The field distributions of Lau fringes for two different gratings are theoretically and experimentally investigated. The majority of the methods that are used to deduce the intensity distribution function of the Lau effect are rather complicated, among these, the method based on the cross-spectral density function is relatively easy. The process of deducing the intensity distribution function of Lau fringes generated by double identical gratings is studied based on the method, and the method is tried to be applied in a more general situation, two different gratings. The feasibility of the method in the situation of two gratings with the same grating constant but different duty ratios is discussed, and the simplified intensity distribution functions of two cases, in which the arranged positions of the two gratings are swapped, are achieved. The theoretical predictions are well demonstrated by the experimental results. Thus, the partially coherent theory based on the cross- spectral density function also works in the situation with two gratings of the same grating constant and different duty ratios.

In order to use white LED as a lighting source and communication part，a novel modulation scheme called reverse dual header pulse interval modulation (RDH- PIM) is proposed for indoor visible light communications based on the analysis of on- off keying (OOK)，pulse position modulation (PPM)，digital pulse position modulation(DPIM)，and dual header pulse interval modulation (DH- PIM). The symbol structure,bandwidth requirement and average transmit power are analyzed and compared, and the slot error rate is derived. The simulation results show that OOK has the minimum bandwidth, while RDH- PIM has the highest average transmit power and its bandwidth efficiency is notably better than PPM and DPIM. Hence, RDH-PIM is superior in the optical wireless communication system.

Aiming at the problems and performance shortage of digital pulse interval modulation (PDM), a novel dual-amplitude fixed length digital pulse interval modulation (DAFDPIM) scheme is proposed. The structure of the modulation is described in detail. The transmit power, bandwidth requirement, transmission capacity and error performance are discussed. Then these performances are compared with several other improved DPIM modulation. The theoretical analysis and simulation results show that this novel DAFDPIM can achieve a good balance on various performances and make up the lack of the DPIM with unfixed symbol length. Hence, this novel modulation scheme is superior in optical wireless communication system.

Polarization compensation is one of the key techniques of a polarization encoding quantum key distribution (QKD) system. This paper introduces the principles of polarization compensation by polarization controllers or a bidirectional optical structure. Some typical polarization compensation schemes suitable for polarization encoding QKD system based on optical fibers are sketched, such as an all-fiber polarization compensation scheme based on a bidirectional optical structure, an interrupting scheme of polarization compensation, a time division multiplexed (TMD) polarization compensation scheme and a wavelength division multiplexed (WDM) polarization compensation scheme.

The new indoor location method based on visible light communications has irreplaceable advantages over traditional wireless location methods. As for the new location method, the light distribution has direct impact on the location performance. In the condition of meeting the indoor illumination requirements, the cramer-rao bound (CRB) and the optimal light distribution with the best location performance in a typical simulation environment is inferred, after that, simulation analysis is given using the Gauss-Newton algorithm, and the results demonstrate the validity of the theory.

Aiming at the unstable characteristics of the particle filter algorithm which is easily affected by background noise in complex dynamic scene while it is tracking target, an improved Kalman particle filter (KPF) target-tracking algorithm is put forward. The method of using embedded Kalman particle filter is used to predict the predicted status value of particle filter secondarily. And the secondary sampling technique is used to enhance particle richness, and thus eliminates the influence of background noise to a certain extent. Besides in order to meet the requirements of Kalman on linear motion and to eliminate the effect of rapid background change on tracking accuracy, the gray projection algorithm is promoted to calculate the background migration for motion compensation. The experiment results show that the improved Kalman particle filter algorithm can effectively track the moving object in the complex dynamic scene, which proves that the propposed KPF algorithm has high precision, strong robustness and good real-time performance.

To achieve high- precision passive ranging of binocular CCD over a long distance, two algorithms of cross-correlation matching algorithm and cubic surface fitting algorithm are put forward, to match two pictures by binocular CCD in a sub- pixel level. The ranging principle of the binocular ranging system is introduced, and the ranging images are matched and a grayscale cross- correlation algorithm is proposed based on template.According to the results of cross-correlation, the sub-pixel level matching algorithm that uses the cubic surface fitting method to fit the sub- pixel coordinates of correlation peaks is proposed. The errors of the experimental results are analyzed and the formula of calculating system errors are corrected. Experimental results show that the actual measurement accuracy of a target within 3 km is better than 0.5% , which meets the accuracy requirements of the high-precision binocular ranging.

