There exist various of fog drop size distributions in advection fog and radiation fog, which result in the different attenuation performances as light propagates in fog field. Mie theory can describe the scattering and attenuation of aerosol particles in fog field, while light propagation follows the principle of dynamic particles conservation. In this paper, fog drop size distribution is applied to modify the scattering phase matrix of aerosol particles, and the scattered light′ s polarization can be solved when infrared light penetrates into aerosol particle clusters. The results show that aerosol particles′ depolarization mainly depends on fog drop size distribution, fog drop refractive index, absorption coefficient and incident wavelength. In the forward-scattering area, depolarization decreases as visibility increases, while the opposite trend occurs in most backwardscattering area.

The magnetic field in fiber optic gyroscope (FOG) will cause Faraday effect, resulting in Faraday phase error. Experimental results show that the axial magnetic field sensitivity is more obvious than the radial magnetic field sensitivity. The clockwise (CW) and coienter- clockwise (CCW) light which propagate in the polarization maintain (PM) fiber in Fiber- optic gyro will generate a nonreciprocal phase error associated with axial magnetic field. In this paper, the geometrical axial magnetic field sensitivity caused by helically wounded optical fiber is studied; coupled- mode theory and finite element analysis are used to induce the FOG′s specific expression of Faraday nonreciprocal phase difference generated in axial magnetic field. The simulation analysis is given based on the theoretical results. Research show that circular birefringence caused by the geometrical torsion in the fiber of the fiber coil is the main causes of the geometry Faraday phase error. Furthermore, the study results show that axial magnetic field sensitivity will increase with decreasing radius.

A multiple ground stations scheme satellite-to-ground laser communication is proposed with the geographical distribution of cloud cover and climatic features considered. The effect of attenuation caused by atmospheric scattering and atmospheric turbulence is analyzed for different paths from geosynchronous earth orbit (GEO) satellites to five ground stations. Link characteristics between the GEO satellite and the five ground stations are simulated using the satellite tool kit (STK) software. The results show that Ali region in Tibet has the best longitude and latitude conditions with a horizontal angle of 52 °, which is most beneficial to laser satelliteto-ground communications. The power attenuation shows a decreasing trend as the wavelength increases due to scattering under the same weather conditions. The optical power attenuation is intensified as visibility falls. The average power attenuation caused by atmosphere decreases along with the rise of horizontal angle. The longer the wavelength λ , the smaller the scintillation index; the scintillation index decreases rapidly when the diameter of receiving aperture increases; the scintillation variance is improved as altitude increases. The analysis is helpful with field experiments of satellite-to-ground laser communication.

Taking the photoelectric tracking and measuring system visible light camera lens as an example, through simulation analysis for the camera lens, the reason leading to the stray light spot is found. With the carrying out stray light suppression design, and comparing with the testing result of actual optical system, it's proved that the software analytical method is reliable. By building model for optical system，the scattering paths are ascertained. For each off-axis angle within 2° to 3°, stray light analysis is conducted respectively to identify the main stray light source. Comparing the result of analysis with the testing results of actual optical system, the analysis is proved to be correct. Then the structure of system is modified, and suppress stray light is suppressed. The simulation results show that when the off- axis angle is between 2.20° and 2.65°, stray light takes shape an obvious spot in the center of the image, and point source transmittance (PST) is 2.92 × 10- 4. By modifying the structure, the stray light spot is eliminated, and the PST is reduced to 3.53 × 10- 5. Stray light spot and its source, obtained through software analysis, are the same to the testing result, which proves the correctness and accuracy of the software analytical method.

In order to achieve the space target detection and identification based on the satellite photoelectric imaging system, an image processing system is designed with combination of a leading processor digital signal processor (DSP) and an auxiliary processor field programmable gate array (FPGA). A method of the satellite targets recognition is put forward. The targets are detected with the modified differential method in sequential images on the starry background, in the absence of a priori knowledge conditions. The satellites are identified with the minimum distance classifier and their templates are acquired based on the different profiles of the satellites and natural stars. Therefore, the rapid detection and identification of the satellite targets can be achieved via the template matching algorithm. Experimental results show that compared with traditional method, the running time is reduced by 15%~40%. It satisfies the accuracy and real-time requirement of satellite target detection and identification with practical value.

To decrease the frame frequency requirements of space-borne imager and improve the hyperspectral imager′ s observation ability of a dark object, motion compensation model and its engineering computation realization method are proposed. Firstly, The motion compensation theory of hyperspectral imager is introduced. Furthermore, The motion compensation model according to the uniform speed compensation method on the hyperspectral imager′s focal plane is established. The max observation time and interval are also presented in this paper. Finally, the optimized engineering computation method of the mathematical model is indicated.

