Tradition Zernike modal wave front reconstruction method is improved in which a lot of surface integrations are avoided. Collimated thermally bloomed beam corrected by adaptive optics (AO) is numerically simulated. The results show that, because of model aliasing error, the Zernike reconstruction mode order is finite, which means that there exists a largest reconstruction mode order. When chosen reconstruction mode order is greater than the largest order, correction efficiency decreases quickly. And the largest order has no relation with thermal blooming strength. For a 69 elements AO system, which sub-aperture distribution is 8×8, the largest reconstruction mode order is 37. Compared with direct slope wave front reconstruction method, Zernike modal method can increase the adaptive optics system stability through choosing reconstruction mode when correction of thermal blooming distortes wave front.

In the atmosphere, the exponential decay of the gas concentration with altitude causes the uneven distribution of atmospheric refractive index. With the propagation of the target radiation in the atmosphere, the radiation path turns into curves due to refraction. While getting target distance, oxygen absorption rate is calculated along the apparent path, which makes the existence of an intrinsic error term of oxygen absorption passive ranging named refraction absorption error. In order to analyze the impact of the refraction absorption error on passive ranging, the oxygen concentrations of the radiation path and apparent path are individually calculated. The relationship between the refraction absorption error and target real distance under different apparent zenith angles is established, through the method of making oxygen content of radiation path equaling that of apparent path. The results show that the refraction absorption error increases with the increasing of the path length at the same zenith angle. When zenith angle is less than 90°, the change of refraction absorption error is very complex, but could satify precision of shorten ranging under 100 km and long range alarm above 150 km. When zenith angle is greater than 90°, the change of the refraction absorption error is simple and the value of that is very small, and therefore precision ranging in the whole ranging can be realized. The conclusion can provide a theoretical support for the error correction of passive ranging technology based on oxygen absorption, and prove the applicability of the passive ranging technology.

Combined atmospheric radiative transfer (CART) model based on moderate resolution imaging spectroradiometer (MODIS) level2 cloud products, atmospheric infrared sounder (AIRS) level 2 atmospheric products and AIRS L1B product is used to simulate and analyze brightness temperature at the top of ice clouds atmosphere at 9 μm (band from 1070 cm-1 to 1135 cm-1), 11.03 μm (band from 886 cm-1 to 928 cm-1) and 12.02 μm (band from 815 cm-1 to 850 cm-1) bands. Brightness temperatures between AIRS observation and simulation brightness temperatures with retrieved ice clouds parameters and MODIS cloud product at three bands are compared and analyzed. The probability distribution of brightness temperature difference between simulation with retrieved ice clouds parameters and AIRS observation is studied. Results show that distribution of brightness temperature simulated based on retrieved ice clouds optical thickness and cloud top height is consistent with AIRS observation at three bands. Correlation coefficient of brightness temperature between them is bigger than 0.98.The brightness temperature difference between model simulation and AIRS observation at 11.03 μm and 12.02 μm bands is at the range from 0 to 5 K, and 0 to ±0.5 K at 9 μm band. It is definitely accurate and reliable to simulate atmospheric radiative properties under actual atmospheric conditions with retrieved ice clouds parameters.

Segmenting satellite remote sensing cloud images is an essential step of analyzing satellite cloud image data. In order to segment satellite remote sensing cloud images more accurately, a satellite remote sensing cloud image segmentation method based on Chan Vese (CV) model incorporating edge information is proposed. Satellite cloud image is diffused and a smooth image is obtained. The edge information is calculated based on the smooth image. The edge information is incorporated into the CV model, and a distance regularized term is added to avoid the reinitialization of the level set function during its evolution. Experimental results show that, compared with conventional CV model, region-scalable fitting energy level set model and bias field correction level set model, the proposed method can segment region of cloud more accurately and the speed is faster.

The cold atom absorption signal produced by the silver plated microwave cavity is observed, which finishes the last step of the integration of the microwave cavity and the integrating sphere. This setup which doesn′t use reflective material and won′t influence the magnetic field distribution is not only simpler, but also benefit for the signal to noise ratio of the clock signal. Meanwhile, the cooling performances of the cooling microwave cavity are studied with different cooling light injection schemes, diffuse reflective coefficients and apertures. The results show that the scheme of injecting the cooling light from the end surface can get more cold atoms, and the improvement of the reflective coefficient increases the cold atom numbers. Two 10 mm apertures are used in order to take full advantage of cold atoms in the integrating sphere, and the absorption signals for different apertures show that the 10 mm apertures used here won′t affect the cold atom number.

Echelle gratings with 90° apex angle have been successfully fabricated on 14° off-cut (110) silicon wafer by combining silicon anisotropic etch technique with inclined photolithography. The diffraction efficiency of blazed orders is measured in a wavelength region of 1500~1600 nm. The measurement results agree with theoretical results based on the C method. The grating has a strong blazing effect at wavelengths from 1500 nm to 1550 nm. The measured diffraction efficiency is about 52%~75% of theoretical value, thereinto, the peak efficiency is about 58%. At last, we discuss and calculate the diffraction efficiency of grating blazed orders caused by groove depth error in the production process. The results show that theoretical diffraction efficiency of blazed orders in consideration of groove depth error is about 77%~85% of perfect groove efficiency at wavelengths from 1500 nm to 1550 nm.

