This PDF file contains the front matter associated with SPIE Proceedings Volume 11337, including the title page, copyright information, table of contents, and author and conference committee lists.

Methyl thiol(CH₃SH) is a colorless, flammable, smelly toxic gas. A large amount of methyl thiol gas comes from organic chemicals and agricultural production, and its olfactory threshold is very low (2ppb), which not only causes pollution to the environment, but also seriously affects people's quality of life and physical health. At the same time, methyl thiol also belongs to the human body of the endogenous trace volatile organic compounds (VOCs), and periodontitis disease is closely related. Therefore, the detection of methyl thiol is very important for the assessment of the environmental atmosphere and exhalation analysis. In this paper, the concentration of methyl thiol in the atmosphere was retrieved, simultaneously with methane and water vapor, by using artificial neural network (ANN) method based on wavelength modulation spectroscopy (WMS). A mid-infrared spectral band of 3392.4~3394.7 nm was selected to cover the absorption of the three gases, which can be available by tuning an interband cascade laser in our laboratory. In order to determine the concentrations of the three gases simultaneously from the measured WMS signal, the error back propagation (BP) ANN classification algorithm model was established by a series of simulation WMS signals. The second harmonic (2f) signal detection with WMS for different concentration ratios of the three gases under atmospheric conditions was simulated by means of the Hitran and PNNL databases. Of these, 450 groups were used as training samples and 60 sets of data as testing samples. Feature extraction of peak and valley and principal component analysis (PCA) methods were used to reduce the dimension of spectral signals. Then BPANN was trained, and best validation performance of network learning is 0.000241 at epoch 46. The average relative errors are 0.0047 and 0.000742, respectively when validating with testing samples by using the two dimensional reduction methods. The results prove the feasibility of these two methods and BPANN learning algorithm. Finally, the mixed spectral data of WMS-2f signal obtained from the actual experiment were fed into the established BPANN model. However, there are large deviations between the output results of the BPANN model and the actual concentration of the three gases. The relative deviation of methane, water vapor and methyl thiol are 88.92%, 1.69% and 59.94%, respectively. Because there is the background signal, including etalon signal, noise and residual amplitude modulation, superposed in the actual WMS-2f signal, which makes the poor consistency between the experimental data and the ideal simulation data. Overall, the measurement model can be used for qualitative analysis of the actual mixed gases detection. The accuracy of quantitative analysis will be improved by BPANN model trained by more realistic simulation signals in our future work, which can be used for gas recognition and concentration measurement in the actual detection of mixed gases.

This paper aims to give a preliminary way to estimate uncertainty on the frequency peak between 2 and 150 GHz determined by Brillouin Scattering Stimulation and corresponding to the speed of phonons inside a material excited by a 532 nm wavelength laser. The guideline follows the Guide to the Expression of Uncertainty in Measurement. A first estimation indicates that the speed of the phonons can be known at 2 to 5 % at 2 sigmas.

The absolute measurements of spectral radiance, irradiance and intensity in infrared wave range are very important for infrared target recognition, material emissivity measurement and so on. Recently, many researchers focus on how to accurately measure absolute infrared spectral radiation, in which one key point is how to suppress stray radiation. In this paper, an absolute infrared spectral radiance measurement system was built up. The system contained a fixed-point blackbody source, a variable temperature blackbody source, a radiant source to be measured, Fourier Transform Infrared Radiometer (FTIR), optical system, non-contact infrared thermometer and so on. Emissivities of the standard source and the radiant source to be measured are 0.999 and 0.995, respectively. According to Planck’s law, their absolute spectral radiance should be similar at the same radiation temperature. In experiment, temperatures of the standard blackbody and radiant source to be measured were set to 500°C, and the FTIR was used to measure spectral radiance. The results show spectral radiance of the standard source is 14.9% smaller than the radiant source to be measured at 10μm wavelength. A thermal infrared imager and optical simulation software were used to analyze the possible reasons. To solve the problems, a shielding plate and a field aperture was installed respectively at the entrance of the optical system and before the FTIR to suppress stray radiation. Moreover, sizes and positions of the shielding plate, optical system, and field aperture were analyzed by optical simulation software and mathematical calculation. After optimization, the experimental results show the difference of spectral distributions between the standard source and the radiant source to be measured is only 1.42% at 10 μm wavelength, suggesting stray radiation is effectively suppressed in the system.

Combined with two-channel one-dimensional field of view imaging technique and Spatial Heterodyne Spectroscopy (SHS), hyper-resolution spatial heterodyne spectrometer can be used for hydroxyl radical OH detection with limb observations from a satellite. The accuracy of field registration of the spectrometer two channel directly affects the detection accuracy of hydroxyl radical OH density, and the spatial stop and spectral stop of each channel are in different positions on the path of light. The method of spatial and spectral dimension field registration is given first, and then the method of field of view registration between channels is given. The quantitative effect of the parameters of the registration method on the accuracy of the field registration is analyzed theoretically, and the verification test is carried out based on the long focal length collimator. The results show that the accuracy of field of view registration in this paper is better than 99.2%. It provides a theoretical basis for the tolerance of the spatial field of view of the spectrometer.

In order to achieve some special functions, high topography is often introduced in the manufacturing process of chip, which will directly lead to the sharp change of critical dimension (CD), especially for the implant layers post poly process. In this paper, a scheme of reducing the CD range of implant level lithography is proposed. The numerical simulation is carried out through using Fourier optics theory, Fraunhofer diffraction formula and Abbe principle，then the experiment is designed. The simulation results indicate that for advanced process, such as 110nm and 130nm generation, the normalized image logarithmic slope (NILS) of aerial image in the resist on the wafer can be maximized by appropriately increasing numerical aperture (NA) as well as decreasing σ, then the inter-field critical dimension uniformity (CDU) can be greatly improved. The experimental results show that the CD range can be decreased about 41% for the topography of 3000Å, and the better improvement can be achieved for the topography of 1600Å, up to 50%. The research results of this paper provide potential guiding significance for CDU control in implant level lithography process with high topography.