When a satellite photoelectric imaging system is carried out on detection and recognition for space point target imaging, the point target will produce the phenomena of dispersion and striation because of the influence of diffraction and aberration of the system and the relative motion between the system and the target. A mathematical model of target imaging dispersion is derived based on the visible light reflectance characteristic of space target and the point spread theory of system, and the effect of diffraction and aberration on dispersion characteristic of the target imaging are analyzed and simulated; the relative motion relationship between the system and the target is analyzed. Expression for the striation length on image plane of the target is deduced within single frame integration time, and the influence of orbit altitude and observation angle on the striation is studied. Results show that the aberration makes dispersity increase and intensity of image patch decrease; striation length increases with the target′ s orbit altitude reducing and observation angle increasing under the condition of certain parameters and orbit altitude of imaging system.

Aiming at the influence of compression and transmission on the degradation damage of stereo videos, a reasonable data processing method is designed based on the evaluation data obtained from lots of subjective evaluation experiments, and then the final processed results are analyzed. The method includes three aspects: weeding out abnormal cases, removing abnormal values and averaging values. The experimental results show that this method is obviously better than the traditional Grubbs test. The data of stereo videos processed by the H.264 compression algorithm are analyzed by the method above, and the conclusions are drawn: the quantization parameter (QP) affects the damage degree of video quality; information carried by the reference viewpoint takes a more dominant place; high- resolution videos contribute to the compensation of degradation; the ability of females to accept visual impairment is stronger than that of males. The conclusions provide technical support for the communication technology optimization of stereo videos.

In order to achieve a sub-micron scale displacement adjustment in the field of precision adjustment using the laser bending technology, a laser micro displacement adjustment and measuring platform is built. A fiber laser is focused on the metal sample using f- θ lens and moves at constant velocity in a line direction through a galvanometer. The output displacement of the sample′ s free end is measured in real time. A simple closed- form model of laser micro displacement adjustment is established. The effect of laser power, scanning velocity, defocus distance and position of laser irritating on the output displacement is investigated. The experimental results show that an adjustment displacement with submicron scale repeatability on the metal plate sample can be realized in this platform and the best choice to achieve precision adjustment is to adjust the position of laser irritating. An adjustment with little damage to the sample surface is achieved through optimizing the process parameters.

A three dimensional finite element model is employed to simulate the cladding process of Ni-Cr-BSi coatings on 16MnR steel under different parameters including laser power, scanning speed and spot diameter.The temperature and residual stress distribution, the depth of the heat affected zone (HAZ) and the optimized parameters for laser cladding remanufacturing technology are obtained. The orthogonal experiment and intuitive analysis on the depth of the HAZ are performed to study the influence of different cladding parameters.A new criterion based on the ratio of the maximum tensile residual stress and fracture strength of the substrate is proposed for optimization of the remanufacturing parameters. The results show well agreement with that of the HAZ analysis.

Narrow pulse laser can be obtained from laser diode (LD) pumped acousto-optically (A-O) Q-switched all solid state lasers (SSLs), which is useful in many applications such as laser ranging, laser radar, etc. According to Q-switching rate equation, the relationships between pulse average power, pulse width and inverted population density are explained by theoretical analysis and reasonable model. LD side pumped Nd:YVO4 crystal which is polarized absorption and emission in a flat-flat cavity is used to achieve narrower pulse width. On conditions that the pumped current is 32.6 A, the repetition rate is 33.5 kHz, the cavity length is 62 mm, the transmittance is 50%, the shortest pulse width of 4.4 ns is obtained. On conditions that the pumped current is 31.6 A, the cavity length is 77 mm, a 1064 nm laser output with the pulse width of 5.5 ns and the peak power of 26 kW is obtained. Cavity length, repetition rate and transmittance of output mirror as functions of pulse width have been discussed.

A scheme is investigated that laser with wavelength λf is produced by backscattering of incident laser with wavelength λi and an incident electron beam with its velocity v0 passing through a magnetic field with its period λw . The characteristics of the scheme are as follows. Provided that v0 is large enough, λi-λf.When superconductivity sheets with their gaps cover the waggle magnets, or when incident laser is strong enough, the longitudinal length of effective backscattering region s can markedly decrease. Thus, the laser with its wavelength λf can be realized. A laser resonator parallel with the incident electron beam can produce incident laser with high enough intensity. It is possible that the power of an outputting laser beam is larger than that of an incident laser beam, although the number of the photons of the outputting laser beam is less than that of the incident laser beam.

The challenges for infrared window materials are investigated in consideration of future hypersonic application. Some durable middle- wave infrared materials are compared in terms of high- temperature transmission range, infrared emittance, high- temperature mechanical properties, and thermal shock resistance.Yttria ceramics is considered as the best candidate for hypersonic application, and is possible to satisfy extending request such as multi- color or multi- mode integration, beyond visual range and wide viewing angle,and radar latent or anti electromagnetic disturbance.

