A wavelength tunable lidar is designed based on OPO laser. The output wavelength of the lidar can be tunable continuously in the range of 192~2750 nm. The optical splitting system of the lidar is composed of rotatable gratings and circular apertures. By adjusting the diffraction angle of the rotatable gratings, the lidar can receive the return signal at the specific wavelength. The photomultiplier tube and InGaAs detectors are used to transform the optical signal into electric signal in the corresponding wavebands. Subsequent data acquisition and processing are performed by data acquisition system and PC. Numerical simulations are performed with the standard atmospheric model. The detection ability of the lidar in the different wavebands is verified by the simulation results. The lidar is of important significance for fine detection of microphysical properties of near-surface aerosols.

The GF-1 optical high resolution images have been collected to study mode-2 ISWs of northern Dongsha Atoll in the South China Sea. Based on optical remote sensing images from April to October 2014, mode-2 ISWs spatial distributed in northern Dongsha Atoll, following mode-1 ISWs. Compared with mode-1 ISWs, the crest of mode-2 ISWs was shorter and the length was about 20% to 40% of mode-1. The distance between the positive and negative peaks of mode-2 ISWs was also shorter, the length was about 10% to 50% of mode-1. The fine structure of mode-2 ISWs was investigated by high resolution optical remote sensing images, which offers the references for quantitative study of the energy propagation, fragmentation and dissipation of internal solitary waves.

An innovative weighing sensing unit using optical fiber Bragg grating sensors was developed. Based on lever cantilever with an adjustable fulcrum, the weighing range and sensitivity can be adjusted. During the differential operation of the shifts of Bragg wavelength, the shifts of Bragg wavelengths caused by the temperature fluctuation can be compensated. As a result of theoretical analysis, there is a threshold for the value of the distance between the fulcrum and the brace. When this distance equals the threshold, weighing sensitivity will be zero. Experimental results show that the average linearity is larger than 0.998 and the average relative error between the theoretical weighing sensitivity and the experimental weighing sensitivity is 6.46% within the range of 0~200 grams of force.

A long period fiber grating bend sensor was fabricated in mismatched twin core fiber by CO2 laser irradiation. Theoretical analysis indicate that the fiber core located at the edge of the cladding greatly enhances the residual stress. Under CO2 laser exposure,the long period fiber grating experiences a high quality. Moreover, the fiber grating is sensitive to polorization property due to the asymmetrical structure, the polarization dependent loss value of the long period fiber grating is as high as 20.8dB at the resonant wavelength of 1 553.3 nm. Sensing experiment reveals that it can distinguish the orientation of the curvature by the resonant peak showing a red or blue shift. The fiber grating experiences significant sensitivities of 2.37 nm/m－1 and 1.80 nm/m－1 with the micro-bending range of 0~1.235m－1 for +y and －y axis directions. The proposed sensor has the advantages of simple structure and high sensitivity. It could be used in struction health monitoring applications including roads and bridges.

Strain transfer theory of two-way coupled between the Half-plane and the Fiber Bragg Grating sensor was established, the relationship between the measured strain of the surface-bonding Fiber Bragg Grating sensor and the strain of the Half-plane was obtained. The theoretical solution, the Finite Element solution and the experimental date were compared to verify the correctness of the theory, and the relationship between the strain transfer rate and the Young′s modulus of the Half-plane and the half bonding length was analyzed. The result show that the error of the theoretical solution and experimental value is very small, less than 4%, the strain transfer rate increases with the increasing both the Young′s modulus of the Half-plane and the half bonding length, it has some reference value for the design and application of Fiber Bragg Grating sensors.

A single-mode fiber surface plasmon resonance refractive index sensor based on U-shaped structure was designed. The sensor is fabricated by coating the gold nanometer layer and the TiO2 modulation layer on the surface of single-mode optical fiber whose cladding is partiallyremoved and then isbent into U-shape. The impact of different bending radius and thickness of TiO2 on the sensing performance was studied by using finite element simulation software COMSOL Multiphysics. Through analyzing four different bend radii(R=0.3 cm,0.5 cm,0.8 cm,1 cm), we found that with the increase of the bending radius, the surface plasmon resonance signal intensity increases and the peak shifts to shorter wavelength slightly. The performance of the sensor with different thickness of the TiO2 modulation layer from 0 to 40 nm was studiedunder the condition of bending radius of 0.5 cm. With the increase of the thickness of the TiO2 modulation layer, the surface plasmon resonance peak shifts to longer wavelength and the sensitivity of the peak to the analyte refractive index increases significantly. The sensitivity of the sensor in the low refractive index region (nd=1.333) reached 5 959 nm/RIU and the sensitivity of the high refractive index region (nd=1.383) reached 11 092 nm/RIU at the bending radius of 0.5cm and the thickness of the TiO2 modulation layer was 40nm. Compared with the results of no modulation layer, the sensitivities increase by about doubled.

