Using stellar scintillation to measure isoplanatic angle θ0 is now a widely used method. Based on the theoretical analyses, more accurate calculation formula is derived. With formula derivation and numerical simulation, it shows that the best aperture diameter is around Fresnel length. Equivalent wavelength of polychromatic scintillation and range of turbulence path length are analyzed, and the calculation of proportionality factor C of θ0 and scintillation is discussed. Proportionality factor for Fresnel number in a range from 0.5 to 1.1 can be accurate fitting by cubic polynomials. Proportionality factor should not simply take a fixed value at a wavelength of 500 nm, while it should be calculated by the fitting formula in practical applications.

Atmosphere turbulence is one of the main causes of degraded image quality in the area of detecting space objects based on optical telescope on earth. Atmosphere turbulence results in distortion of wavefront, and it causes different kinds of blurred images. In order to recover original images from blurred images, a method to evaluate point spread function based on atmosphere coherent length is proposed, and the theoretical formula is deduced. Sobel method is used to evaluate the image qualities of recovered images after same times of blind convolution, and the value of atmosphere coherent length is found out when the value of image quality is maximal. This atmosphere coherent length is applied to point spread function and the restored image is got after blind convolution. With many kinds of image quality evaluation indices, it is proved that this method can make us get a good restored image without measuring the value of atmosphere coherent length.

In order to improve the detection accuracy of all-fiber differential absorption lidar (DIAL), it is very important to develop configuration of all-fiber DIAL system with circulator at close range. Relationship between detection accuracy of DIAL and laser echo energy is analyzed. At close range, crosstalk of circulator affects the detection accuracy. The influence of crosstalk on detection accuracy is analyzed at different heights. Combined with the example of CO2 concentration detection and simulation, signal to noise rate (SNR) and relative error with height are analyzed. The research shows that crosstalk can interfere with laser echo and seriously affect detection SNR and accuracy. The study has important significance on the design and improvement of all-fiber DIAL system.

The impact of water cloud optical properties on atmospheric polarization properties is researched, and atmospheric polarization pattern under water cloud condition is simulated. By using the polarized radiative transfer based on Monte Carlo model, the changes of atmospheric polarization properties with the optical thickness and effective radius of water cloud from 350 nm to 700 nm are simulated. By calculating Stocks vector of discrete points in the whole sky, atmospheric polarization pattern of water cloud is researched and compared with the polarization pattern of clear sky. The results show that the degree of polarization (DOP) decreases with the increasing of water cloud optical thickness, which is more obvious with the wavelength upward trend. DOP decreases with the fall of effective radius to a certain extent, but it has less influence on short wavelength. With the increasing of solar altitude angle, DOP of the whole sky becomes lower. The area of DOP at about 0 makes the angle of polarization (AOP) imprecise. The research on atmospheric polarization pattern of water cloud provides theoretical basis for the specific application of polarization navigation sensor.

The bright laser sodium beacons are beneficial to enhance the accuracy and sensitivity of wavefront sensing. But the recoil and downpumping limit the increase of the excited state probability and decrease the sodium spontaneous radiation rate and the number of return photons in the process of laser interacting with sodium atoms. By investigating on the recoil and downpumping effects which the narrow band and broad band lasers act on sodium atoms in mesosphere, the conclusions show that the effects of recoil and downpumping of the narrow band laser are more severe than the ones of the broad band laser, but the spontaneous radiation rate is faster than that of the broad band laser and the number of return photons is distinctly more than the one excited by the broad band laser, when the low energy continuous wave laser interacts with the sodium layer in the mesosphere. However, the broad band laser has the easily unsaturated merit and the less recoil effcts.

The ground state, infrared spectrum and Raman spectrum of the NH3 molecule are optimized using the density functional theory (DFT) B3P86. The excitation characteristics of NH3 molecule are studied by symmetry-adapted cluster/symmetry-adapted cluster-configuration interaction (SAC/SAC-CI) method with basis set D95++. It is shown that the infrared spectral frequency and Raman spectral frequency of NH3 molecule for the ground displacement are completely consistent; vibratory infrared and Raman spectra are active, which are consistent with the theoretical data. A two-dimensional vertical vibration (ν3,5) of infrared intensity is 0.206 km/mol, almost zero, which is related to the excitation characteristics of NH3 molecules. The C3V group becomes D3h group when NH3 molecules are excited from the ground state. This change causes the increases of symmetry and energy. This kind of change doesn′t result in Jahn-Teller effect, but results in the electronic state and dynamic interaction. The electronic state and dynamic interaction are analysed theoretically. It is found that the theoretical analysis is in agreement with the calculated results.

Traditional scene-based nonuniformity correction algorithms for infrared focal plane array suffer from two major drawbacks: slow convergence rate and low correction accuracy. Aiming at these problems, a new method based on extended total variation is proposed to correct the nonuniformity for infrared focal plane arrays. Based on the analysis of total variation-based de-noising performance, the scope of total variation is extended for motional infrared image sequences. By minimizing the total variation of corrected images, iterative formula to compute the gain and offset factors is obtained using steepest descent method. For eliminating the ghosting effect, an adaptive threshold method is designed. The experiments show that compared with the existing methods, this method can effectively remove the noise in original infrared images and largely retain image information at the same time. The image quality is therefore improved.