An attempt is made to research how does the laser processing parameters impact the width of melted zone in the high carbon alloy steel Cr12 surface using Nb:YAG laser as a heat generating source.The microstructure and chemical composition distribution of Cr12 steel after laser-remelting are observed and analyzed by using optical microscopy, scanning electron microscopy(SEM)and energy spectrometer(EDS). Different widths of melted zone, which are processed by different laser processing parameters, are measured. Hardnesses of laser melted zone are also investigated. The results show that Cr12 steel gets three layers structures, including the melting zone, heat affected zone and the matrix. The microstructure of melted zone has very fine equiaxial crystal and columnar crystal, which eliminats the impurity phase, and the alloying elements are evenly distributed after laser-remelting process. The microhardness of heat affected zone is improved significantly, and the width of melted zone changes along with laser parameters variation and defocusing distance has the most effect on the width of melted zone.

Energy band structure and optical properties of the cubic Ca2P0.25Si0.75 with strain on the (111) surface are calculated by the First Principle pseudo-potential method based on the density functional theory (DFT), and the effect of strain on energy band structure and optical properties is analyzed. The results show that under the compressive strain range of - 8% ~0% , it is direct semiconductor but the band gap decreases with the increase of strain, the conduction band moves to low energy while the valence band moves to high energy; when the tensile strain is 0%~2%, the band gap increases with the increase of strain, when the tensile strain is 2%, the direct band gap is maximum, Eg=0.60441 eV; when the tensile strain is 4% , it turns to indirect semiconductor. The dielectric constant and the refractive index of cubic Ca2P0.25Si0.75 increase with the tensile strain; when the compressive strain is - 2%~0% , the dielectric function and the refractive index decrease; when the compressive strain reaches -2%, the dielectric function and the refractive index are minimum, then they increase with growth of the compressive strain. The absorption and reflectivity decrease with the increase of compressive strain, while they increase with the increase of tensile strain. The energy band structure and optical properties the cubic Ca2P0.25Si0.75 are influenced by strain, which is an effective means to adjust photoelectric transmission performance of cubic Ca2P0.25Si0.75.

Electronic structure and optical properties are systematically investigated by using first-principles plane-wave calculation method based on density functional theory, and the changes in the band structure, density of states and optical properties are comparatively analysed for GaN under pressure. The calculated results indicate that Ga—N bond lengths become shorter, the populations become larger, the covalent becomes stronger and the ionic becomes weaker when the pressure increases. The calculated electronic structure shows that the conduction bands move to high energy direction, while the whole valence bands shift to low energy direction, the band gap becomes wider, the hybridization of 3d states electron of Ga atoms and 2p states electron of N atoms is enhanced significantly. Results of optical properties reveal that absorption spectrum occurs absorption edge near 1.6 eV when there is no stress. With the pressure increasing, the complex dielectric function and absorption spectra of GaN move towards high energy, the absorption spectrum occurs obvious blue shift and the photoelectric conversion efficiency is improved.

The thermoluminescence (TL) properties of high quality 0.5% atom fraction Cu doped YAP crystal (YAP:Cu) which is grown by medium-frequency induction Czochralski method is systematically studied by RisF TL/OSL–DA-15. The research results show that, YAP:Cu crystal has two TL peaks which locates at 431K and 482K, and the 482 K peak is the main glow peak. The peak position does not shift with the change of irradiation dose and belongs to the first- order peak. The TL response of YAP:Cu crystal shows excellent linear characteristics in the dose range of 10- 5- 102 Gy. YAP:Cu crystal is a potential ionization irradiation dosimetry material with excellent TL properties.

In order to meet the miniaturization, portability and wide-angle needs for modern medical endoscopes, an ultra-small medical endoscope lens with a wide angle is designed combining with modern plastic aspherical and injection molding technology and using Zemax optical design software. The lens uses two plastic aspheric lens, whose optical structure is in the form of a negative-positive construction and are located by the sides of the stop. The design result shows that F number is 6.0,the field of view is 150° , the total length of the lens is 3.38 m and the lens diameter is 2 mm. The modulation transfer function (MTF) of all fields at half of Nyquist frequency are more than 0.45. Through the test of the lens, the image is clear and the detail of human internal organization can be well observed, which meets the requirement of medical application.