To improve the imaging quality of Fresnel lens, a wavefront sensorless adative optics system is used to compensate the wavefront aberrations in Fresnel lens imaging system for point source.During the aberrations correction, the stochastic parallel gradient descent algorithm is adopted to optimize the image clarity evaluation function,which is converged after dozens of correction iterations. The performance of Fresnel Lens imaging system is improved notably by adaptive optics, that the efficient radius of far-field is reduced by 43%, the corresponding second moment is 0.9975 near to the theoretical limit value 1, the image clarity and the peak value of intensity are enhanced more than once, the corresponding FWHM is upto 1.2DL,and more sufficient medium frequncies are raised up in Modulation Transfer Function (MTF). The results demonstrate that the aberrations in Fresnel lens imaging system for point source is fastly and effectively compensated by the wavefront sensorless adative optics system, which is can be applied to the space telescope due to its simple implementation structure.

The Finite Element Analysis(FEA)based optimization procedure aiming to obtain the optimum mirror parameters was first improved, it was found that the degradation of surface figure accuracy was mainly caused by spherical aberrations through Zernike polynomial surface fitting using 21 terms. After that, another duralumin prototype VCM (aperture 135 mm, central thickness 8mm and initial curvature radius 2 807 mm) was fabricated and tested. Because of the improvement of the fabrication process, the initial surface figure accuracy of the second mirror is superior to λ/80 (632.8 nm). When a pressure of about 0.07 MPa is imposed, the saggigus variation reaches nearly 37 μm and the corresponding surface figure accuracy is still superior to λ/40 (632.8 nm) with spherical aberrations removed. Compared with the first prototype VCM, the performance of the second one has been improved prominently.

In order to test imaging performance of an optical remote sensor in complex space environment, a space environment simulation system with a wide rang irradiation and high contrast is designed, including a solar simulator and a dark target simulator. According to the radiation characteristics of sunlight and earth reflection light, a wide range of solar simulation irradiance is achieved by adjusting xenon lamp current regulation and using attenuation chips. A dark target simulator is designed to simulate the weak observation target, based on the analysis of the scattering characteristics of the material and the design of the reasonable structure. The experimental results show that the irradiance range can reach 0.4~1 260 W/m2 in the 1 000 mm×1 000 mm irradiation area, and the irradiation uniformity can reach ±4.82%.The extinction ratio of the dark target simulator can reach 1×10－7 .The device can solve the problem of the quantitative test of imaging performance for the dark target in the space with strong background light, which provides a reliable platform for the performance test of remote sensor.

In order to integrate and optimize the manipulation of photoelastic modulator and data processing in the measurement system of crystal electro-optic coefficient by photoelastic modulation, and realize a highly sensitive, fast, low cost and highly integral crystal electro-optic coefficient measurement scheme. According to the characteristics of the photoelastic modulation and modulation signal, a field programmable gate array is used to fulfill the control of the photoelastic modulator and the extraction of measuring data. The field programmable gate array provides the drive signal of the photoelastic modulator and controls the AD sampling simultaneously, and it also produces the cosine and sine reference sequences to achieve the DC term, the co-component and quadrature component of the first term, these terms are input in a computer to solve out the crystal electro-optic coefficient. A lithium niobate sample was tested, the results show that the repeatabilitiy and sensitivity of the system is 0.0016×10－12 m/V, the measurement rate is 1 ms/ data point. Compared to the other crystal electro-optic coefficient measurement methods, the proposed method has higher measurement sensitivity and faster measurement speed, which lays the foundation for the realization of the intelligent system for measuring the the crystal electro-optic coefficient by photoelastic modulation.