A simplified model is developed for defective multilayer spectrum simulation in extreme ultraviolet (EUV) lithography. Influence of defect on the reflected light is modeled by phase perturbation and amplitude attenuation of reflection coefficient. An analytical expression of defective multilayer diffraction spectrum is given. In the simplified model, the phase perturbation is dependent on the defect parameters of the 6th layer of the multilayer and the amplitude attenuation is dependent on the bottom defect parameters. Compared to advanced single surface approximation (SSA) model, accuracy of the multilayer spectrum of the simplified model is improved with nearly the same simulation time. The amplitude errors of 0~+3 orders of the multilayer spectrum are decreased more than 50% in 6° incidence angle. The errors are also with little fluctuation in different incidence angles, especially smaller than 12°. The analytical expression of defective multilayer diffraction spectrum is beneficial to analysis the effects of defect to multilayer spectrum and provides the basis for formulation of defective mask correction.

Interference fringe period is a very important parameter of phase locking in scanning beam interference lithography system. The deviation between period setting value and nominal fringe period value will cause stitching error of interference fringe between adjoining scans. To get features of scanning lithography manufactured grating diffraction wavefront, according to the characteristics of step-and-scanning lithography and working principle of dynamic phase locking, the mathematical model of scanning beam interference lithography is built. According to this model, variations of printed error and lithography grating period are given. Experiments are done to verify this model. Results show that period setting error in phase locking system will cause periodic printed error. Periods of lithography grating vary with period settings. Lithography grating period is equal to period setting value with tiny period setting error. When interference beam waist radius is 0.9 mm, step over distance is 0.6 mm and fringe period is 555.6 nm, periodic printed error is less than 1 nm with period setting relative error less than 278×10-6. If the dose contrast is more than 0.9, period setting error must be controlled within 92.6×10-6. The variable range of period setting value and lithography grating period is 102.8 pm.

To enhance the security of optical stealth transmission system, an optical stealth scheme based on code shift keying-optical code division multiple access (CSK-OCDMA) technology is proposed, and a 2.5 Gb/s experiment system is setup. The optical source of stealth channel is a low cost distributed feed back (DFB) semiconductor laser, and the public channel is optical transform unit (OTU) near wavelength division multiplexing (WDM) optical networks. The experiment demonstrates that the stealth channel can transmit back to back without bit error, and the penalty for public is only 0.1 dBm. When the stealth channel work without bit error is promised, the difference between public and stealth channels can be 24.6 dBm for the largest. After introducing the forward error correction (FEC), the system can transmit 100 km without bit error.

A novel single-polarization single-mode (SPSM) rhombic-hole terahertz (THz) photonic crystal fiber (PCF) is proposed. The influence on the characteristics of SPSM is studied by changing the number, size and location of the defects in fiber. A full-vector finite element method is used for modeling, and the simulation results are as follows. In the case of two defects in PCF, with the increase of defect size, SPSM operation range moves towards high-frequency, and its width is increased slightly. In the case of four defects in PCF, the characteristics of SPSM is affected by the defects near the core region easily. Based on this conclusion, four same defects are introduced around the core region in fiber. Compared with the case of two defects, SPSM operation range (1.07 THz to 1.36 THz) moves towards high-frequency and its width (0.29 THz) increases significantly for four defects case, which is 1.32 times than the case of two defects. So the fibers have wide applications in some systems that have strict requirements about the polarization states, and have practical significance.

A parameter modulation method is proposed to increase the aperture of time lens implemented by electro-optic phase modulation. The implementing principle of this method is theoretically deduced. The effects of modulation parameter Q on the aperture of time lens and pulse compression ratio are discussed for the application of optical pulse compression with time lens. Numerical results illustrate that the proposed method can extend the aperture from 15.6% to more than 50% of whole modulation period and increase the compression ratio from 3.11 to 4.46 for the temporal imaging system with ideal compression ratio of 5 at the modulation frequency of 20 GHz. Besides, modulation voltage in high-frequency temporal imaging system can be reduced by selecting input and output fiber with opposite second order dispersion. The parameter modulation method can effectively improve the aperture of time lens implemented by electro-optic phase modulation and optical pulse compression ratio in temporal imaging system by only adjusting the modulation voltage of electro-optic phase modulation without other components. This method can offer a simple and effective way to improve the performance of time lens based on electro-optic phase modulation.

The stability of the polarization encoder is one of the key issues affecting polarization coding communication. The stability of the polarization encoder based on lithium niobate (LN) phase modulator is studied in depth, and is described by time variant vector. The experiment results show that, for the LN phase modulator, the principal state of polarization-dependent loss (PDL) is consistent with the principal state of polarization-dependent phase shift, indicating that PDL can not affect the stability of the polarization state. A “inertia” of polarization rotation is observed in experiment. On the one hand, increasing voltage from 0 to a value, after stopping the increase of voltage, the polarization state can not be stable before about 30 min; on the other hand, decreasing voltage from a value to 0, after stopping the decrease of voltage, the polarization state can not be stable before several minutes too. It can have negative effects on low-speed modulation. For high-speed modulation, the changes of the average power can cause polarization jitter.

