On the basis of total internal reflection edge illumination, a method can be used to identify the damage on front or rear surface of the thin DKDP crystal by the birefringence of DKDP crystal. When an ultraviolet ray incidented upon a DKDP crystal whose thickness was 11 mm, a displacement of 254.738 μm(theoretical value) between o-ray and e-ray on the exit surface will be caused due to the birefringence of DKDP crystal. The damage located on the rear surface of DKDP had double-images, which could be modulated by polarizer placed in front of CCD camera. The damage located on the front surface of DKDP had a single-image, which couldn′t be modulated by polarizer. The method had the ability of avoiding extracting the information of a damage repeatedly, and improving the accuracy of damage identification. The experiments demonstrate that the method can distinguish the damage on front or rear surface of the thin DKDP crystal whose thickness is 11 mm.

For an N-element deformable mirror, the model-based wavefront sensorless adaptive optics (AO) system only needs N+1 imaging acquisitions, which means rapid convergence. An AO system was simulated with an 88-element deformable mirror and a CCD. The convergence and the correction performance of AO system under noise were investigated. Results showed that the convergence under noise is the same as that of AO system under no noise. The correction effect is very close to each other under different noise for the same turbulence condition. Compared with correction results under 50 dB, averaged RMS relative errors of 30 dB are 4.75%, 4.04% and 2.58% respectively according to given turbulence conditions from weak to strong. Above results verified that the model-based wavefront sensorless AO system has a relative strong anti-noise capability.江苏省高校自然科学基金(14KJB510004)

In order to achieve high accuracy and high stability of methane gas concentration in complex environment, this paper proposed the half-wavelength scanning detection method which using sawtooth modulation based on spectral absorption principle, and this method greatly improved the performance index of the system. In the process of detection, the method of sawtooth modulation realized wavelength modulation and intensity modulation of Distributed Feedback(DFB) laser, scanned Lorentizen absorption linear of methane gas. And it improved the accuracy of detection through eliminating the measurement error and the influence of laser wavelength drifting. Due to the symmetry of methane absorption spectra, relative to full-wave scanning would appears sine curve after differential circuit and could not establish the relation between absorption intensity and digital value, the half-wave scanning would appear concave curve after differential circuit, and could establish the relation between absorption intensity and digital value. The experimental results show that this method could accurately measure methane gas concentration, and the measurement range of methane gas concentration is 0%-10%, the accuracy increased from 100 ppm to 10 ppm(1 ppm=10-6), stability is increased from 0.3% to 0.01%. The system was not affected by temperature in complex environment and has high accuracy, good stability, and strong anti-interference capacity after improvement.

In the process of measuring laser beam quality by using the CCD, the influence of nonlinear optoelectronic response of the CCD on the beam propagation ratios M2 was analyzed in the paper through comparing the wavelength of different lasers. As the beam width values from four different wavelength lasers measured by non-linear calibrated CCD were relatively large, the measuring accuracy of laser beam quality will be affected to a certain extent. Therefore, a new calibration method of optoelectronic response based on the CCD will be put forward. By setting up a laser beam quality measurement system based on CCD measurement and building the near-field and far-field transmission model of Gaussian laser beam as well as multiple sampling from laser beams′ caustic profile in different positions of a certain transmission direction, the photoelectric response linear range can be obtained with statistical methods. The result of simulation and experiment shows that by using the optoelectronic response character′s calibration result of the CCD to make nonlinear gray level restoration on images, the laser beam quality factor M2 can be measured more accurately and the relative error can be decreased by 2.36% compared with the measuring result by the international standard laser beam profiler. The method mentioned in the paper can effectively increase the measuring accuracy of the laser beam quality factor M2 and it has great application values on evaluating the laser beam quality.

The convex crystal spectrometer, consists of a convex crystal and CMOS camera which assembles CsI(Tl) scintillation, has been designed and fabricated to record X- ray spectra in the energy range of 1.84-7.38 keV by QTZ(1010) (2d=0.851 2 nm) X-ray crystal at one shot. The spectral resolving power was 880 at 2.375 keV, dynamic range of at least 1 000. This spectrometer has characteristics of online aiming, high resolving power, and wide energy range and less noise counts. At Shenguang-III laser facilities, soft X-ray spectroscopy from Titanium laser-produced plasmas was obtained by the spectrometer, main lines of Titanium ions have been identified in the excellent agreement with theoretical calculation and other experiment results. On the DIM of Shenguang-III laser facilities, the spectrometer can work stably and adapts to the over loading electron magnet pulse environment.