Surface roughness on blaze plane of silicon echelon grating can induce the scattering of incident light, which means that the size of surface roughness is important to the application of echelon grating in spectrometer industry. In order to reduce the scattering light of echelon grating, an important thing is to decrease the surface roughness on blaze plane of echelon grating. In the silicon wet etching process, the pseudo-mask is formed by the hydrogen bubbles generated during the etching process, which causes high surface roughness and poor surface quality. Based upon the ultrasonic cavitation and wettability enhanced by isopropanol (IPA), ultrasonic vibration and wettability enhancement are used to improve surface quality of echelon grating during silicon wet etching process. The surface roughness is smaller than 15 nm when using ultrasonic vibration and it is smaller than 7 nm when using wettability enhancement. Combining ultrasonic vibration and wettability enhancement,the surface roughness is smaller than 2 nm when the range of IPA mass fraction, ultrasound frequency and power is 5%~20%, 100 kHz and 30~50 W, respectively. The surface roughness is equal to 1 nm when the range of mass fraction of IPA and ultrasound power is 20% and 50 W and the ultrasound frequency is 100 kHz. The experimental results indicate that the combination of ultrasonic vibration, wettability and optimizing of experimental parameters can fabricate the echelon grating with lower surface roughness.

An optical comb filter based on the Sagnac ring loop is proposed. The comb filter response function is generated on the basis of the birefringent effect of the polarization maintaining fiber (PMF) within the loop. By utilizing the radio frequency (RF) signal along with the direct current (DC) to drive the phase modulator (PM) inserted in the Sagnac loop mirror, the independent tunings of the notch depth and filtering wavelength are realized. The response function of the proposed Sagnac filter is expressed theoretically with Jones matrix, and the effects of the optical filter notch depth and filtering wavelength on RF signal and the DC bias are analyzed. Based on the analysis results, the experimental link is set up to verify the theory. The results show that the tunable range of the notch depth from 0 dB to 30 dB is achieved. Besides, the filtering wavelength influenced by the DC from 0 to 12 V is continuously adjustable in the free spectral range (FSR) of 0.5 nm, and the wavelength tuning efficiency is 0.043 nm/V.

The polarization state generator (PSG) with ergodicity of polarization states (EPS) is an important instrument for measurement of polarization state, and the descriptions of polarization state and polarization devices are the base for control algorithm. A new description of PSG using the quaternion method is proposed and analyzed. A quaternion of three polarization controller is derived, and the equations of rotation axis and rotation angle are obtained. In the experiment, the quaternions of single-stage polarization controller are measured, and the corresponding equations of stress quaternions are obtained when the single-mode fiber is squeezed and the voltage of piezoelectric transducer (PZT) is changed. Finally, using these quaternions, the polarization state generator can be achieved.

Based on the optical model of D type of side-polished photonic crystal fiber (SPPCF), both the attenuation of optical power and the field distribution of propagation modes in the device of SPPCF are calculated and analyzed with the variation of geometry factors, such as residual radius after side polishing, axial rotation angle, and the length of side-polished area, by using three-dimensional finite difference beam propagation method (FDBPM). The analysis results show that when the residual radius is longer than -1.5 μm, the shorter the residual radius is, the larger the attenuation of the optical power in SPPCF is; the optical power of LP01 mode of the SPPCF is attenuated in the side-polished area, and recovered after light passes through the side-polished area. When the residual radius is longer than 0.5 μm, there is a small difference between the attenuations of optical power of PCFs polished at different axial rotation angles. When the residual radius is small enough, high order modes appear during the process of the light passing through the side-polished area. The mode field distribution is the most dispersive one and many high order modes appear in side polished area when the axial rotation angle is 30°. When the residual radius is longer than 1.5 μm, the change of the side-polished length has a little impact on the attenuation of optical power in SPPCF; when the residual radius is shorter than 1.5 μm, the attenuation of optical power changes in oscillation as the side-polished length varies. The analysis may provide a theoretic guide to device fabrication of SPPCF.

Photonic millimeter-wave frequency multiplication based on external modulation is considered as an attractive solution for high-frequency and frequency-tunable millimeter-wave signal generation due to its simplicity and stability, in addition to the large frequency tunability, and high spectral purity of the generated millimeter-wave signal. A generalized approach to achieve microwave frequency-multiplying generation based on external modulation using a dual-parallel Mach-Zehnder modulator (DPMZM) is presented. A theoretical analysis is developed, and the operating conditions are given to achieve frequency quadrupling, sextupling, and octupling millimeter-wave generation. Finally, a novel scheme for photonic generation of frequency quadrupling millimeter-wave signal without wideband microwave phase shifter and optical filter is proposed. The impact of the finite extinction ratio (ER) and modulation index of DPMZM on the generated millimeter-wave signal is also evaluated.

The bending effects of single mode fiber, polarization maintaining fiber, photonic crystal fiber and polarization maintaining photonic crystal fiber on fiber optical gyroscopes (FOG) performance are analyzed. A comprehensive model is established, and then based on high-precision FOG application, the power, spectrum width, and mean wavelength after transmitting sample fibers are measured by using the erbium-doped superfluorescent fiber source when changing the bend radius. Based on the measured data, the scale factor stability and random walk coefficient of FOG are calculated. The results show that bending effect of photonic crystal fiber is very small and can be neglected in FOG, while the bend radius should be controlled when using other two conventional fibers.

