For the research of marine remote sensing calibration of China, a mathematical model of bulk-skin sea surface temperature is proposed to improve the measurement precision of skin sea surface temperature to 0.3℃. Skin sea surface temperature is measured by the self-designed automatic multi-spectral infrared radiometer system installed on the PY-301 oil platform in the northern part of the South China Sea, the measurement accuracy of the radiometer is better than±0.5 ℃ through standard blackbody calibration, pupil correction and skylight correction. The effect of wind speed on the bulk-skin sea surface temperature is analyzed based on the model, the skin sea surface temperature is corrected by the proposed model and Donlon model, the biases of corrected results are －0.007 6±0.297 1℃ and 0.044 6±0.324 8℃, respectively. Results prove that the proposed model is effective and can improve the measurement accuracy of skin sea surface temperature.

To enhance visual contrast and image quality for underwater image with conventional light source, an image enhancement algorithm based on iterative histogram equalization is proposed. Firstly, underwater image is decomposed into detail layer image and illumination layer image through Retinex model, and an image enhancement model is derived to improve the contrast effect of image on the basic of Weber contrast constant. Then, an image enhancement algorithm based on iterative histogram equalization is proposed to enhance the contrast of illumination layer image, and S-shade function is employed to stretch the contrast of detail layer image. Finally, the stretched detail layer image and enhanced illumination layer image are mixed to derive the preferable enhanced underwater image. Experimental results show that the visual contrast of underwater image is enhanced validly by the proposed algorithms, and the entropy and mean structural similarity index are higher than other image enhancement algorithms. Meanwhile the visual effect is ascended observably.

The observation method is analyzed and the performances parameters of corresponding spectrometer are obtained based on the characteristic spectrums of the major elements in the underwater environment. The telescope and the imaging spectrometer are separately designed and coupled together. The telescope adopted double Gauss refractive system and realized optimization of the telecentric design with few optical materials. The imaging spectrometer based on the Dyson mounting also performed excellently with the analysis of optical path and the added lenses. The final design obtained the excellent performances that the field of view is 28°, the F number is 3, the spectral resolution is 3.5 nm, and the spatial resolution is 1 mrad in the waveband of 350 ~700 nm. The prototype verified the design theory.

The experimental system to write long-period fiber gratings was set up based on femtosecond laser pulses with a central wavelength 800 nm. In this system, the femtosecond laser pulses were induced in the fiber core of the normal SMF-28 by adopting a micro-objective of 20×, and the processing of writing long-period fiber gratings was monitored by adopting the horizontal and vertical dual-CCD video. The long-period fiber gratings with different period, different period number and different duty ratio were inscribed in no-hydrogen-loaded SMF-28 fiber. The experiment result shows that the maximum resonance peak loss of 11.65 dB will be generated at the wavelength of 1 300 nm and out-of-band loss is lower than 2 dB when the laser pulse energy is selected of 1.3 mW, the period of grating is 500 μm and the duty ratio of grating is 0.6, and the resonant wavelength of grating is not apparent drift with the length of the grating. More further, the optimal spectral characteristics of grating can be designed through the adjustment of grating duty ratio, and the resonance peak will be changed from multi-peak to single peak.

In order to solve the practical problem of low displacement sensitivity when a cantilever beam or deformed ring is used as an elastic deformation structure of a fiber Bragg grating displacement sensor, a new elliptical displacement amplification mechanism was chosen to amplify the mini-shifting of the displacement, and the displacement resolution of the sensor was adjusted by changing the mechanical size of the elliptical amplifier. When the length of the elliptical displacement amplifying structure is 60 mm, the width is 19.8 mm, and the maximum width in the middle is 30 mm, the magnification of the mechanical displacement is amplified by 2 times. When the range changes from 0 to 100 nm, the resolution of the fiber Bragg grating displacement sensor measured in the experiment is 6.1 pm/mm, and the linear correlation coefficient of displacement and corresponding wavelength shift is 0.998 52. The sensor can be effectively applied to high-precision on-line monitoring for structural displacement of mechanical equipment and civil engineering.

