HCl gas is one of the waste incineration emissions. It does not only corrode the incineration equipment and monitoring instrument, but also harms human health. Effective online monitoring of the HCl gas concentration ensures normal use of the incineration equipment and function of the monitoring instrument. An online HCl concentration analyzer based on tunable diode laser absorption spectroscopy (TDLAS) is presented. The laboratory tests show that the linearity error of the analyzer is not higher than ±1% F.S and the stability of the analyzer is good. The analyzer has been successfully applied to the exhaust vent of a waste incineration equipment for continuous monitoring. The results show that the 1.742 μm absorption spectrum can be used to measure HCl concentration. The analyzer has the advantages of short response time, high reliability and the measurement does not be interfered by background gas, dust and window stains.

The relationship between aerosol extinction coefficient and PM2.5 mass concentration is analyzed, it is proposed that the PM2.5 mass concentration profile can be retrieved by combining the side-scatter lidar system based on charge-coupled device (CCD) and PM2.5 detector. From case study, when the variation of relative humidity is small, PM2.5 mass concentration is proportional to aerosol extinction coefficient at ground. The characteristic of PM2.5 mass concentration profile of near-ground on April 13, and December 16, 2014 at Dongpu island of western suburb of Hefei city is analyzed as changing with time, changing with altitude, and air pollutant concentration is comparatively large in close surface. The experimental results show that the side-scatter lidar system based on CCD combined PM2.5 detector is an effective new method of exploring pollutant mass concentration profile in near-ground.

To study the relative spreading of truncated Gaussian Shell-model (GSM) beam propagating through non-Kolmogorov turbulence, the extended Huygens-Fresnel principle and integral transform technique are used to derive the expressions for the mean-squared width and relative width of truncated GSM beam propagating through non-Kolmogorov turbulence. The variation of the mean-squared width and relative width versus waist width w0, coherence parameter α , truncation parameter δ and generalized exponent parameter γ are analyzed numerically. The results show the beam spreading is less affected by turbulence with the smaller α and δ , and the influence of non-Kolmogorov turbulence on beam spreading increases first and then decreases due to increasing waist width w0 and γ . The results obtained above are explained physically.

Weak light detector has very important application in medicine, space exploration field, etc. As a kind of weak light detector, silicon photon multiplier(SiPM) possesses excellent performance. SiPM with bulk integrated quenching resistor which is developed at novel device laboratory (NDL), has a strong ability of single photon detection. Aimed at improving the photo detection efficiency(PDE) of bulk integrated quenching resistor SiPM in the blue violet region(360~420 nm), the thesis presents a kind of deep trench isolation SiPM. The structure of the device is optimized through the simulation, and the preliminary experimental results have been obtained.

Based on the bandgap properties of photonic crystals, an one- dimensional photonic crystals multichannel filter with a comlicated periodic structure is designed. Using transfer matrix method, and through the Matlab simulation, two appropriate photonic crystal materials are selected and its structural parameters are determined. Simulation results show that the filter can obtain multiple high- emitting windows in the current main communication wavelength range, and the required number of channels be regulated.

For laser communication acquisition, tracking and pointing system on the spot position detection accuracy demand, based on complementary metal oxide semiconductor detector, light spot position detection accuracy evaluation method, and using this method to quantify the commonly used filtering algorithm on the spot position detection accuracy effect are proposed. High precision displacement platform is used to test camera, random error and systematic error, then the median filtering, mean filtering, high pass filtering, morphology filtering processing of spot images are applied, and the filtered centroid positions are calculated. The light spot position detection accuracy before and after filtering is compared, and the influence of filtering algorithms on detecting position is evaluated. Experiments show that the accuracy of the spot detection can be reduced and the method of avoiding the deterioration of accuracy of the problems mentioned above is proposed according to the experimental results.

A novel optical add-drop multiplexer (OADM) based on the Mach-Zehnder (M-Z) interferometer and the fiber Bragg grating (FBG) is proposed. The OADM consists of a M-Z interferometer, two optical circulators and three FBGs. The FBG between two circulators acts as an optical switch. The OADM can add/drop one of the input multi-channels or pass the channels directly by adjusting the relative wavelength of the FBG. The channel isolation of the OADM is more than 23 dB, and the same frequency crosstalk is below -40 dB. The system can not only just download a specific wavelength, but also adjust the wavelengths of upper and lower carriers. The novel OADM has many advantages such as simple structure, low cost, good flexibility. It can be used in practical wavelength division multiplexing (WDM) system.