A system for interference-based optical multiple binary image encryption by random phase mask multiplexing is proposed. The encryption process is realized digitally and the decryption process can be completed optically or digitally. Multiple binary images can be analytically hidden into two phase only masks (POMs). For decryption, the diffraction filed of the two POMs are superposed by utilizing the beam splitters to form a complex field, then the complex field is further modulated by the private key, as a result of which the original plaintext assosicated with the private key is retrieved. The regenerated image can be directly recorded by CCD camera. The encryption algorithm for this new method is quite simple and does not need iterative encoding. In addition, the decryption system is easy to be realized physically. The multiplexing capacity is analyzed through the correlation coefficient. Computer simulation results confirm the validity of the proposal.

A new digital image optical encryption method based on compressed sensing is proposed. With the advantage of the characteristics of compressed sensing as well as double random phase encoding technique, multi-encryption of digital image is realized. Compressed sensing is utilized to compress and encrypt a digital image with the random measurement matrix as secret key. Arnold transformation is used to scramble the encryption image with low data volume. The encryption image is encrypted again by double random phase encoding technique to realize the multiple encryption of image. Security overall process is taken into account in the scheme. The multi-encrypted information is embedded into the host image and transmitted. At the receiver, original image information is reconstructed. The experimental results show that the encryption scheme has such features as low data volume, strong robustness, high key sensitivity, and can resistance brute force attack.

The influence of the sampling pinholes and recording aperture on imaging quality in coherent diffractive imaging based on sampling array is analyzed using scalar diffraction theory. A mathematical formula for describing the influence is derived. The theoretical analysis shows that the limited size of the recording aperture can result in a crosstalk between adjacent sampling pinholes. This crosstalk effect is the main source of the wavefront reconstruction error and the imaging noise. Through digital analysis of the changes of the sub maximum of the crosstalk function under different recording aperture conditions, it is found that the sub maximum does not descend monotonously when the size of the recording aperture increases, while it oscillatorily decreases with enlargement of the recording aperture. An optimal size of the recording aperture is defined and an analytical formula is given. Further experimental results show that the background noise will descend to its minimum when the radius of the recording aperture is just equal to the optimal size.

A spectral inversion model of solid Mach-Zehnder imaging spectrometry is derived strictly. Based on the model, the influences of the reflector translation error on the spectral inversion are analyzed. Zemax software is used to establish the simulation model of the imaging spectrometry. The simulation model is then adopted to simulate the function of solid Mach-Zehnder imaging spectrometry and verify the validity of the theoretical derivation. Both theoretical analyses and simulation results indicate that the reflector translation error of solid Mach-Zehnder imaging spectrometry influences the spectral inversion, and the spectral inversion error relates to the sum of the reflector translation errors in the two shearing light paths. Therefore, it is necessary to strictly control the sum of two translation errors or compensate the measurement errors properly to improve the spectral accuracy of the measurement system.

Phase extraction precision directly affects the accuracy of phase-shift interferometry. In the wavelength tuning interferometry, a phase calibration is necessary for the test system, because phase shift is determined by interference cavity length and wavelength variation. But an accurate phase calibration is not easy to achieve. The phase shift error can be caused by an inaccurate calibration, which can decrease the phase extraction precision. A phase extraction algorithm based on iteration is proposed. This iteration algorithm does not need to calibrate the phase of the test system, and it can obtain the testing phase and phase shifts through alternate iteration method under the condition that the testing phase and phase shift are unknown. A series of simulations are done to compare the phase extraction accuracy, and the results suggest that the phase extraction accuracy of the proposed algorithm is quite better than that of the traditional four-step phase shift algorithm.

Spectroscopic ellipsometer is a common instrument for measuring film thicknesses and optical properties, whose accuracy largely depends on the calibration procedure of ellipsometry system. We propose a new calibration method by measuring several standard thin film samples with known thickness and dielectric function to obtain the experimental Fourier coefficient spectra. Fit these spectra to theoretical spectra which includes the calibration parameters using least-squares method and then solve these parameters of the ellipsometry system, including the azimuth of polarized elements, the retardation of waveplate, the azimuth of waveplate and the incident angle etc. We have extended this method to broadband spectrum of 200~1000 nm and verified the validity by measuring the SiO2 thin films in the thickness range of 3~13 nm and demonstrated good measurement accuracy of 0.194 nm. This new method is easier and faster than traditional calibration method.

Projector defocusing technique can eliminate projector nonlinearity in real-time three-dimensional shape measurement. However, the high frequency harmonics brought by defocusing can weaken the sinusoidal feature of the defocused fringe pattern, which can cause obvious measurement error. The Sierra Lite dithering algorithm using a serpentine raster is proposed to generate binary dithered fringe patterns. This method improves the sinusoidality of the defocused fringe pattern. Absolute phase is retrieved by applying fringe patterns generated by this method in traditional phase-shifting algorithm with projector defocusing. Simulations and experiments are carried out to verify the proposed method. Results show that both the sinusoidality of the defocused fringe pattern and phase quality are improved greatly. Compared with the fringes generated by Bayer ordered dithering or Floyd-Steinberg dithering, the proposed method achieves higher performance and can generate fringe patterns more sinusoidally, which is more proper for projector defocusing profilometry.