In order to obtain high performance of polarization splitting grating, the subwavelength sandwiched metal grating structure was designed and analyzed. The optimal grating parameters were made by using the rigorous couple wave theory and genetic algorithm. Based on the optimized grating structure, high diffraction efficiencies of 98% and 96.5% can be achieved for TM transmission and TE reflection of 0th order in the 800 nm wavelength range, respectively. The optimized grating has an extinction ration of over 20 dB from 747 nm to 854 nm, and a large angle, from -27° to 27°, which met the expectations for high efficiency, high extinction ratio and wide spectrum and large angle. The fabrication tolerance around the optimized grating parameters was discussed, numerical results showed that the designed grating has good manufacture tolerance to period and groove depth and covering layer thickness. The subwavelength metal grating own many good characters such as simple structure, stable performance, low damage for the incident wave and obvious polarization, which will make the subwavelength metal grating have wide application prospect in the fields of optical polarizing elements, laser system, polarization imaging, etc.

To meet the requirement of high speed OOK wireless communication, a 340 GHz waveguide zero-bias detector was designed, fabricated and measured. Firstly, high frequency electromagnetic software HFSS was adopted to establish the accurate model of the quasi vertical diode (QVD) according to its physical structure, from which impedance of the diode could be extracted with the nonlinear equivalent model of the diode. Then, passive circuits such as waveguide to microstrip transition structure and lowpass filter (LPF) were designed, which also had the function of impedance match. Finally, the designed detector had been fabricated and measured. The measured results show that the detector has a peak responsivity of 2 210 V/W at 334 GHz and a typical responsivity of 1 400 V/W over the frequency range from 315 to 357 GHz ,with a typical noise equivalent power of 5 pW·Hz-0.5. At last, the proposed detector was selected to carrier out the 340 GHz high speed OOK signal demodulation experiment. And results show a bit error rate (BER) below 10-12 at 10 Gb/s and a bit error rate (BER) of 3.15×10-7 at data rate up to 15 Gb/s at room temperature, which proves that the detector can well meet the requirement of high data rate OOK communication system.

The mechanism of the radiation-induced loss in optical fibers was researched in this paper. Firstly, the structure characteristics of the pure silicon core optical fibers and traditional doped silica-core optical fibers were systematically analyzed. According to their structure characteristics, the difference of the resistance to radiation between the pure silicon core optical fibers and traditional doped silica-core optical fibers was studied. Secondly, the experimental conditions of anti-radiation standards at home and abroad were investigated. The experimental conditions including the dose rate and total dose used as anti-radiation standards had been compared. The effect of different radiation dose rates on the radiation experiments of optical fibers was analyzed. The selection principle of gamma radiation experimental conditions used in space radiation environments for fibers was given. Finally, the anti-radiation properties of a domestic pure silicon-core optical fiber with the dose rate of 0.1 rad(Si)/s were estimated, and the fiber loss after the radiation with the total dose of 20 k rad(Si) was 1.934 dB/km. The assessment results of the space radiation performances satisfied the needs of space environments for the aerospace model in the project, and the conclusion of the radiation assessment was available.

Based on the generalized Huygens-Fresnel principle and the modified von Karman spectrum model, the analytic expressions for intensity distribution of radial Gaussian array beams after incoherent combination that propagation in the atmospheric turbulence were derived. And the self-coupling characteristics of array beams was analyzed numerically with the change of transmission distance and the radial radius. Finally self-coupling characteristics of array beam of different radial radius with the change of the transmission distance had been measured by using a beam analyzer. The experimental results show that when Gaussian array beams propagate in atmospheric turbulence horizontaly, array beam will combine a beam from a certain distance with the increasing of transmission distance. And the average intensity of the combined beam is like-Gaussian distribution; under the same transmission conditions, the smaller the radial radius, the better the self-coupling characteristics of the array beams is.

