Backscattering coefficient is an important parameter in ocean optics and determines to a large extent ocean optical properties of coastal case Ⅱ water, whose dominant constituent is suspended material. The remote sensing retrieval of the backscattering coefficient is important for the research of ocean optics and ocean color remote sensing. Based on in situ data acquired in nearshore area of the Bohai Sea in 2005, the empirical retrieval model for backscattering coefficient bb(λ) (λ=442 nm, 488 nm, 532 nm, 589 nm, 676 nm) based on remote sensing reflectance is developed. The model is validated by in situ data with mean relative errors for bb(442) and bb(589) retrievals about 30%, those for bb(488) and bb(676) better than 40% and that for bb(532) ～57%. Model′s sensitivity to the input error is analyzed by introducing ±5% error of remote sensing reflectance artificially. It′s found that for the majority of different cases of input error, the model is stable and reliable with the output error fluctuation less than ±10%. The model is applicable to the turbid coastal water of the Bohai Sea and could be utilized in the spatio-temporal variation analysis of ocean optical properties as well as optically significant constituents retrievals based on inherent optical properties.

The optical characteristic of littoral aerosol influenced by typhoon is analyzed, through measuring aerosol optical thickness with sunphotometer CE317 in a Langley method in the 19th typhoon period in 2005. Aerosol is changed obviously after typhoon, the thin particle amount decreases and thick particle amount increases. Aerosol optical thickness, ngstrm parameter α and atmosphere turbidity parameter β reach to the lowest ralue of 0.132(550 nm),0.861 and 0.079 respectively. The percentage of thin particle and thick particle in a unit volume amount, the size distribution of aerosol and amount concentration of aerosol particle are measured by aerodynamic particle sizer spectrometer, which agree well with the above α,β value.

The effect of turbulent atmosphere on the propagation of coherently combined laser beam is studied. Propagation of coherently combined laser beam in turbulent atmosphere is numerically calculated by using generalized Huygens-Fresnel principle. The statistical characteristics, i.e. power in the bucket (PIB) curve and fractional power curve are calculated. It is revealed that the propagation of coherently combined beam suffers less in weak turbulence, and the irradiance distribution and PIB curve in the receiving plane are the same as its counterparts in free space. However, the beam spot will spread faster as the effect of turbulence gets stronger, and the energy centrality reduces evidently. The spectral degree of coherence of laser beam after propagation in the turbulent atmosphere is calculated. It is revealed that degrading in beam coherence causes the declining of coherent combinination. The way for eliminating the effect of turbulent atmosphere is discussed.

Transmission characteristics and mode structure of both metal hollow fiber and dielectric-coated metal hollow fiber for terahertz wave are studied. Theoretical evaluation shows that the TE11 mode is dominant in metal hollow fiber and has high coupling efficiency when a linearly polarized light source is launched. HE11 mode is mainly supported in dielectric-coated metal hollow fiber with an optimum thickness for the dielectric film. The transmission loss of the TE11 and HE11 mode is 8.4 dB/m and 2 dB/m respectively at the wavelength of 200 μm for the hollow fibers with 1 mm bore size. The effects of optical constants of metals and dielectric materials on attenuation coefficient are also discussed to optimize the transmission performance of dielectric-coated metal hollow fiber. Aluminum is the best choice among the commonly-used metals based on published optical constants. The optimum value for the refractive index of the dielectric film is 1.41. According to the primary measuring results, polyethylene is a proper choice as its refractive index is 1.51 and it brings low absorption in terahertz waves.

2008-01-16

A quasi-distributed fiber Bragg grating (FBG) sensor based on arrayed waveguide grating (AWG) is researched in theory and experiment. This sensor system has the advantages of easy operation, high response speed, low cost and high resolution. Its interrogating technique is based on the double-channel intensity–demodulating and the demultiplexing of an arrayed waveguide grating. The experimental result shows that the wavelength and temperature interrogation of the system have high linearity for the wide bandwidth of FBG, and the wavelength and temperature measurement accuracy reaches 2 pm and 0.2 ℃ under the effects of system stability and FBG crosstalk.