A new frequency discrimination technique with high-precision called dual-frequency quad-edge technique which bases on a single solid Fabry-Perot (F-P) etalon and a tunable semiconductor laser is proposed. The function expressions of the reflection spectrum and the transmission spectrum are deduced. The frequency discrimination principle of dual-frequency quad-edge technique is analyzed. According to the frequency discrimination principle, the architecture of the frequency discrimination system and the corresponding analysis and processing methods for detection signals are given. Then, the measurement error caused by noise also is analyzed and the specific error formula is derived. The detection performance of this frequency discrimination technique is analyzed by comparing with that of the conventional double-edge frequency discrimination technique base on F-P etalon. The results show that the frequency discrimination accuracy of this frequency discrimination technique can improve 2.82 to 3.03 times through the simultaneous detection of the transmitted and reflected signals from the F-P etalon, while the optical path of this new technique is simple and the system cost is low due to the use of a single solid F-P etalon.

A method based on dual wavelength digital holography is proposed to measure the refractive index distribution and surface profile of micro-optics elements. Micro-optics elements are immersed in refractive index matching liquid to reduce the frequency of transmission light. The digital holograms of micro-optics elements are obtained under illumination of two different wavelengths, the refractive index distribution of micro-optics elements can be obtained according to phase distribution under two wavelengths. Surface profile of micro-optics elements can be calculated based on the refractive index distribution. Theoretical analysis and optical experimental results are performed to demonstrate its validity.

Routing scheme of a kind of polymer five-port optical router is proposed, and it can optically route four channel wavelength data streams along certain definite-path in two-dimensional (2D) plane, owing to the resonance function of cross-coupling two-ring resonators with four different ring radii. Due to the large contrast between polymer core refractive index and the left/right cladding index, the four ring radii are as small as 14 μm, and the mode amplitude bending loss is as low as 10-4 dB/cm. Under the case of lights with different wavelengths inputting into different ports, the relationships between wavelength and routing path are derived. Simulation results on the device reveal that the insertion losses of each channel wavelength along each routing path are within the range of 0.03~0.62 dB, the maximum crosstalk between the on-port along each routing path and other off-ports is less than -39 dB, and the device footprint size is about 626 μm×495 μm. Compared with the previously reported silicon optical routers, this device possesses similar ring radius and similar device size. In addition, because of zero static power consumption, low crosstalk and insertion loss, simple processing technology and low cost, the proposed device shows potential applications in optical networks-on-chip (NoC).

In order to improve the focal spot performance caused by continuous phase plate (CPP) in the laser facility for inertial confinement fusion (ICF) system, a theoretical calculation and analyse model for CPP with wavefront distortion is proposed, and off-line measurement system with three harmonic generation laser for the far-field intensity is built up according to the working conditions of CPP in the laser system. The comparison between calculation and measurement for the 330 mm×330 mm CPP and wavefront distortion component is carried out. The pattern and parameters are matched very well, so the correctness of calculation model and the credibility of measurement system are certified. The results show that the CPP′s focal spot performance is effected by the incident wavefront distortion severely. The CPP′s focal spot is changed largely when the disc of confusion caused by wavefront distortion is equal to half of the focal size caused by CPP. The changes include that the capacity usage ratio descends more than 4%, the focal spot radius increases over 20 μm, the super-Gauss order of the focal spot profiles reduces 1.3, the root mean square (RMS) value of inhomegeneity reduces 6%, and the percentage of side lobe increases over 0.5%.

An integrated theoretical analytic platform is developed, which consisted of the thermodynamic model, beam transformation model, energy transition model and active unstable resonator model. The main conclusion of theory analysis is that: the beam-quality and optical-optical efficiency are weakly impacted by the length of resonator on fixed gain; the optimal efficiency and beam-quality are different corresponding to magnification for unstable resonator. The experiment of phase plate with passive resonator compensation is accomplished, the beam quality is improved from 5.48 times of diffraction limit to 2.46, with the output power of 12.1 kW.

Based on the coupled Ginzburg-Landau equations and Jones matrix of all devices, a numerical model of an all-normal-dispersion mode-locked fiber laser by nonlinear polarization rotation is proposed. The polarization states of different points across the pulse are calculated along the cavity. It is found that when the linear birefringence of the fibers is strong, the evolution of polarization state in the fiber rounds a period of one beat length. Over one beat length, the state of polarization changes from right-handed elliptic to linear,left-handed elliptic, linear, and then back to right-handed elliptic. Different from a common saturable absorber, the modulation depth of the equivalent saturable absorber of the nonlinear polarization rotation varies with the wave plates angles. The dependence of modulation depth on wave plates angles is calculated. The results show that compared with the half wave plate and quarter wave plate before polarization beam splitter, the one after polarization beam splitter has a more obvious effect on modulation depth.

In order to validate the effect of beam smoothing and to get the radiation characteristics of gas-filled hohlraum, the energy fraction of backscattering light and the streaked spectrum are measured by the backscattering measurement system on Shenguang-III prototype facility. The results indicate that in the current experimental conditions, beam smoothing can effectively inhibit the backscattering light fraction. The energy fraction of backscattering light is 25%~35% without beam smoothing, and the energy fraction decreases to 2%~4% with beam smoothing. The fraction of stimulated Raman scattering in gas-filled hohlraum increases markedly from 2%~4% in empty hohlraum to 10%~13%. The results of spectrum measurement indicate that beam smoothing can improve the uniformity of plasma. Stimulated Raman scattering occurs at the early stage of the laser effect for gas-filled hohlraum, but it occurs at the late stage for empty hohlraum.

