A support vector machine-based machine learning method is proposed to estimate atmospheric optical turbulence profiles. Using sounding data collected in coastal areas, the measured temperature, pressure, relative humidity, wind speed, wind speed shear, and temperature shear profile data are used to estimate the atmospheric optical turbulence profiles on different days. The estimated profiles are compared with the actual measured values. Error analysis results show that the root mean square errors of the estimated atmospheric optical turbulence profile and actual measurement profile are 0.4461 and 0.3939 and the correlation values are 70.42% and 62.17% on 2018-05-05 and 2018-05-10, respectively. The results demonstrate that a support vector machine model trained and learned using actual measured data can accurately estimate the atmospheric optical turbulence profile in coastal areas. Despite some errors, the general trend is consistent. The feasibility of estimating atmospheric optical turbulence profile by support vector machine method is verified, which lays a foundation for directly estimating atmospheric optical turbulence profile by using conventional meteorological sounding data and establishing relevant models.

A phase-shifting moiré method based on the techniques of water transfer printing grating and digital image processing was proposed for measuring the large deformation of superelastic materials such as polyurethane. Gratings were bonded onto the surfaces of a specimen and a reference object using the water transfer printing technique, and digital phase-shifting moiré fringe patterns were obtained by subtracting the specimen image from the reference grating images. The phase related to in-plane deformation was extracted from the phase-shifting moiré fringe patterns using the Carré algorithm. By using only one specimen grating image and one reference grating image to automatically yield deformation information with high accuracy, the proposed method could be used for dynamic deformation measurements with low cost, high efficiency, and high accuracy. Experiments were performed to quantitatively determine the deformation of polyurethane hoops under compression and study the mechanical response of a polyurethane bar under impact loading. Results demonstrate the validity of the proposed method.

H9N2 subtype avian influenza virus (AIV) is a low-pathogenicity AIV that seriously threatens the healthy development of the poultry industry and public health systems. By developing rapid, sensitive, and accurate methods suitable for field detection of H9N2 AIV, we could efficiently control the viral infection and its spread over time. This study proposes a novel biosensor with high specificity and a low limit of detection (LOD) for H9N2 AIV detection. The sensor employs a dual-resonance long-period fiber grating (DR-LPFG) modified with TiO2 nanoparticles (nano-TiO2). Anti-H9N2 monoclonal antibody molecules (anti-H9N2 MAbs) are covalently bound to the TiO2 surface carboxyl groups on the surface of the DR-LPFG, thus preparing the biosensor. The biosensor measures the variation of the dual-resonance wavelength spacing (Δλ) caused by the specific interaction between the fixed anti-H9N2 MAbs on the surface of DR-LPFG and H9N2 AIV antigen. In experimental tests, the Δλ sensitivity of the nano-TiO2 coated DR-LPFG sensor is about 1063.44 nm/RIU (where RIU is the refractive index unit) in the refractive index range 1.3320--1.3760. The LOD of the proposed biosensor for H9N2 AIV is ~2.7 ng/mL, 96.1% greater than that of a DR-LPFG-based biosensor modified with Eudragit L100 copolymer. The biosensor saturates at 50 μg/mL, and its affinity coefficient to H9N2 AIV is ~3.57×10 8 mol -1·L. The biosensor also shows a high specificity and a rapid detection for H9N2 AIV, affirming its high application potential in biomedical fields such as clinical diagnosis and drug analysis.