Crosstalk from square wave modulation signal causes output signal instability and deteriorates threshold value and scale linearity in FOG. Excessive modulation uses bigger phase to restrain noise. According to the principle of correlative demodulation and crosstalk model, the output expression of FOG containing excessive modulation crosstalk would be derived and the modulation phase is an important effect factor of crosstalk. To solve the problem that deeper modulation phase would enlarge the crosstalk, a method of variable square wave modulation was put forward to restrain the crosstalk. With periodicity of response cosine function and repeatable modulation wave, the modulation signal and demodulation signal would be generated nearly independently. The correlative demodulation result would be zero in some delay time and reduce the crosstalk amount. Simulation and experimental results indicate that this method can improve one order of magnitude of restrain effect of crosstalk compared to square wave modulation. The zero bias stability and threshold value would be improved about 40% compared with square wave excessive modulation.

Fast steering mirror platform which is composed of piezoelectric ceramic has hysteresis characteristic, it affects the control of the fast steering mirror. In order to control fast steering mirror effectively, open loop control method based on Prandtl-Ishlinskii(PI) inverse model was adopted. Firstly, the PI model was used to build the mathematic model of the hysteresis characteristic of the fast steering mirror and the parameters of PI model were identified by least mean squares method; Secondly, the parameters of the inverse model of PI were solved based on the reversibility of the PI model; Lastly, the effectiveness of the open loop control method based on PI inverse model was verified. According to trajectory tracking experiment data, in the case of sine wave trajectory, root mean error is 1.23% and maximum error is 2.45%; in the case of triangle wave, root mean error is 1.3%, maximum error is 2.37%. It proves that open loop method based on PI inverse model is feasible and can effectively control fast steering mirror.

In order to satisfy the requirements of high-precision surface figure error quality and geometry parameters controlling in the on-axis three mirror space camera of large-aperture convex aspheric, multiply process combination and test technique based on the foundation of deterministic lapping and polishing were proposed. In the process stage, ultrasonic milling was firstly introduced to form the aspherical surface form, then robot lapping and polishing were used to rapidly grind and polish, at last, ion beam figuring was used to finish the aspheric fabrication. In the test stage, the geometry parameters and surface figure error of aspheric were firstly controlled by using the coordinate measuring machine(CMM) and then tested by using Hindle sphere testing after the aspheric surface accuracy in interferometric test range. An example for fabricating and testing a convex hyperbolic secondary mirror with diameter of 520 mm was given, the surface figure error of mirror was 0.015λ(λ=632.8 nm), the geometry parameters control accuracy of ΔR and ΔK are 0.1 mm and 0.1%, respectively, all the fabrication results of aspheric satisfy the specifications requirements of the optical design.

Based on the accuracy of the first-order Born approximation, the scattering properties of a spatially partially coherent plane-wave light incident on a quasi-homogeneous random medium were investigated. The analytical expressions for the spectral density and the spectral degree of coherence of the scattered field in the far zone were derived. The influence of the spatial coherence of the incident field and the properties of the scattering on the spectral density and the spectral degree of coherence of the scattered field was examined. Compared with a fully coherent light, the spectral density and the spectral degree of coherence of the field generated by scattering of a partially coherent light were analyzed. The results indicate that the spatial coherence of the incident light has an important role in the behavior of the spectral density of scattered field. With an increase of the correlation length of the GSM beam, the effective angular width of the spectral density of the scattered field decreases. The spectral degree of coherence of the scattered field increases with decreasing beam width of the incident light or effective radius of the medium. The scattered field is fully coherent when the appropriate choices of the effective radius and the correlation length of the medium, the spatial correlation length of the incident light are made.

Coude light path consists of several optical elements, which have large interval, so the alignments become very difficult as the increase of telescope aperture, as a result, computer aided adjustment technique was applied to analyze reflecting light path error, such as Monte Carlo statistic tolerance. First, an analytical model based on robot kinematics equation of D-H notation was derived for Coude light path alignment scheme. Then, the theory of Monte Carlo simulation was studied, its application in Coude path alignment was discussed. By the analysis of the weight of every mirror in the effect of the path alignment, the final adjustment order was confirmed. Lastly, Monte Carlo methods was made as the optimization algorithm to find out the perfect result of the Coude alignment. Simulation results indicate that by the use of the Monte Carlo methods, the radius of object circle is reduced from 5 mm to 0.3 mm, the adjustment of Coude path is simple, fast, and precision is improved, as a broad applicable tolerance design method can solve the adjustment of all reflecting light path.