Since the asymmetry of laser gain leads to the unequal of scale factor corrections between left circularly polarized and right circularly polarized gyros in the cavity, zero-lock laser gyro (ZLG) bias is sensitive to magnetic field when frequency stabilization point is not matched with magnetic insensitive point, which degrades the precision and limits work condition of ZLG. The relation between scale factor corrections and gain-to-loss ratio is analyzed according to Lamb semiclassical theory, as well as the relation between magnetic insensitive point and discharge current. The influence of discharge current changing on control signal is eliminated from signal processing system and experimental verification is performed. It is proved by both theoretical calculation and experimental results that the magnetic insensitive point varies linearly with gain-to-loss ratio as the discharge current changes linearly, which means that the magnetic sensitivity can be reduced by changing discharge current.

In order to solve the problem of space extended target tracking on the condition that the background of image is simple, the texture of target is lack, and the revolving and translating target is distorted gradually, one method of target tracking based on the inertia ellipse and pose compensation is proposed. The inertia ellipse is used to measure the pose of target accurately. The pose and location are compensated in uniform reference frame, and the principle of the closest distance is adopted to feature point matching. It is approached that the extended target is tracked accurately. Furthermore, experiments involving emulating image and real image indicate that the proposed method is effective, the error of tracking transferred target is less than 0.26 pixel, the error of tracking revolving target is less than 0.28 pixel, and the error of tracking real extended space target is less than 0.30 pixel, which indicates that the proposed method is effective on tracking the extended space target.

Focused on the problems that it′s difficult to obtain high precision mosaic image of object having duplicate texture in the automatic visual inspection system, a new two-dimensional (2D) image mosaic method based on sub-pixel grating positioning is presented. The method uses grating to record positions of object and calibration plate to accurately calibrate angles of X and Y axes between platform and camera, and build a 2D stitching model based on global Cartesian coordinate system to complete image stitching. Experimental results show that the method′s calibration repeatability reaches 10-4 rad order of magnitude, with average physical error of 8 μm, and stitching precision increases nearly 8 times than that of not correction, 2 times better than the method that has been reported. The method has been successfully used in the online automatic inspection equipment for ceramic substrate of navigation satellite′s receiving antenna circuit. The research result can be widely applied in machine vision automated inspection fields that require sub-pixel level detection precision.

A series of polyether polyurethane (PU) gel electrolytes are prepared with polyethylene glycol (PEG) and isocyanate as monomers, and adding liquid electrolyte formulated by 1,4-butyrolactone (GBL), (C4H9) 4NI and I2. The structure of the polyurethane gel electrolyte is characterized by dynamic mechanical thermal analysis (DMTA), Fourier transform infrared spectrometer (FTIR), differential scanning calorimeter (DSC) and X-ray diffraction (XRD). The results show that this type gel electrolyte has a good thermostability and amorphous structure. The influence of PEG molecular weight and isosyanate monomer on the conductivity of PU gel electrolyte is analyzed. It is found that the conductivity of PU gel electrolyte increases firstly and then decreases with the PEG molecular weight increasing. When the PEG molecular weight is 10000, the conductivity of the gel electrolyte reaches a maximum of 6.13 mS/cm. However, change of isocyanate monomer has almost no effect on the conductivity of the electrolyte. That may be related to the formed network of PU gel electrolyte by scanning electron microscope (SEM) characterization. The quasi-solid-state dye-sensitised solar cells (DSSCs) assembled with PU gel electrolyte prepared by different PEG molecular weight show different photovoltaic properties. A high photoelectric conversion efficiency of 4.29% is achieved at 100 mW/cm2 when PEG molecular weight is 10000.

The possible geometrical structures of Mg2Sin(n=1~9) clusters are performed structural optimization by using the density-functional theory (DFT) at the B3LYP/6-311G (d) level. For the lowest energy structures, the stabilities and spectrum properties are investigated. The calculated results indicate that the most stable structures of Mg2Sin clusters favor the three-dimensional structures when n≥3. The impurity magnesium atoms in the Mg2Sin clusters can reduce the chemical stability of silicon cluster with small size. Mg2Si4 and Mg2Si6 are the magic numbers. The number of the infrared vibrational peak for Mg2Si4 cluster is only one, but the Raman vibrational peaks are much more. The Mg2Si4 cluster exhibits strong Raman activity at higher frequency band. On the contrary, Mg2Si6 cluster has more Raman vibrational peaks and one infrared vibrational peak, it exhibits strong infrared activity at the whole frequency band.

Edge enhancement and extraction of biological samples′ images are one of the key technologies for the processing of medical images, and the basis of samples′ morphological analysis. In general, the realization for image edge enhancement is through post processing of original images by computer programming. However, spatial differential confocal microscopy system has been applied to directly obtain the high resolution and contrast edge enhanced microscopic images of samples while the confocal microscopic images are obtained. The biomedical application is demonstrated not only for edge enhancement imaging for a mask and a resolution test target (RTA-07) that shows the resolution of the system is 1.5 μm, but also for edge enhancement imaging for biological cells like RBCs and oral epithelial cells. The obtained edge enhanced microscopic images can be used for simply sample morphological analysis and calculation, such as the scale and area, which has a practical application significance in the research of biomedicine.