Short-period fiber Bragg gratings with gratings planes tilted at a weak angle corresponding to the fiber axis show core mode, as well as a large number of cladding-mode resonances in transmission. Tilted fiber Bragg grating (TFBG) with different cladding diameters is achieved after the cladding of the tilted fiber Bragg grating is etched by hydrofluoric, and then the sensitivity of refractive index is investigated. While the surrounding refractive index changes from 1.333 to 1.4532, the high-order cladding modes are more sensitive than the low-order ones for the same diameter. The sensitivity of the cladding modes is enhanced with the decrease of cladding diameter, and it is custom-built more sensitive to surrounding refractive index. Therefore, this way not only can solve temperature-crossing sensitivity problem, but also can satisfy the custom-built sensitivity in the real-time monitoring systems by etching the clad of TFBG in different degrees. It can be applied to biochemical environmental sensing and concentration measurement of chemical solutions.

A method of realizing the wideband stimulated Brillouin scattering (SBS) slow light was proposed using double broadband pump in a single-mode optical fiber. The theoretical models of this double broadband pump SBS slow light and its pulse broadening are presented. Dispersion analyses indicate that there exists the optimum spectral separation between the central frequencies of the double pump beams with respect to the inherent spectral width of the pump laser, which makes it possible to effectively reduce the signal pulse broadening related to the group velocity dispersion. Theoretical calculations show that the SBS gain bandwidth and the signal pulse's group delay using the proposed scheme can respectively be enhanced to 1.7 and 2 times of those using just one single broadband laser of the two pump beams.

Face recognition under varying illumination is difficult, and we propose a new illumination normalization method based on inherent texture features within micro-neighborhood, which transforms the nonlinear process of grey level changes with illumination into a linear process in the micro-neighborhood. So, some harmful influence on image recovery by uncertainties including that from image structure is avoided. The inherent texture future is illumination insensitive, the structure of which is coded. The least squares estimation is used to estimate the relationship of grey level changes at certain illumination direction and the coded features, and illumination normalization is then performed according to the estimated relations. The computational complexity of this algorithm is low. The experimental results show that by implementing the algorithm in face recognition system, we can achieve an average recognition ratio of 94.1% on Yale B database with 90° illumination change.

A major drawback of the original contourlet transform is frequency aliasing, i.e., its basis images are not localized in the frequency domain. We analyze the cause of this problem from the aspect of Laplace pyramidal (LP) transform to make sure that the aliasing is caused by the reason that the two lowpass filters of LP transform do not satisfy with Nyquist-Shannon sampling theorem and its stopband frequency is more than π/2. Based on this reason, we design a new low-pass filter with stopband frequency smaller than π/2 and propose an anti-aliasing contourlet transform. The anti-aliasing contourlet is superior to contourlet transform in the respects of the regularity and localization of basis function, and depresses the frequency aliasing efficiently. Numerical experiments on peppers image denoising show that the proposed anti-aliasing contourlet transform can significantly outperform the original transform both in terms of peak signal-noise-ratio(PSNR) by 2.3 dB with noise root-mean-square of 30 and in visual quality. It also depresses the scratch phenomenon after anti-aliasing contourlet transform denosing.

Image registration technique has been widely studied and used in many fields, such as computer vision, remote sensing, medical diagnosis and treatment, environmental monitoring. Presently, registration happens after the color image is transformed into gray one in most algorithms, which causes color information loss and may lead to wrong registration. For this reason, a color image registration algorithm based on color scale invariant feature transform (CSIFT) is proposed. Firstly, color invariant value is calculated at each location in color images. Secondly feature points are extracted and neighbor information around these points is described using color invariant value as input information. Thirdly the points between two images are matched using the nearest neighbor method. Finally transformation parameters between images and the registered image can be determined using matched features. Experimental results indicate that high accuracy and small errors can be achieved when parameter values are transformed in color images, and mapping relationship can also be acquired correctly in the condition of unknown transformed relationship. This method is fast in operation in most conditions.

