around 60 nm thickness are deposited on the slab glass substrate by radio frequency sputtering technique. Then large-area uniform nanoporous gold films (NPGF) with strong adhesion are fabricated by chemical dealloying at room temperature. The resonance spectrum of NPGF exposed to the air in the visible-near-infrared region is obtained by a self-built broadband spectral surface plasmon resonance (SPR) detection platform. The Fresnel formula and Bruggeman dielectric constant approximation equation are used to fit the experimental results. The porosity of NPGF is about 0.38. The response characteristics of the NPGF-SPR sensor to Pb2+ ions and melamine molecules adsorbed from the individual aqueous solutions with different concentrations are investigated. The experimental results show that the NPGF-SPR sensor can make obvious responses to both Pb2+ ions and melamine molecules in the aqueous solution with 1 nmol·L-1 concentration. The comparison experiment shows that the NPGF-SPR sensor is much more sensitive than the conventional SPR sensor with a dense gold layer.

In order to realize the microminiaturization of the Fourier transform spectrometer (FTS) further, the micro lens array is introduced to FTS based on stepped micro-mirrors, which is used to collect each interference optical field unit modulated by stepped micro-mirrors synchronously. Because of the spatial modulation mode, the system wavefront aberration causes the wavefront distortion of each interference optical field unit. The scalar diffraction model of the interaction between the optical field with wavefront aberration and the stepped micro-mirrors, and the micro lens array is built. By means of calculation, the wavefront aberration is found impairing the intensity of each point in interference image at different levels, and introducing the low-frequency spectrum noise to the recovered spectrum. The analyses show that the intensity attenuation of interference image points results from the intensity modulation by wavefront aberration Strehl ratio of each interference optical field unit, and the low-frequency spectrum noise is mainly from the Fourier spectrum of Strehl ratio. According to the modulation characteristic of the wavefront aberration on interferogram, a method that using the wavefront aberration Strehl ratio to correct the interferogram intensity is proposed. The results indicate that this method improves the distortion of the recovered spectrum effectively.

The missile boost section has high temperature and large area of plume. The missile can be accurately identified according to the spectrum characteristics of the plume. Applying the plume spectrum into the space-based early warning system can improve the missile defense ability, but the huge spectral information results in a lot of time from obtaining spectral information to identifying spectral information. So, we find the characteristic spectrum which can represent the spectrum of the missile plume, and use fuzzy algorithm to process the characteristic spectrum data, so as to achieve the purpose of accurate and rapid identification. Analysis shows that the characteristic spectrum image has higher signal-to-noise ratio than full band infrared image, and fuzzy algorithm is better than spectral angle measurement (SAM) on real-time and accuracy.

Holographic concave grating (HCG) spectrometer has many advantages, such as flat-spectrum, miniaturization, large aperture and high resolution. Firstly,the imaging formula of HCG is deduced based on information optics and its imaging characteristics are analyzed in both perpendicular plane to the slit and parallel plane to the slit. In the perpendicular plane, HCG spectrometer has good flat-spectrum; in the parallel plane, HCG spectrometer overcomes the spectral line bending and chromatic distortion of the traditional plane grating and realizes the straight spectral line imaging. In addition, the restriction of the intrinsic sagittal field curvature of HCG spectrometer to the field of view expanding is pointed out. According to the theoretical analysis results, it is proposed that symmetrical structure eliminates field curvature of HCG spectrometer. Then the aberration compensation spectrometer is designed and optimized with the utilization of ZEMAX software. Both traditional single-spherical-mirror HCG spectrometer with 0.4 mm slit length and aberration compensation HCG spectrometer with 8 mm slit length are designed with the same relative aperture F# of 3, spectral resolution of 20 nm/mm and spatial resolution of less than 25 μm. The results show that the field of view of the aberration compensation HCG spectrometer is successfully expanded 20 times larger than that of single-spherical-mirror HCG spectrometer.

Illumination estimation in complex and multi-illumination scenes is a difficult and hot point in computational color constancy field. An illumination estimation algorithm based on exemplar learning in the logarithm domain is proposed. The effects of illumination on chrominance of an image are studied, and the log-chrominance histogram is extracted as the illumination consistency feature. The frame of exemplar learning is introduced, and the illumination of target scenes is estimated by known-illumination exemplars with similar features. Image segmentation is applied by the algorithm firstly, then illumination estimation is performed for each segment independently, and segmental illuminations are fused together to calculate the illumination for the whole image. Experiments are carried out on several single illumination and multiple illumination data sets. The experimental results show that compared with other advance methods, the proposed method reduces the median error of the illumination estimation by 5%-14% with higher accuracy and higher robustness.

An impoved Adaboost algorithm, together with a profile segmentation method based on dynamic programming (DP), is proposed for automatic detection and segmentation of bioresorbable vascular scaffold (BVS) in intravascular optical coherence tomography (IVOCT) imaging system, to achieve auto estimation on the strut malapposition. During detection, the multi-layer decision tree is applied to the construction of Adaboost classifier, in order to detect the position and size of each strut. Then, the DP algoritm is adopted to segment the struts’ boundaries based on detection results. Finally, combined with the segmentation results, struts malapposition is caculated. Experimental results show that our method reaches the detection recall rate of 91.6% with the precision of 87.3%, and the average Dice coefficient of segmentation is 0.80. It suggests that our method can accurately achieve the detection and the segmentation of BVS struts in IVOCT images, and has high robustness.