Projecting a binary encoding sinusoidal grating calculated by the error diffusion algorithm can not only solve the problem of the effect on nonlinearity of a digital projector but also improve the projection speed by taking the advantage of binary high-speed switching characteristics of digital micro-mirror in digital light processing (DLP) projectors when a digital projector is used in the optical measurement system. As insufficient resolution of projector can degrade the quality of the electronic binary encoding sinusoidal fringe pattern, it influences the measurement accuracy further. Two typical encoding algorithms of error diffusion (Floyd-Steinberg distance weighted and Serpentine raster Sierra Lite) are firstly compared. Then, aimed at the problem that the quality of sinusoidal grating is not good enough to be suitable for the high accuracy measurement when high density binary encoding grating is projected by a DLP projector with lower resolution because of the less number of the sampling points in a grating period, two resolutions are proposed: One is that a cylindrical lens is introduced in the light path of the measurement system to smooth the resulted binary encoded sinusoidal grating along the grating line direction by the optical convolution operation of the lens. The other one is that superimpositing multi-frame binary encoding sinusoidal gratings with different microstructure is used to reduce the standard error of the binary encoding sinusoidal grating and guarantee the accuracy of phase-shift measurement method. The proposed method not only takes the advantage of high-speed characteristics of DLP projectors for projecting binary images, but also improves the sinusoidal characteristic of the binary encoding sinusoidalgrating caused by the limited resolution of DLP obviously. Simulations and experiments both verify the validity of the above two methods.

When a light beam passes through the liquid, there will be a shading effect for the total reflection at the interface between the liquid and the air, which can be formed into a round shading pattern, and the radius of the shading pattern is concerned with the liquid refractive index. Based on this principle, a device of measuring seawater refractive index is established with He-Ne gas laser as the light source, and the shading pattern is detected by a digital camera with high resolution. The refractive index of seawater is calculated by MATLAB digital image processing program. Furthermore, the relation between the refractive index and the temperature is investigated, the results indicate that there is a linear relationship between seawater refractive index and change of the temperature. Research results show that the method is characterized by its easy achievement, good repeatability and high measurement precision, the application of seawater refractive index measurement is feasible.

A novel smoke detection system using laser is developed to measure the smoke concentration in real-time and quantitatively. A linear relation between transmitted light and scattering light of laser through the smoke is established based on the design of lateral scattering optical structure and the circuit of digital signal processor as a core. According to this linear relationship, the transmitted light is converted to the scattering light, and then the concentration of smoke is calculated. In this way, the computational complexity is reduced, and the problem of measuring low concentration smoke is solved. Finally, compared with existing product, the result shows that this proposed system is simple in structure, stable ,real-time and has good economic benefits.

In recent years,quantitative phase imaging is widely used in biological tissues and cell imaging. At first, used laser or superluminescent diode is used as the light source in quantitative phase imaging. Now it mainly adopts the white light to image, as it can overcome the influence of speckle and improve the axial resolution. In this paper, the principle of low-coherence interferometry techniques is introduced. Diffractive method with 16 order binary grating is utilized to realize the green light gamma correction of the Holoeye Pluto digital electric-addressed liquid crystal spatial light modulator, and the linear relationship between phase and gray is obtained. An experiment setup is constructed (SLM), the gamma correction and the quantitative phase imaging can be completed in the same setup. The actual size of the phase ring is calculated in the 20× objective of the Olympus, and four phase grating rings are made, their phase corresponding to 0, π/2 , π and 3π/2 . The four phase grating rings are loaded on the liquid crystal SLM to complete the phase modulation of the scattered light. It shows that the green light can be applied to spatical light interference microscopy (SLIM), and realizes the SLIM observation. It has certain significance for the SLIM study in the future.

The experiment of laser cooling of molecules generally needs multiple lasers with narrow linewidth and passive-stabilized frequency. We propose to use Pound-Drever-Hall (PDH) technique to lock the cooling laser onto the diode laser stabilized by the saturated absorption spectroscopy of Rb atom through the transfer optical cavity. The linewidth and long term drift of the cooling laser frequency could be controlled. The Fabry-Parot (F-P) optical cavity is designed and made, and the optical stabilization system is set up, and the optical transfer cavity is locked onto the reference laser through PDH technique.