In the Fourier transform profilometry (FTP), the existence and expanding of zero frequency component of the deformed fringe pattern has an influence on the measurement range and accuracy of Fourier transform profilometry. After eliminating the zero frequency component of the deformed fringe, the measurement range of FTP will be three times of that of the traditional FTP. According to Hilbert transform having the nature of 90°phase shift and the direct current (DC) component becoming zero, a new method based on piecewise Hilbert transform is proposed to suppress zero frequency component of the fringe pattern. The zero frequency component of the fringe can be suppressed well because the background of the fringe is a slowly varying function and background distribution in each half period of the fringe should be regarded as constant. So, the proposed method can suppress the zero frequency component of the fringe well. The proposed method enlarges the measurement range of FTP and reduces its measurement error. In the paper, the theoretical analysis is given. Computer simulations and experimental results demonstrate the effectiveness of the proposed method.

Facing the problem of low efficiency and unstable quality in the traditional hand finishing tricot lace cutting field, a novel tricot lace real- time recognition method based on feature recognition is proposed. The method works by adaptive thresholding, line detection, image segmentation and reducing the fake contours, which can recognize accurately the profile features and locations of tricot laces. It has high stability even in complex factory lighting environment. It can satisfy the real-time request and promote computational efficiency by improving the computational efficiency of the method. The automatic vision cutting system based on the proposedmethod can highly improve production efficiency and quality.

Based on the statistical property of image noise and combining with BayesShrink theory, a method of image denoising based on wavelet domain Contourlet transform is presented. Using BayesShrink theory to estimate the threshold, considering the local correlation of the neighborhood, then improving the adaptive method of selecting threshold, finally obtaining the optimal threshold Ti,j [σX(LD)], this algorithm has implement the image denoising. Furthermore, analyzing the peak signal to noise ratio (PSNR) and its computational complexity. The simulation results show that the superiority of this algorithm which has obviously improved the visual effect and PSNR when compared to DWT- NABayesShrink method, DTCWT- BayesShrink method and CbATD method.

In order to research related edge plasma physics and accurately measure electron temperature and electron density with Thomson scattering system in HL- 2A Tokamak device, a new kind of near infrared (NIR) bremsstrahlung emission measurement system with high space- time resolution is built for the first time. Under different discharge and heating conditions, the bremsstrahlung signals in NIR range are successfully obtained and compared with those in visible and soft X- ray range, so that the reliability of the NIR system is confirmed. The radial profile of the NIR bremsstrahlung signals is presented by Abel inversion of bremsstrahlung emission from fifteen horizontal chords which axisymmetrically distribute along the plane in the cross section.

In order to analyze the variation rule and influence of the modulation in the one-dimensional phase shifting lateral shearing interferometer (PS LSI). The principle of the PS LSI based on one-dimensional Ronchi grating is researched. The inference intensity formula and intensity modulation function are reduced. By substituting the each Zernike aberration into the modulation function factor, the influence due to Zernike aberration and shear ratio are analyzed. The measurement range is mainly limited by the high order spherical aberration and large shear ratio. Finally, an experimental setup is designed to measure the wavefront aberration of a NA=0.25 microscope objective at 632.8 nm wavelength, in which using two one-dimensional gratings with 9 μm and 18 μm period respectively. The results show that when grating period is 18 μm, the measurement result is correct; when grating period is 9 μm, the reversed points exist in the modulation, the aberration is beyond the measurement range, and the correctness of the modulation function analysis result is validated.

To scale the output power of all- solid- state continuous- wave Nd∶GdVO4 laser of single- frequency operation at 1342 nm, the composite Nd∶GdVO4 laser crystal is used as laser medium, and its relevant parameter is optimized. The theoretical calculation shows that the thermally induced diffraction losses is proportional to the cross- section dimension of laser medium, and the pump power of thermal fracture limit is the decreasing function of it. A ring laser resonator is designed to make the laser single-frequency operation. The experimental result shows that the maximum output power is 3.1 W, and the conversion efficiency increases by 30%.