In order to monitor the marine oil spill state used ultraviolet band, the Bi-Directional Reflectance Distribution Function (BRDF) measurement device which the turning radius is 1500mm and the large field of view ultraviolet imager which the working band is from 300nm to 400nm are used to study the spectral characteristics of oil spill ultraviolet reflection. The datas are measured by three kinds of oil samples through the field test, the results is showed that the uncertainty of the ultraviolet reflectance distribution function measurement device is 3.68%; There is different between the oil samples target and sea water BRDF in the ultraviolet wave range under the condition of the zenith angle of 0° and 30° degrees, relative azimuth angle of 0° and 45°. So the conclusion can be usedto monitormarine oil spill stateswiththe ultraviolet optical remote sensor from 300 nm to 380nm band.

Image edge detection process is problematic in that noise suppression and detail retention can not be taken into account, this prompted us to propose an edge detection algorithm based on Bertrand surface model. On the basis of determined pixel edge,selecting strip domain along edge direction as fitting area,with the Bertrand surface characteristic of normal lines at various points along generatrix line are in one plane, transforming the pixel information in fitting surface area into active coordinate of edge curve,and fitting coordinate and normalized gray value to obtain normal distance between sub-pixel edge and pixel edge for sub-pixel edge detection.Adopt the vision measurement system to experiment with the gauge block line edge,andcompared to the improved algorithm of sub-pixel edge detection based on Facet surface fitting, the results show that algorithm of edge detection based on Bertrand surface model has high location accuracy, the first grade gauge blocklinear error is within 1 μm, and the multiple measurement error is －0.811 μm,it also has high reliability. The oil pump body measurement demonstratesthat this algorithm can be applied to precision measurement of mechanical parts, especially suitable for measurement of center distance, bore diameter, and so on.

Aiming at the practical requirements of accurate alignment between high-precision star sensor and the test equipment in ground calibration experiments, a nanoscale five-dimensional adjustment frame for calibration of star sensors is designed. The influence of optical axis alignment error on star sensor test was analyzed in detail. In order to ensure docking accuracy, the design idea of adopting the mechanical structure of stacked type was put forward. Then, the design scheme of a two-dimensional translation module and the three-dimensional adjustment module were discussed. After that, the simulation modeling and mechanical analysis of the adjustment frame were carried out. Finally, verification experiments were conducted on the designed micro-adjustment mechanism. The testing results show that, the displacement resolution can reach 25 nm, the angle resolution can reach 0.1 arcsecond; and the stability is quite high. Therefore, the designed micro-adjustment mechanism can meet the technical indicator requirements of accurate docking between star sensor and test equipment, and it can ensure calibration credibility of the star sensor.

A physical model of diode-pumped alkali vapor lasers, which combines the rate equations of population densities, the axial differential equations of pump and laser power, the radial differential equation of temperature, is reported in this paper. Taking into account the measured distributions of the pump and laser beam radii and the hypothetical distributions of the intensities, this model not only reproduces the observed peak temperature of 346℃, 480℃ and 696℃, which respectively correspond to pump powers of 50 W, 220 W and 370 W for the lasing condition, but also reproduces the observed peak temperature of 321℃, 414℃ and 609℃ corresponding to the same pump powers for the non-lasing condition. A wide region of heat source density of quenching is observed. For the lasing condition, quenching contributes approximately 85% of the total heat energy, whereas for the no-lasing condition it occupies over 95%, showing that quenching is very important and non-ignorable in temperature calculation.

In order to improve the efficiency of automatic alignment,combined with Ethernet, a new optical path automatic alignment control and detection scheme was describled. The proposed near-far field parallel alignment method implements forward feed back compensation based on coupling matrix and Jacobian image matrix. By introducing the image local adaptive thresholding, image binaryzation, and the fuzzy stepping motor control algorithm, the precision of near-far field image detection was improved with less processing time. The results show that the average far-field alignment error is smaller than 0.44% of spatial filter pinhole diameter, which meets the alignment system requirements(5% of spatial filter pinhole diameter), the alignment time reduces from the original 30 mins to 12 mins.