In order to solve the crosstalk problem between decrypted images, quick response (QR) code is introduced in the image encryption system based on principle of interference. The encryption process is realized on computer digitally and the decryption process can be completed optically or digitally. For encryption, multiple sets of the information to be encrypted is first transformed into the corresponding QR code, then these QR codes are analytically hidden into two phase only masks (POMs). For decryption, the diffraction field of the two POMs is superposed by utilizing the beam splitters. After that the wavefront propagates to different distances and the intensity of the complex field, which are exactly the decrypted images. Directly scanning by a smartphone, original information can be completely retrieved. The encryption method successfully solves the problem of crosstalk noise. Simulation results are presented to verify the validity of the proposed approach. The feasibility and robustness against occlusion and noise attacks are verified by a series of numerical simulations.

After long time working, the response characteristics of infrared focal plane array (IRFPA) often drift slowly, and the image quality always degrades. Aiming at the problem, the characteristic of residual noise after two point correction (TPC) is analyzed. An adaptive non-uniformity correction algorithm is proposed based on the TPC algorithm. The images after TPC is decomposed by wavelet, and the Bayesian threshold is used to estimate signal and noise variance point by point, the residual nonuniformity noise is calculated and removed. Experimental results show that the proposed algorithm can remove the residual nonuniformity noise effectively and avoids the image degradation caused by the response drift of IRFPA.

The conflict of high dimensionality and the very limited number of available training samples is one of the problems in the classification of hyperspectral images. At the same time, the redundance between different bands brings trouble to the classification. The ensemble learning provides a new way for solving the problem mentioned above. Based on the correlation between different bands, a band grouping is carried out. By selecting different bands from different groups new subsets of spectral bands is formed. The redundance reduces bands in the new spectral band subsets are independent and used to train the maximum likelihood (ML) classifiers which can be used later for ensembling. The combining of classifiers is done by the simple majority voting and the ensemble classifier is formed. Experimental results of the hyperspectral remotely sensing image demonstrate that the method presented here has an excellent classification result and outpeforms many other methods.

Coded exposure (CE) is based on technology of spread spectrum. By advantage of CE, imaging restoration can be used by method of inverse filtering. A method of fast restoration of blurred vibration image based on CE is introduced, as well as basic theory of coded exposure and vibration detection, to achieve the best code. The vibration path is detected by using fiber-optic gyroscope, and point spread function (PSF) is estimated by means of statistic, which can reduce algorithm complexity, and improve operating rate. The method put forward aims at remotely-sensed blurred image, which is blurred due to vibration of satellite platform. Experimental results indicate that this method has absolute advantage in processing speed and image restoration result, and it is significant for getting high resolution remote sensing images fast.

The performance of integral imaging three-dimensional (3D) display is limited by the limited depth-of-field. A method for enhancing the depth-of-field of integral imaging is proposed. This method adds an aperture stop array in the conventional integral imaging system, and the aperture stop array is used to limit the divergence angle of each pixel in the display panel. The principle of integral imaging is analyzed and the relationship between the size of aperture stop and the depth-of-field is studied in detail. Both the proposed method and conventional method are simulated by optical design software ASAP, and the simulation results show that the depth-of-field of the proposed method is 1.5 times of the conventional method when the aperture stop diameter accounts for 64% of the pitch micro-less. The experimental results verify the correctness of the theoretical analysis.

In the use of auto-focusing technology based on image processing of aerial camera, the precision decreases due to the influence of image′s noise. Currently the relationship between signal to noise ratio (SNR) of image and auto-focus precision is mainly based on the experimental results and subjective judgments, but there is no universal theory and exact conclusion on them. The relationship and an exact mathematical expression are analyzed and given between the SNR and auto-focus precision, experiments show that the SNR of image has a positive correlation to auto-focus precision, the higher SNR of the image, the higher precision of the auto-focus precision. Through the standard of the expectation and variance of focus measure, the influence of SNR on precision is analyzed, and results show that the influence of noise can be weakened by calculating the focus measure more times. Experiments are designed and the changes of SNR with variance of focus measures are reconded by applying the same focus method in different conditions. Results show that when the SNR of image rises from 27 dB to 39 dB, the variance of focus measure function decreases from 0.262 to 0.0611, meaning that auto-focusing accuracy is improved by about 30%. The result proves the correctness of the theoretically analysis.

As the critical dimension in integrated circuit fabrication moving toward nodes-2Xnm and below, source and mask optimization (SMO) has been one of the most effective solutions of resolution enhancement techniques (RETs) to extend the process window and decrease process factor of 193 nm ArF lithography. We propose an efficient SMO method based on stochastic parallel gradient descent (SPGD) algorithm. The gradients of the objective function are estimated by random disturbance and utilized to guide the optimization, which avoids to calculate the analytic expression of the gradients. The complexity of optimization is reduced. The proposed SMO method is demonstrated using three mask patterns, including a periodic array of contact holes, a cross gate and dense lines. Three kinds of mask pattern error (PE) are reduced by 75%, 80% and 70% respectively. The numerical results show that our method can provide great improvements in printed image quality.