Optical fiber shape sensing technology can measure three-dimensional spatial information such as attitude, orientation, track, and position. It has broad application prospects in precision interventional medicine, variant aircraft, and continuum robots. The optical frequency-domain reflectometer features high spatial resolution and distributed measurement. Compared with the wavelength-division multiplexing technology of fiber gratings, it has distinct advantages in improving the spatial resolution of shape sensing, the accuracy of shape reconstruction, and the sensing length. In this paper, the physical relationships of bending deformation with strain and wavelength shift of the Rayleigh scattering spectra of the optical fibers were established after the principle of distributed strain sensing of the optical frequency-domain reflectometer was expounded. The mathematical relationships of the bending size, bending direction, and torsion with the three orthogonal components of the spatial curve local frame were determined. Finally, the three-dimensional shape reconstruction of the optical fibers was achieved via the line integral of the tangential component. A shape sensor based on the Ni-Cr shape memory alloy wire and encapsulated by three optical fiber bundles was designed and prepared in experiments. The average maximum errors of the two-dimensional and three-dimensional shape ends are 0.58% and 3.45% of the total length of the sensor, respectively.

To reduce the measurement error of mode power caused by the crosstalk in mode demultiplexers of photonic lanterns, we propose a wavelength mapping method based on single mode calculation. The operating principle of this method is described in detail, and the corresponding detection unit of mode power is developed. The transmittance matrix characteristics of the detection unit are analyzed in hybrid mode calculation and single mode calculation, respectively, and the feasibility of the wavelength mapping measurement method is verified by experiments. The experimental results show that single mode calculation is insensitive to the polarization perturbation in few-mode fibers, with the polarization dependence of mode transmittance less than 0.025. A three-mode erbium-doped fiber amplifier under 1480 nm forward pumping is built, and the wavelength mapping method is used to test the three-mode simultaneous amplification performance. The mode gain and differential mode gain are up to 26 dB and less than 2 dB, respectively.

In order to effectively solve the problem of suboptimal spectrum efficiency of a differential optical spatial modulation scheme (DOSM), a high-dimensional DOSM (HD-DOSM) including spatial, time, and digital signal domains is proposed by using pulse position modulation (PPM) with high energy efficiency and pulse amplitude modulation (PAM) with high spectrum efficiency to construct the space-time dispersion matrix which satisfies the differential process. After the differential coding principle is introduced in detail, the upper bound of the theoretical bit error rate of HD-DOSM is deduced, and its performance is compared with the DOSM system. The results show that the proposed scheme achieves a compromise between spectrum efficiency and error performance. When the spectrum efficiency is 1 bit·s -1·Hz -1 and the bit error rate is 1×10 -3, the signal-to-noise ratio (SNR) of HD-DOSM is improved by about 2 dB, compared with DOSM based on PAM. Meanwhile, the transmission rate of HD-DOSM improves by 2 bpcu (bit per channel use). Based on the sparsity of the transmitted signals, a stepwise detection algorithm is proposed to detect PPM symbols first, which effectively reduces the computational complexity of the decoding algorithm at the receiver. When the PPM order is 4, the complexity of the proposed scheme is reduced by about 75% compared with the maximum likelihood detection algorithm.

To immune the influence of compositions and refractive indexes (RIs) of working media on the accuracy of liquid level measurement, a reflective fiber-optic liquid level sensor is prepared. The sensor is composed of a side-emitting plastic optical fiber with a low cladding RI, reflector, optical fiber support rod, and air sealing device. First, the effect of the RI of the optical fiber cladding on the liquid level measurement of different working media and the same working medium with different RIs is studied theoretically and experimentally. Then, in order to improve the sensitivity of the sensor, the effects of fiber spiral diameter and pitch on the sensitivity of the sensor are studied. Finally, the effects of liquid level change velocity and working medium temperature on the response characteristics of the sensor are studied. The results show that there is a linear relationship between the output of the sensor and the liquid level when the RI of the working medium is larger than the RI of the optical fiber cladding, the change velocity of the liquid level is 10--100 cm/min, and the temperature range of the working medium is 10--70 ℃. Moreover, the measurement results are not affected by the composition, RI and liquid level change velocity of the working medium, the sensitivity of the sensor can reach 0.0101 cm -1, and the maximum relative error is less than 6.85%.