Combing the theory of coherent beam combination (CBC) and the technology of beam steering by liquid crystal optical phased array (LCOPA), a method of CBC based on array of LCOPA array is proposed in this article. On the basis of explaining this kind of CBC theory, combined beam is researched from three aspects: beam direction, intensity and beam quality. Analysis results indicate that the reason for error of beam direction is the discontinuity of maximum points of array interference factor. Based on the results a measure to induce error by adding array space is adopted. Then some special beam directions at which the peak intensity matches theoretical value are screened, which are the coincident points of maximum values of electrode interference factor and array interference factor. Furthermore, numerical simulation indicates that this CBC method makes a certain contribution on improving beam quality. Finally, experiments of CBC based on 1 × 3 and 2 × 2 array of LCOPA are carried on and combined beams with beam directions of 0° 、0.17° 、0.34° are obtained. This experiment proves the validity of theory analysis and the feasibility of CBC based on array of LCOPA.

Based on the process of laser cladding Al/Ti composite powder above 7050 aluminum alloy, and by using an orthogonal experiment, an optimized cladding coating parameters are achieved with the laser power of 1.5 kW, the scanning speed of 150 mm/min and the defocusing amount of 50 mm. The highest temperature in the laser spot center is obtained from the simulation under the parameters in the orthogonal experiment. Using the range analysis, the relative significances of the three respective parameters, laser scanning speed V, laser power P and defocusing amount S are achieved in the order, from big to small. By analyzing sizes of the molten pool and several typical curves of sample temperature changing with the scanning direction in the condition of the orthogonal experiment, it has been discerned that the bonding strength of the sample front is poor because its molten pool depth in the substrate is too small to obtain a good combination between the cladding material and the substrate; moreover, the deformation and ablation occur at the sample end due to the substantial temperature accumulation origining from its poor heat dissipation. The grain morphology of Al/Ti cladding coating is mainly cellular dendrites with equal and dense distributions.

In order to solve the discharge instability problem caused by bulk mass and high gas pressure in a fast axial flow (FAF) CO2 laser, a preionization device is presented. The device is installed outside the laser discharge tube and the preionization electrode includes an anode of laser discharge tube and a 35 mm far copper collar. A multivibrator, a RC charge-discharge circuit, and an SCR are combined together to make up the preionization circuit with the discharge frequency of 10～20 kHz for the purpose of strengthening the initial electron density and reducing the laser firing voltage. The experimental result indicates that the preionization device decreases the laser working voltage by 1.69 kV and voltage varicance by 2.6 kV. Such a preionization device can meet the preionization requirement of an FAF CO2 laser and is an effective tool for improving laser′s discharge stability.

The selective laser sintering (SLS) is one of the important 3D printing technologies. In the sintering process of the polymer material the uneven shrinkage will cause warp and decrease the size of parts. The SLS processing parameters playing the major influence are discussed. Based on the theory of the gray relational analysis (GRA) in the SLS experiment with the polypropylene (PP) composite powder, the results show that the most important parameter is the scan speed. Considering the comprehensive effects of the warp and molding accuracy, the optimized fabrication parameters of the forming process are got as follows: the scanning speed is 1.9 m/s, the laser power is 16.5 W, the scanning width is 0.12 mm and the single layer of powder is 0.15 mm.

Because a lot of defects will be formed in thick cholesteric liquid crystals (CLC), which destroys its photonic bandgap structure and dramatically reduces the transmissivity, its applications in photonics have been dramatically limited. In order to overcome this problem, we developed a method to improve the alignment of the liquid crystal (LC) molecules in the CLC sample. The procedure is as follows: firstly, high enough AC voltage with 1 kHz is applied to swithch on the CLC sample. After switching on and off the sample at this voltage for several times, massage is done on the CLC surface for a while. The results show that after massage, the defects inside the CLC sample can be dramatically reduced, therefore the planar structure of CLC is greatly improved, and the transmission is drastically increased. It indicates that this method can be used for fabricating thicker CLC samples. Above all, it provides a useful fabrication basis for the CLC′s applications in photonics.

The photoelectric characteristics of solar cells can be changed after heated, which ultimately influence the converting efficiency of solar cell. Electroluminescence spectra of GaInP/GaAs/Ge triple junction solar cell under constant voltage are investigated in order to understand the working properties of such cells under concentration and heating condition. It is found that the luminescence peaks of GaInP top cell and GaAs middle cell change and reverse after the solar cells are heated. By considering the current-voltage characteristic and external quantum efficiency, the origin of this phenomenon is found to attribute to the introduction of deep level defects in the crystal. GaAs middle cell is found to be more tolerant to heat-induced damage than GaInP top cell.