Integrated blackbody is a blackbody radiation source with the emissivity approximate to 1, which is coupled of materials with different infrared emissivity as the cavity wall and the cavity bottom. The integrated blackbody theory is the theoretical basis of materials infrared spectral emissivity measurement device at ultra-high temperature developed by National Institute of Metrology, China (NIM). Infrared emissivity is the most important factor for evaluating the infrared radiation characteristics of integrated blackbody. Based on Monte Carlo simulation, infrared emissivity of the integrated blackbody coupled of different high emissivity materials and infrared emissivity of the integrated blackbody coupled of low emissivity material and high emissivity material are calculated theoretically in the near infrared wavelength band at room temperature and high temperature environment. The simulation results show that, the infrared emissivity of the integrated blackbody coupled of different high emissivity materials can reach 0.998 and the infrared emissivity of the integrated blackbody coupled of low emissivity material and high emissivity material can reach 0.988. The above simulation results of integrated blackbody infrared emissivity have reached the requirements of industrial blackbody radiation source. The simulation results are verified based on the method of blackbody infrared emissivity measurement by integrating sphere reflectometer at room temperature environment at wavelength of 0.633 μm. Measurement results on multiple wavelengths show that the deviation between the integrated blackbody infrared emissivity simulation results and the measurement results is less than 0.3 %.

Fourier Transform Imaging Spectrometer(FTIS) is an instrument cable of acquiring two-dimensional spatial information and one-dimensional spectral information. The FTIS has attracted much attention and is widely applied in the fields like military reconnaissance, remote sensing, biomedicine, environmental monitoring, etc. The FTIS acquires the spectral intensity in different wavelengths by performing Fourier transform on the white light interference signal of the target generated by the FTIS. The spectral curve obtained directly by Fourier transform reflects the relationship between the wavenumber order and the spectral intensity. So wavelength calibration is required to convert the above relationship into the relationship between the wavelength and the spectral intensity, which makes it more intuitive. Therefore, wavelength calibration is a necessary step for FTIS to recovery spectrum. The traditional wavelength calibration method can only get the wavenumber order in the range of integer because of the picket fence effect in Fourier transform. It will definitely ignore the fractional part which results in the inaccurate wavenumber order, which will directly affect the precision of the wavelength calibration result. In order to solve this problem, a high-precision wavelength calibration method based on Fourier transform imaging spectrometer is proposed according to the principle of FTIS and Fourier transform. This method can calculate the wavenumber order with the precision of percentile, which will reduce the error of wavelength calibration effectively. As a result, the precision of spectral calibration can be increased eventually. This method realizes high-precision wavelength calibration by the way of adding zero to the interference fringe in the spatial domain. The core of the method is getting a more precise wavenumber order. The brief process of obtaining wavenumber order is as follows: First, the FTIS acquires the interference fringe of a monochromatic laser. Second, the original interference fringe is extrapolated with zero. Third, the subtle spectrum can be obtained by performing Fourier transform on the extrapolated interference fringe. Finally, the precise wavenumber order is calculated by dividing the abscissa of the peak value by the extrapolation multiple. The principle of this method is investigated and related simulations are then carried out. The simulation results indicate that the wavenumber order calculated by the method have the same precision with the preset parameters, which illustrates that the method can calculate the wavenumber order more accurately. Therefore, the method can improve the precision of the spectral calibration. Besides, related experiments are also performed. The laser interference fringes of different wavelengths generated by the actual FTIS all apply the method to get the wavenumber orders in the frequency domain. Then a curve which is the wavelength calibration function is fitted using the discrete relation between the wavelengths and the wavenumber orders. A laser whose wavelength is known is measured by the FTIS with the wavelength calibration function got by the proposed method. The error of the wavelength measurement result is one-fifth of the traditional method. The simulations and the experiment results indicate that the proposed method can improve the precision of the wavelength calibration, which provides the theory and technology support for spectral measurement using FTIS. It also provides a possibility for the development of FTIS towards the super resolution direction.

Cirrus scattering is not only related to the angle of incidence, the angle of scattering, the wavelength, and the polarization state of the light, but also closely related to the roughness of the subsurface of the ice crystal. In this paper, we study different hexagonal plate-shaped ice crystals that are subject to standard gamma distribution with smooth, moderately rough and severe roughness.Scattering characteristics such as extinction coefficient, absorption coefficient and phase matrix of the cirrus cloud are compared to compare the effects of ice crystallites on the scattering characteristics under different surface roughness. The results show that under the same conditions, the rougher the surface of the ice crystals, the smaller the extinction coefficient and the single scattering albedo of the cirrus, the larger the absorption coefficient of the cirrus; the smoother the curve of the six elements of the phase function, the phase matrix The impact is also greater. Therefore, the surface roughness of the ice crystal grains has a great influence on the bulk scattering characteristics of the cirrus clouds. The work done in this paper will further study the influence of the surface roughness of ice crystals on the radiation transmission characteristics of cirrus clouds and the bulk scattering and radiation transmission characteristics of cirrus clouds. It is of great significance for target detection, tactical applications and free-space optical communication.

Aiming at building the real-time measuring system of surface morphology of Plasma-Facing Components (PFCs) in fusion devices, an optical approach based on Laser Speckle Interferometry (LSI) is in development in our laboratory. To preserve high temporal resolution, the temporal phase shifting approach was introduced. However, this approach is sensitive to vibrations, which decreases the accuracy of morphology measurement. Considering the periodic vibration of the tokamak device itself, it is important to study the influence of the periodic vibration on online surface morphology measurement of PFCs. In this paper, we specify the effects of amplitude and frequency of periodic vibration on surface morphology measurements based on LSI measurement system. Benchmark tests are performed on the Molybdenum (Mo) material, which is commonly used as PFCs in Experimental Advanced Superconducting Tokamak (EAST).

Confocal Raman microscope (CRM) is one of the most powerful analytical instruments. The lateral spatial resolution is one of the key parameters for evaluating its imaging performance. In this paper, a novel knife-edge method is proposed for measuring the lateral resolution of CRMs. A virtual knife-edge phantom is developed by coating a thin layer of chromium pattern on a piece of polished monocrystalline silicon. It can avoid the edge-enhancement effect in conventional knife-edge methods. The edge spread function (ESF) and resolution of a commercial CRM at different configurations are measured to test the performance of the phantom, whose lateral resolution is from 0.8~8 micrometers. The Fermi function is used to fit the experimental data of the ESF and calculate the lateral resolution. Different types of phantoms are also developed and tested for comparison study. It is proved by experimental results that the virtual knife-edge method can be used to measure the ESF and resolution of CRMs and shows better performance than conventional methods.