In oceanic wireless optical communication systems based on orbital angular momentum multiplexing, oceanic turbulence will bring the channel crosstalk. To solve the problem of channel crosstalk, a spatial diversity mitigation scheme is proposed. Random phase screen method is used to simulate phase perturbation caused by ocean turbulence and split-step transmission method is used to simulate the beam diffraction. Equal gain diversity combination is used to process signal at the receiver. 4-orbital angular momentum-multiplexed channels and 8-spatial diversity are used in the system. The influences of orbital angular momentum mode sets, oceanic turbulence strength and communication distance on the bit-error rate are investigated. Simulation results show that bit error rates decrease obviously with the modes spacing increases from 1 to 2 in the orbital angular momentum multiplexed sets. Performances of bit-error rates remain steady as modes spacing become larger. Bit-error rate will also increase with the increasing transmission distance and turbulence strength. Results show using diversity combination on orbital angular momentum-multiplexed systems can effectively mitigate the performance degradation from oceanic turbulence.

The nonlinear spectroscopic experiments were carried out that femtosecond laser pulses generated by Ti: sapphire laser are used to pump high nonlinear double zero dispersion photonic crystal fibers. When the central wavelength of the pump pulse is 800 nm, in the anomalous dispersion region, the ultra-wide bandwidth continuous spectral output from the double zero dispersive photonic crystal fiber is observed. Compared with that of the single zero dispersive photonic crystal fiber, double zero dispersive photonic crystal fiber has higher conversion efficiency, stable and smooth spectral band. Both the high efficiency blue shifted dispersive waves and the broadband red shifted dispersion wave in the normal dispersion region at long wavelength are obtained. Consistent with the phase matching condition of theoretical analysis, the physical mechanism of the phase matching is clarified. With the increase of pump power, the long-band dispersion wave has a significant shift to long-wave band and the short (visible) band dispersion wave intensity increases significantly. When the pump power is 0.68 W, the pump is almost completely converted. The ratio of blue shift dispersion wave to residual pump output power is 257∶1, and the efficiency of spectral conversion is as high as 99.6%. The blue shift dispersive waves has a wide band of 309 nm, and the red shift dispersive waves in near infrared band is connected with the soliton wave to form a supercontinuum spectrum with a bandwidth of 628 nm. The experiment results have reference value for the study of ultrashort pulse laser frequency conversion and broadband light source.

A novel simple structure of photonic crystal fiber is optimized based on silica as the backing material, which has a cladding of hexagonal symmetric array uniform circle air hole and a larger the area of fiber core by missing central air column and reducing six air holes around the central core. Based on finite difference time domain method with the boundary conditions of anisotropic perfectly matched layers, its dispersion, nonlinear, confinement loss and fundamental mode field is numerically investigated. Numerical results indicate that the proposed fiber shows ultra-low loss, low non-linear and flattened dispersion performance. Its confinement loss is less than 10－7 dB·km－1 over communication band, which is 2.93×10－8 dB·km－1 and 7.33×10－10 dB·km－1 at wavelength of 1.55 μm and 1.31 μm, respectively. Furthermore, it appears double zero dispersion point and a certain ultra-flatten dispersion in the longer wavelength range, which flattened dispersion is 0±1.7 ps·km－1·nm－1 over 1.05~1.65 μm. Another, its non-linear coefficient is only 4.88 km－1W－1 at wavelength of 1.55 μm. It is obviously to obtained admirable application in the field of long distance high speed optical communication system due to its ultra-low loss low non-linear and flatten dispersion capability.

In order to realize fiber-optic temperature sense based on macrobending loss properties of sinlgle-mode fiber, temperature sensing properties of macro-bend single-mode fiber were studied theoretically and experimentally. Temperature correction is made for a classical macrobending loss theoretical formula of single-mode fiber. Then simulation analysis of effects of bend radius, wavelength and temperature on bend loss of a single-mode fiber with core-infinite cladding structure is made based on the formula. After that, a single-mode fiber temperature sensor with an inner absorption layer and an outer nickel layer outside the cladding layer of the fiber is designed and made. Finally, experimental tests of temperature sensing performance of the sensor are carried out and discussed. Results show that macrobending loss of the fiber with core-infinite cladding structure is sensitive to bend radius, wavelength of light resource and temperature, and the temperature response of the sensor is linear. In addition, the proposed fiber-optic sensor shows a temperature resolution of 0.4 ℃. It′s worth noting that the temperature sensitivity and resolution can be increased by decreasing the bend radius and raising the wavelength of light resource. Thus such single-mode fiber can be treated as core-infinite cladding structure single-mode fiber, which can be used to develop macro-bend optical fiber sensor based on macrobending loss properties.