To avoid collisions caused by night vehicles halation, a video anti-halation system of infrared and visible images fusion was designed. Visible light image and infrared image were enhanced by MSR enhancement algorithm to solve the difficulty in achieving the dark place information caused by low-light level of night visible light image, and the contrast of infrared image was improved, which consequently improved the definition of the fusion image; And the halation was eliminated by the method of infrared and visible images fusion based on YUV and wavelet transformation. Compared with the YUV and wavelet fusion algorithm, the fusion algorithm proposed in this paper can increase the entropy, mean value, average gradient and standard deviation by 1.6%, 13.5%, 25.3% and 0.6%, respectively. Experiment results show that the designed system can effectively eliminate the halation, and improves the image brightness and details in the picture, which improves the safety of night driving.

To comprise the light damping performance of the large aperture telescope due to the growing dimension and usage of steel truss, the tuned damping technique was discussed here and a quick approach of Tuned Mass Damping(TMD) would be presented. First and foremost, after being compared with traditional damping strategy, the special damping instrument was chosen as the solution. And then, using dynamic integration method, the simplified model was built to describe the fundamental motion of a large telescope under test. Lastly, according to this large telescope, the TMD was designed to suppress the shifting of the main mirror. Additionally, a testing system with first order natural frequency of 172 Hz was experimented, the response corresponding to frequency was declined after adding the TMD and the TMD for main mirror whose first natural frequency at 14 Hz in the large telescope was designed as 7.015 kg in mass and 5.506 N/mm in stiffness. Hence, a design method based on dynamical model deducing was investigated. Considering the current large telescope damping targets, the TMD was chosen to tune the dynamical response of large telescope. TMD not only contributes to construction of next generation large telescope, but also is a convenient method to update the old ones.

Based on the summary for the sea fogs of different areas of China sea, an overall distribution model about its micro-physics structure was put forward and its characteristics for China sea fog was summarized. The scale parameter was calibrated for most common sea fog, the extinction coefficient of different sea fogs were quantitatively analysed according to Mie theory, then, the attenuation coefficient was calculated in accordance with the formulars given by Mie and the final attenuation level was known. After a comparison, it witnessed a good agreement between theoretical calculation and experimental statistics. According to Mie theory, under the condition of salty fog drop, the average extinction coefficient of intermediate infrared radiation under common advection fog was 2.90, the extinction coefficient decreased monotonously along with the increase of scale parameter; while under the condition of pure water, the average extinction coefficient of intermediate infrared radiation was 3.35, the extinction coefficient increased monotonously along with the increase of scale parameter.

Color night vision technology is able to fuse the dual-spectral image of low-light-level and infrared image into a color one suited to human observation. Furthermore, a appropriate scene parsing method on the color night vision image could additionally facilitate human observation by providing automatic content analysis. An online scalable scene parsing method was proposed aiming at the rich and changeable color night vision in practice which required algorithms with high flexibility. The proposed method was based on a non-parametric model that needed no training process when predicting scene categories. It matched the query image and the sample images in database using both global and local features, and then transfered semantic labels of the best-match samples to the query image. Moreover, the database can be dynamically expanded according to different usage scenarios. The experimental results show that proposed method achieves satisfactory accuracies on color night vision images that obtained by a variety of color night vision methods, including the statistical color mapping, TNO, and NRL, throughout diverse scenes, including cities, countryside and others.Markov random field

Aiming at acquisition probability with human in the loop, the terminal searching process of infrared imaging missile and the features of human-in-the-loop seeker were analyzed. The calculation models were built for the horizontal and longitudinal instantaneous field of infrared imaging view. The condition turning to another side search was investigated, including excessing the maximum search sector and over boundary of target area. The criterion of target discovery was presented, which integrated distance constraint and azimuth constraint. According to flow process, the factors which influenced acquisition probability was simulated, such as missile course, start searching distance and length of target area side and so on. Results show that acquisition probability excesses the minimum value 21% when searching along diagonal line of target area; the optimum start searching distance is different as the length of target area side changes, and if the length is less than 7 kilometer, the acquisition probability is greater than 0.85; improving the coverage of infrared imaging seeker or speeding up angular velocity of operator turning ray axis will increase acquisition probability.