In this paper, the photoacoustic detection of aqueous solutions mixed glucose and salt was experimentally studied based on the established photoacoustic detection system in the lateral mode. In the experimental system, the OPO pulsed laser was used as the excitation light source and the non-focused ultrasonic transducer was used to capture the photoacoustic signals. In the experiments, the test mixed aqueous solutions with different concentrations of glucose and salt were prepared by using the pure water. The time-resolved photoacoustic signals and photoacoustic peak-to-peak values of mixed aqueous solutions with different concentrations of glucose and salt were acquired with the average times of 128. Results show that the photoacoustic peak-to-peak values of mixed aqueous solutions increase with the increase of glucose concentration and salt concentration. At the same time, the ultrasonic velocity in the mixed aqueous solutions increases with the increase of glucose and salt concentrations. To better predict the glucose concentration in the mixed aqueous solutions, a kind of modified glucose concentration prediction models combined the photoacoustic peak-to-peak values with the ultrasonic velocity were established under the different concentrations of salt. The root-mean-square error (RMSE) of models were obtained and compared with the individual models of photoacoustic peak-to-peak value or the ultrasonic velocity. The prediction results show that the prediction RMSE values of modified model are less than that of the individual models, the RMSE value of predicted glucose concentration under 100mg/dl concentration of salt is about 8.75mg/dl.

Monitoring the deformation caused by wall erosion and deposition on the Plasma-Facing Components (PFCs) in tokamak has been essential issues for the maintenance of a long duration plasma discharge and safety. As an in situ, real-time and non-destructive optical diagnostic technique, Laser Speckle Interferometry (LSI) based on temporal phase-shifting approach has been considered as the most potential approach for the measurement of erosion and deposition on PFCs. This paper focuses on the measurement of the deposition morphology and thickness based on the temporal phase-shifting laser speckle interferometry. Here the deposition was conducted by Pulse Laser Deposition (PLD) in a vacuum chamber, which is simulated to the deposition process on PFCs. The LSI measurements are compared with those of profilometry and the results show that the temporal phase-shifting laser speckle interferometry is capable of online measuring deposition morphology as well as thickness. The LSI approach has great possibility for the further application on the real-time monitoring impurity and fuel deposition on PFCs in fusion devices.

This paper studied the data process methods of Laser-Induced Breakdown Spectroscopy (LIBS) and proposed a spectral intensity correction method utilizing laser energy monitoring and plasma morphology imaging, combined with neural network algorithm to improve the spectral stability. We set up a LIBS system, which had a laser beam sampling module to monitor laser output energy and a CMOS camera imaging module to capture plasma flame outlines. A back propagation neural network (BPNN) model was designed for standardizing the spectrum to a lower relative standard deviation (RSD) of emission line intensities, in which training spectrum, sample energy and image parameters were inputs, and the average of all the training spectrums were outputs. This method was applied in both aluminum and soil LIBS tests, and got effective results in reducing spectral intensity fluctuations. This data processing method not only provided a practical access to acquire stable spectrum information for both qualitative and quantitative LIBS analysis but also showed a bright future of combining LIBS data processing with machine learning methods.

Based on the terahertz time-domain spectrum (THz-TDS) system, the measurement results of multilayer submillimeter interlayer structures are analyzed. An algorithm is developed to extract the peak information of the corresponding reflection signal and restore the intensive submillimeter interlayer structure.

OH radicals in the upper and middle atmosphere are important oxidants and play an important role in atmospheric photochemistry. Current space-based payload can only obtain profile information. In view of the inhomogeneity of atmospheric two-dimensional distribution field, a hyper-spectral OH radical tomography detection scheme based on onedimensional imaging spatial heterodyne spectroscopy is proposed. Horizontal and vertical multi-dimensional atmosphere are detected by combining two orthogonal field-of-view one-dimensional imaging spatial heterodyne spectrometers, and the multi-line-of-sight crossed required for atmospheric tomography detection is achieved by platform movement. Based on this technical scheme, the optical and structural design of the prototype is carried out, and the data form of the interferogram acquired on-orbit is simulated. OH radicals can’t be measured on the ground, so the OH radicals can be obtained by photochemical reaction chamber in the laboratory. The OH measurement results obtained by the prototype agree with the HITRAN simulation results.

In the past few decades, environmental pollution problems have become more and more serious because of development of modern industry and science technology. The real-time detection and identification of atmospheric pollutants, has aroused widespread concern. Differential Absorption Lidar (DIAL) technology has become a common method for atmospheric remote sensing pollution measurement. 9~11-m-band lasers have small scattering cross sections for the air pollution cloud particles, so the laser output energy is required to reach the Joule level. The system engineering is difficult to realize detection of air pollution clouds with technology. The developed remote sensing pollution detection system is used to detect the types, concentration, orientation and distance information of common industrial chemical pollution. It is mainly divided into two parts: DIAL channel and Front Range Detecting Lidar (FRDL) channel. This paper mainly discusses remote sensing of air pollution clouds using FRDL. The working principle of FRDL is to use the Doppler effect of aerosol on the laser backward Mie scattering to realize the measurement of the aerosol cloud. In July 2017, the verification test was completed at a certain place in the north of China. The simulated pollutant spraying device and sampler were set at 400m in front of the 5km target. The measured results are in agreement with the actual situation.

Fixed focal length lens was used by the optical module of the traditional centering instrument. Under the principle of reflection measurement, the measurement range is limited when defocusing imaging the curvature center of the measured surface. In view of the above situation, a high resolution centering instrument was developed by switchable lenses. The measurement principle of center aberration of optical lenses was introduced and the calculation formulas of center aberration was given. The optical system of optical measurement module was designed and optimized. According to image quality evaluation results, it can be concluded that the optical system has high imaging quality and meets the requirements of high-precision using. The measurement range of the instrument is -∞ ~ -2 mm and 2 mm ~ +∞, the measurement resolution is better than 2 μm.