Wide field, high spectral resolution and high spatial resolution are the development directions for the imaging spectrometer. However, in order to extract the two-dimensional spectral information accurately, spectral and spatial distortion needs to be controlled within a small fraction of a pixel. The prism-grating imaging spectrometer is proposed. The mathematical model of prism-grating component is constructed by means of the vector method, and the optimization of structural parameters is determined through analyzing quantitatively the spectrum distortion characteristics of different prism-gratings. The optical system of ultraspectral imaging spectrometers with a direct vision is devised base on the Prism-Grating component. The spectral coverage, slit length and F number of the system are visible light from 400 nm to 800 nm, 14 mm and 2.4, respectively. The results demonstrate that the spectral resolution is 0.5 nm/pixel, and the modulation transfer function (MTF) for different spectral bands are more than 0.7 at the Nyquist spatial frequency of plane array charge coupled device (CCD). Both smile and keystone are less than 1 μm, and reduced to 13.5% of a pixel.

The mathematical representation of the modulation transfer function (MTF) decline caused by reticle alignment error is deduced. And the relationship between the focal length ratio (FLR) and the alignment precision of reticle is analyzed. When FLR equals to 1, the alignment error of reticle equal to 0.0012 mm which causes the MTF drops to 0.01. Based on that, the manuscript reports a method according to the Zernike coefficient as a quantifying criterion to guide alignment process. Interferometer, collimator and special reticle are used to generate interference fringes. The verified experimental results and mathematical analysis indicate that the new procedure can improve alignment accuracy of collimator reticle remarkable, and the MTF decline of the photoelectric imaging system under calibrating is reduced to 0.013. The environmental elements effect the calibration result. Using this alignment method, the collimator has the same focal length as the system under testing can be used in very high precision optical testing and calibration.

The hemisphere transmittance of transmission diffusers in space remote sensing instruments changes because of the solar vacuum ultraviolet radiation, which will affect the on orbit calibration result of instruments. The characteristics of solar ultraviolet radiation spectra and the UV irradiation dose are analyzed when diffusers are on orbit, a standard deuterium lamp is used as the light source for solar ultraviolet spectrum simulation at 115~200 nm, the fused quartz diffuser is irradiated at a specific distance. After 48 h solar ultraviolet irradiation, the fused silica diffuser′s hemisphere transmittance in 250~1000 nm decrease, the degradation at 250 nm is about 3%, in the change near-infrared wavelength is less than that in ultraviolet, and the degradation at 1000 nm is about 1%, after the diffuser is washed, the hemisphere transmittance returns to the original value.The test results show contamination that on the diffuser is a major factor for the hemisphere transmittance degradation, the result is very important for transmittance diffuser protection, on-orbit calibration and degradation correction.

Lidar detection requires strict calibration and stabilization on transmitted wavelength. The backlash errors, which occurs in wavelength control of the tunable laser, seriously reduce the detection accuracy. In order to solve the backlash problem of the tunable laser, a algorithm which can offset the positive and negative backlash error by jumping back and forth is proposed and firstly applied to the frequency stabilization of the high detection of vertical profiles of atmospheric CO2 concentration. The experiment result indicates that the algorithm not only can improve the adjusting precision of the tunable laser′s wavelength, but also eliminate the backlash error of the laser′s wavelength adjustment caused by multiple reverse. This method reduces the shortage of the wavelength adjustment caused by mechanical rotating and has great significance for the development of hyperspectral laser technology.

Considering the uneven illumination of Chang′E-3 pancam images sequences and the particularity of the lunar surface image, a new panoramic mosaics method based on speed up robust features (SURF) algorithm is put forward to achieve the panoramic mosaics of Chang′E-3 pancam images. The feature points of images are extracted using SURF algorithm, and euclidean distance of SURF descriptor is used as the measurement to obtain the corresponding image points. The transformation matrix are calculated and optimized between adjacent images by Levenberg-Marquardt algorithm. Fusion images can be achieved by using the fade in fade out method based on linear interpolation, realizing seamless mosaic of the lunar surface image. The results show that this method can achieve mosaic of Chang′E-3 pancam images in a rapid and accurate way, and the mosaic satisfy the demands of rover for selecting detect target and path planning.

A single camera stereo vision sensor based on plane mirror imaging is researched on the basis of traditional binocular stereo vision sensor. Placing a plane mirror in front of charge coupled device (CCD) camera, a picture with parallax image is obtained by shooting target object and its virtual image. This is equivalent to shot the target object from different angles by the camera and the virtual camera in plane mirror, so it has the function of binocular stereo vision. The mathematical model of single camera stereo vision sensor is established. The impact of the parameters to the field range and the measurement accuracy is analyzed. The parameters of the sensor are designed, and the corresponding experiment has been done. The experimental results show that the measuring method is convenient and effective. It also has the advantages of simple structure, convenient adjustment, and is especially suitable for short distance measurement with high precision.