The threshold gain of a composite external cavity semiconductor laser is analyzed. By introducing equivalent reflectivity, the formula of threshold gain coefficient and threshold current density of this composite external cavity semiconductor laser are established. By adopting numerical simulation, the influence of the first-order diffraction efficiency of blazed grating, beam splitter reflectivity and resonator output end reflectivity on the threshold gain is discussed and analyzed. Finally, this composite external cavity structure is analyzed and further optimization possibility is explored.

By contrast with distilled water under the same condition, heat transfer characteristics of microencapsulated phase change material suspesion (MEPCMs) of which the phase change temperature is 50 ℃ are investigated in a micro-tube of radius of 1 mm. It appears that for Reynolds number (Re) ranging from 300 to 1000 both the average heat transfer coefficient and the average Nusselt number (Nu) of MEPCMs with different mass concentrations are higher than that of distilled water, and increase with Reynolds number increasing. Moreover, the wall temperature of the MEPCMs suspension is lower than that of the distilled water at the same Reynolds number, and it decreases as Re increases. In addition both the average heat transfer coefficient and the average Nusselt number increase as the mass concentration of MEPCMs increases, whereas the wall temperature decreases.

The mechanism investigation of beam quality evolution within laser oscillator is of crucial importance for high beam quality laser output. Combining the thermal effect and gain guiding effect, a theoretical model of laser oscillator is presented. The beam quality evolution inside a laser oscillator is numerically simulated and experimentally verified. The mechanism of beam quality evolution is investigated based on the theoretical model. When the laser beam with negative spherical aberration passes through the laser crystal, the negative spherical aberration can be compensated by the positive spherical aberration of the crystal, resulting in beam quality improvement. This mechanism is meaningful for high beam quality output of laser oscillator and amplifier.

The large output power semiconductor optical amplifier with single frequency developed. Output optical power of the amplifier relationship with injection of current is experimentally investigated at different seed laser powers and temperatures. The results of experiments show that the out power with injecting current of 5 A can be up to 1600 mW after injecting the seed laser with power of 30 mW at 1015 nm and the amplification factor is up to 17.3 dB. Moreover, the output power of the amplifier becomes larger as temperature decreases. The output power of semiconductor optical amplifier diode system is very stable once the system reaches thermal equilibrium. Therefore, it can be applied to laser cooling crystals doped with rare earth ions, as well as the optical lattice clock of mercury atoms after frequency quadrupling.

Micro-electromechanical systems (MEMS) based on two-dimensional optical scan system is one of the core parts in the new generation three-dimensional imaging lidar system, which is developing towards to direction of low-cost, miniaturization and high-definition. Because of the limited aperture and maximum scan angle of the MEMS off- the- shelf, which can scan along two axes in bi- direction with high frame frequency, the laser beam reflected off the MEMS needs scanning angle expender and beam expender. We discuss the restrictive relationship between the spot size of the scan beam which is expended by Keplerian telescope system and the scan angle, derives the relationship between scan angle and the beam expender ratio, proposes the structure of a scan and zoom beam expender system which is based on MEMS and Keplerian telescope for three-dimensional imaging lidar system, and then on this basis gives an eleven piece type scan and zoom beam expender optical system designed by the optical design software Zemax, the result of the Zemax simulation has been shown perfectly conformed to the theoretical calculation.

Off-axis three-mirror (TMA) systems are based on coaxial three mirror systems, which can avoid the obstructions through field off-axis and aperture off-axis. Traditional methods obtain coaxial system parameters such as structure intervals by calculating obscuration ratios and amplifications three mirror, which fails to limit the physical size of system directly. Based on traditional method, a new method is proposed to calculate coaxial configuration parameters by offering the interval of three mirror and distances between three mirrors and image plane. Configuration parameters are initialized by Matlab and further optimized via Zemax. According to the existence of an intermediate image or not, Cook TMA and Wetherell TMA are designed with effective focal length of 1500 mm and entrance pupil of 250 mm. Experimental results demonstrate that the modulation transform functions at the spatial frequency of 50 lp/mm are above 0.6, and the root-mean-square radii of diffusion plaques are below 5 μm . The proposed method can determine system size and the image quality meets the requirements.

In the optical design stage, tolerance sensitivity control is undoubtedly a very important link. It determines the processing cost of the lens, and the imaging quality of the final product. Based on the geometric aberrations theory, a large-aperture industrial lens is designed by Zemax. The tolerance analysis shows that some surfaces of the behind group have very high tolerance sensitivity. By writing a special ray tracing program, the reason of why the tolerance of optical system is sensitive have been found. In order to reduce tolerance sensitivity, the method of optimization aperture angle is put forward. According to the relationship between senior aberration and aperture angle, the optimized value of aperture angle is found. The results show that this method can effectively control the tolerance sensitivity.