Graded-index multimode fibers attracted interest in nonlinear regime for their unique nonlinear dynamics characteristics. We report the supercontinuum generation pumped by a superluminescent pulse amplification in graded-index multimode fiber. Efficient supercontinuum was generated and the beam profile cleanup was observed. The speckle characteristics of this supercontinuum is measured and compared to another supercontinuum induced by a homemade mode-locked fiber laser. It is found that the supercontinuum generated by superluminescent pulse amplification attains a smoother speckle structure and lower optical coherence. Our results indicate that the superluminescent pulse amplification could be a more effective means to produce low coherent supercontinuum sources than traditional lasers.

The identification of tea varieties and producing areas has an increasingly important market value as the continuous development of the tea industry. A method combining laser induced breakdown spectroscopy (LIBS) and neural network algorithm is proposed in order to identify tea varieties and producing areas rapidly and accurately. In this paper, LIBS spectra of six major tea varieties and eight green tea samples from different producing areas in the range of 200-430 nm are collected, elemental analysis and spectra pre-processing are performed, principal component analysis (PCA) method is applied to select the features, and error back propagation (BP) neural network is used to model the tea classification problem. Key issues such as feature dimensions, network parameters, network structure, and the size of dataset are discussed. The result shows that the best model accuracy reaches 100%, indicating that this method can be used to establish a practicable tea classification model as long as sufficient data are obtained, which is feasible for solving the problems of the identification of tea varieties and producing areas.

As a new Raman spectroscopy technology, Spatially Offset Raman Spectroscopy (SORS) can realize the detection of bilayer-and even multilayer-compositions nondestructively and non-invasively, providing the possibility of vivo biological diagnosis. In this paper, the detection of CO₃^2- and PO₄^3- covered by PTFE was realized, which are the main mineral components of bone tissues.

Haze weather has always degraded the visibility and clarity of the distanced targets of image sensing. Short wave infrared (SWIR) spectral region has been a good candidate to extend the imaging distant in hazy days. In this paper, we present a horizontal imaging model of SWIR multispectral imaging in hazy weather and the corresponding dehazing method. We performed SWIR multispectral imaging experiments under the different haze conditions. The optical aerosol properties are retrieved from the pm 2.5 concentration and AERNET data using Mie Theory. Finally, the aerosol optical properties is applied in the dehazing method to improve contrast of the obscured multispectral SWIR images.

Aspheric surfaces are widely used in modern optical systems. At present, five-axis machine tools are widely used for aspheric surfaces grinding and shaping. The technology of milling aspheric surface with five-axis machine tool is studied. According to the B-C double turntable five-axis machine tool, its kinematics model is analyzed. The tool path algorithm of rotating symmetrical aspheric cup grinding wheel is studied. A five-axis machine tool processing model of cup grinding wheel is established. By calculating contact points, planning tool axis vector and surface vector. The mathematic mapping between tool axis vector and rotation angles of B and C axes is obtained, and the algorithm model of tool path based on vector method is established. Finally, the aspheric surface with diameter 100mm, quadric surface coefficient k=-1 and curvature radius 300mm is machined by five-axis machine tool through simulation and example analysis with MATLAB. The result is measured by three-coordinate measuring instrument, and the PV value of the surface is 5.25um. The RMS value is 0.88um, which verifies the correctness of the tool path algorithm for cup grinding wheel.

A 100GHz millimeter high speed linear camera and a 100GHz radiation source has been combined with a transmission band which running at a uniform speed to form a set of initiative terahertz imaging system. According to the characteristic of initiative terahertz imaging system, an iron circle was used to be as a target, and the imaging effect has been tested when the target was covered by some silk, black insulation rubber, white silicon rubber, paperboard, expandable polyethylene, polystyrene cystosepiment, leather cloth or carbon fiber cloth. The change law of the brightness has been studied and an equation has been built to indicate the brightness of the target varies with the thickness of the covered sheets. As a result, 100GHz millimeter wave can penetrate many objects to detect metal target except carbon fiber cloth, rubbers and other special objects. When the imaging system is used to be a set of security check, the power of the radiation source must be enough great to catch the weak signal coming from the metal target covered by opaque materials to millimeter wave. When an unknown or black object appears in watching screen, the security check must be done by hand to confirm whether there is a piece of metal or other special object.

Laser-induced breakdown spectroscopy (LIBS)is a real-time and rapid analysis method, which can realize quantitative analysis of element concentration in solid, liquid or gaseous samples. In this paper, a micro-LIBS system was designed for the quantitative analysis of heavy metals concentration in polluted water. The composition of the elements in the polluted water is abundant. Therefore, the characteristic spectral lines of heavy metal elements in polluted water are easy to be overlapped with adjacent characteristic spectral lines due to the spectral line broadening. This paper introduces the Fourier self-deconvolution (FSD) method to solve the problem of characteristic spectral overlap in LIBS quantitative analysis of heavy metals in polluted water. Fourier self-deconvolution (FSD) can decrease the spectral linewidth by taking deconvolution on the spectral using the shape information of the spectral itself. By combining the FSD with other methods such as baseline removal, wavelet domain denoising, spectral normalization and outlier discarding, the LIBS detection limit of Pb concentration in polluted water can reach 79.66 ppm.

Micro computational spectrometers based on disordered media have been investigated by many researchers to obtain high resolution or broad bandwidth. In this paper, a computational spectrometer based on a disordered medium that is called random pixelated grating is proposed. Using the principle of diffractive optics, we stimulate the correlation between the spectrum and speckle patterns to estimate the resolution and bandwidth. According the to the simulation results, a resolution of 0.06nm at 500 nm, and a bandwidth of 240nm from 380 nm to 620nm can be achieved.