Off-axis reflective afocal optical systems have important applications in space telescopes. Freeform surfaces can correct the asymmetric aberrations in off-axis reflective afocal systems. It is very important to design the initial layouts of freeform off-axis reflective afocal systems. In this paper, an orthogonal seed curve extension (OSCE) algorithm was proposed to design the initial layouts of freeform off-axis reflective afocal systems directly. Off-axis afocal three-mirror and four-mirror systems with magnifications of 10 and 20, respectively, were designed to verify the feasibility of the method. The results show that the root-mean-square (RMS) wavefront error of the initial layout of the off-axis three-mirror system is 0.36 λ, and that of the off-axis four-mirror system is 0.18 λ. The RMS wavefront errors of the two initial layouts after optimization are both less than 0.02 λ.

The crosstalk of scintillation screen signals is the main factor that affects the spatial resolution of X-ray detectors. The spatial resolution of fiber-coupled GAGG_Ce single crystal scintillation screen CCD/CMOS detector is studied based on the point spread function theory. The ray crosstalk of GAGG_Ce single crystal scintillation screen and fluorescence crosstalk are simulated by Monte Carlo program EGSnrc and optical simulation software Zemax respectively. The simulation results show that fluorescence crosstalk is the most important factor affecting the spatial resolution of the detector for low-energy X-ray radiation imaging. In addition, the method of suppressing fluorescence crosstalk by reducing the numerical aperture of optical fiber panel is studied, and the relationship among numerical aperture of optical fiber panel, detector spatial resolution and X-ray conversion factor is obtained. The correctness of the simulation results is verified by the self-made CCD detector test.

To realize a fast and reliable thickness measurement of multilayer coatings based on terahertz technology, an adaptive teaching-learning-based optimization algorithm was proposed. In this algorithm, the standard Kent chaotic mapping was improved to increase the initial population diversity. Moreover, the teaching and learning phases were enhanced based on step adjustment optimization and suboptimal individual optimization to achieve improved optimization accuracy and efficiency of algorithm. Then, the proposed algorithm was combined with a theoretical model for measuring multilayer sample thicknesses with terahertz waves. A method for determining the thickness of the coatings was developed. Finally, multilayer coatings were prepared and terahertz nondestructive testing experiments were performed. Results show that the efficiency of the proposed method is twice that of the global optimal algorithm. The thickness, refractive index, and extinction coefficient of the multilayer coatings can be obtained quickly in a single measurement in only ~50 s. The relative error of the measured multilayer coating thickness is within 1.5%, and the maximum standard deviation is no more than 1.7 μm. Based on the terahertz measurement signal, the proposed method can be used to efficiently, accurately, and reliably determine the thickness of multilayer coatings.

Due to the wide wavelength coverage and dense transmission peak sequence of its spectrum, the Fabry-Perot etalon (FPE) for wavelength calibration of astronomical high-resolution spectra is expected to achieve higher calibration accuracy than traditional calibration sources. However, the unknown wavelengths of FPE transmission peaks pose a challenge for calibration. In this study, without precision measurement devices (such as Fourier transform spectrometers), the thorium-argon (ThAr) lamp, a conventional calibration source equipped on astronomical high-resolution spectrometers, was used to provide the FPE with wavelengths. Then, the errors in the ThAr wavelengths were corrected by using the dense transmission peak sequence of the FPE and the smooth relationship between the penetration depth of the dielectric reflective coating and the wavelength. Accurate wavelengths of the FPE transmission peaks were thus obtained, and wavelength calibration was performed. The calibration test on the fiber-fed high-resolution spectrometer of the Xinglong 2.16-m telescope showed that the wavelength calibration accuracy of the FPE reached 0.053 pm, which was significantly higher than that (0.290 pm) in the case of the ThAr being used alone.