Based on the requirements of light source used in fluorescence polarized immunoassay analysis device, light emitting diode (LED) is proposed to use as stimulating source and illuminating system with small size, compact structure and high collimation is designed. Referring to the luminous characteristics of LED, a new system combined with refractive and reflective freeform surfaces is designed for collimating. Equations between the source and target surfaces are presented through the theory of geometrical optics to get the surface parameters. The simulation results show that the collimating system can achieve ± 2.4° diverging angel for a 1 mm × 1 mm LED surface source with efficiency no less than 85%. Accomplishing the expected of compact construction and high collimation, the paper offers an effective reference for compact design of fluorescence polarized immunoassay analysis device.

Tertiary mirror (M3M) of thirty meter telescope (TMT) and its prototype reflector (M3MP) are elliptic reflector. Their support structure takes 18 points whiflletree. Telescope support optimization methods are reviewed in this paper. By using the multidisciplinary integrated optimization software ISight, the support points of M3MP are optimized. The SlopeRMS of M3MP′ s mirror surface error when the optical axis is vertical is selected as objective function. And the global optimization algorithm simulated annealing algorithm was used to optimize. Final surface error SlopeRMS is decreased 14.3% compared to the initial support points. The results show the effectiveness of optimization method.

In order to design a wide spectral range and ultra wide-angle optical system that is suitable for spaceborne and meet the requirements of the global atmospheric aerosol monitoring. And to solve the problem of image surface uniformity of the wide- angle lens. The inverted telephoto structure is selected according to the performance requirements, the relationship between the angle magnification parameters of the former group and aberration control and rear cut-off distance is analyzed in theory. The pupil aberration that affect the illumination of image plane is also analyzed. Infer that increasing the angle magnification of the former group is unnecessary for getting great aperture coma. Through the use of low dispersion glass and parabolic lens, the optical system is designed and the spectral coverage is 443~910 nm, The F number is 4.5, full field angle of view is 118.8°, the distortion is less than 10%. Each band modulation transfer function (MTF) is more than 0.75@20 lp/mm. Simulation analysis is carried out on the relative illumination of system imaging using the sequential and non sequential methods respectively, the results of the two methods are consistent, show that image plane illumination uniformity of the system is better than 95%, the indicators meet the requirements.

The instability of polarization degree influences the performance of fiber optic gyro in SLD start- up process, which severely restricted the research on quick start of fiber optic gyro. It is analyzed that the polarization characteristics of TE mode, TM mode and influencing factors theoretically, it is concluded that the degree of polarization increases with the increase of drive current and reduces with increase of temperature, a high-speed data acquisition scheme is designed to test the changes of polarization degree, drive current and temperature of chip in SLD start-up process, it has been obtained that the rise time of drive current is about 0.3 s, the stability time of temperature is about 3 s and the polarization degree of SLD is about 4.3%, and the effect of polarization characteristics on polarization error of fiber optic gyro has been analysed when SLD starts up.

Three-dimensional light-emitting diodes (LEDs) have been the preferred light source for bulb lamp due to their 360° illumination. However, compared with other light sources, this encapsulation requires better cooling function owing to its heat dissipation channel changing from longitudinal to transverse. Therefore, this work attempts to design the best thermal dissipation model of the three-dimensional LEDs through thermal simulation software. By comparing optimization of the substrate and chip pattern mode, the temperature of substrate decreases from 130 ℃ to 83 ℃ under the same drive current condition. In order to verify the accuracy of simulation, two samples are made to test the performances of thermal dissipation. The temperature of samples can achieve equilibrium in 300 s. Moreover, the test results are in accord with the simulation results. Experimental results show that the optimization of three- dimensional light- emitting LED lights with good heat dissipation performance can satisfy the industrialization product demand of the three-dimensional light-emitting LED lights.