A novel occlusion detection approach is proposed for depth image by using Random Forest. The occlusion related features of each pixel in the depth image are extracted, and then the Random Forest classifier is used for detecting whether each pixel is an occlusion boundary point or not. All the occlusion boundaries in the input depth image are obtained. This work is distinguished by three contributions. A new occlusion related feature named depth dispersion is proposed and the Gaussian curvature feature is introduced, and both of them are used for occlusion detection by combining with other features. All the occlusion related features in depth image are analyzed and evaluated by using the importance and extraction time as criterion. On this basis, five features such as average depth difference, maximal depth difference, mean curvature, Gaussian curvature and depth dispersion are selected for designing the occlusion detection classifier. A new occlusion detection approach takes the Random Forest to solve occlusion detection problem in depth image. The experimental results show that, compared with the existing methods, the proposed approach has higher accuracy and better generality.

A novel yellow-green BaMoO4:Pr3+ phosphor is successfully prepared via high-temperature solid-phase method, and its structure, morphology and luminescence properties are studied. The X-ray diffraction (XRD) patterns results show that the samples obtained after sintered at 1300 ℃ have the scheelite structure. The morphology of the sample has irregular shapes which can be observed by scanning electronic microscopy (SEM). The excitation spectrum of phosphor sample consists of strong charge transfer (CT) band and characteristic excitation peaks of Pr3+. The main excitation peaks are at 447 nm (3H4→3P2), 472 nm(3H4→3P1) and 485 nm(3H4→3P0), respectively. The emission spectrum peaks locate at 527 nm(3P1→3H4,5), 542 nm and 551 nm (3P0→3H5), 596 nm(1D2→3H4), 614 nm(3P0→3H6) and 642 nm(3P0→3F2), respectively. The strongest peak appears at 642 nm. The optimum doping mole fraction of Pr3+ is 0.2%~0.3%. The results show that BaMoO4:Pr3+ is a promising yellow-green phosphor which can be effectively excited by blue light emitting diode (LED).

A linear empirical formula of the absorption-peak wavelength depending on quantum dots (QDs) diameters is presented by measuring the near IR-absorption spectra of PbSe QDs with three diameters (4.5, 5.0, 5.6 nm). Both the absorption cross-section and absorption coefficient of QDs varying with the doping concentration and wavelength are determined by absorption-spectrum method and according to Lambert-Beer′s law. There is evidence to show that the absorption is weak dependent on the doping concentration, which can be expressed by an exponential decrease with the increased doping concentration. The photoluminescence (PL) spectrum of QDs is measured, and the PL-cross-section peak varying with wavelength is determined according to McCumber′s relationship between the absorption and emission. As the primary spectrum data of the QDs, the suggested cross-sections are useful for designing photoelectronic gain devices and sensors doped with QDs.

Hydrothermal etching method is employed to prepare four Iron-passivated porous silicon (IP-Si) samples of different etching time. The sponge-like morphology of the samples is observed by scanning electron microscope (SEM), and larger diameter difference of etching holes and lower morphology smooth are found as a result of increasing etching time. Under 250 nm excitation, all samples emit strong orange light with peak around 620 nm and full width at half maximum (FWHM) of 130 nm. And no correlation between photoluminescence peaks and etching time is found. Together with the result of Fourier transform infrared spectroscopy study, the physical mechanism for the photoluminescence of IP-Si is interpreted by using the quantum confinement-luminescence center model, and the non-bridging oxygen hole center is ascribed as the radiative recombination luminescence center.

An all-fiber pulse laser based on master oscillator power amplification (MOPA) configuration is reported. Using the acousto-optic Q switch, the pulse laser seed with average power of about 500 mW is obtained. A pre-amplifier amplifies the seed power up to 10 W. The main amplifier is based on the Yb-doped double clad fiber pumped by a pigtailed laser diode with a center wavelength of 976 nm. In the experiment, pulse laser with repetition rate of 40 kHz at the center wavelength of 1064 nm is realized. The pulse width is 2.4 μs, the average power is greater than 100 W, and the corresponding pulse energy is 2.63 mJ. The M2 factor of output beam is 1.2.

In order to reduce the weight and volume of the head-mounted display (HMD), a planar waveguide HMD is designed based on semi-transparent film array. Two orthogonally placed semi-transparent film arrays are used to expand the eyepiece′s exit pupil, as well as to make the HMD compact and light in weight. By analyzing the structure of planar optical waveguide, an optical system model is established. Then, imaging quality and irradiance distribution of the system is discussed. This system has a gross weight of about 36 g, a field of view (FOV) of 15°×20° and an exit pupil of 7 mm×12 mm. The distortion is less than 0.13%. The root mean square (RMS) spot diameter is less than 3.75 μm. The RMS wave aberration is less than 0.045λ. The modulation transfer function (MTF) is higher than 0.58 at the spatial frequency of 40 lp/mm across the entire FOV. The results indicate that planar waveguide of semi-transparent film array can enlarge eyepiece′s exit pupil effectively. This system satisfies the requirements of the HMD optical system.