The measurement of displacement and strain fields of smooth and accurate crack tips is one of the key issues for digital image correlation (DIC) method. The traditional subset-based DIC method is commonly used, but the results of subset cross crack calculation are invalid. The improved subset-splitting based DIC method gives low-accuracy results due to the reduction of the number of pixels in the subset. This study proposes a novel Hermite-element based local DIC (HELDIC) method. In HELDIC, the region of interest (ROI) is divided into independent meshes, the data with low precision of element boundary is eliminated by using large block regions of element envelopes, and then the Hermite element position is adjusted to minimize the amount of data removed. The improved pointwise least square (PLS) method is used to smooth displacement fields and obtain strain fields, and finally improves the smoothness and accuracy of strain fields at crack tips. The experimental results show that the deformation field computed by the proposed method is closer to the crack tip and crack face than that calculated by the traditional local DIC method, and the strain field mean error under the specific element and subset size conditions can be reduced by more than 30%, and the HELDIC method is an effective method for the crack tip deformation field calculation.

Given the environmental influence, poor repeatability, and low efficiency of the outdoor calibration of the rotating pyroelectric sunshine duration recorder (RPSDR), an indoor calibration method using RPSDR with a system of the bi-xenon lamp source integrating sphere was proposed. According to the composition, structure, and measurement principle of the RPSDR, a calibration system based on the bi-xenon lamp source integrating sphere with the xenon lamp solar simulator outputting direct radiation and the dome xenon lamps simulating diffuse radiation was designed by technologies such as solar simulation and environmental simulation with the integrating sphere. The structural parameters of the integrating sphere were putforward, and the irradiance distribution and spectral correction of the xenon lamp source were analyzed. A comprehensive RPSDR calibration method for indoor sunshine threshold calibration and outdoor sunshine duration verification was established. According to the tests, the irradiance uniformity on the effective irradiation surface of the calibration system was 2.5% with the center point and 1.6% without the center point. On the effective irradiation surface, the irradiance stability per hour at the threshold point was 0.68%, and the light source matched with the AM1.5 class A solar spectral energy distribution. Experiments of indoor threshold calibration and outdoor sunshine duration comparison were carried out on an RPSDR. The results show that the relative error of sunshine duration measured with the RPSDR after calibration is less than 1% and the absolute error is no more than 0.26 h compared with the reference values measured with the pyrheliometer, which meet the requirements of the meteorological industry for sunshine duration observation.

Phase unwrapping plays an important role in three-dimensional (3D) measurement technologies, and its analytical accuracy directly affects the accuracy of 3D modeling. Due to undersampling and discontinuity of the wrapped phase, it is difficult to obtain correct phase information for traditional spatial phase unwrapping, while temporal phase unwrapping requires additional auxiliary information. For 3D face modeling in complex scenarios, a phase unwrapping network based on multi-scale attention is proposed in this paper. In this network, the encoder-decoder structure is used to fuse multi-scale features, and an attention sub-network is embedded into the decoding network for contextual information collection. A FACE dataset of 5000 samples and a MASK dataset of 100 samples are constructed, and each sample contains the truth values of wrapped phases and continuous phases for training and testing of phase unwrapping. The root-mean-square errors of the proposed network are 0.0387 rad and 0.0273 rad on the FACE dataset and the MASK dataset. The structural similarities are 0.9850 and 0.9793 respectively. The phase features can be extracted quickly and accurately in areas such as undersampled and phase discontinuous ones to ensure the correctness of phase unwrapping. Finally, the effectiveness and feasibility of the proposed network are verified by comparative experiments.

A spatial-temporal combined phase unwrapping method is proposed, which improves the noise suppression ability and phase unwrapping reliability of the three-frequency temporal phase unwrapping method. The fringes with sensitivity greater than 1 are used to replace the fringes with sensitivity of 1 in the traditional three-frequency temporal phase unwrapping method. By calculating the wrapped phases of these fringes, the spatial phase unwrapping of them is carried out, and the unwrapped phases are used to guide the unwrapping of the other two high sensitivity wrapped phase images. Compared with the traditional three-frequency temporal phase unwrapping method, the proposed method reduces the frequency multiple difference between the three sets of fringes when the spatial frequencies of the highest sensitivity fringes of them are the same, thus reducing the influence of noise on phase unwrapping and improving the reliability and accuracy of three-frequency temporal phase unwrapping.