The characteristics of one-dimensional narrow-band photonic crystal including different materials are primarily studied based on experiment. By the means of the electron beam evaporation, a series of narrow band photonic crystal reflectors are prepared in the visible light. The experimental results show that the refractive index ratio can affect inhibition ability of light wave at the corresponding frequency of the photonic crystal. For the same refractive index ratio, the maximum reflectivity is increasing with increasing of periods while band gap is decreasing. For the different refractive index ratio, the smaller the refractive index ratio, the narrower the photonic crystal band gap, the more periods are required to achieve the highest reflectance. Moreover, a hetero structure photonic crystal are also constructed, which can significantly narrow the photonic band gap of photonic crystal, realizing a narrow high reflectivity of the photonic crystal mirror in a shorter period.

The method of the dielectric loaded is presented to obtain low loss in propagation of the surface plasmon polaritons (SPPs). Comparing the conventional insulator-metal-insulator (IMI) waveguide and the waveguide with dielectric loaded, it is demonstrated that the method of dielectric loaded can reduce the loss in propagation and achieve smaller group velocity. A silica layer between a silver film and silicon layer is employed to improve the propagation performance of SPPs in the“trapped rainbow”system based on graded grating structure. Time domain finite difference simulation demonstrates that the improved structure is able to localize light of different frequencies at different positions and offers the advantage of supporting slow SPPs with a much lower propagation loss and deeper sub-wavelength confinement. The proposed structure has a wide range of applications in optical processing and optical communication.

Polarization imaging detection technology in the complicated environment on the recognition of target detection enjoys obvious advantages and broad prospects. Polarization properties of atmospheric transmission channel environment are particularly important. The parallel plates convection device is adopt to develope simulation of atmospheric turbulence. Based on this, experiments are conducted to study the change regularity of the polarization of laser transmission characteristics under turbulent environment, combined with the laser emission and polarization parameter detection device. The results show that linearly polarized light will appear obvious depolarization phenomenon passing through the atmosphere, but circularly polarized light shows weak depolarization phenomenon, which is very good to maintain the original rotation to continue transmission, and the strong turbulence affects more heavily than weak turbulence on the polarization transmission. The results prove circularly polarized light transmission polarization can maintain good performance in the atmospheric channel.

Based on Wyner tapping channel and the composite channel, the information transmission ability of a channel is considered in which legitimate transmission channel set is a classical channel and wiretap channel set is a quantum channel. The goal is to design coding and decoding scheme, so that the receiver can decode the message sent by the sender perfectly (decoding error probability close to zero), while the degree of confusion of eavesdropper to messages is as high as possible. On this basis, it is guaranteed that in the case of Alice′ s knowing of information of channel condition, there is the security capacity of classic composite channel when quantum wiretaps; at the same time, the lower bound of security capacity of this channel is known in the case of Alice′s unknowing of information t of channel condition.

A scheme for atom localization via measuring population of the upper level in a quasi-Λ-type four-level atomic system is proposed. The function of conditional position probability distribution based on population of the upper level is obtained by solving the Schr?dinger equation using the perturbation theory. The position and width of the atomic location peak are analyzed theoretically and their equations are obtained. It is found that when the coupling field and probing field are in accord with the configuration of electromagnetically induced transparency (EIT) or when the probability amplitudes of the atom transitions from the upper level to the near-degenerate lower levels are destructive interference, atomic location cannot be obtained. But near the EIT window, the atom can be localized precisely. The peak position and its width of atom location are determined by the coupling field intensity and the space between the near-degenerate lower levels.

In order to confirm the optimal extraction method for edge spread function (ESF) in knife-edge method, four extraction methods based on the cubic spline interpolation and SG filtering, including Spline、SplineSG、MSG and SASG method are presented. By the experiments using simulation images and remote sensing images, in which only additive noise exists or white noise exists as well at the same time, effects of the four methods are analysed and compared. Experimental results show that Spline and SplineSG method have almost the same results, and the calculating accuracy of line spread function (LSF) and modulation transfer function (MTF) is nearly 2 to 3 times better than SASG method and 3 to 5 times better than MSG method in simulation experiments. While SASG method has the same results compared with Spline and Spline SG method in the practical experiments using remote sensing images. The improving effect of the image quality image restoration is 1.5 to 2 times better than MSG method. When the stripe noise is obvious, SASG method works best. Thus, according to the noise situation, SASG method or Spline method can be chosen for ESF extraction in the implementation process of the knife-edge method.