To improve the accuracy of the automatic detection and classification of apples on the tree, image features and artificial neural network classifier are applied to segment the apple images. First, apple image samples and background image samples are chosen. Then the color feature and the texture features of the samples are calculated. The color feature (R/B ratio) is calculated based on RGB color model, and the texture features (contrast and correlation) are calculated by gray level co-occurrence matrix (GLCM). These three parameters are used as the input to the back-propagation neural network (BPNN) classifier. The result of the output layer is a numerical value in the runge of 0~1. It is classified into fruit and background based on a certain threshold value. The results of the segmentation show that the success rate is over 87.6%, and the influence of light is neglectable. It is feasible to use the algorithm in practical recognition of apple.

A classification method to distinguish the neonatal pain expression from non-pain expression is proposed, which combines Gabor wavelet transform with support vector machine (SVM). At first, each neonatal facial image, which is normalized to the size of 112 pixel×92 pixel, is transformed by the 2D Gabor wavelet to extract 412160 Gabor features. Since the high-dimensional Gabor feature vectors are quite redundant, AdaBoost is introduced as a feature selection tool to remove the redundant ones. In experiments, 900 features are selected from 412160 original Gabor features. Finally, the selected Gabor features are fed into the SVM for final classification. This method takes the advantages of the favorable ability of Gabor feature in representing facial expression, the effective function of Adaboost in feature selection, and the high performance of SVM in the solution to small sample size, high dimension problems. Experiments with 510 neonatal expression images show that the method is quite effective. The best recognition rates of pain versus non-pain (85.29%), pain versus calm (94.24%), pain versus cry (78.24%) are obtained.

A new method was studied for measuring the shape of transparent objects by image processing based on polarization analysis on reflected light from the object surface. Polarization characteristic of reflected light from transparent object surface was studied and it shows that reflectivity varies with direction of reflected light while natural light is reflected via transparent surface object, i.e., the reflection will exhibit characteristic of partly polarized light. The relations of intensity reflectivity and incident angle and intensity and polarizer direction were studied, and the relation between reflectied intensity and incident plane orientation was deduced. The relation of polarization degree of reflected light and incident angle was established based on definition of polarization degree, considering Fresnel equation and reflection law. Thus the surface normal direction can be determined and the shape of transparent object is obtained. Polarization images were taken experimentally and three-dimensional shape of object was reconstructed by image processing. Experimental results show that the proposed method is effective and valid for shape reconstruction of transparent object.

Inverse fringe projection is a fast and robust optical 3D shape inspection techniqu,which is applied to online or batch inspection. A new method for generating inverse fringe is proposed,which builds the normal mapping transform relationship between projector coordinate and camera coordinate. A pixel on the projector coordinate has two suits of phase,through which its position on the camera coordinate can be located, which is called the register of projector pixels on the camera coordinate. Since the required fringe map in the camera is just simple sinusoid image, so it can easily get the inverse fringe by reading the phase of register point directly.Standard phase difference in simulation and real experiment reaches 7.044×10-6 and 3.34×10-2 separately,which gets a higher precision than former methods.Then the reason accounting for the high precision is analysed.Both simulation and experiment prove the feasibility of this method.

There exists an optimal angle magnification to make the optodectronic imaging system and human eye matching optimally, and under this condition the optoelectronic imaging system presents the optimal performance. A new evaluation method, minimum resolvable contrast (MRC) channel width, is proposed based on the physical meaning of MRC which can attain the optimal angle magnification for CCD imaging systems. The expression of MRC channel width is built through viewing experiments of CCD imaging systems. The impact of the change of several system parameters on MRC channel width is also analyzed. Results show that the optimal angle magnification attained from MRC channel width has good consistency with practical application.