Laser damage resistance of different kinds of engineering ceramics under nanosecond laser irradiation were studied and compared with those of stainless steel and aluminum alloy. The results show that the laser damage characteristics of different materials are different. The damage threshold of alumina ceramics is the highest, while the damage threshold of silicon nitride ceramics is lowest. Compared with metal materials, the damage thresholds of engineering ceramics are higher than those of stainless steel and aluminum alloy. Due to the difference of the melting point and thermal conductivity, different kinds of ceramic material have different damage morphologies. The difference of laser damage threshold of different materials was analyzed theoretically; the absorption coefficient of ceramic materials is less than metals. The absorption coefficient have an effect on the energy deposition area and heat diffusion rate influencing the evolution process of the temperature, which ultimately affect the laser damage threshold value and damage characteristics of materials.The experimental results provide guidance for the selection of mechanical support materials for high power laser devices.

In the femtosecond laser drilling of silicon material, in order to the influence of the surface plasma effect and hole geometries on the redistribution of the follow-up laser energy, the theoretical model and muti-pulse ablation experiment were established. Theoretical calculation of the damage threshold 0.21 J/cm2is in line with the experimental model measured threshold 0.20～0.25 J/cm2. When the carrier density reaches the critical value Ncr, the excitation of the plasma causes the surface reflectance to rise rapidly. With a larger of laser fluence from 0.5 J/cm2 to 3.0 J/cm2, ablation depth increases to about 1.1um, and while the pulse width from 150fs reduced to 50fs, ablation structure become more similar to the oval ablation profile. What’s more, the effect of different hole structure on the laser beam propagation inside the micro-hole of silicon wafer is obtained by numerically using FDTD method. It’s found that the position of the maximum laser intensity point would be closer to the hole enter by decreasing taper angle from 79℃ to 49℃, which finally cause the excitation of plasma more likely. Besides, under different polarization beam irradiation, the energy distribution at the bottom of the hole induced different special ablation structures. The results show that by increasing laser fluence and decreasing pulse width, the ideal initial pore structure can be obtained so that the subsequent pulse energy is concentrated at the bottom center making the drilling efficiency higher.

Bivalent and trivalent Eu ionsco-doped SrSO4 phosphors were synthesized via the precipitation method by using trivalent Eu ions as the sole dopant source. The crystal structure, morphology and photoluminescence of the synthesized SrSO4 phosphors were investigated by the X-ray diffractometer, scanning electron microscope and spectrophotometer, respectively. It was found that the resultant SrSO4 microcrystals are co-doped with both the bivalent Eu ions and the trivalent Eu ions. The typical size of the SrSO4 microcrystals is in the range of 1~10 μm. Under the ultraviolet excitation of 325 nm, the synthesized SrSO4 microcrystals can give off strong purplish pink photoluminescence, which consists of a broad emission band centered at 379 nm and three narrow emission peaks at 575, 591 and 612 nm, respectively. The bandstructures and defect level of SrSO4 are calculated with density functional theory in the framework of local density approximation, and the photoluminescence mechanisms of the bivalent and trivalent Euco-doped SrSO4 are discussed in terms of the calculated bandstructures. The broad emission band centered at 379 nm can be attributed to the transition 4f65d1→ 4f7 of the bivalent Eu ions in the SrSO4 matrix while the three sharp emission peaks at 575, 591 and 612 nm can be assigned to the transitions of trivalent Eu ions from its excited state 5D0 to its ground states 7F0, 7F1 and 7F2,respectively. It has demonstrated that bivalent Eu and trivalent Euco-doped SrSO4 can be utilized as an efficient purplish pink phosphors.

The problem of band-gap structure were studied for the spatial beam phononic crystal to solve the stability of complex structure such as space truss, framae and so on. The axial, torsional, flexural and coupled vibration equations of beam element were solved by the traveling method. The dispersion equation and band-gap properties were forward obtained by the traveling wave method combined with the continuous conditions of force and displacement at the node of beam phononic crystal and Bloch theory. Genetic algorithm was used to reverse obtained the spatial beam phononic crystal structure with specified location and width of band gap by optimizing the material and structure size, taking relative bandwidth (the ratio total width and lowest angular frequency of band gap). The optimal solution was obtained by combing with engineering experience and economic benefit. This paper provided a new way for the study of band gap structure of spatial beam phononic crystal.