Laser polishing on the metal surface, as a new type of laser processing technology, has an advantage of high machining efficiency, nice material removal effect, excellent material utilization and so on. The types of metal materials used in laser polishing are presented. The laser polishing application machine types are analyzed. The theory models of laser interact with metal surface when laser polishing the metal surface are discussed. The process parameter and polishing effect of laser polishing on the metal surface are reviewed in detail. The current situation and the trend of laser polishing on the metal surface are evaluated and prospected.

The latest progress of single-junction non-concentration crystalline silicon solar cell research of which photoelectric conversion efficiency up to 25% is summarized. The reason why passivated emitter, rear locally-diffused (PERL) structure, interdigital back-contacted (IBC) structure, hetero-junction with intrinsic thin-layer (HIT) structure and hetero-junction back-contacted (HBC) structure solar cells have so high efficiency is explained. Combined with the current status of China′ s silicon-based photovoltaic industry, the development trends are predicted, and the technical demands are analysed.

Infrared photodetector is a device that can transform invisible infrared radiation into electrical signal. It is widely used in many industries. Recent years, graphene has aroused extensive attention among scientists and engineers in optoelectronic fields due to its unique properties such as wide spectral absorption from ultraviolet to far-infrared, ultrahigh carrier mobility at room temperature, good mechanical flexibility and environmental stability. These characteristics make it promising in fabricating ultra-wide spectrum, ultrafast, uncooled, large area array, flexible and long-life photodetectors. The latest research progress in graphene-based infrared photodetectors are reviewed. It mainly includes near-infrared (0.76~1 μm), short-wave infrared (1~3 μm), medium-wave infrared (3~ 5 μm), long-wave infrared (8~12 μm) and ultra-wide spectrum graphene photodetectors.

Solid state laser with high energy and high power laser output by combining several low energy and low power beams overcomes the limitation of crystal material volume, thermal effect and the repetition rate, which has made rapid development in recent years. As, based on stimulated Brillouin scattering (SBS), which is one of the most important research directions in this field, laser beam combination method has received extensive attention of scholars all around the world. Present studies on the serial laser beam combination based on stimulated Brillouin amplification are reviewed. Characteristics of collinear and non- collinear methods and SBS laser beam combination problems are analyzed, and the development direction is prospected.

In order to accomplish the project of infrared telescope with φ2 m aspheric segmented primary mirror, the infrared telescope optical system design is finished, its primary mirror consists of a circular center mirror and 8 sector-shaped segment mirrors. For the purpose of analyzing the influences of segmented mirrors′ maladjustments on whole optical system, a wavefront aberration representation is derived through aspheric surface equation, then the linear relation between wavefront aberration and interference bright fringe is established, and based on optical raying tracing, the linear relation is verified by using simulation method with fringe Zernike coefficients. A linear retrieval method of stitching errors base on Zernike coefficients is proposed, a Python-based program is compiled in order to simulate errors retrieval in the stitching process of single sector-shaped segment. The simulation results show that when the stitching translation tolerance is less than 0.1mm (or angular tolerance is less than 0.1°), testing by interference method, the retrieval deviation is better than 0.5%, and continues to decrease to near zero.

Rice is the main food crop for human beings, whose germination rate is one of the most important indexes to evaluate rice quality. The germination rate of brown rice named Nan Jing 46 is predicted by using hyperspectral imaging system. Hyperspectral images of 960 samples which are full and not moldy are captured, and the spectral region is from 400 nm to 1000 nm. The mean spectra are extracted from the region of interest of each image and principal component analysis (PCA) is applied to select characteristic wavelengths from the full- spectrum. The prediction models are established based on spectrum data of characteristic wavelengths of different rice parts using 4 prediction methods, including partial least squares (PLS), radial basis function neural network (RBFNN), general regression neural network (GRNN) and back-propagating neural network (BPNN). After repeated tests, the top area of brown rice (containing the germ) is chosen as the characteristic part, which has the best prediction performance ( Rp =0.970). The order of the prediction accuracy from low to high is PLS, BPNN, RBGNN, GRNN. Among these methods, GRNN has the highest prediction accuracy ( Rp=0.982, fRMSEP =0.978). The results indicate that it is feasible to detect the germination rate of brown rice by the hyperspectral imaging system.