In order to find a more simple and effective method to solve the formula of the all lens elements movable zoom lens, in this article, the computer program is adopted. With the given initial parameters (magnification of all elements、distance), the initial data are computed for the target optical system and the system data are optimized using the restrictive conditions (two tangent data difference、curvature of the zoom curve and total length of the system) as the command. Then the optical- power distribution which satisfies the condition is given out and the data of the optical system are computed. In order to test the practivity of this method, a four movable components zoom lens is designed as an example by using the initial data, given by the computer program, on the optical design software. Comparing the data of the optical power distribution with the Zemax simulation results, we find they agree well with each other, which proves the practicality of the method.

Based on the third order aberration theory, a merit function is established, genetic algorithm is employed to find the initial structure parameters with minimum merit function then the initial structure is loaded to ZEMAX for further optimization. A telecentric three- mirror reflective system with effective focal length of 1700 mm, entrance pupil diameter of 200 mm and field of view of 18°×0.6° is designed by making the yfield off axis. The performance of the system is close to the diffraction limit and it is unobstructed and suit for the field of space optical remote.

In view of the difficulty in improving the irradiation uniformity of the current solar simulator, the paper introduces a new type of cluster- type optical integrator. The process of the cluster- type optical integrator based on the theoretical analysis of the symmetric optical integrator is introduced. The solar simulator optical system is simulated with LightTools software. The results show that: after using the cluster-type optical integrator, the irradiation non uniformity of solar simulator is significantly improved, irradiation non-uniformity in the range of Φ 50 mm is less than 0.2%, and in the range of Φ (50~120) mm is less than 1.5%. The results satisfy the requirements of high irradiation uniformity.

Resonant cavity enhanced Ge film photodiode on Si substrate is proposed, and the effect of the pair value of Si/SiO2 forming the top and bottom mirrors, thickness of the Ge absorption film, and mesa area of the active zone on the characteristics of the device such as external quantum efficiency and bandwidth is theoretically calculated. The optimized structure is as follows: the pair value of Si/SiO2 is 2 and 3 for top and bottom mirrors, respectively, the thickness of Ge film is 0.46 μm and the mesa area is less than 176 μm2 . Under this condition, an external quantum efficiency of 0.64 at a wavelength of 1.55 μm , which is 30 times larger than the conventional one, and a bandwidth of 40 GHz are achieved.

Layered light-emitting diode (LED) of GaN photonic crystal (PC) with periodic air holes is studied. Photonic band structures of the photonic crystal are obtained by plane-wave expansion method. The effects of air-hole radius on band gaps are analyzed, and the results show that the widest band gap is 21.5%. A point dipole polarized in the x-y plane is located in the center of the second GaN layer and is excited by a Gaussian pulse profile for the wavelength of 450 nm. Based on the three-dimensional finite-difference time-domain method, extraction efficiency of the LED is obtained. The effects of the PC thickness and air-hole radius on relative extraction efficiency of layered GaN-LED are analyzed. The results show that the maximum relative extraction efficiency of 2 can be obtained with the optimal structural parameters.

The light propagation manipulated by surface plasmon polaritons is applied widely in micro-nano integrated optics and optical communication. The model of metal slit array structure with liquid crystal filled in the slits is proposed. Using surface plasmon′ s transmission effect, several novel metallic micro-nano optical lens are designed by setting the slit width and director angle of liquid crystal. The finite-difference time-domain (FDTD) method is adopted for numerical simulations of three slits, six slits and five slits array structure. The results show that three functions of the light deflecting, light splitting and light focusing are achieved. The deflecting angle, splitting angle and focus length can be manipulated, and the light propagation controlling can be reached by changing the slit width and director angle of liquid crystal. This design has a good application prospect for its simple structure and easy frabrication by experimental equipment like electron beam lithography system.

Most methods used in virus and bacterium detection are based on confirmation of reactions between unknown samples and known probes. Since several bacterium species can survive in one sample, these methods have to be used to perform detections one by one with different probes, Which are with low efficiency. An experiment using mixed probes to detect two blended proteins at the same time is designed. By monitoring the binding curves of these two probe-target reactions with an optical reflectivity difference method, it is explicit whether there are two different proteins in the sample. The demonstration experiments show potentials of this method for higher throughput detection of viruses or bacteria.

The state of the art of high repetition rate mode-locking technology is introduced. Recent developments of high repetition rate mode-locked solid-state laser are described briefly, followed by a detail review of examples. Mode-locked solid-state lasers are known with high output power, high repetition rate and good stability. Scaling up the repetition rate of solid-state lasers may not only benefit optical metrology and provide a new time-frequency reference, but also find applications in space communications, laser radar and other research fields.