Ghost image is the main factor which degrades imaging definition and contrast of lenses under backlight illumination. In order to avoid its influence, a reduced ghost image lens with typical Petzval lens is studied. With matrix paraxial optical theory, characteristics of the ghost image are discussed and analyzed in detail, and then suppression method is suggested. According to application requirement, a ghost image reduced lens is optimized and developed. Evaluation of the designed lens′s image quality shows that the ghost image intensity is low and uniform, but its imaging performance is close to diffraction limit. Imaging result under backlight illumination shows that the developed lens has excellent suppression performance of ghost image. The correctness of design and analysis are verified. The suggested suppression method is potential for reducing ghost image of other optical systems.

The photo-thermal conversion characteristic of cavity absorber in parabolic trough solar concentrator is researched by theory, simulation and experiment. The thermal radiation loss model of cavity absorber in parabolic trough solar concentrator is established and demonstrated. Results show that while the irradiance distribution of cavity tends to be uniformity, the thermal radiation loss is reduced. The optical efficiency and standard deviation of cavity absorber at different positions are simulated by the optical design software TracePro. Results show that better optical performance can be obtained if the installed position is less than the focal length. The thermal efficiency of the cavity absorber is 35.53% with the temperature of 201.3 ℃ and the installed focal length of cavity absorber is 98.75% of system focal length which is 1200 mm parabolic trough solar concentrator by experimental verification.

In order to eliminate spectral line curvature of plane grating and prism imaging spectrometer, a novel approach by combining prism-grating (P-G) with the compensation of lens′ distortion is presented. The spectral line curvatures of prism and grating and spectral curvature of compound P-G device are calculated, respectively. The character of spectral line curvature and spectral curvature are analyzed, then the compound P-G device and imaging spectrometer with eliminating spectral line curvature are designed. The optimized optical system has a spectral resolution better than 2 nm and the root mean square (RMS) spot radius is less than 8 μm. Moreover, both the spectral line curvature and spectral curvature of system are less than 2 μm. It is proves that compound P-G device′s spectral line curvature and spectral curvature of the full-wide working wavelength can be eliminated with the compensation of lens′ distortion. It is concluded that the imaging spectrometer with P-G dispersing device shows a spectral line curvature less than 1/4 pixel of the detector, which meets the use request on the premise of imaging quality.

As the genetic algorithm is robust and independent of the specific optimization objectives, a method is presented that the best design of meridian line of progressive addition lenses is found through genetic algorithm. The polynomial coefficients of the meridian line are represented by binary character strings（chromosome） based on the smoothing equation. The multiple objectives of the power and astigmatism of the progressive addition lens are transformed into a single objective function through punish function and linear combination method. Selection, crossover and mutation operations are processed on the chromosomes to produce new generation population according to the objective evaluation function. The processing is repeated to find the best polynomial coefficients of the meridian line. Two optimizing examples are implemented and the optimized progressive addition lens is manufactured and tested. The results demonstrate that two optimized designs and the practical manufactured progressive addition lenses consist with each other.

Here the core structure of a new variable optical attenuator (VOA) based on microfluidics is presented, where the microfluid and compressible air are used to continuously change the optical energy by adjusting the attenuator. Based on this core structure, two variable optical attenuators using different driving technologies are given. By the propagation theory of Gaussian beam, Helmholtz equation, mode-coupling theory and Mathematics software, the optical field and characteristics of this VOA are researched in theory and the diffraction effect is discussed. The theory results indicate this VOA has big attenuation range (50 dB), quick response (0.01 s), small insertion loss and strong return loss. The presented attenuator can provide a new method for development of small, integrated and adjustable optical communication devices.

The Talbot effect of the two-dimensional optical beam splitter fabricated by selective etching of MgO-doped LiNbO3 (MgLN) crystal is analysed based on the Fresnel diffraction theory. Numerical simulation is applied to study the intensity distribution of near-field optical diffraction under various duty cycle D and Talbot distance coefficient β. Based on the theoretical result, the selective etching optical beam splitter is designed and fabricated with various duty cycles. Through optical experiments, the fractional Talbot diffraction imaging map is obtained at different Talbot distances. The results obtained show that good near-field diffraction images can be achieved at D=52%, β=2, which verifies the results of the numerical simulation research.

A new kind of chemiluminometric sensing cell based on hollow fiber is proposed by combining sol-gel enzyme immobilization and dielectric-coated metallic hollow fiber. The fabrication techniques for coating sol-gel sensing membrane inside the hollow fiber are studied. Transmission mode and luminescence mode of the new device are simulated, and optimization of system parameters is discussed according to the calculation results. A hollow fiber based sensing system is designed and established for detecting hydrogen peroxide concentration. And it is applied to detect the hydrogen peroxide concentration in contact-lens disinfectant solution. A high sensitivity (10 μM) and good repeatability are achieved. The system has potentiality in biochemical research, environmental protection and food industry, owing to its easy operation, rapid response and miniaturization.