In order to eliminate the influence of background clutter and noise in the infrared images for the detection of infrared dim targets at sea, an infrared image dim target detection method based on temporal-spatial non-local similarity is proposed. The method makes full use of the non-local auto-correlation of the sea surface background image patch between the infrared image sequences of adjacent frames and the similarity between non-local background image patch in the frame. Based on this characteristic, a temporal-spatial image patch model is introduced. The model is effectively solved by accelerating the proximal gradient method. The experimental results show that compared with the traditional infrared dim target detection method, the proposed method can not only preserve the feature of the target more effectively but also increase the peak signal to noise ratio of the detected infrared image by 1.2 times and improve the signal to clutter ratio by 1.8 times.

In order to overcome the tracking difficulty caused by distorted shape and motion law of the target of non-similar imaging in infrared wide-field staring system, a gradient entropy weighted centroid model is proposed. The multi-targets tracking is achieved by combing Kalman filters with this model. The model adopts gray value gradient to describe the probability distribution of dim target. The gradient entropy weights in 8 directions of target are obtained to indicate the correlation between the different regions and centroid of the target. Meanwhile, multi-direction maximum gradient method is proposed to extract the sky-ground line in wide field and obtain the position of the deep space background. Then, the starting point is detected through background suppression. The linear path planning is adopted to solve the mutual interference of Kalman filtering models when the targets meet. The experiment results show that the proposed method can track aeromodellings, airplanes and missiles in three environments in field view of 70° and 180°. Compared with the traditional tracking method, the proposed method has a lower center location error and a high accuracy, and the average frame rate is increased by about 1.5 times.

As the wide spectrum range of Cerenkov luminescence light leads to an extremely diverse optical properties of tissues, the simplified spherical harmonics approximation or diffusion equation based imaging model cannot balance accuracy with effectiveness. The adaptive hybrid simplified spherical harmonics with diffusion equation model is applied as a forward model for multispectral Cerenkov fluorescence tomography. To provide the perfect balance between accuracy and efficiency, based on the tissues optical properties, the proposed model can adaptively select an approximate equation to describe the Cerenkov luminescence light propagation, and give full play to the advantages of traditional model. The accuracy and efficiency of the proposed model are validated with both regular geometries and digital mouse model based simulations. Corresponding results reveal that a comparable accuracy and much less computation time are achieved compared with the simplified spherical harmonics model, a much better accuracy compared with the diffusion equation as well as better adaptability than simple combined models of simplified spherical harmonics and diffusion equation. The adaptive hybrid simplified spherical harmonics with diffusion equation model model is best suited as an optical transmission model for multispectral Cerenkov fluorescence tomography.

The resolution measurement model of three-dimensional integral imaging display system is established, and the shape, scale and fringe width of the model are designed. The model can be used to measure the reconstructed depth of field and field angle of integral imaging display system. First, the parallax map is obtained by taking the test model from multiple angles according to the integral imaging technology. Then, the parallax image definition line is calibrated according to the method of the two-dimensional resolution test card. Finally, the composite image calculated by parallax images is loaded onto the integral imaging system and the the resolution of three-dimensional objects reconstructed by the system can be tested. Experimental results show that this design supports the observer to test the display resolution in different angles and depths, and quantifies the resolution of the integral imaging display system. The model contains 8-level resolution definition line, which basically meets the test range of current three-dimensional display system resolution and can be used to measure the reconstructed depth of field and field angle of integral imaging display system.