This paper studies the influence of buoyancy convection caused by the laser energy absorbed by air during the propagation of high-power laser in a closed channel on the thermal blooming effect. A physical model of the thermal blooming effect under buoyancy convection is constructed. Two factors that affect beam quality, namely heat conduction and convection heat transfer, are analyzed by a numerical calculation method. It is found that buoyancy convection can reduce the thermal blooming effect in the closed channel and cause beam centroid drift. The far-field spot shape, beam quality, and spot centroid drift of array beams with different arrangements are studied. The results show that the buoyancy convection under the interaction among the array beams is greater, and the reduction of the thermal blooming effect is more severe. The conditions of beams at different positions with different arrangements are different. Beam quality and centroid shift can be optimized by choosing the appropriate arrangement. In addation, we verified that axial wind can be adopted to suppress the thermal blooming effect. The results show that buoyancy convection can promote the reduction of the thermal blooming effect. When the axial wind increases, the thermal blooming effect vanishes, and the influence of buoyancy convection gradually disappears.

In this work, we propose a full current model in order to interpret the mechanism of terahertz (THz) wave generation from single-color femtosecond laser filamentation under transverse and longitudinal direct current fields. The model consists of two processes, i.e., oscillation of the microscopic plasma current and radiation of the macro current transmission line. Both processes are combined to describe the terahertz (THz) radiation characteristics such as terahertz wave enhancement and spatial distribution evolution. Compared with the well-known transition-Cherenkov radiation theory, the proposed full current model can achieve phase matching under the condition of equal light speed, and has a clearer physical picture and simpler formulas. Moreover, it can reproduce the experimental results well.

High output power and long-term reliability are the prerequisites for the wide application of high power semiconductor lasers, but the optical catastrophic damage (COD) caused by cavity surface degradation at high power density restricts the maximum output power and reliability of semiconductor lasers. In order to improve the COD threshold of 915 nm InGaAsP/GaAsP semiconductor lasers, the primary wafer is epitaxially grown by metal organic chemical vapor deposition equipment. The influence of quantum well intermixing on the luminescence of the primary wafers is investigated. Moreover, the peak blue shift and luminescence intensity are measured by photoluminescence spectrum. The experimental results show that the peak blue shift reaches 62.5 nm when the annealing temperature is 890 ℃ and the annealing time is 10 min. A large peak blue shift is obtained by intermixing the primary sample, and the peak intensities are kept above 75% of the peak intensity of the original wafer in the annealing temperature range of 800--890 ℃ and 10 min annealing time.

In order to explore the optimal heating temperature of the InGaAs photocathode, the high-temperature cleaning experiments were carried out at different temperatures by using the ultra-high vacuum interconnection setup for photocathode preparation and characterization, and Cs/O activation experiments were followed. By scanning focused X-ray photoelectron spectroscopy, in-situ analysis of InGaAs samples after chemical cleaning, heat cleaning, and surface activation was performed, to detect the desorption of surface impurities and the change of chemical element composition at different temperatures. The results show that the carbon contaminants and oxides are completely removed at 625 ℃, resulting in an atomically clean surface. However, the In element is volatilized at this time, which leads to the decrease of In composition and makes the infrared response of InGaAs material unobvious. Therefore, 600 ℃ is treated as the optimal heating temperature. Combined with in-situ ultraviolet photoelectron spectroscopy, it is found that the secondary electron cut-off edge continuously shifts towards higher binding energy as the temperature rises, indicating that high temperature cleaning can effectively reduce the work function. After Cs/O activation, the work function value is further reduced, and the negative electron affinity state is achieved, which improves the near infrared photoemission performance of the InGaAs photocathode.