Diffractive optical elements (DOEs) are widely used in different kinds of optical systems with its special dispersion characteristics, which include the dual-band lens. However, the single-layer DOEs (SLDOEs) suffer from the problem that the diffraction efficiency decreases significantly as the wavelength deviates from the design wavelength. So the selection of DOE is not necessary. A high diffraction efficiency of the multilayer diffractive optical element in the dual frequency band was investigated, Based on the scalar diffraction theory. The relationship between substrate material selection and diffraction efficiency of obliquely incident dual-band multi-layer diffractive optical elements under universal working conditions is derived. The influence factors of diffraction efficiency are analyzed. A material selection for quickly obtaining high-bandwidth integral diffraction efficiency is proposed. By this method, the optimal base material combination of the multilayer diffractive optical element can be quickly selected in a large-angle dual-band system. A medium wave-long wave infrared double frequency lens is designed by the ZEMAX commercial software.The transfer function of the system is greater than 0.4 in the medium wave and greater than 0.3 in the long wave. So the chromatic aberration of hybrid lens is corrected in infrared dual-band, and high image quality can be achieved.

Optical instruments usually use optical transfer functions to represent the target image quality. It can represent the spatial characteristics of the imaging spectrometer and the transmission characteristics of signal output and input in the frequency. However, for the imaging spectrum instrument, it can obtain both the spectral and spatial information at the same time, so it is also necessary to use the spectral transfer function to represent the spectral characteristics of the imaging spectrometer. In this paper, first, the working principle of double AOTF imaging spectrometer was introduced. Second, the spectral transfer function of double AOTF imaging spectrometer acoustics optic crystals was established. It is obtained by integrating the spectral transmission function within the wave difference range when the wave number difference is greater than zero. Last, the spectral transfer function in the 400nm-900nm of double AOTF imaging spectrometer acoustic optic crystals with the central wave difference and same were calculated. The results show that the wavelength difference was higher than that of the small spectral transfer function.The research results of this paper provided reference for the design and research for new imaging spectrometer.

Structured illumination microscopy (SIM) is a kind of wide-field super-resolution (SR) imaging technique which can double the resolution than convenient microscope. Because it doesn’t need any special fluorescent labels and high illumination intensity, it’s an ideal technique for high frame multicolor subcellular imaging in large field of view. Nevertheless, most of the previous multicolor SIM schemes use multiple excitation light to excite different fluorescence labels sequentially, not only making the system complex, but also limiting the ability to observe dynamic interaction between subcellular structures. Quantum dot (QD) is a kind of novel fluorescence label which has a wide absorption spectrum. Utilizing this special property of QD, we present a simple solution of multicolor SIM. The solution uses only a single LED as excitation light source and keep the ability to simultaneous image different colors. To demonstrate the capabilities of our system, we imaged the Blue-ray disc labeled by dual-color QDs.

The spectral imaging technology of adaptive classification is a new spectral technology based on traditional spectral imaging technology. Based on the traditional imaging spectrometer, the following research is carried out in this paper: Firstly, this paper introduces the development and theory of the spectral imaging technology of adaptive classification, then designs the optical system of the adaptive feature-specific spectral imaging classifier, and finally verifies the performance of the system through classifying experiment. The experimental results show that the classifying accuracy and speed of the information processing of the adaptive feature-specific spectral imaging classifier are better than those of the traditional imaging spectrometers.

For the demand of inland water quality monitoring, a ground-based multi-spectral imaging method has been developed. By means of developing an instrument which can gather the multi-spectral data of the waterbody, the method can be used for real-time monitoring the contamination of inland waters, such as cyanobacteria bloom and phytoplankton. The research is focused on the technology of high-resolution multi-spectral data extraction and the theory of contaminant inversion model. Four branches of light beams of simple spectrum are obtained with spectral filters and are recorded by four groups of lens and detectors respectively. The four interested wavelength is chosen as 565 nm, 620 nm, 660 nm, 750 nm, according to the typical reflection peaks and dips of the contamination with a spectral resolution of 15 nm. The optical design features a field of view of 25.2×19.3 degree with a 16mm focal lens. The camera’s resolution is 1628×1236 with the pixel size of 4.4 microns that reaches the spatial resolution of 0.945 arc min. The multi-spectral image is obtained through out-door experiments by monitoring the inland lake—Dianchi at a distance of 5 kilometers. After data revision, we can identify the constituent of the underwater contaminant and explain the pollution situation of cyanobacteria bloom in a certain period quantitatively. The inversion and extraction accuracy can reach at least 85%. And the long-term observation can explore the seasonal pattern of cyanobacteria bloom outbreak.

Aiming at the complex structure, difficult installation and high cost of the multispectral camera optical system used for phenological observation, a miniaturized and snapshot multispectral camera scheme is proposed. A compact and multi-channel image parallel optical system is designed by using a four-sided pyramid prism as an important optical element. The field-of-view of the system is ±3°, the working band is 400nm-600nm, the focal length is 50mm, and the F number is 5. The design results show that the single wavelength modulation transfer functions (MTF) at Nyquist frequency is better than 0.5, the root mean square radius (RMS) of all field of view is less than 7.4μm, and the distortion is less than 0.5%, which can meet the design requirements of multispectral cameras.

The Off-axis Three-mirror Simultaneous Imaging Polarimeter (OTSIP) is a kind of polarimetric remote sensor with high spatial resolution. In OTSIP, simultaneous measurements were performed by means of prism dividing amplitude. Due to various equipped polarizers and complex polarimetric characteristics of OTSIP, its instrument matrix will deviate from the ideal value. In order to ensure the polarimetric accuracy of OTSIP, the development of an efficient polarimetric calibration is indispensable. In this paper, a calibration method using a standard linear polarization light source and circular polarization light source was proposed. The first three columns of the instrument matrix were firstly calibrated by a linear polarimetric calibration source to obtain the calibration coefficients via the least-squares fitting algorithm, and then the fourth column of the instrument matrix was calibrated by a circular polarimetric calibration source. Moreover, the nonideality of circular polarization state light was significantly improved by averaging measured results at 0 and 90° azimuths. As for the full field of view polarization calibration, a linear fitting method to each element of the instrument matrixes at multiple field of view angles was used. The resulting polarimetric measurement accuracy showed that the linear and circular polarization measurement accuracy was better than 1% (DOP<=0.3), validating the effectiveness and feasibility of this polarimetric calibration method. This method greatly improves the calibration efficiency of the OTSIP, making it possible to calibrate the polarimeter in flight.