Two schemes such as single pixel signal to noise ratio and extinction ratio are used to evaluate transmit-receive isolation ability based on the practical application of the tracking and communication detector in laser communication system. A method to inhibit the back scattering light was presented which boring a hole in the secondary mirror and increasing light trap. It is derived that when aperture ratio of secondary mirror K is 0.1~0.3, it dose not affect the emission efficiency,the measured results show that the improved Cassegrain optical antenna Transmit-Receive isolation is lower than －40 dB while not affecting the emission efficiency of system, and meet the requirements of laser communication system acquiring, tracking and communication.

A control algorithm to achieve working bias stability for Mach-Zehnder Modulator (MZM) is proposed. Its utilize first-order and cotangent value of Average Optical Power (AOP) with FPGA technique. Firstly, we describe the reason for stabilizing the MZM at the common point. Then, control theories for keeping the bias point at different working point are studied by numerical simulation. At last, arbitrary working point control system is built. Experiment results indicate that, the fluctuation of output average optical power is less than ±5% (within one hour) under the condition of 5 dBm laser output power (1 550 nm), 4.2 V half-wave voltage, 3 dB insertion loss and 1Gbps/1Mbps speed. The system has the ability to maintain the bias at any point in the optical power curve and improved the reliability of MZM in optical communication.

According to the requirements of sensitivity for gas detection system, based on the characteristics of methane absorption spectrum, combined with the technical experience, the technical indicators of the filter was determined. The "split technology" was used to design the gas filter for the gas filter, which reduced the film stress. The films were deposited by electron beam heating, and the process parameters were optimized according to the test results. The peak transmittance of the filter reached 85.14% at the wavelength of 7.669 μm, and the full of its passband at half maximum is 59 nm, covering the methane gas absorption area. The cut-off depth is OD3 and the narrow-band filter can suppress the background noise well.

An all-optical modulator based on long-range surface plasmon resonance with metal nano-wires array is proposed. It respected for the Kerr effect to induce refractive index changes and numerically investigated respected for using the finite-difference time-domain simulation. The all-optical modulator is realized with low intensity of pump light. The diameter of metal nano-wire, the thickness of buffer dielectric layer and the intensity of pump light have a significant influence on the reflectance spectra of all-optical modulator. The coupling performance of the all-optical modulator is improved by allocating the parameters of metal nano-wire and buffer dielectric layer reasonably. The results show that the mode coupling ability of the all-optical modulator is optimal when the diameter of metal nano-wire and the thickness of buffer dielectric layer are 40 nm and 1 800 nm, respectively. There is a linear relationship between the change of reflectivity spectrum and pump intensity, which the correlation coefficient is 0.998 1. The reflectance of incident light reaches 0.82 by applying the intensity of pump light as low as 0.5 GW/cm2, which can realize all-optical modulation of optical signal to light very well.

Based on the rigorous coupled wave analysis method, the subwavelength grating wavefront control method was analyzed, three subwavelength grating structures with the function of convex lens, cone lens and blazed grating were designed. These devices achieve good focus and blazing effect. By calculating the grating transmittance at different grating thickness, grating teeth and grating groove width, the transmittances of the three wavefront manipulation devices are all above 97% after selecting the combination of suitable grating parameters. Compared the performance of silicon-based planar structural devices with conventional structural devices, the lens and the cone lens of the planar structure, the Full Width at High Maximum of the focal spot is approximately equal to that of the conventional lens and cone lens, but the peak intensity is increased to 1.64 and 2.35 times. The peak intensity of the planar relative to the conventional blazed grating is increased to 3.77 times.

A measurement method of short carbon nanotubes by multi-angle depolarized dynamic light scattering is developed to reduce the measurement error from the inaccuracy of the scattering angle by linear fitting of the results at different angles. And the reproducibility of the measurement system is improved by this new method as well. The principle of multi-angle dynamic light scattering measurement of short carbon nanotube is studied, and an experimental measurement system is set up. The signal collecting and processing system is developed by LabVIEW based on a photon counting. The Calibration test is carried out by standard short carbon nanotubes suspensions. The measurement results of the diameter and the length of the samples at 90°, 100°, 110°, 120°, 130° and 150° are compared with that at the single angle (i.e. 90°). It shows that the repeatability error of the diameter and the length measured by the multi-angle depolarized dynamic light scattering method are 6.27 % and 6.36 % respectively, and better than those of the single angle method (i.e. 13.22 % and 12.45 %).