To improve the precision and credibility of infrared guidance hardwave in loop(HWIL) simulation test, the system error of infrared guidance HWIL simulation was studied and analyzed. The main error source of infrared guidance HWIL simulation system and mechanism was analyzed in detail, the guidance HWIL simulation model and the system error model were established from the perspective of the simulation mechanism. Based on the comparison and analysis on the missile trajectory calculating result with or without the loading error model, the influence of various error sources on the simulation test accuracy was analyzed quantitatively. The simulation analysis shows that the error of turntable mechanical and performance have little impact on precision of simulation test and can be ignored, and the effect of infrared seeker axial position error is obvious, needs to be addressed in the process of simulation test and to ensure that within a certain error range.

The near space global atmospheric temperature field from 20-100 km was achieved using 3-dimensional variational (3DVAR) assimilation method, of which the observation data was taken from TIMED\SABER temperature data and the background data was taken from WACCM model. Obvious variations could be seen in the near space global atmospheric temperature field after 3DVAR assimilation. An evaluation analysis based on statistical method was accomplished. The results indicate that the errors of the near space global atmospheric temperature field get a general decrease after 3DVAR assimilation, with the maximum error decreasing from 17 K to 7 K. The application of this 3DVAR assimilation algorithm can provide more accurate initial fields to near space atmospheric environment forecast model.

Fe-based bulk metallic glasses are very attractive because of their excellent mechanical properties and corrosion resistance. Fe-Cr-Ni-Co-B amorphous alloy powders were cladded on a 304L stainless substrate by laser cladding technique. The microstructure and corrosion resistance properties were analyzed by XRD, OM, SEM and electrochemical measurement. The results show that the microstructure of the cladding coating is uniform and compact and there are no obvious cracks and stomata. In regions near the interface with the substrate, the microstructure exhibits planar crystalline and columnar crystalline solidification morphology. It is mainly strips-like dendritic crystalline in the coating, which exhibits various size and growth directions because of different composition and cooling rate in different region. The coatings mainly consist of Fe64Ni36 and (FeCrNi) solid solution phases. The coating microhardness shows a uniform distribution. The average hardness of the coating was 480HV0.2, which was about 2.5 times of the 304L stainless substrate. The coatings show excellent corrosion resistance with a higher Ecorr and lower icorr than the 304L stainless substrate.

Based on the phenomena that electro-optical devices with "cat eye effect" can reflect input light beam exactly back along the direction the beam incidents, a resonator of novel configuration was formed by utilizing the "cat eye" system as an equivalent resonant mirror of laser. The equivalent reflectivity of "cat eye system" was defined to describe the ability of reflecting input light exactly backward. Laser oscillation was achieved by pumping a Nd:YAG rod located between a corner cube prism and a cat eye system. These properties make it possible to be applied in electro-optical countermeasures.

The principle of producing dual-wavelength laser was presented in laser crystals of four energy level system with double lower level. The threshold formulas of dual-wavelength simultaneous oscillation in two-mirror cavity were introduced. It was found by calculation that the existence of space hole-burning effect made the threshold condition widened to a region from a curve, which was helpful for dual-wavelength oscillation. Moreover, the effect of the crystal length and pump power on the dual-wavelength threshold were calculated, results show that, before the gain saturation happens, the longer the crystal length is and the higher the pump power is, the more easily the dual-wavelength laser will appear. Finally, the dual-wavelength threshold curves of several common Nd-doped laser crystals were calculated, which showed by comparison that Nd:YAP crystal is more suitable for producing dual-wavelength laser due to its two similar emission cross sections.