Diffuse speckle contrast analysis (DSCA) measures blood flow in deep tissues by the sensitivity of speckle contrast signals to the displacement of red blood cells (RBCs). Currently, the most common model for describing the displacement of RBCs is a Brownian diffusion-like process. In fact, RBCs undergo shear-induced displacement in blood flow. In this paper, the reduction in speckle contrast due to shear-induced motions is studied by theory and Monte Carlo simulations. We provide the solution for the speckle contrast function in a semi-infinite geometry, and establish the quantitative relationship between speckle contrast and absolute blood flow in a realistic vascular network. Based on this relationship, we can determine the relative contributions of diffusive RBCs motions on the speckle contrast.

High-resolution original video image acquisition has higher and higher requirements for data caching. How to perform real-time, high-speed, complete and effective caching of large-capacity data has become the focus of high-speed image data collection. This article will introduce the FPGA, which is produced by Xilinx, as the main control unit for data storage and processing, supplemented by an experimental platform built by other peripheral circuits. On this experimental platform, the performance of DDR SDRAM in high-speed image data acquisition is studied. Firstly, it introduces the block diagram of the high-speed image data transmission system, the principle of data acquisition subsystem and DDR SDRAM, and the basic principle of high-speed image data read and write control. In addition, the DDR SDRAM read and write data stream speed and bus occupancy rate are simulated and tested during high-speed image data acquisition. Finally, through a lot of experiments, the bandwidth utilization rate of the DDR SDRAM is up to 41.5% when the clock frequency of the DDR SDRAM is 200MHz, which improves the operating speed of the image data acquisition system and reduces the power consumption of the system.

In the photoacoustic spectroscopy detection system, photoacoustic (PA) cell is the most important component of the system. The conventional structure of photoacoustic cell is H-shape and this type of photoacoustic cell is complicate to design. The portable resonant photoacoustic cell structure is proposed in this paper. The buffer chamber is integrated with the resonator and the structure is more simple. The portable photoacoustic cell is a tubular structure with concave mirror at both ends and a small convex mirror on the side away from the incident window. Laser can enter the resonator directly without buffer chamber and reflect more in resonator. By simulation made by TracePro software, the luminous flux of longitudinal and cross section is analysed. The simulation results shows that the sensitivity of this photoacoustic cell has increased by 69.7%.

With the development of infrared imaging detection technology, it is not enough to recognize valuable target information quickly and accurately in complex environment simply by energy and graphics. Modern infrared imaging detection and recognition systems have begun to make use of more physical features, such as dynamic or static differences of spectral energy distribution in one or more work bands, to improve the target recognition and anti-jamming ability of infrared imaging systems. Distinguishing differences in physical characteristics of objects, backgrounds or disturbances from time, space, spectrum and energy dimensions is becoming a main direction of development of IR imaging detection technology. In an effort to improve technology for performance testing and hardware-in-the-loop (HWIL) simulation of multi-spectral imagers, we have been developing a wide-band infrared spectral engine based on spatial light modulator (SLM). The wide-band infrared spectral engine is comprised of a blackbody IR source, a Digital Micromirror Device (DMD) and some optical components, and it is capable of generating the spectral distributions with programming each of the DMD’s spatial pixels. The problem of mismatch between the unit-under-test (UUT) spectral and the infrared image projector spectral in the HWIL simulation can be resolved in this way. A prototype of the wind-band infrared spectral engine has been designed and developed. A brief summary of previous work will be presented with a more detailed discussion of the recent test of the prototype. By using spectrometer, moving guide and some other devices, a set of test equipment has been built. And thought some stripe test patterns with different spatial frequencies, the key performance of the wide-band infrared spectral engine prototype has been tested. It was found that the waveband of the wind-band infrared spectral engine prototype is from 3 μm to 5μm, while the spectral control accuracy of the wavelength is less than 100 nm.

In this paper, we investigated how to use calibration-free (CF) LIBS to quantitatively analyze hydrogen and deuterium in titanium samples in ambient helium gas. First, the LIBS spectra of two metal titanium samples with hydrogen (H)/deuterium (D) concentration ratios of 1.5 (0.6 : 0.4) and 0.67 (0.4 : 0.6) were obtained by a LIBS experiment set-up. Then, based on the Boltzmann plot of the Ti elements, the plasma electron temperatures of the two samples were determined to be 5746K and 5736K, respectively. The corresponding electron density measured by the Stark broadening profile of Ti II (375.9nm) is 7 × 10¹⁵ cm^-3 and 7.73 × 10¹⁵ cm^-3. According to the experimental data, the McWhirter criterion was verified and LIBS plasma was in LTE, so CF-LIBS method can be used to analyze the concentration of hydrogen isotopes. The H/D concentration ratios of the two samples were calculated using free calibration method to be 1.48 and 0.81, and the relative errors were 1.33% and 20.9%, respectively. The experimental results demostrated that laser-induced breakdown spectroscopy combined with the free calibration method can be applied in the quantitative analysis of hydrogen isotope.

Nitrogen (N), phosphorus (P) and potassium (K) are not only plant macronutrients but also soil fertilizer indicators, soil N, P and K rapid analysis are of significant importance to agricultural industry. This paper reviewed the recent progress and applications of laser induced breakdown spectroscopy (LIBS) on soil N, P and K detection. To reduce sample diverseness and spectral interferences, samples were mixed, milled, pressed to pellets, and even prepared with a simulated soil matrix of sand. The LIBS instrument was commonly set up with a fundamental frequency laser of 1064 nm and 10-102 mJ, detector usually set to the wavelength of ultraviolet, visible and short-wave near-infrared, collecting spectral at time window of a microsecond scale. Several means were employed to remove air interference and enhance signal quality, including low-energy laser, femtosecond laser, sequenced laser pulse, pre-ablate, optical path optimization, spatial confinement, buffer gases purge and reduced pressure. 746.83 nm was the commonly used N emission line, under the condition of interference avoidance from air N, correlated curves have been used to predict N concentration. Usually used P characteristic line, such as 255 nm, was located at ultraviolet range, methods of linear regression, intensity correction and calibration-free LIBS have been used for soil P analysis. 404.72 and 766.49 nm were the widely used K lines. Beside linear regression, internal standard and calibration-free LIBS, multivariable data mining methods, including partial least squares and support vector machines, were used to analyze soil K. Furthermore, variable selection methods of genetic algorithm, variable importance in projection and the coefficients graph were employed to improve model precision. These researches demonstrates that although challenges remain in terms of matrix effects, spectra and model processing, and instrument development, LIBS is a potential technique for rapid, in suit and multi-elements analysis on soil nutrient.