In order to resolve the contradictions between large exit pupil, wide field of view (FOV) and lightweight, small size, a helmet mounted displays (HMDs) system is designed, using freeform surface described by radial basis function. The principle that radial basis function describes freeform surface is introduced, and the approaches for aberration correction are analyzed. A new way is tried to determine a starting point of optimization quickly while designing. At last, the imaging quality of the optical system is analyzed. A HMD with 45°×32°, 15 mm pupil, 50 mm eye relief is designed. The modulation transfer function (MTF) value is more than 0.6 within the entire FOV at the Nyquist frequency. The magnitude of maximum distortion occurs at (-22.5°, 16°) in the field and it is measured in simulation to be -1.54%. The size of the system is 56 mm×128 mm and the weight is 136 g. The design results show that the optical system of HMDs has low aberration, and it can provide user clear symbol or video images. This HMDs system, which has good image quality, small volume, and light weight, can be applied to the next generation avionic HMD technology.

In order to meet the requirements of uniform illumination of near-field on the lateral panels for double side LED light box and double side LED flat light, a free-form LED projector with cylindrical lens array is presented. According to the edge-ray principle based on the non-imaging optics theory, the surface shape of the projector is designed by using the direct method and overlapping, and the Lambert light source of the LED is redistributed under the action of the reflection rotation surface, refraction rotation surface and the cylindrical lens array. The cylindrical lens array free-form surface projection model of the lateral near-field uniform illumination is established, and TracePro software is used to simulate the designed model for ray tracing. The results show that the luminous efficiency is 96.03% without considering the reflection loss, and the uniform illumination with the projector of the lateral panel sized 240 mm×360 mm is 95.6%.

In order to realize the engineering application of optical system computer-aided alignment and reach the goal of spatial location error correction for optical elements according to the misalignment by calculation, a method of transition between the misalignment by calculation and alignment quantity of adjusting mechanism is presented. Coordinate transform and least squares optimization algorithm are used to establish the misalignment-alignment quantity relation model. The coordinate datum transform between them are finished. Simulation results show that the accuracy of translational alignment quantity can reach 10-6 millimeter order and the accuracy of angular alignment quantity can reach 0.02″ order, which are calculated by self-compiled program according to the method. The accuracy of calculation is much higher than the accuracy needed for optical system computer-aided alignment. In the simulation of alignment, compared with the result of alignment on the basis of misalignment by calculation, the result of the method is much better. For different chucking methods of optical elements and adjusting mechanisms, related parameters of the method can be assigned to meet the requirements of different working conditions. The method provides the reference basis for engineering application of optical system computer-aided alignment.

Wavefront coding is a new imaging system based on optical digital mixed techonology. By using the modulating action of the cubic phase mask on the stop, the point spread functions (PSFs) of the system in a certain scope nearby the image surface will be the same; then the sharp image will be acquired by using the image deconvolution algorithm in a certain depth range of the field of the system to extend the depth of field. A novel design method of wavefront coding microscope on the basis of the traditional microscope is proposed. The 10×, 40× wavefront coding microscope system is designed and manufactured. The wavefront coding microscope system based on the traditional microscope system can extend the depth of field and improve the imaging quality effectively.

With the uprating requirements of space remote sensing, the aperture of the remote sensor is getting larger and larger. The influences of both the support of optical elements and gravity deformation on the optical system are difficult to conquer. Therefore, it is necessary to compensate the descending optical performance which is caused by the surface error of the primary mirror by means of adjusting the position parameters of the optical elements on-orbit. A large aperture coaxial three-mirror optical system is introduced. The variation of primary aberrations caused by tilting, off-centering and varying of axial position of the secondary mirror are theoretically analysed. The on-orbit compensation ability of the secondary mirror is deduced consequently. Zernike polynomials are used to simulate the surface error of the primary mirror. The spherical aberration, coma and the astigmatism of the primary mirror are compensated respectively by adjusting the positional freedoms of the secondary mirror, which are proved by both simulation results and feasibility analysis. The results show that the adjustment of the positional freedoms of the secondary mirror can compensate both the coma and some astigmatism of the primary mirror, but a little spherical aberration.

In order to improve the accuracy of surface testing by long trace profiler (LTP), a LTP with wavefront equal-optical-path multiple-beam splitter is proposed. This structure can separate the incident beam into several coherent beams with equal-intensity and zero optical path difference. The position and the intensity distributions of the interferential fringe on focal plane of the Fourier transform (FT) lens are analyzed in theory. The effects of parameters of multiple-beam splitter on the width and amplitude of zero grade interferential fringe and the amplitude of secondary maximum interferential fringe are discussed. A new beam splitter based on multiple-beam interference is designed by choosing appropriate parameters, and compared with traditional beam splitter by simulation. The collimator and FT lens in the measurement system are designed. The complete optical model is established in Zemax and verified by experiment. The results show that multiple-beam interference LTP can realize the measurement of the slope of the surface under test. The width of interferential fringe on the detecting plane is smaller than traditional double-beam interference, and the intensity is more concentrated. It can improve the accuracy of the LTP measurement.