Based on the noise of different gradient data, several typical gradient integral algorithms are studied and discussed, an improved Southwell global integral algorithm was proposed. Taking the similarity and root mean square error between the reconstructed surface and the original surface as the performance parameters, the gradient data was simulated. A fringe reflection experiment platform was built to reconstruct the standard concave spherical mirror, and the fringe reflection measurement results were compared with the actual component parameters. The experimental results show that the radius error of the concave sphere reconstructed by the improved Southwell algorithm is 0.09%, the structural similarity is greater than 0.999, and the reconstruction speed is 1.2 times that of the original algorithm. Compared with the traditional integration algorithm, the improved Southwell algorithm achieves higher reconstruction quality and reconstruction efficiency, and meets the requirements of non-contact, high accuracy and strong stability of the mirror object measurement.

A curved surface measurement method based on monocular vision system is proposed to measure the curved surface of the special-shaped parts. First, the monochromatic vision system which is composed of a tricolor LED ring structure light source and a three-color CCD color camera is used to collect a single color image that contains the surface characteristics of the measured surface. Secondly, the correlation of color distribution features of the images, the regular of gray level variation and characteristics of adjacent regions are analyzed, and the segmentation method is designed to complete the target surface segmentation. Then, the calculation equation of the measured surface height is derived based on the image model of the monocular vision system and the related parameters of the material and the experimental environment. Finally, the height of the measured points is reduced by solving the height accumulation component between adjacent pixels. On this basis, the surface curvature measurement model is established and the curved surface is measured. The surface curvature measurement experiments respectively for 3D printing surface samples, screw thread and SIM card slot are carried out based on the proposed method. Comparing with the laser triangulation measurement method results, it shows that the errors are all less than 3.6%, the measurement accuracy is 0.000 1 rad, and the time length of measuring is less than 0.6 s. The experimental results show that the proposed method has good adaptability for measuring object edge, height abrupt change, height gradual change and other types of surface. It can achieve high precision measurement and fast measurement speed.

An image spherizing algorithm-baesd deformation detecting method for micro-channel plate is proposed. A rigorous mathematical deduction on image spherizing model is described in detail, subsequently a straight line image is chosen as standard picture and the imaging simulated test for deformed micro-channel plate is performed. According to the simulated results, the mechanism of image twisting phenomenon is described. At last, the deformation detection scheme of double lines method is proposed. The experimental set-up is designed and the detection standard is defined based on the simulated data and the planeness of micro-channel plate that measured by scanning electron microscope. The experimental result which obtained by interferometer showed that the actual profile characteristics of deformed micro-channel plate is consistent with the theoretical analysis. A micro-channel plate will be treat as defective product when the rotation angle of two orthogonal lines in the reflected image on the surface of micro-channel plate is greater than 40°, whereas the product will meet the military standard when the rotation angle is smaller than 7°. The accuracy of the proposed method can reach 1 μm and it has been applied to the production process of micro-channel plate.

Based on the Maxwell equations and the thermodynamics theory, the thermal and mechanical effects of the 10.6 μm narrow band filter are analysed under the irradiation of the pulse laser at different incident angles and different polarizations.The temperature field and the stress field are studied at different incident angles and polarizations. The drift effect of the narrow band filter caused by the thermal and mechanical effects are calculated. The damage thresholds under different incident angles of the laser are compared and discussed. The results show that with the increase of incident angle, the amplitude and position coordinates of the peak temperature rise change greatly. The peak value of the temperature rise induced by the P and S polarized light irradiation decrease gradually with the increasing incident angles. The position coordinates of the peak temperature rise gradually close to the interface of the filter and air along with the change of incident angle. The difference of the the thermal and mechanical effects between P and S polarized light irradiation becomes more and more obvious. The passband drift characteristics under different laser incident angles with the same laser energy are compared. When the incident angle is small, the central wavelength deviation of the filter reaches over 200 nm, and the transmittance of 10.6 μm decreases to less than 6%.With the increase of incident angle, the melting damage threshold of the filter gets bigger and bigger. The difference of melting damage threshold between P and S polarized light is very small when the angle of incidence small. When the incident angle is greater than 30°, the melting damage threshold difference between P and S polarized light becomes larger and larger.The incident angle and polarization state of the laser should be considered in order to realize the laser damage to the narrow band filter with a small power.