In this study, we have developed a kind of single-layer graphene-based surface plasmon resonance (SLG-SPR) biosensor with wavelength interrogation to detect C-reactive protein (CRP) by sandwich immunoassay. For the nature of the biosensor itself, with the decrease of the incidence angle (θ), resonance wavelength (λ_R) increased gradually. The refractive index sensitivity (S) and θ are inversely proportional relationship while S and λ_R are positively proportional relationship. Then we studied two kinds of sensitivity properties of these two SPR biosensors respectively. The refractive index (RI) sensitivity of the two biosensors is approximately the same and the high sensitivity of SLG-SPR biosensor due to the excellent adsorption properties of graphene. The experiment shows that the changes in resonance wavelength (▵λR) of SLG-SPR biosensor are higher than that of the gold film based SPR (Au-SPR) biosensor when the final sandwich structures were formed. Meanwhile, we have applied the Fresnel reflection equations and Bruggeman approximation formula to calculate the volume fractions of adsorbates in different adlayers, and the dispersion curves of the effective RI of adsorbates with different volume fractions of adlayers and the cAb isothermal adsorption curves that conforms to Langmuir equation were obtained. In conclusion, the SLG-SPR biosensor with a higher detection sensitivity than the conventional Au-SPR biosensor in detecting CRP and it has the advantages of low-cost, stability, highly efficient for the clinical determination of CRP levels.

At present, the resolution of cooled type infrared thermal imaging systems is generally low. In order to realize longdistance target detection, it is necessary to design a high-performance and high resolution infrared thermal imaging system. The methods of improving resolution both domestic and overseas are discussed and compared. A method of fast imaging in four quadrants by using a micro-scanner to drive an optical lens is proposed. The method has high control precision, simple process and easy realization. Four low-resolution images are spliced into one high-resolution infrared thermograph with high imaging quality. The infrared thermal imaging system designed by this method can search, locate and track targets tens of kilometers away with outstanding indexes and excellent performance.

Spectral imaging technology is a information acquisition method that can obtain three-dimensional information of the object, which is widely used in remote sensing, material classification and other fields. Spectral imaging micro-system is a compact, low-cost spectral imaging system based on structure of single-chip integration. It is suitable for utilizing on unmanned airborne and has a good prospect in the field of geological exploration and mineral classification. Coal gangue is a kind of gray rock associated with coal, which is also a kind of solid waste in mining industry. Due to demand of environmental monitoring and effective mining, it is urgent to effectively monitor the distribution of coal in minerals. This study carries out the experiment on classification of coal and coal gangue samples with the spectral imaging micro-system of visible-near-infrared spectrum. And experimental results show that 80% of the pixels in the sample can be accurately classified.

It is aimed at environment pollution gases remote sensing in wide infrared spectrum, using the technique of long wavelength infrared Fourier transform spectrometer, by extended the detector responsive spectral range, to detect the spectral ‘fingerprint’ characteristic under the certain condition. The paper specifically described experiments in the spectral range 7.0 cm-1～14.5μm (700-1450 cm^-1). The application example by used instrument PARES100 is showed, with both the spectral radiance difference and brightness temperature, the 11 kinds industry common chemical and toxic vapors gas were successfully detected, and the approximate concentration that could been measured in terms of concentration and path length times.

Spectral imaging technology is a non-contact detection technology that combines spectrum technology and imaging technology. It can be obtained more information than traditional RGB imaging. The algae outbreak is one of the more serious environmental problems in Yuqiao Reservoir and the algae seriously affects the daily water safety of people and destroys the ecosystem of the reservoir. In this paper, the UAV spectral imaging system based on FP cavity spectral imaging chip is used to monitor the reservoir area. Through the spectral data processing, the distribution of algae in the reservoir area was obtained.

The dynamic population processes of infrared radiation in dysprosium-doped different host materials (LaF₃, Y₂O₃, YAlO₃ and silicate glass) are theoretically investigated. The radiation and non-radiation transition rates of each energy level are calculated using Judd-Ofelt (J-O) theory and according to “energy-gap law”. It is demonstrated that the non-radiative transition rate increases significantly as the phonon energy increases, indicating that the choice of host materials has a great influence on the infrared transition processes. By solving the rate equations we establish, it is found that the population profiles of the same energy levels are almost the same, but the time to reach equilibrium population varies greatly among different materials. The population probability of ⁶H_9/2 and ⁶H_11/2 energy levels increases first and then decreases, whereas that of 6H13/2 and ⁶H_15/2 monotonically increases or decreases with time. The excited state ⁶H_13/2 has a quite long decay lifetime of 38.97 ms in dysprosium-doped LaF₃, which is a good metastable state for mid-infrared emission.. These results are helpful to the material selection and application of infrared lasers.

In order to further improve the supervision of food safety, the research of rapid inspection technology for food additives with package, which can identify the ingredients of additives quickly and accurately without destroying, has become an urgent need for social development. Spatially offset Raman spectroscopy (SORS), as a derivative of new Raman spectroscopy technology, can further suppress Raman scattering and fluorescence of surface samples, and solve the problem of subsurface sample detection. SORS mainly utilizes the lateral scattering of photons generated by excitation light in multi-layered samples. By controlling the spatial offset (▵S) between the collection point and the incident point, it can realize rapid, accurate and non-destructive detection of the food additives covered by the opaque/semi-transparent medium. This work established an optical detection system based on SORS technology. Sodium nitrite and sodium benzoate samples were placed in PTFE containers instead of packaging, and the best spectral intensities were obtained by changing the offset distance ▵S. Compared with conventional Raman spectroscopy (CRS), the relative intensity of SORS spectra is significantly increased, and the spectra of food additives can be distinguished efficiently.