To meet demands of researches on nanoscale photothermal effect, a real-time dynamic controllable nano-heating source is demonstrated, which is based on the robust dynamic manipulation of gold nanoparticles by plasmonic nanotweezers. Based on finite element method, the relationship between photothermal effect of gold nanoparticles and the strength of surface plasmon polariton electromagnetic field is elaborated by numerical simulations. The confinement and enhancement of electromagnetic field induced by hybridization of surface plasmon polariton and localized surface plasmon polariton with the nanotweezer system is explained and then the photothermal effect during the progress of nanoparticle capturing are analyzed. Further, the methods to real-time control of its power are delivered. To validate the heating ability of gold nanoparticles in the plasmonic nanotweezers, experiments are implemented. Integrated with plasmonic nanotweezers, the precise manipulation of metal nano-heating source supports a reliable and flexible method for the research of nanoscale thermal effect.

Imaging process and the two-dimensional data collection influenced by space-time speckle effect for a resolution of the synthetic aperture imaging ladar (SAIL) are analyzed. Based on the previous research, the influences of the speckle effect introduced by different scopes and locations of the receiving antenna are compared. Correspondingly, the photocurrent, the compression in range direction and the final images of the resolution are simulated. Simulation results show that the image intensity of the resolution is significantly decreased, and the space-time varying speckle effects, introduced by different scopes and locations of the receiving antenna, exhibit remarkable different influences on the resolution imaging. Our research provides a certain reference for the reduction of the speckle effect in SAILs.

Five kinds of typical Yang-boosting Chinese herbal medicine are identified and classified based on near infrared spectroscopy (NIR) and latent semantic analysis (LSA) methods. Latent semantic analysis is used for characteristic extraction and classification of preprocessed spectral data of 5 kinds of Yang-boosting Chinese herbal medicine. The spectral characteristic data, after spectral pretreating and characteristic extraction by principal component analysis (PCA), are respectively subjected into the K-nearest neighbor (KNN), BP-artifical neural networks (BP-ANN) and least squares support vector machine (LS-SVM) classification models whose results then are compared with the result of latent semantic analysis model. In the characteristic wavenumber range of 4119.20~9881.46 cm-1, spectral data pretreated by multiplicative scatter correction (MSC) are substituted to LSA classification model when spacing dimension of underlying language is 3, and accuracy rates of both training set and test set are 100%. The results show that latent semantic analysis, which has a good application prospect and practical significance, can be used as a new method for spectral information extraction and classification in the near-infrared spectroscopy identification of Yang-boosting Chinese herbal medicine.

For spectral information redundancy and correlation in phytoplankton spectral analysis, interval Monte Carlo partial least squares (IMC-PLS) which effectively solves the problem of feature wavelength selection is presented based on partial least squares (PLS). Feature region is preselected according to the location of the pigment fluorescence peaks, the internal informations of a single band and the contributions of different random band combinations to the model are plenarily used. Based on three-linear feature of fluorescence spectra, emission wavelength band and excitation wavelength band are considered as a unit. The result shows that comparing with the uninformative variable eliminotion (UVE), feature wavelength points and computation time obtained by IMC-PLS decrease by 80.1% and 81.3% and average relative tolerances (ARTs) by inversion of four algae concentrations decrease by 0%, 34.3%, 55.9%, 30.5%. IMC-PLS algorithm effectively solves the problem of real-time monitoring, and provides theoretical support for the development of a discrete three-dimensional fluorescence spectrometer meanwhile.

Building universal deduction models for predicting the soil total nitrogen (TN) content by using data mining of large soil spectral libraries is one of the most important applications of hyperspectral analysis. In this study, 1661 soil samples representing 17 soil types from 13 provinces of China (e.g., Tibet, Xinjiang, Heilongjiang and Hainan) are employed for modeling the soil TN content using global partial least squares regression (PLSR), locally weighted regression (LWR) and fuzzy K-means clustering combined with PLSR (FKMC-PLSR). Another 104 paddy soil samples collected from Zhejiang Province are used to validate the established models. Results showed that when predicting soil TN from a large dataset, global PLSR underestimates high values of TN, which generates an overall low prediction accuracy. By contrast, LWR and FKMC-PLSR perform better than global PLSR. It is suggested that the results can provide useful information for establishing robust and universal models for soil TN prediction using large soil spectral libraries.

A new method for determining the average junction temperature of AlGaInP-based light emitting diode (LED) array is developed based on the difference of normalized spectral distribution. The normalized spectra of three LED arrays with various injected powers and substrate temperatures are measured with a spectrometer, and the relationship between the differences of normalized spectral distributions and the average junction temperatures of LED arrays is analyzed. The accuracy of evaluating junction temperature with the difference of normalized spectral distributions is compared with the proposed method using center wavelength shift. The results show that the difference of normalized spectral distributions, measured with a spectrometer of 1 nm sample interval, changes linearly with the variation of average junction temperature whether it is induced by the change of the injected power or the substrate temperature, and the linearity is better than that of the method using center wavelength shift. Therefore, the difference of normalized spectral distributions can be used to estimate the average junction temperature, and the accuracy is better than the method using center wavelength shift.