Using grating diffraction of a new far field alignment package, the spatial filtering pinholes alignment in two spatial filters especially on the same optical path is achieved. This scheme overcomes the shortcomings of pinholes size requirement of traditional method, realizes two pinholes center aligned while maintaining beams far|field alignment function. The new method has been successfully applied to the Israel project. The facility experiment results show that the alignment accuracy is less than 3% of the pinhole diameter which is 15 times of the beams diffraction limit, which meets the requirements of facility debugging (<4% of the pinhole diameter).

According to the generalized Huygens-Fresnel diffraction integral, the dynamic evolution of a noncanonical optical vortex with phase topological charge (topological charge) of m=+1 and +2 in the background of a Gaussian beam passing through a tilted lens is studied. It is found that after passing through the tilted lens,the noncanonical strength and topological charge of the noncanonical optical vortex with topological charge of m=+1 remain unchanged, while the noncanonical optical vortex with topological charge of m=+2 will split into two noncanonical optical vortices with the same noncanonical strength (the noncanonical strength is equal to the noncanonical strength of the noncanonical optical vortex with topological charge of +2 at the initial plane) and the same topological charge of m=+1 due to the influence of noncanonical strength. The position of the noncanonical optical vortex after passing through the tilted lens depends on the relative propagation distance, off-axis parameter, noncanonical parameters, tilt coefficients, waist width, and the sum of the topological charge remains unchanged during the propagation.

Green laser with large pulse width and high single pulse energy was developed, which has a pulse repetition frequency synchronized with high speed camera frame frequency and is applicable for fiber coupling output. Together with the application of plano-convex unstable resonator, the laser was equipped with a flash-lamp pumped Nd∶YAG crystal, a KTP crystal for intracavity frequency doubling and a passive Q-switching crystal. A laser light output was realized with a wavelength of 532 nm, the maximum repetition rate was 300 Hz, the pulse width was 70 μs, the average power was 38 W, the single pulse energy was 126.7 mJ and the divergence angle was 3.5 mrad. The laser was further coupled to an underwater fiber of 800 μm in diameter, achieving a 92% coupling efficiency.

Classical analogy of electromagnetically induced transparency-like effect was demonstrated by a all-dielectric metasurface structure based on TiO2, which composed of two cross perpendicular dielectric bars and four dielectric bricks. Under the excitation of incident electromagnetic field, electric Mie resonance, which is directly excited by the incident electromagnetic field in the dielectric bar, can excite the magnetic Mie resonance in the dielectric bricks by the interaction of each other, and then produce the destructive interference between the resonant modes, thus the phenomenon of electromagnetic induced transparency occurs. By using the simulation software and the "two oscillators" coupled model, the simulation calculation and quantitative analysis of the electromagnetic induced transparency effect were both carried out. Results show that a transparent window with a transmittance of nearly 96% is generated at 0.552 THz under the normal incidence of electromagnetic wave. Owing to its C4 rotation symmetric and multiple dark mode resonant elements of the proposed structure, the induced transparency effect is characterized by a broadband transparency window and insensitive to the incident electric field polarization.

Eu(BA)3Phen ternary complexes by benzoic acid and 1,10-Phenanthroline were synthesized and the fluorescent nanofibers with polyacrylonitrile polymer were prepared by electrostatic spinning technology. Scanning electron microscope, fluorescence and absolute spectra were used to study its microstructure and fluorescence characteristics, respectively. The results claim that Eu(BA)3Phen complex doped polyacrylonitrile fibers are randomly arranged with uniform diameter ~ 200 nm. Under ultraviolet-B radiation, the nanofiber emits lightful red fluorescence. With the content of europium complex increased, the emission intensity of nanofibers is significantly enhanced due to the effectiveness of energy transfer. Under the excitation of 308 nm light emitting diode with 115.61 mW pumping power, the total emission photons are derived to be 25.71×1011, 61.50×1011 and 106.12×1011 cps, corresponding to 1 wt%, 2 wt% and 4 wt% Eu(BA)3Phen doped polyacrylonitrile nanofibers, respectively. Among them, the number of emitting photons by the 5D0→7F2 transition of Eu3+ reaches 15.98×1011, 41.21×1011 and 70.76×1011 cps, respectively. The maximum stimulated emission cross-sections of Eu3+ from 5D0→7F2 is calculated to be 4.12×10－21 cm2, showing the strong light radiation ability of nano-fluorescent fibers. Fluorescence quantification reveals the high photon-conversion efficiency of Eu(BA)3Phen doped polyacrylonitrile nanofibers and provides the broader application prospects in the field of sensitization of flexible solar cells as a ultraviolet-visible conversion layer.