The key problem in the satellite-to-ground laser communication is primarily to mitigate the effect of atmospheric turbulence. After propagating through the atmosphere with a long distance, the wave-front distortion of signal light brings about the degradation of bit error rate (BER). The experimental development of the satelliteto-ground laser communication based on the domestic and abroad research progress is described. Some effective methods and discusses to overcome the turbulence effect on the high rate communication are presented. Finally, coherent detection technology based on interference principle and differentical phase shift keying (DPSK) modulation is emphatically analyzed in the phase demodulation, and the advantages are summarized. It is predictable that this technology will become more practical and play an important role in its application areas.

With the development of integration technology, all kinds of integrated optoelectronic devices based on nonlinear optical waveguide become current research hotspots. However, the low level of nonlinearity characteristics of traditional substrate materials has been the primary problem for the development of optical waveguide devices. The research status of the third-order optical nonlinearity of chalcogencide glasses is introduced, and the research results show that nonlinear response time can be up to femtosecond, which is attributed to the distortion of chalcogencide atoms under bright light, and nonlinear refractive index has significant correlation with homopolar metallic bond. The research progress of chalcogenide optical waveguides is reviewed on substrate classification, manufacture process and nonlinear application. Considering the existent problems in the current research, it is proposed that the environmental substrate material, perfect manufacture process and new-type optical waveguide devices are the directions of the future study.

Focusing on the sensing parameter, research progress in optical detection of wake in the last 15 years is summarized. The existing four methods of optical detection of wake are concluded, including the continuous laser scattering intensity detection, the imaging detection, the pulse return detection and the polarization detection. The fundamental principles, progress and some problems of the above methods are introduced. The direction of future work is introduced considering problems such as novel sensing parameters, signal processing and anti-interference technology, setting up the database of wake properties and expanding related applications.

For the all optical fiber current sensor, how to carry on the temperature compensation has been the difficulty and focus of research at home and abroad, and it is also the only way to make these sensors to the utility. Examples and data are first used to show the temperature effect on the performance of all fiber current sensor. Then, based on analyzing all fiber optical current sensor principle and structure, the mechanism of each factor which is affected by temperature is illustrated and the latest progress is given. Finally, the effects and the practical advantages and disadvantages of each method are analyzed. Ultimately, it can be drawn: by using a single method to control factors on the performance of all-optical current sensor is not ideal, but through the control of multiple factors and carrying on data processing in the final output are better ways to achieve better temperature compensation effect, so that the output of the entire fiber-optic current sensor is more accurate and more stable.

Elastography is a technique based on Young′s modulus, shear modulus,stain and stress in soft tissue. With the development of optical coherent tomography (OCT), optical coherence elastography (OCE) becomes popular because of its micron meter level resolution, real- time image processing and noninvasive imaging. The classification of OCE, several kinds of dominant OCE and elastography reconstruction are reviewed. The method of applying mechanical load and estimating displacement and strain is discussed. OCE has a great potential in detecting the clinical and pathological mechanical properties, especially in the diagnosis of cancer, cardiovascular disease and eye disease. The research development of OCE is summarized and its prospect is also discussed.

The trapping force of the optical tweezers is studied using T-matrix method when the particle is in sizes comparable with the wavelength of the incident light.The T-matrix depends only on the composition、size、 shape and orientation of particles, independent of the incident field.The basic principles and the calculation methods of T-matrix method are reviewed.The calculations of trapping force and torque of the single particle and two or more particles using T-matrix method are summarized.The prospect provided by T-matrix method for optical tweezers is also analyzed.

In the interaction of ultra-short and ultra-intense laser pulses with the film target, the target-normal sheath acceleration (TNSA) is considered as an efficient acceleration scheme to gain energetic ions and is studied intensively. The reason is that the space-charge field on the backside of the target is much more intense and longer lasting, so the acceleration ions have a good collimation and mono-energetic spectrum. The theoretical model, experimental results and simulation are introduced, then the optimal target structure to generate high quality ion beams is analyzed, and finally the progress of the TNSA at home and aboard is summarized.

Reconstructing the spectral reflectence of the object surface from RGB signals of digital camera is one of the important studies of spectral color managament. A new algorithm based on back propagation (BP) neural network and principal component analysis (PCA) is proposed to realize the spectral reflectence reconstruction of color atlas. The optimal structure of BP neural network and the number of principal components are studied in the spectral reflectence reconstruction experiments of three color atlases and the accuracy of the algorithm is also testified. The experimental results show that the new algorithm of appropriate BP neural network combined with PCA is satisfied to accurately reconstruct the spectral reflectence of the same kind of color atlas.