In the past decade, since the discovery of graphene by Geim and Novoselov, a tremendous research effort has been devoted to graphene and other two-dimensional materials due to their fascinating properties. Interestingly, recent results found that ABC stacking in FLG can be controllably and locally turned into ABA stacking by illuminating the ABC region with a train of laser pulses of 790 nm wavelength, which can be visualized by TEM in dark field mode. The graphene-based terahertz devices will be reviewed in Section 2 first, including the fabrication of graphene THz modulators and then two interesting different approaches that enable the ABC stacking in FLG to be controllably and locally turned into ABA stacking are further discussed and analyzed, when both stacking occur in the same FLG device. On the other hand, MXene with ultra-thin atomic layer thickness exhibits abundant physical and chemical properties. With outstanding energy conversion efficiency, light-to-heat conversion of MXene has gained renewed research interest in the recent researches and found itself in energy and medical applications. Thus, to utilize Mxene for beneficial usage, the fabrication and relevant experimental results of MXene will be discussed and overviewed in Section 3, which would cover the stability and degradation, energy dissipation process, near-infrared light absorption of MXene. Finally, it is concluded that both heat and light conditions could significantly promote the degradation of MXene in aqueous solution, which provides guideline for fundamental study and future biomedicine delivery applications.

As a chemical detection technology for analysis of in-situ, real time and multiple materials, Laser Raman Spectroscopy is competent to take quantitative research for ingredients in ocean environment, and achieve long-term in-situ supervision of acid radical ionic concentration in seawater. Due to the inevitable interference in the actual detection environment, the spectral data often contains some outliers, the existence of which has a significant impact on the performance of the quantitative analysis model. In order to remove the outliers accurately in the in-situ detection and online analysis, the MMD algorithm was combined with the PLS quantitative analysis model (PLS-MMD model) to detect and remove the outliers in the calibration set. It was demonstrated that the PLS-MMD method can effectively eliminate the abnormal spectra in the calibration data. After removing outliers the accuracy of the measured seawater sample concentration was improved with the relative error decreasing from 1.468% to 1.160%. Correspondingly, the prediction stability of in-situ seawater is also improved.

High-resolution optical microscope is a crucial imaging equipment in the field of Biomedical Sciences, drug analysis, field investigation and so on. However, the existing commercial microscopes are bulky, cumbersome and expensive, which are only operated by professionals in specific places such as laboratories and have a high threshold for use. In this study, we designed a miniature (20cmx20cmx16cm) lightweight (1.2 kg) low cost (700 USD) inverted optical microscope, the field of view is 0.48mm x 0.38mm, and the resolution can reach 2.19um, we seal the whole imaging system in a very small space, isolated dust and vapor interference from the outside to optical system, to ensure the quality of image and the stability of work. The internal objective lens can be finely focused on the z-axis electronically, ensuring that the microscope accurately focus samples of different thickness. At the same time, low price and stable performance allow small biological laboratories or field teams to use in a variety of harsh environments. In addition, we demonstrated the application of the microscope in different fields, such as imaging living cells in incubators and observing biological samples in the field. Therefore, this portable and economic microscope provides the basic functions of a bulky and expensive microscope at a low cost.

The simulation can evaluate the performance of the optical system and provide guidance for its improvement. At present, most of the research on imaging modeling of hyperspectral system is based on modulation transfer function method. However, this method has its limitations. Therefore, this paper proposes a reliable method for imaging modeling of hyperspectral optical system based on ray tracing: (1) In the spatial dimension, the vignetting coefficients corresponding to the image sampling points are obtained by ZEMAX, and the diffuse spots model of optical system is obtained by tracing the position of the light on the image plane which emitted by the object points after passing through the mesh points on the pupil surface. (2) In the spectral dimension, the spectral lines on the detector are obtained by non-sequential ray tracing, and separate the spectral lines of different wavelengths. The spectral bending coefficient and spectral distortion coefficient can be obtained by least square fitting. In this paper, high spatial and high spectral resolution images served as input sources for imaging simulation. By changing the grating constants, band range, defocusing quantity of the optical system and length of the slit, the changing trends of the output images in radiation intensity, spatial correlation, spectral characteristic curves and vignetting curves are analyzed, and the reliability of the model is verified.

Non-contact, non-invasive, high-resolution tomographic 3D detection of has been widely demanded in various fields of scientific research and engineering applications. Optical coherence tomography (OCT) is an emerging three-dimensional and non-destructive detective technology. Based on low coherence interference (LCI). OCT, with its relatively high axial resolution and deep detection depth, is unique in non-destructive detection field. OCT uses the distinctive feature that low coherence length of broadband light source to achieve accurate positioning in the tissue under test, and then form a three-dimensional tomography by horizontal scanning. OCT boasts great potential in bio-medicine field. At the moment, OCT has been used in clinical application of ophthalmology, but it is still remain in the immature research stage in other medical detection fields. For exploring the possibility of OCT in detecting cardiovascular and cerebrovascular diseases, we formulated a complete frequency domain OCT (FD-OCT) system by using 850 nm low coherence light source with the conditions in laboratory. Our system is built under the theory of spectral domain OCT (SD-OCT), an important subclass of FD-OCT. The system establishment can be divided into four parts. First, interference optical path setup: a fiber-optic Michelson type interferometry is used in this system. Second, the acquisition of signal, in FD-OCT, the broadband interference is acquired with spectrally separated detectors, the optical path and adjustment mechanism of the spectrometer are designed by our own self, and a CCD scientific camera is used to acquire signals. Third, three-dimensional image restoration, the depth scan can be calculated by a Fourier-transform form the acquired spectra, we use Matlab to complete signal process, furthermore we use rolling guidance filter to improve the signal to noise ratio (SNR) after the depth signal is restored. Last, beam scanning, a 2-axis motion stage is used to acquire three dimensional information. The imaging performance of this OCT system has also been calibrated through the cover glass experiment. The system has been used for completing the tomographic detection of onion and human skin. It has been shown that varieties of cardiovascular and cerebrovascular diseases can be detected earlier under the test of blood vessel. With the system that mentioned before, we have successfully conducted the real-time tomography of human upper arm on the basis of single point detection and obtained various information such as cardiac pulse map at multilayer location under skin of upper arm, heart rate signal in different tissue under skin, depth and diameter width of small artery, blood flow velocity, providing a new possibility for clinical detection.