The lighting advantages become more and more obvious for the white high power light emitting diode (HP-LED) as the next generation lighting source. But the light decay mechanism is complicated because of the compositions of the LED chip, YAG phosphor and even the thermal management of packaging. In order to investigate the light decay mechanism of the white HP-LED, the effects of temperature on the silicone-gel with phosphor, YAG phosphor particles and the silicone-gel are studied, respectively. The optical properties of the blue LED chip are kept in steady state by the HP-LED substrate temperature controlling. The silicone-gel with phosphor, YAG phosphor particles and the silicone-gel is heated by a heating source respectively. The tested results show that the optical radiant power decreases as an exponential relation with the temperature increasing from 27 ℃ to 220 ℃. The thermal properties of the phosphor layer coated on the HP-LED are studied. Results show that the phosphor layer coating can affect the radiant power and the pn junction temperature of the HP-LED. The above results show that the white HP-LED is a heat source interacted both with the LED chip and the YAG phosphor particles.

Using the mid-infrared absorption property of methane molecular at 3.31 μm, a portable methane detector is designed and developed. Long-term measurement on the output voltage is performed under the sample gas with volume fraction of 0×10-6 to study the device′s stability. The results show that, because of environmental temperature change, semiconductor electronic components′ parameters, optical components parameters, and methane molecular absorption coefficients all drift. To suppress the effect of temperature change on detection performances, the relationship between the output sensing voltage and ambient temperature is studied experimentally, and voltage shift caused by temperature drift is compensated. Experimental results after temperature compensation show that, the variation range of output sensing voltage can be reduced weekly from 1% to 0.46% under the sample gas with volume fraction of 0×10-6, and the gas volume fraction value can be dropped from 86×10-6 to 37×10-6. The Allan variance of the detection device is also plotted for the sample gas with volume fraction of 3250×10-6. The Allan variance value almost tends to be a constant when the sampling period is longer than 500 s, and the standard deviation value is less than 10×10-6. Therefore, by virtue of temperature compensation, the effect of environmental temperature change can be well eliminated, and the instrument′s stability can thus be improved.

Entangled optical field generated by a non-degenerate optical parametric amplifier (NOPA), has been considered as an important resource of continuous variable quantum information research. With the development of quantum networks and quantum computation, multi-partite entangled states with more sub-modes are required to complete more complex research of quantum information. Generally, Multi-partite entangled states can be obtained by means of coupling several Enstein-Podolsky-Rosen (EPR) entangled states or squeezed states with classical coherence through different beam splitters. The threshold of the NOPA is reduced from 250 mW to 45 mW by using a wedged nonlinear crystal. When pumping power is 23 mW, the correlation noises of quadrature amplitude and quadrature phase of the EPR entangled optical fields are 5.5 dB below the corresponding quantum noise limits. Thus we can pump much more NOPAs with only one laser source and obtain the multi-partite entangled states as needed.

During the imaging process of space camera, small fixed gains are often used to avoid image saturation. As a result, obtained images have problems such as dark as a whole, short of digital number levels. An automatic on-orbit adjusting gains method of space camera based on lighting conditions is put forward. In this method sun zenith angle at substellar point is calculated in real time according to current position of spacecraft and time. Function relationship between sun zenith angle and radiance at entrance pupil of space camera corresponding to maximum reflection index of targets is established by non-linear curve fitting. In this way real-time calculation and adjustment of gains are realized. Results of contrastive experiment with results of simulation by satellite tool kit (STK) and computation by MODTRAN indicate that radiance fitting errors are no more than 0.3 W/(m2·sr) as sun zenith angle belongs to [20°,70°].Relative errors are no more than 2.2%. Difference error between calculated sun zenith angles and those simulated is about 0.39°(3σ). Results of on-orbit imaging experiments indicate that digital number levels are improved from 98 to 183 and entropies are improved about 19.2% after adjusting of gains as sun zenith angle is 62.5°. Targets will be easier to be recognized as more digital number levels can be obtained.

In synthetic aperture imaging ladar (SAIL), laser space-time speckle effect severely reduces the image quality. Based on the previous research about space-time speckle effect, integrated speckle characteristics are first investigated, and the physical model of integrated speckle over antenna aperture is established. According to simulation results, two-dimensional distribution of antenna-integrated speckle field is first presented, and its dependences on the scale and the initial position of receiving antenna are analyzed by specific examples. We also find the rational scale of receiving antenna and the preferable integration area to the space-time varying speckle field. Consequently references on the design of the rational receiving antenna, which could partly suppress the speckle effect, are provided, and it is meaningful to study how the space-time speckle effect degrades the visual quality of the SAIL image.

For the nonlinear, non-stationary and weak radar life signal with serious noise interference and multiple singularity points, denoising is the essential means before analyzing the useful signal. The radar life signal model is established based on the principle of Doppler effect and the statistical characteristics of noise. Wavelet transform and lifting wavelet transform are applied respectively on the radar life signal under strong noise background for denoising. The results show that for radar life signal under strong noise pollution, it is an efficient denoising method to use wavelet transform or lifting wavelet transform. The lifting wavelet transform denoising effect is better than traditional denoising methods of wavelet transform. The signal-to-noise ratio (SNR) and mean square error (MSE) are higher than those of traditional wavelet denoising. In the radar life signal denoising, the wavelet basis function is sym8 and the number of decomposition layers is 3.