Angle variation formula of illumination, which is induced by moving lens, or moving retroreflecting right-angle prism, or rotating mirror, was derived according to imaging principle. The extent of the angle change of illumination depends on three parameters, such as focal length of the lens, object distance, and divergence angle of light source. The three methods introducing angle diversity were compared. The experimental results are consistent with the theoretical analysis. The results demonstrate that 20 μm displacement for the retro-reflecting right-angle prism and 0.02° of rotating angle for the mirror can easily achieve two completely independent speckle patterns under the same conditions, which provides a basis to design a motion scheme introducing angle diversity to suppress laser speckle.

Filamentation has stimulated growing research interest since the first observation of filament generated by an intense femtosecond laser pulse in air. Possible applications of filaments have also been proposed and demonstrated in laser induced electrical discharge particle acceleration, lidar remote sensing, THz radiation generation, and pulse compression. The characteristics of filamentation with a modulation of background energy distribution was presented by changing the confinement parameter of ring Airy beam numerically. The length of filaments longer than that of the Gaussian beam with faint background energy of the same peak power was achieved. By analyzing the spatial and temporal evolution progresses, it was found that the Airy beam airy-function-like energy distribution along radius of the background energy was the prerequisite to achieve peak intensity along the propagation direction. With comparison of spectra evolution consequences, it was found that the changing of the confinement parameter of Airy beam doesn't have significant influence on the spectral broadening. But when changing the beam from ring Airy to Gaussian, the spectra is broadened dramatically.

TA15 titanium alloy bulk specimens were prepared with spherical powder and forging substrates in laser deposition manufacturing. The effects of annealing temperature and soaking time on microstructure characteristics and microhardness were investigated by optical microscope (OM), scanning electron microscopy (SEM) and microhardness instrument. The experimental results show that alpha phase grows fully resulting from annealing temperature increase and longer soaking time at same annealing temperature. The width of the alpha phase becomes larger with the extension of the soaking time. The percentage content of alpha phase grows with annealing time extension. Alpha phase exists different growth direction in different annealing soaking time. There are some certain relationship between microhardness and volume content of alpha phase, microhardness is enhanced with the increases of percentage content of alpha phase.

The laser-induced damage threshold (LIDT) of optical films is an important index for assessing the film′s properties of laser tolerance. Accurate measurement for the LIDT is the foundation of laser tolerance estimation and data comparison of the thin films. Based on the analysis and computer simulation, the optimization ways of laser-induced damage threshold was presented in this paper. The results show that the error of the energy density increased with the increase of the laser energy at a fixed laser spot. Therefore, in the case of satisfying the need, it is better to choose low laser energy for the testing system. Under the fixed laser energy, there will be a critical laser spot. The error of the energy density changed strongly with the spot size change: smaller spot size, bigger energy density error. The small gentle energy density error can be obtained at the laser spot size greater than the critical laser spot, vice versa. Therefore, it is better to choose the spot size equal or greater than the critical laser spot size. The fitting maximum error is equal to that of the error of the maximum laser energy level. Thus it can be seen that the uncertainty of a LIDT test system can be reduced through designing suitable laser parameters.

On the basis of the fact that digital processing algorithm is used by high repetition frequency multi pulse laser rangefinder, the bandwidth of the receiving circuit, the digital sampling accuracy and the filtering algorithm affect the accuracy of ranging. The algorithm of improving measuring precision was put forward by analyzing the error of ranging. Firstly, based on the accumulation of the laser echo signal to improve the signal to noise ratio (SNR), it was followed by the processing of center differential signal, slope threshold condition of echo signal and eliminated the pseudo peak point, thus peak position was determined preliminarily; and then according to the characteristics of the waveform after initial positioning, the corresponding exponential function was selected to modify the waveform of the asymmetric sinc function to obtain the relative exact position of the crest point, so as to calculate the more accurate target distance. Finally, the improved algorithm was simulated in MATLAB, the simulation results show that the proposed algorithm can improve the accuracy of laser range accuracy.