A hollow ellipsoidal earth simulator optical system emitting ultraviolet (UV) is designed, half of the sphere is illuminated by the UV light source, the other half is not illuminated. It′ s combined into a number of LED components and light array working to achieve the luminescence brightness of 0.2~1.2 W/(sr·m2) adjustable within the spectral range by controlling the UV LED lamps, and the inhomogeneity of surface emitting brightness is better than 20% ; so the geometric and radiation characteristics of the earth under different brightness conditions can be simulated. The composition and working principle of the earth simulator is introduced, the inhomogeneity of the earth simulator′s radiation brightness is analyzed using the optical analysis software called Lighttools, and the deformation of the opto- mechanical structure of the high orbit UV earth simulator at 0 ℃~45 ℃ is analyzed by the finite element analysis software called Ansys. The results show that the inhomogeneity of sphere surface brightness is 9.5%, the maximum average of the radiance is 1.42 W/(sr·m2), the deformation of the optical mechanism influenced by temperature is very tiny and the design requirements are fully satisfied.

Uneven radiant quantity along the radial and different ink curing speeds of all sorts of color ink appear in the process of rotating painting ink UV-curing. In view of these problems, a design using the UV LED with two kinds of different wavelengths is proposed to form a fan- shaped array on a cylindrical surface. The curing system can achieve even curing along the radial, and the technique problem of different colors of ink curing at the same curing time is solved. The simulation result shows that the UV LED curing system meets design requirements with Tracepro and is important for further expanding the application field of UV LED.

Thermal structural optical integrated analysis is an effective way to estimate optical image quality during optical and mechanical design stage. Thermal structural optical integrated analysis of a small lens system is conducted. The results indicate that thermal aberrations of the system are higher, affecting optical properties of the system. Contribution to the thermal aberrations induced by change of refractive index is larger than that by surface deformation. Thermal conductance between the lens and the support structures, air turbulence in the upper and lower windows, and environmental convection of the outer surface of the mechanical structure influence the thermal aberrations finitely, and the primary influence factor is thermal load. Reducing thickness of the lens and absorption rate of materials will decrease thermal load and thermal aberrations of the system decreased effectively.

As the aerospace technology develops rapidly, more requirements on the aerospace optic system are needed. With excellent physical properties, SiC becomes a very promising material for speculums. The mechanism of polishing on SiC mirror surface is studied, the experimental method of SiC polishing is introduced, and the polishing process is analyzed quantatively. The key factors affecting the surface quality of SiC mirror, such as tools, abrasives, load, rotational speed and slurry pH are studied, chosen and optimized by plenty of experiments and theoretical analysis, and better results are obtained.

The traditional lunar simulator have characteristics shortcomings of complex design principles, high cost and poor radiation. In this article, we apply liquid crystal light valve technology to design a new lunar simulator, and focus on the light source of lunar simulator. Application of liquid crystal on silicon (LCOS) optical splicing technology effectively improves the accuracy and simulation capabilities of lunar simulator. Through the control program to adjust LCOS pixel voltage, LCOS modulates the incident light into different states, so it can simulate different radiation characteristics and phases. Simulation results show that: the design of the light source simulated by lunar simulate can simulate the phase diversity, and uneven brightness is good. Using LCOS device simulator effectively improves the control precision, rednces the volume of the simulator compared with the traditional simulator.

Fresnel reflection-based optical fiber sensor for quasi-distributed refractive index (RI) detection using the optical time domain reflection technique as an interrogation method is proposed. Ambient RIs at different positions along the long fiber link can be obtained by monitoring the Fresnel reflection signals. The experimental results show that the measurement range can reach 16 km, and the refractive index sensitivity is from 38.785 dB/RIU to 305.430 dB/RIU (RIU means refractive index unit) when the RI is from 1.3486 to 1.4525.

Since the problem of aero-optics is raised by Gilbert in 1982, the studies of theoretical and experimental indicate: the performance of airborne/missileborne laser energy system and laser information system is seriously reduced by aero-optical aberration. However, the limited bandwidth of feedback control adaptive optics system is not satisfied with the requirement of the high frequency aero-optical aberration realtime correction. Milestone works such as aero-optical mechanism, measurement and correction are reviewed. The objective of the paper is providing the theoretical and technical references for the aero-optical researchers.

The existence of —OH in the heavy oxide glasses leads to enormous loss in mid-infrared region due to worsening optical properties. Thus, removal of water in glass especially for mid- infrared application is a critical step. The effect of hydroxyl groups on the optical, spectroscopic and the optical fiber properties of the mid- infrared heavy metal oxide glass is discussed, the widely used dehydration techniques in recent years(reaction atmosphere process, budding dry gas, fluoride dehydration, chloride dehydration, etc.) are reviewed,their dehydration effects and the research progress are presented, and the status and the development direction of dehydration techniques in mid-infrared heavy oxide glasses are summarized.