Cone-beam X-ray luminescence computed tomography (CB-XLCT) imaging is a new medical imaging technique that can effectively detect early tumors in vitro. Sparse-view CB-XLCT imaging brings this technology a step closer to real-time imaging of CB-XLCT technique. Nevertheless, it suffers from a much more severe ill-conditioned inverse problem compared with traditional multi-view imaging, which poses a challenge to the extension of the traditional approach. A sparse non-convex Lp (0pL1-norm and L0-norm to evaluate the efficiency and robustness of the proposed method. The experimental results demonstrate that our proposed method can effectively solve the inverse problem of sparse-view CB-XLCT imaging and possesses expandability.

The advanced glycation end (AGE) product detection based on skin fluorescence spectroscopy is widely used in the screening and evaluation of diabetes and its complications. However, this method is limited by the specific absorption and scattering characteristics in biological tissues and a variety of fluorescent components. In this study, the optimal excitation wavelength combination for measuring skin tissue fluorescence spectra was determined by analyzing the three-dimensional fluorescence spectra of common fluorescent components in human skin tissues. A discrete three-dimensional fluorescence spectrum measurement system was built that integrated the measurement module of tissue diffuse reflectance spectra. The methods of extracting tissue physiological parameters under the diffusion theory and separating discrete three-dimensional fluorescence spectra by multi-peak Gaussian fitting were studied. A clinical community cohort study was then carried out. The results showed that the mean relative concentrations of melanin and deoxyhemoglobin in the diabetic group were lower than those in the normal control group, while the reduced scattering coefficient at 500 nm was higher than that in the normal control group. These differences were statistically significant. No significant difference was found in the relative concentration of oxyhemoglobin. Under the multi-peak Gaussian fitting, 78 fluorescence features were obtained for each subject, and 50 fluorescence features remained after features with insignificant differences (p>0.1) were eliminated. Differential tissue physiological parameters and fluorescence characteristics were pooled, and a diabetes screening model was built by the logistic regression analysis. According to the analysis results of the receiver operating characteristic (ROC) curve, when the proposed method was applied to diabetes screening, the area under the ROC curve of the prediction training set was 0.793, and that of the prediction test set was 0.799. In contrast, that of the single-wavelength skin fluorescence (Sf365) was 0.731, which indicated that the proposed model had a better diagnostic value than that of the single-wavelength fluorescence.

In order to construct an optical triode model, a PT (parity-time) symmetric coupled microcavity with the semiconductor magnetic material InSb is designed. By optimizing structure parameters, the pole effect of PT symmetric structure with strong magnetic coupling is achieved. By changing the input current signal into the change of the applied magnetic field to magnetic materials near the pole frequency, the input current signal at the pole state can be amplified. The amplification can be either in phase or out phase. As a result, a special optical triode model is realized.

The traditional radio navigation technology does not meet the requirements of high-precision angle measurement, whereas the superior characteristics of entangled quantum signals can break through the technical barriers faced by traditional radio navigation. Therefore, this paper proposes a navigation angle measurement scheme based on hybrid entangled quantum signals prepared by a cavity electro-opto-mechanical converter. According to the theoretical analysis and simulation, compared with traditional angle measurement methods, this scheme makes full use of the entanglement characteristics in discriminating angle measurement signals and thereby effectively differentiates useful signals from irrelevant signals. Its accuracy is better than that of the classic scheme, and it also has a strong anti-interference ability that the classic scheme does not have.

The development of optical fiber sensing technology in China for more than 40 years is accompanied by the economic development and the traction of market demand. Several typical subdivision techniques of optical fiber sensing in China are summarized in terms of their development history, technical status, and major problems, so that readers can better understand the development of optical fiber sensing technology in China and grasp the exponential growth of market requirements of China’s optical fiber sensing technology.