The numerical simulations and experiments were employed to investigate the effect of boundary constraint conditions of thin plate on residual stresses and plastic deformation induced by laser shock peening. Two boundary conditions, bottom fully constrained and both ends clamped, were used to compare residual stresses distribution and deformation morphology of 7075 aluminum plates after impacted by multiple laser shock peening. The results show that micro-dents were generated in impacted regions of both cases after treated by laser shock peening. The plate still kept flat without cross-sectional deformation when its bottom surface was fully constrained, while the overall upward convex deformation was produced in the impacted region of plate with both ends clamped. Moreover, the maximum compressive residual stresses existed on the surface of both cases, which was 299.0 MPa in the plate with bottom fully constrained and 251.6 MPa in the other case. Different styles of residual stresses field are also found in the thickness direction. The residual stresses from the impacted surface to the bottom was "compressive residual stresses -tensile residual stresses" in the plate with bottom fully constrained, while it was "compressive residual stresses-tensile residual stresses-compressive residual stresses" in the plate with both ends clamped.

To get line-of-sight angular rate in a target tracking system, a method of measuring LOS angular rate based on image sequences, obtained by a single imaging detector, was introduced in this paper. With the sequence images, body LOS angles were obtained by the moving target image coordinates, missile attitude angles were got by images matching, and the LOS angular rate was calculated with these two variables. Experimental results show the idea is practical. Combining with the image tracking algorithm, the body LOS angle can be obtained in real time. Missile attitude angles are obtained well by the images matching, with the attitude transform error less than ±5%. And the LOS angular rate can be better restored using Kalman filter, with body LOS angle and missile attitude angle containing noise. The method has a practical value, for being applicable to micro-aircraft′s guidance and detection, eliminating gyro inertial elements, and reducing the weight of detecting devices.

Multi-aperture imaging is a new imaging method combining with compound eye concept, which has a small size, large field of view, high-resolution images reconstruction and other advantages. However, due to the low resolution of sub-images, the improvements for the image resolution and field of view are very limited. A novel imaging method which could achieve both super-resolution and large field of view was proposed. The random coded mask was designed based on the framework of compressive sensing and placed on each sub-aperture. Instead of directly imaging and converging on the image sensor, the incident light field of each sub-aperture would be modulated by the coded mask. Then, the random projections of the input object could be acquired by the low-dimension image sensor within a single exposure. Finally, the sparse representation-based optimization algorithm was applied to reconstruct super-resolution and large field of view images from all low-resolution sub-images, which had more object pixels than the number of pixels of the image sensor. Both the theoretical model and simulation results show the feasibility of the proposed method. Moreover, this method greatly reduces system equivalent focal length and has a thin structure, which can provide theoretical guidance for the design and application of the micro-optical electromechanical system.

The influence of intensity correlation order on correlated imaging for moving target was researched. The image quality of correlated imaging for tangential and axial moving target in different intensity correlation order was discussed by changing the signal light order and the reference light order.Based on the schematic of Nth-order lensless correlated imaging for moving target, analysis of the influence of different intensity correlation order was performed with emphasis on the correlated imaging mathematic model, and the simulation experiments were performed. The results suggest that it can not effectively eliminate the motion blur by changing the intensity correlation order, and the image quality will be better with the increase of signal light order. However, the best quality can be obtained by the lowest-order with background subtraction, and the image quality of axial moving target will decrease more serious.

The dielectric properties of single-crystal MgO were studied by terahertz time-domain spectroscopy in the frequency range extending from 0.5 to 9.5 THz. The refractive index, power absorption, and the complex dielectric function were extracted from experimental data. At low terahertz frequencies band (<2 THz), the absorption coefficient was extremely low and increased with increasing frequency. Meanwhile the corresponding refractive index had low dispersion, increasing from 3.12 to 3.15. Two prominent resonances were observed at 3.16 THz and 8.11 THz and were well-described by a multiple-oscillator model through theoretical fitting. The interaction of incident photons and the transverse optical (TO) phonons in the crystal were studied and it gives good evidence to further applications in developing broadband terahertz components and terahertz spectroscopy.

Terahertz interferometric imaging offers considerable potential in many imaging applications due to its simple imaging principle, less detector elements and efficient data acquiring ratio. An interferometric imaging system scheme was proposed based on the research of Terahertz interferometric imaging principle. Simulation experiments were carried out to analyze the impact of imaging frequency, radius of circular array and detector number on imaging quality and frequency bandwidth of the imaging system. The experimental results show that the radius of circular array is smaller while the frequency is higher for available imaging with the other conditions being changeless. Adding detector number would improve the imaging quality but not obvious while bigger than one certain number and the frequency bandwidth of uniform circular array for available imaging is wide. The conclusions from the simulation results may offer some theoretic evidence and technical support for the design of terahertz interferometric imaging system and practical applications.