A scheme for improving the long-term stability of a wideband tunable optoelectronic oscillator based on intermediate frequency phase-locked loop technique is proposed. In the scheme, an external tunable local oscillator is used to down-convert the RF signal of the optoelectronic oscillator to generate an intermediate frequency signal, which is independent of the oscillating frequency of the optoelectronic oscillator. Phase-locking of the intermediate frequency signal to a stable reference source can improve the long-term stability of the wideband tuanble optoelectronic oscillator. The impact of the phase-locked loop on the phase noise performance of the optoelectronic oscillator is also analyzed. Experimental results show that the frequency tuning range of the optoelectronic oscillator is 5~15 GHz, the phase noise is －121.2 dBc/Hz at 10 kHz offset and the long-term stability is 6.9×10－11/103 s. It indicates that the proposed method can significantly improve the long-term stability of a wideband tunable optoelectronic oscillator.

In order to achieve the full response of three primary colors(red, green, blue) of organic photodetectors and the improvement of devices performances, the spectral broadening of organic active layer based on tri-phase bulk heterojunction formed by Poly(3-hexylthiophene) (P3HT)∶［6,6］-Phenyl-C61-butyric acid methyl ester (PC61BM) doped with narrow band material poly-{［4,8-bis［(2-ethylhexyl)oxy］-benzo［1,2-b: 4,5-b′］dithiophene-2,6-diyl］-alt-［3-fluore-2-(octyloxy)cabonyl-thieno［3,4-b］thiophene-4,6-diyl］} (PBDT-TT-F) was investigated. Additionally, the dark current was reduced due to the increase of electron injection barrier by the replacement of anode buffer layer so as to improve the devices performances. The influence of PBDT-TT-F doping concentration and buffer layer thicknesses on devices optoelectronic performances was discussed systemly. On this basis, the photodetectors with 400~750 nm wide spectra was obtained. At －1 V bias, the linear dynamic range and the detectivity reached 81, 80, 81 dB and 2.7×1012, 2.0×1012, 2.6×1012 Jones respectively under illumination of three primary colors. The results show that the absorption spectra of the active layer can be broadened by adding a small amount of spectral broadening material under the premise of maintaining the morphology and electrical properties of the original binary bulk heterojunction. Utilizing Molybdenum trioxide (MoO3) with optimized thickness to replace original Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate)dry re-dispersiblepellets］ (PEDOT∶PSS) anode buffer layer so as to further improve the performance. Hence, the linear dynamic range and the detectivity of the devices were enhanced obviously. The present study paves the way for high detectivity and broadband organic photodetectors based on tri-phase bulk heterojunction.

A coupling structure which consists of a metal-insulator-metal resonator centered off from the metal square core and two side-coupled waveguides is designed. The propagation characteristics of the structure are studied by finite element method. The results show that the Fano resonance can be obtained and modulated by adjusting the deviation angle and deviation distance of the metal core in the cavity. The Fano resonance is caused by the symmetry breaking or geometric effect, which affects the intensity of the field distribution in the coupling region between the left and right waveguides and the cavity. The variation of field distribution mode is caused by the interference between the waveguide mode and the cavity mode. In addition, the spectral position and modulation depth of Fano resonance are very sensitive to the deviation parameters. By calculating the refractive index sensing characteristics under different deviation angles and deviation distances, the refractive index sensitivity is up to 1 508 nm/RIU, and the quality factor is up to 1 308. The research results provide a theoretical basis for designing more flexible, simple and efficient on-chip plasmonic nanosensors.

A fluorescent aptasensor was developed and applied to detect aflatoxin B1 based on Au@Fe3O4/aptamers/aminofunctioned carbon quantum dots magnetic nanocomposites which were constructed self-assembly. The selective interactions between aflatoxin B1 and the aptamer in the samples cause release of the aminofunctioned carbon quantum dots which remains in the solution after magnetic separation. A linear fluorescence signal response to aflatoxin B1 concentration is obtained over a wide aflatoxin B1 concentration range of 0.001~1.00 ng/mL with a detection limit of 0.3 pg/mL, and the correlation coefficient is 0.996 4. The performances of the fluorescent sensor are significantly improved as the background fluorescence is effectively removed by magnetic separation.