In order to carry out the research of adaptive optics (AO), we develop a series of continuous surface deformable mirrors (DM) based on piezo-ceramic actuator, and the controllable number of the actuators of each DM is 21, 97, 137 and 961, respectively. Many in-and out-door AO correction experiments are carried out, in which the DM is used as the wavefront corrector of the AO system, and the experiments reach the expectation. With the 137-element AO system for the 1.23-m telescope, the close-loop correction of the 0.2″ binary star is attained, which approaches the diffraction limit of the 1.23-m telescope at 700~900 nm band. The basic structures of the DM, the testing of each main parameters and key performance of each DM are presented. The applications of each DM in the AO system are also showed. The development and application progress of the DM are presented.

Multi-wavelength erbium- doped fiber lasers (MW- EDFL), which play an important role in dense wavelength division multiplexing (DWDM), have been the focus of optical communications in recent years. The history of MW- EDFL is reviewed briefly. The operating principle of MW- EDFL is reviewed, including the suppression of mode competition to obtain the multi-wavelength output. The principle of comb filters, including the Lyot filter, Sagnac interference loop and Mach- Zehnder interferometer, is discussed in detail. The recent research achievements of MW- EDFL are introduced and their pros and cons are analyzed. Moreover, their promising future is presented.

Terahertz (THz)-wave has brought huge application prospect to the study of basic disciplines, medical imaging and nondestructive testing, for its unique features in spectrum and transmission performance, and it has significant scientific strategic importance. The development process of THz-wave parametric oscillator (TPO) is mainly summarized from several aspects: nonlinear crystals used in THz generation, resonator structures including external cavity, intra-cavity and pump-enhanced cavity, THz wave output coupling schemes, surface-emitted structure, pump light parameters and injection seeding. With the development of new materials and new structures, TPO will play an important role in more fields.

There is an urgent need to develop a rapid on-site green detection technology for the growing heavy metal pollution of fruit and vegetables. Laser induced breakdown spectroscopy (LIBS) is an emerging technology in detecting material composition. In order to verify the feasibility of the detection of heavy metals in leafy vegetables by LIBS this article discusses the application of LIBS to quantitativly analyze trace elements theoretically. With fresh ipomoea aquatica as the sample, the spectra with and without Pb pollution are analyzed using coaxial double pulse LIBS device. Pb 405.78 nm is selected as the spectral line of Pb, seven samples emission spectra are detected, and fitting curve is obtained, the correlation coefficient is 0.9857. Relative error of predicted concentration from calibration model is between 0.928% ~15.05% , with an average of 8.31% , and when in high pollution level it is less than 3% . The test results show that, the feasibility of LIBS detecting heavy metal elements in ipomoea aquatica is proved.

In order to explore the effect of the flow rate of Ar on the properties of diamond-like carbon (DLC) films. The DLC (a- C:H) films are prepared on Si substrate by RF- PECVD technology with n- butane(C4H10) as the reactant, the effect of Ar on the properties of DLC films is studied by changing the flow rate of Ar. Determination of Fourier transform infrared spectroscopy, hardness, thermal stability and roughness of the surface demonstrates that the relative content of H in the DLC and the hardness of DLC films decrease with the increase of the flow rate of Ar, the hardness decreases from 23 GPa to 20 GPa, and the roughness of the surface increases from Ra= 3.732 nm to Ra= 8.628 nm, the flow rate of Ar almost has no effect on the thermal stability of DLC films, but the stress decreases from -1.8 GPa to -1.1 GPa.

Reaction bonded silicon carbide (RB-SiC) is a kind of mirror substrate material with good performance, however, it′s difficult to obtain fine surface without special treatment for the intrinsic defects. Xray diffraction (XRD) is used to measure the crystal structure of the RB-SiC substrate, polycrystalline silicon carbide and polycrystalline silicon are the main composition. The residual pin holes and steps on the surface observed by scanning electron microscope (SEM) and atomic force microscope (AFM) cause the scattering and decrease the optical performance directly. A silicon surface modification coating is deposited on the RB-SiC surface by the plasma ion assisted deposition (PIAD), and the defects are eliminated, a fine optical surface is achieved after polishing the silicon surface modification coating. Total integrated scattering of bare RB-SiC and the surface after surface modification is measured by a self-made scatterometer, the results are 9.37% and 1.84% , respectively, the value after modification is only 1/5 compared to that of the bare RB-SiC. Great optical performance improvement of the RB-SiC mirror is achieved, and it′s almost close to the performance of the fine polished K9 glass.