Considering the present situation of the basic oxygen furnace (BOF) steelmaking endpoint control, a neural network model was established to judge the steelmaking endpoint. Based on the furnace mouth radiation information acquisition platform, the spectrum and image characteristics were analyzed using the fiber spectrum division multiplexing technology and the color space conversion method. The results indicate that they are similar at early-middle stage but inverse at the steelmaking late stage. Some appropriate variables were selected from the law curve as the neural network model parameters and the model was trained and forecasted on the basis of an improved back propagation (BP) neural network correction coefficient algorithm. The experimental results show the response time is less than 2 s which meets the requirements of online endpoint judgment, and the prediction accuracy of the proposed algorithm is better than that of the conventional algorithm. The system works stably and the anticipated effect is achieved.

The reflectometer in spectral radiation standard and metrology beamline of Hefei National Synchrotron Radiation Laboratory mainly measures reflectance and transmittance of vavious reflecting coatings in X-ray and vacuum ultraviolet wavelength region. To ensure the accuracy and reliability of the measurement, the error sources of the reflectometer and their influence on measurement were investigated. Based on experimental data and theoretic calculation, it has been found that the accuracy of the measurement is significantly dependent on the stability of the synchrotron radiation, the detector and the fixing of the sample. Several typical forms of the radiation fluctuating, detector damage and sample fixing are summarized, and their influences as well as influence of light spot size on measurement are analysed quantitatively and qualitatively. Some effective measures are taken to control the measurement error within 2%.

In order to monitor the subsidence and deformation of the unconsolidated strata, a monitoring structure with fiber Bragg grating (FBG) sensors embedded in the borehole and the sensing network system are proposed. With the results from laboratory, the 6 nm wavelength bandwidth of the FBG sensors used for rock strata deformation monitoring is presented. By analyzing the signal resolution factor of the multi-point sensor, the maximum practical six-channel multiplexing of the testing system determined by dominated optical source bandwidth has been researched. A distinctive FBG array composed of 18 FBGs based on wavelength division multiplexing/spatial division multiplexing is designed and implemented. Engineering practice shows the double-loop design can improve the survival rate of FBGs in mines.

Aiming at the characteristics of a single crystal silicon sphere diameter measuring system, multiple-beam interference and dual-beam interference of the reflected light of a plane wave and those of the central reflected light of a Gaussian beam with normal incidence are analyzed. Also numerical simulations for the reflected interferential intensity of a Gaussian beam center in different situations are presented. Furthermore, the influence of five-step phase-shifting algorithm on Gaussian multiple-beam interference is studied, and the maximal phase errors are shown with some specific parameters. The maximal phase error is 0.08% for beam waist ω0=5 mm and propagation distance z=2000 mm.

A new method based on simulated annealing algorithm (SA) and least-squares support vector machine (LS-SVM) (SA-LS-SVM) was proposed to select the characteristic wavelength for visible-near infrared (Vis/NIR) spectroscopy discrimination. In order to find suitable numbers of characteristic wavelength and corresponding characteristic wavelength, discriminating rate was used as object function for SA, and LS-SVM was adopted as discrimination model. The Vis/NIR spectroscopy characteristic wavelengths of three categories of lubricant were processed by SA-LS-SVM, principal component analysis (PCA) and partial least squares (PLS) respectively, and then predicted by back-propagation artificial neural network (BP-ANN). The results of experiment showed that discriminating rate by using combination of SA-LS-SVM with BP-ANN reaches 100% only using 4 characteristic wavelengths from total of 751 wavelengths, while discriminating rate did not reach 100% by other methods. The proposed algorithm not only reduced the number of spectral variables, but also improved the discriminating rate.

A method of precision evaluation for field large-scale measurement instruments is proposed with multi-instrument stations and multi-reference points. The measured data from multi-instrument stations are unified in the global coordinate system using spatial data registration based on quaternion. The measurement uncertainty is obtained by statistics of measurement values based on controlling points coordinate invariable constraint, so that the uncertainty of each sensor component is acquired. The optimal controlling points are calculated by multi-sensors information fusion technique, and the effect of coordinate transform error is decreased. Taking laser tracker as an example, the simulation and field experiments show that the uncertainty error of range and angle are decreased to 1 μm and 0.1″, respectively.