According to the application requirements of criminal investigation and material evidence, a kind of large aperture ultraviolet (UV) Fourier transform imaging spectrometer is developed which works in the wavelength range of 254~380 nm. The time-spatial modulated structure with high flux is used for the prototype to overcome the problem of insufficient energy in existing systems. The prototype uses image plane interferometer combined with Offner imaging lens to achieve approximately linear distribution of optical path difference (OPD) on raw interferogram. The maximum OPD can be achieved as large as the spatial modulated interferometers in UV band, and the maximum resolution of wavenumber is 80 cm-1 in theory. As the front objective lens and the UV beam splitting cube are made of fused silica and the imaging lens is catoptric, the transmittance is high in the whole working waveband. The experimental result shows that the raw interference pattern can be taken by the prototype on the short wave end. The spectral image data cube can also be taken and rebuilt correctly. The prototype can identify the emission peak at 365 nm when the mercury lamp is used as the illuminator.

The system performance index of spatial heterodyne spectrometer (SHS) influenced by elements tolerances, which include the angle tolerances, thickness tolerances, index of inconsistency and so on, is analyzed through processing interference images with non-sequence model of spatial heterodyne spectroscopy. Following the grade of the manufacturing tolerance put forward by non-sequence model, and incident spectrum of SHS recovered by Fourier transformation, the prototype instrument of SHS is built and tested in the laboratory, and the performance characteristics are verified. The goal is to design an interferometer that all components do not need any further position or angle adjustment. According to distribution results of tolerance by analysis, the instrument is produced, and the results show that the instrument performance indexes are in agreement with the theoretical characterization.

The pearlitic heat resistant steel 12Cr1MoV is chosen as the research object. Different microstructure samples are made by different heat treatment processes. The microstructures of these samples are pearlite and ferrite, lath martensite and a small amount of residual austenite, martensite and sorbite. The spectral intensity of laser-induced breakdown spectroscopy (LIBS), plasma temperature, electron density and the relation between microstructure and the ionic to atomic spectral line intensity ratio of Fe element are compared and analyzed. The experimental results show that the spectral intensity of martensite is strongest, the spectral intensity of ferrite and pearlite is almost similar to that of lath martensite and a small amount of residual austenite, the spectral intensity of sorbite is weakest. The plasma temperatures of samples are almost consistent. The electron density of martensite is the maximum and those of remaining samples are similar. There is a certain correlation between Fe ionic and atomic line intensity ratio and microstructure, which indicates that LIBS has the potential to be used as detection tool of microstructure variation of heat transfer surfaces in power plant boilers.

Raman spectral characteristics of ammonium sulfate solution are studied experimentally and several typical Raman peaks of SO2-4 in ammonium sulfate solution are obtained. There is a linear relationship between the concentration of SO2-4 and the corresponding Raman peak intensity. A relational database between the Raman spectral parameters and the ion concentrations is built according to the experimental results. In order to validate the experimental results, the geometry of SO2-4 is optimized and the vibrational frequency of the ions is calculated by Gaussian 03 and Hartree-Fock methods (ab initio calculation). Through the comparison between the theoretical vibrational frequency and the experimental results, it is found that the experimental results and the theoretical calculations coincide quite well. The results confirm the feasibility of Raman spectroscopy for the quantitative analysis of ammonium sulfate. It also has some reference value on identifying ammonium category, measuring different salt content precisely, producing ammonium salt and so on.

The level characteristics of H2S molecular Rydberg series have been studied with the method of resonance enhanced multiphoton ionization spectroscopy (REMPI) in the range of 484~520 nm, in which the third harmonic output (355 nm) of a nanosecond pulsed Nd:YAG laser excited dye laser is used as excitation source. The result is that regular series include two sets of spectral peak series nested in the way that the spectral peak interval appears twice changes with the increase of the wavelength. It is clear that this spectral peak series corresponds to the Rydberg series. Based on low-lying excited electronic states and potential height Rydberg sequence, this ionization process has been confirmed five photons ionization (four and one). Now the strong spectral peak series has been assigned to the H2S molecule in concentrating to state np (n=5, 6, 7, 8) Rydberg series, and the weak spectral peak series has been assigned to the H2S molecule in concentrating to state ns (n=6, 7, 8) Rydberg series. Quantum losses of the two sequences are δ1=0.92 and δ2=1.52. The results are important to study the optical detection and spectroscopy characteristics of H2S molecules.

Modeling and simulation of multi-alkali photocathode have been studied. The stucture of photocathode is employed with layered model: Na2KSb+K2CsSb+Sb·Cs dipole layer. Effects of the thickness and doping concentration of each layer on the energy band and spectral response character have been discussed. The result shows that when the N-doping concentration in the K2CsSb and Sb·Cs layers is heavier, it can effectively lower the electron affinity, which will be helpful to the transport and escape of the photoelectron. The doping concentration of Na2KSb is not that the higher the better, which comes from the effect of doping concentration on build-in electric field intensity and range. The diffuse distance of electron will get further when under higher build-in electric field intensity, which can make electron have higher probability to reach the surface of photocathode. The highest sensitivity is got when doping concentration is about 1016 cm-3. Influence of thickness on sensitivity is analysed, for a certain wavelength incident light, there exists the optimum thickness. Under the impact of the build-in electric field, different doping concentrations have the corresponding thickness. With higher build-in electric field, the optimum thickness enhanced, meanwhile. For 700 nm incident light, when doping concentration is 1017 cm-3 or 1016 cm-3, the optimum thickness is 80 nm or 200 nm, respectively.