The development of frequency combs has revolutionized the field of precision spectroscopy. On one hand, it can directly link optical frequencies with radio frequencies, and can enable precise frequency measurement with up to 17-digit accuracy. On the other hand, it can be used to directly excite the atomic transitions and generate a new subject named direct frequency comb spectroscopy (DFCS). Ampli fi cation of the pulsed output and nonlinear processes such as wavelength conversion of frequency combs are very desirable in DFCS. However, the accuracy and resolution are often limited during the amplification and harmonic conversion. A significant progress of laser spectroscopy named Ramsey-comb spectroscopy is reported, presenting a potential solution to achieve precise measurement by combining two Nobel Prize ideas.

A Raman spectroscopy denoising method based on complete ensemble empirical mode decomposition with adaptive noise is proposed. Permutation entropy is employed to judge intrinsic mode functions (IMFs), if they are on behalf of noise. The IMFs should be filtered based on threshold value. Then the reconstructed signal is without noise. This method is used to denoise the Raman spectra of ethanol solution. The result shows that the method can effectively remove noise from Raman spectroscopy. Compared with empirical mode decomposition and ensemble empirical mode decomposition, the method does not only achieve better performance at high signal to noise ratio (SNR), but also has obvious superiority at low SNR.

As one of the main air pollutants, the concentration change of carbon monoxide is the important indicator of air quality. For the need of high sensitive infrared spectroscopy detection on CO, which is one of the most important atmospheric pollution components, the characteristics of high resolution absorption spectroscopy detection method are studied, and the high resolution absorption spectra of CO near 1.56 μm are recorded accurately by using a distributed feed-back (DFB) diode laser, which has narrow line width and works at room temperature as light source. The Voigt profile model is used for absorption spectral lines fitting, and the center wavelengths, line intensities and self-broadening coefficients of CO lines are precisely measured and compared with theoretical results.

Considering that the current methods of germination rate detection are complex, time-consuming and affected by seed dormancy, a method for rapid detection of brown rice germination rate based on characteristic spectrum and general regression neural network (GRNN) is proposed. Under the condition of temperature 45 ℃ and relative humidity 90%, rice seeds are aged artificially for 0, 24, 48, 72, 96, 120, 144, 168 h. Spectral data of 160 samples are collected by a near-infrared spectrometer after artificial shelled processing and divided into a calibration set (120 samples) and a prediction set (40 samples). Characteristic wavelengths are extracted after standard normalized variate (SNV) and first derivative (FD) preprocessing. The impact of different modeling methods and characteristic wavelengths on the model is analyzed. The experimental results show that the optimal model is constructed by GRNN with the spectral data of 688, 1146, 1346, 1366, 1396, 1686 nm. The correlation coefficients of the calibration set (RC) and the prediction set (RP) are 0.9743 and 0.9505, and the standard errors of the calibration set (SEC) and the prediction set (SEP) are 1.9161 and 2.3423. The research results show that it is feasible to measure the germination rate of brown rice seeds by using near infrared spectroscopy. The model has better predictive ability in germination rate, and reveals the difference between rice seeds with different germination rate from the perspective of physiological characteristics. This method provides a theoretical basis for the development of portable spectrometer for rice seed germination rate detection.

A space-based target imaging simulation system based on visible imaging is designed and implemented for space point target. The space-based target detection imaging process is analyzed. The imaging simulation process is divided into four parts: orbit simulation, star background imaging simulation, target imaging simulation and charge coupled device (CCD) sensor simulation. In the part of target imaging simulation, satellite structures are simplified as rectangles, cylinders and spheres. The concept of target optical cross section is proposed reference for radar cross section. The brightness of target on imaging plane is calculated easily and quickly using the target optical cross section. The proposed system based on visible imaging achieves space-based space point target imaging simulation over a long distance. The observation simulation image of space target is obtained by the proposed system at any time, on any orbit with different major structures.

A color prediction model of printer based on radial basis function (RBF) neural network optimized by genetic algorithm (GA) and subspace partition is presented to settle the nonlinear of printer and complexity of printing conditions. The color space of printer is divided into subspaces and the models are built in subspaces, GA-RBF neural network model is built by GA optimizing the hidden layer nodes and width parameters of RBF neural network. Prediction accuracy of the proposed algorithm is compared with RBF neural network and cellar Yule-Nielsen spectral neugebaue (CYNSN) model. Experimental results show that GA makes up for the defect of single adjustable parameter of RBF neural network and improves prediction accuracy. Compared with other models, the proposed model has high prediction accuracy and generalization ability. It is feasible for color prediction of printer.