The photosynthetic pigment composition is an important basis of classification of phytoplankton. Three dimensional (3D) fluorescence spectra of five phytoplankton divisions (Cyanophyta, Chlorophyta, Bacillariophyta, Dinophyta, Cryptophyta) are analyzed and 36 characteristic fluorescence peaks which are related to chlorophyll a, chlorophyll b, chlorophyll c, carotenoid, phycocyanin and phycoerythrin are extracted. On this basis, a classified measurement method of phytoplankton based on characteristic fluorescence of photosynthetic pigments is put forward. Pure cultures and mixed cultures of Microcystis aemginosa, Chlorella vulgaris, Fragilaria sp, Glenodinium gymnodinium and Cryptomonas ovate are tested. For the five pure cultures, the measuring errors are 5.15%, 5.63%, 7.90%, 4.85%, 6.55%. For dominant species (mass fraction higher than 50%), the measuring errors are 7.96%, 8.69%, 5.44%, 10.78%, 15.57%. For subordinate species (mass fraction less than 30%), the measuring errors are 18.29%, 17.52%, 20.01%, 29.11%, 20.14%. The characteristic fluorescence spectrometry is a fast and effective phytoplankton classified measurement method. Its measurement accuracy has reached the level of 3D fluorescence spectrometry, while the data volume and calculation time are only 1.1% and 2.2% of the 3D fluorescence spectrometry.

The behavior of the plasma induced by a laser on an alloy steel sample in air is observed by a time-resolved ICCD camera, and the plasma emission spectrum is simultaneously measured. The influences of the lens-to-sample distance (LTSD) on the plasma emission intensity, the plasma temperature and the plasma structure are investigated for a lens of 100-mm focal length. Its physical mechanism is studied, and the spatial distributions on the direction perpendicular to the sample surface are carried out for five different focal positions. It is demonstrated that the lens-to-sample distance has a considerable impact on the spectral signal, the plasma structure and the spatial distribution. The results show that the change of pixel intensity on the plasma image is consistent with that of the plasma temperature. The curves appear two peaks at the position of 92 mm and 107 mm respectively, and the values reach their maximum at 92 mm. It′s shown that the spatial distributions of the plasma temperature vary with LTSD on the direction perpendicular to the sample surface. Space evolutions of the different spectral lines in the plasma are also different.

Nanocomposite films with interconnected pores are fabricated using TiO2 as porous template with poly 3,4-ethylenedioxythiophene:polystyrene sulfonate (PEDOTPSS) as catalyst, and then are developed as alternative counter electrodes for dye-sensitized solar cells (DSC). The porous templates are prepared by depositing the TiO2 nanoparticles on the conductive SnO2 transpanent glass doping fluorine (FTO), followed by annealing. The nanocomposite films are then completed by spin coating of the commercial PEDOTPSS aqueous solution into the template. By optimizing the template structures and the spin coating rates, the nanocomposite film with excellent catalytic activity for the tri-iodide reduction is obtained. When employing this nanocomposite film as the counter electrode for the DSC, the optimum fill factor and efficiency respectively reach to 0.528 and 4.57%, which are greatly higher than those of the cells with the pure PEDOTPSS film as the counter electrode. The fill factor and efficiency of the latter are 0.297 and 1.98%, respectively. The improved photovoltaic performances are attributed to the excellent synergistic effects of the nanocomposite film. The conducting TiO2 skeleton provides high-speed conductive paths for the electrons transportation, and the PEDOTPSS adhered on the skeleton engenders large surface area provides more active sites for the tri-iodide reduction.

Owing to the special optical properties of surface gratings of laser rainbow holographic printed matter, the imaging by white light illumination can generate rainbow-colored interference fringes, which increase the difficulty of color measurement of holographic printed matter. To resolve this problem of laser rainbow cigarette packet product, a special light source--dome light which is special for holographic printed matter is designed, and a 6-channel line scanning charge coupled device (CCD) imaging system based on the dome light is constructed. In the environment, color measurement for laser rainbow holographic printed matter is made by using spectral reconstruction method based on principal component analysis technique. The experiments show that in spectral reflectance reconstruction, proposed method of color measurement has the characteristics of high-precision, and is effective to solve the problem of color measurement of laser rainbow holographic printed matter.

A mobile terminal-based method is established for testing the influence of ambient light on outdoor readability and the relevance of device brightness and ambient light. Gray sinusoidal fringes of different frequencies and different brightness centers are observed under different ambient light and different device brightness. According to the recorded just-noticeable lightness threshold, the influence of ambient light on the just-noticeable lightness threshold is analyzed and the model of simplified ambient contrast and just-noticeable lightness threshold is established. The results show that the influence of ambient light is inversely proportional to the contrast sensitivity of the observed sinusoidal fringes. A quite specific function can be got by the model and it can be applied to the setting of the device brightness under different ambient light.