This paper explores whether the spectral radiance of high-temperature targets in the shortwave infrared band (1300--2500 nm) has a directional effect and the relationship between the spectral radiance and the radiation zenith angle. Using 500 ℃ graphite and metal (304 stainless steel) plates as the high-temperature targets, this paper designs an experiment of spectral radiance measurement with 0°--70° radiation zenith angles of the high-temperature targets in a dark room. The variance analysis is applied to study whether the radiance in the shortwave infrared band gives a directional effect, and the least squares method is adopted to fit the directional spectral radiance of the high-temperature targets and thereby explore its variation rules. The experimental results show that under the condition of significance level α=0.01, the spectral radiance at different radiation zenith angles is significantly different for both the graphite plates and the metal plates. In light of the least squares method, the exponential function is used to fit the directional spectral radiance of the high-temperature targets, and the fitting accuracy is greater than 0.95. The results demonstrate that the metal plate has a more prominent directional effect than the graphite plate. The directional effect of the spectral radiance of the metal plate is affected by wavelength whereas that of graphite is not. The directional spectral radiance of both the two materials has an exponential relationship with the radiation zenith angle (0°--70°).

The feasibility of near infrared spectroscopy (NIRS) combined with stoichiometry for quantitative determination of umami substances and umami intensity in mixed solutions is discussed. The mixed solution of umami substance composed of monosodium glutamate and disodium inosinate is used as the research object to obtain samples of different umami intensity and collect their near-infrared spectral data. Based on the partial least squares regression method combined with the new competitive adaptive moving window interval combination (CMIC) algorithm, and a variety of commonly used variable optimization algorithms, the detection models of umami concentration and umami intensity in mixed solution are established. The experimental results show that the optimal detection models of umami concentration and umami intensity of mixed solution are simplified models based on CMIC algorithm, and the predictive determinations are 0.8886, 0.9182, and 0.8097, respectively. Therefore, the NIRS analysis technique combined with stoichiometry can be applied to quantitatively detect umami concentration and umami intensity in mixed solutions.

There are obvious interference fringes in the push-sweep scanning image of temporally and spatially modulation spatial heterodyne interference imaging spectrometer (TS-SHIS), which will cause the traditional image registration method to have a great influence on the calculation results of TS-SHIS push-sweep scanning image registration. In view of this, an adaptive fringe template construction method based on target interference data is proposed, which is used to eliminate the interference fringes in the TS-SHIS push-sweep scanning image, and the surface fitting plus gradient method is used to register the stripe-eliminated push-sweep scanning image. Simulation and experimental results show that the proposed method can effectively eliminate the interference fringes at the zero optical path difference in TS-SHIS push-sweep scanning images, and the influence of interference fringes on registration calculation is suppressed. The influence of fringe elimination on image registration results is less than 0.02 pixel.

A method for comprehensively analyzing the damage characteristics of optical films is proposed. According to the theory of heat conduction and electron proliferationand, a theoretical model for damage of multilayer dielectric films under laser irradiation is established. Taking HfO2/SiO2 multilayer high reflection film as an example, the temperature field, stress field, and free electron number density distribution in the film system under the action of infrared nanosecond pulse laser are calculated, and the damage threshold of the film system under different input conditions is obtained after comprehensive evaluation of its thermal characteristics and electron proliferation characteristics. The results show that the damage characteristics of HfO2/SiO2 multilayer dielectric films are affected by the standing wave field. The thermal stress damage effect of HfO2/SiO2 multilayer dielectric films is earlier than the thermal melting effect, and the SiO2 layer in the film is thermal damage, but the film has no field damage. In addition, the damage threshold of the film increases with the increase of laser pulse width.

The development of colorimetry relies on the perceptual phenomena and the experimental data. With the increase of experimental data of visual color difference, people tries to explore and develope new color space, which is as simple as the CIELAB color space, but more uniform. The characteristics of CIELAB color space are analyzed, and a color space with four parameters based on these characteristics is proposed, which is called MLAB color space. The determination of the new color space parameters is a nonlinear constrained optimization problem, which can ensure that the optimized space can well predict the COM-corrected visual color difference dataset collected by the expert group of International Commission on Illumination. Comparison based on COM-Corrected dataset shows that MLAB color space is significantly better than CIELAB color space. Tests based on hue linearity and ellipse datasets show that MLAB color space is also improved to a certain extent compared with CIELAB color space.