The mechanism of angular error on measurement result is analysed. Then, the influence way of angular error on inversion results in two approaches, namely, weight coefficient and baseline are studied by simulation of six groups of unimodal particle size distribution system (82 nm, 104 nm, 350 nm, 431 nm, 816 nm and 865 nm) and three groups of bimodal particle size distribution system (137/601 nm, 242/750 nm and 470/895 nm) and measurement of 306/974 nm bimodal particle size distribution system with different angular error. The results show that the influence of angular error on inversion results is derived from the baseline factor and weight coefficient factor simultaneously. The influence of weight coefficient factor on peak error and performance error is much bigger than the baseline factor. There is one exception that for the unimodal narrow distribution of small particles, the influence of baseline factor on peak error is a little more than weight coefficient factor, but the influence of weight coefficient factor on performance error is bigger than baseline factor.

A new tip-enhanced Raman scattering(TERS) model was established by finite difference time domain (FDTD) method, which included a conical tungsten tip with concave arc and silver-coated and a gold nanoparticle. The enhancement effectandparameter optimizationof the TERS model wereinvestigated. Under 632.8 nmwavelength laser excitation, three-dimensional electromagnetic simulations were carried out forthe TERS effect with different conditions, and the simulation resultswerepresented and discussed. The results indicate thatthis TERS model has the maximum field enhancement factor when the incident angle is 72°, the sample diameter is about 140 nm and the tip sample gap is reach 2 nm. The conclusion provides a reference for developing higher efficiency enhancingmetal tips and the Raman spectrometer with best performance.

X-ray communication(Xcom) is a method which applying X-ray as carriers to transmit information in space. After the concept of Xcom was produced by Dr Keith, many institutions and scientists have conducted researches on Xcom and achieved fruitful results. However, most researches are focused on the key devices of Xcom, such as the X-ray emit source, the antenna and the detector, there is nearly no theoretical model for space X-ray communication. In this article, we focused on the power transmission process of space Xcom. To begin with, we analysised the signal channel and transmission model based on the additional gussian white noise(AWGN) model and free space attenuation, established the power transmission equation and link model. Then we analysised the error source of Xcom, established the noise model based on single photon detectors and also given the main noise sources. In other words, we can built mathematical relationship between the power of X-ray source, transmitting distance&speed and bit-error-ration (BER). Finally, we testified the signal photons of Micochannel Plate(MCP) detector output against various anode voltage and modulations. The results accord well with the theoretical analysis, and the power transmission equation and BER model can explain the Xcom process well too. Based on this transmission theory, we can calculate the emit X-ray power against various transmission distance and BER level respectively. As a result, three key parameters which judging a wireless optical communication system have been given as well as the theoretical model. Simulation results showed that with a constant photons flow, Pulse Position Modulation(PPM) has a better BER level than On-Off Keying(OOK) modulation. When the transmission distance is about 10 km, in order to achieve BER less than 10－6 level, the power consumption of X-ray is less than 1mW. According to the power transmission model, in order to improve the BER level of Xcom system, we need a lower dark current detector, an advanced modulation and more transmitting power. These theoretical and experiment results could provide foundations for optimizing the core parameters of XCOM system in our future works.

The Maxwell′s equation of terahertz wave in time-varying plasma is deduced based on time-domain finite difference method of auxiliary differential equation in this paper. A time-varying plasma model with dust particles was constructed by using the constitutive relation. The absorption coefficient, reflection coefficient and transmission coefficient of the dust plasma sheath with time were simulated. The numerical results show that the growth rate of electron density is easily affected by the rise time, and the reflection coefficient of the plasma decreases with the increase of the rising time. The increase of the absorption coefficient is related to reducing the rise time and frequency, increasing the electron density and the density of the dust particles.In addition, the thickness of the plasma plate, the density of the dust particles, and the electron density are direct proportional to the absorption coefficient. When the operating frequency of the wave up to 1 500 GHz, only the electron density is less than 1020 m－3 can pass through the plasma plate. The alteration of the effective collision frequency barely affects the reflection coefficient of the time-varying dusty plasma as the collision frequency is smaller than 3.5×1011 rad/s. The results provide some technical support for the potential applications of spacecraft in the atmosphere of terahertz communication and dust plasma diagnostics.