An innovative piston error detecting and close loop correction method based on pyramid wavefront sensor was proposed for space optical interferometric telescope. Three different wavelengths are used in turn in the method, in which the pyramid sensor is used to measure the piston errors between sub-mirrors, and then the sub-mirrors are controlled to compensate the corresponding piston errors based on the real-time measurement results until the piston errors reach an integral multiple of half of the used wavelength. After that, the real values of piston error are calculated based the known data of wavelengths and quantities of piston compensation of sub-mirrors, and finally the piston errors can be controlled by closed loop correction. The proposed method was analyzed theoretically and researched by simulations in which a telescope with two sub-apertures was taken as research object. The results proved that the piston error between two sub-apertures can be soundly detected and corrected while the piston error is not more than 500 μm. In addition, the novel method meets the precision of nanometer and has good repeatability.

To solve the problem of range dispersion and azimuth Doppler time-variation in echo when imaging maneuvering target with inverse synthetic aperture ladar, the accurate echo model of maneuvering target is built, and an imaging algorithm based on integral cubic phase function-fractional Fourier transform is proposed. In range compression, the integral cubic phase function is used to estimate the modulation frequency of the echo pulse quickly, and then the fractional Fourier transform is used to realize the range compression at the optimal rotation angle. In this way, the range dispersion is eliminated. After motion compensation, the integral cubic phase function-fractional Fourier transform is combined with the Clean technique to achieve the separation imaging of the strong and weak scattering points on each range cell, solving the problem of image defocusing due to the azimuth Doppler time-varying. Finally, the validity of the proposed method is verified by the simulation experiment of scatter point model.

For the performance analysis of the domestic spaceborne laser altimeter in the laboratory and in-orbit calibration technology improvement, the principle of laser waveform full-link simulation was studied in detail, and a full-link simulation method with the fine terrain and flow were designed by considering the in-orbit working environment of the spaceborne laser altimeter, as well as its echo simulation model of was deduced in detail. Then high-precision echo simulation was performed by laser beam splitting based on fine terrain. The Geoscience Laser Altimeter System (GLAS) is used for testing, and the high-precision airborne Lidar point cloud data is used to simulate the waveform of GLAS in flat and mountain terrains. The results show that the simulated waveform are used compared with the real data from GLAS, then the similarity between the simulation waveform and the real waveform is 0.985 in the flat terrain, as well as 0.921 in the mountain terrain. The proposed method and model can achieves high accuracy simulation of the spaceborne laser waveform for the flat areas.

A composite structure of dielectric grating/metal film with silver nanocubes is theoretically designed, and the ultrahigh electric field enhancement factor in the composite structure is numerically simulated using the finite element method. The surface plasmons are excited by the laser with wavelength of 442 nm. By discussing the extinction spectrum of the silver nanocubes with different sizes, and the reflection spectra of the grating with different period and thickness, the optimal parameters are selected, which the side length of silver nanocubes is 70 nm, the period of grating is 312 nm and the thickness is 90 nm. Under the condition of optimal parameters, electric field intensity distribution in the composite structure is calculated. For the resonant coupling of local surface plasmon and propagation surface plasmon in the dielectric grating/metal film with silver nanocubes composite structure. The electric field enhancement factor of hot spot is as high as 1.53×106, which exists in the position between grating ridge and the lower vertexes of silver nanocube. The ultrahigh electric field enhancement generated by the composite structure has the potential to be applied to the study of surface-enhanced Raman scattering.

Highly homogeneous silver nanowire films with few silver nanoparticles are prepared with the method of improved vacuum filtration. Silver nanowires are pressed on the flexible substrates in order after processing vacuum filtration on the same substracte and repeat it for several times. The surface topography and the distributions of transmittance and sheet resistance of manufactured transparent conductive films are discussed. The result shows that the average sheet resistance of the film fabricated by three-times vacuum filtration reaches 7.47 Ω/sq with a transmittance of 82.5%.