The influence of groove depth in one dimensional (1D) subwavelength metal grating on THz spoof surface plasmon ploaritons(SPPs) was theoretically investigateal in detail. Two device geometries were proposed including uniform groove depth 1D metal grating and defect groove depth 1D metal grating. The electric field distribution of metal grating was stimulated by employing COMSOL software. For the uniform structure, the dispersion relation of SPPs propagating along grating can be tailored by groove depth. The metal grating with deeper groove has stronger THz electric field distribution and the spoof SPPs is better confined to grating surface. For the defect structure, electric field distribution characteristics of both sides are determined by the defect groove depth, which can be attributed to reflection and scattering of defect. Based on the proposed theoretical stimulation, the two different subwavelength metal grating structures can provide new functionality for THz wave devices such as wave guiding, attenuator and filter.

Volume Bragg gratings (VBG) fabricated by photo-thermo-refractive glass are widely adopted in linewidth-narrowing of laser diode with external cavities. The model was based on finite element analyses. Through the model, thermal properties of the VBG were researched under conditions of different laser diode (LD) illumining area, different laser power and different gratings′ working temperature. When the LD power was 40 W and the working temperature was 25 ℃, the increase of the maximal temperature are 8.52, 5.07 and 2.20 ℃ at the illuminated altitude of 1.48, 0.88 and 0.28 mm. The discrepancy between the temperatures of the illuminated area and the working temperature was linear to the LD power. By improving the VBG working temperature, the gap between the actual temperature and the working temperature can be reduced. According to the research, the uniformity of the VBG′s temperature can be optimized by choosing illuminated area and LD driving conditions, which will be beneficial to acquire the LD with narrow linewidth.

High Erbium-doped tantalum pentoxide (Er:Ta2O5) films with different Er-doping concentrations was fabricated on silica-on-silicon substrate. The fabricating method of Er-Ta co-sputtering and following thermal oxidation was first proposed. The influence of high Er-doping concentration on refractive index of Er:Ta2O5 films was evaluated by prism coupler. The results indicate that the refractive index of Er:Ta2O5 films decreases slightly while Er-doping concentration increases and the films do not show anisotropy obviously. On this basis, 0, 2.5, 5, 7.5 mol% Er-doped Ta2O5 ridge waveguides were successfully fabricated on Si substrate. The waveguides were observed to be single-mode at 1 550 nm wavelength. Propagation loss of 0.6, 1.1, 2.5, 5.0 dB/cm at 1 600 nm wavelength was estimated using cut-off method, respectively. Although no crystallization of Er2O3 was found among the fabricated Er:Ta2O5 films, Er3+ could affect the crystallinity of Ta2O5 and then increase the propagation loss of the waveguide. Finally net optical gain of 3.1 dB/cm at 1 531 nm was demonstrated in a 2.5 mol% Er:Ta2O5 ridge waveguide when pumped with 980 nm laser.

Three kinds of high-performance fiber lasers were systematically investigated including the single frequency continuous wave (CW) fiber lasers with narrow linewidth and low relative intensity noise (RIN), the high energy long-nanosecond-pulsed single frequency fiber lasers and the high peak power short-nanosecond-pulsed fiber lasers. The single frequency CW fiber lasers operating in 1 μm, 1.5 μm and 2 μm regions were developed. The typical spectral linewidth was less than 3 kHz and the RIN approached the short noise limit. One high energy nanosecond pulsed single frequency fiber laser in 1.5 μm region was developed. It can produce 200 μJ single frequency laser pulses with 100-500 ns pulse width at 20 kHz repetition rate. A fiber laser producing pulses with 700 kW peak power, 3 ns pulse width at 10 kHz was developed. High repetition rate (up to 3 MHz) nanosecond fiber lasers was also developed, which can provide 1-5 ns laser pulses with 200 W peak power. The applications of these lasers in laser LIDARs are addressed in this paper.