The short-term frequency instability of the solid-state laser was measured by using the self-beat of fiber-delay method. The Tm, HoYLF microchip laser which was cooled by liquid nitrogen provided with single longitudinal-mode, narrow linewidth output and the power was up to milliwatt. In experiment, at the fixed fiber length of 500 m, self-beat signals of the laser under the integral time about 2ms, 4ms, 40ms, 100ms were obtained. And under different fiber lengths about 100 m, 200 m, 300 m, 400 m, 500 m, the corresponding time delay is 0.5 μs, 1 μs, 1.5 μs, 2 μs, 2.5 μs, and the self-beat signal of the laser was achieved. The short-term frequency instability of Tm, HoYLF microchip laser is 1.48 kHz/μs. Meanwhile the relationship between laser frequency stability and laser linewidth is discussed.

The effects of rim zone on optical propagation loss of four analytical designs of geodesic lenses are studied by calculating curvature radiuses of their meridional curves for different parameters according to relations between meridional curvature radius of waveguide geodesic lense and optical propagation loss. The relation curves between optical propagation loss and effective aperture radius are obtained. For a fixed radius of lens aperture, the smaller effective aperture radius is (namely larger rim zone), the smaller optical propagation loss is. Curvature singular points are found on the joint of rim zone and true lens of the geodesic lenses described by improved analytical designs and optimal designs. The selection rule of effective aperture radius of the above geodesic lenses and range with low loss are given.

The 3D reconstruction based on binocular stereo vision is a main part of the computer vision technology and it has a variety of applications such as robot navigation, aerial surveying and mapping, medical imaging, industrial inspection, etc.. A new binocular stereo vision method based on comparing gray value of the projection points is proposed to reconstruct 3D world. This method divides the world coordinate system into grids and the nodes are considered as candidates of the object coordinates. A group of points with varying depth information are projected on the two pictures. The difference of the gray values of the corresponding pairs implies the depth information of the object in 3D world. It is proved superior over traditional methods in the effectiveness and efficiency by simulatron experiments using Matlab. Compared with traditional method based on image matching, this algorithm has obvious superiority in simplicity, computation and accuracy. Also, it will not be affected by the nonlinear distortion from the camera.

The paper proposes a stereo vision coordinate measurement system based on optical probe with the function of measuring and calibrating. The system adopts the probe as the imaging object and obtains the three-dimensional (3D) coordinate of the measured object by the images of the optical features on the optical probe got by the two cameras arbitrarily placed. During the measuring process, the extrinsic calibration parameters of the two cameras are calibrat calibrated termly with the measurement data. The key techniques, including the design of the calibration patterns and calibration algorithms of the camera intrinsic parameters and the extrinsic parameters online calibration of two cameras, and stereo vision measurement modeling, are studied. The corresponding schemes to reduce the effect of camera extrinsic and intrinsic parameters calibration and measurement modeling and improve precision are presented. The experimental results show the maximum error is 0.11 mm.

With the help of ab initio full-potential linearized augmented plane wave method, the calculations of the electronic structure and linear optical properties are carried out for CaCO3. It is found that the CaCO3 compound has a direct band gap of 4.29119 eV. The hybridization of C atomic 2s and O atomic 2s orbitals forms the anion groups ［CO3］2-. Furthermore, the different origin of the mean peaks of imaginary part of dielectric function of CaCO3 has been discussed. The absorption coefficient, electron energy loss coefficient, refractive index, and extinction coefficient of CaCO3 are studied.

The electronic structures of c-HfO2 were calculated by using first-principles ultra-soft preudopotential approach of the plane wave based on the density function theory (DFT). The total density of state and partial density of states as well as the band structure of c-HfO2 were obtained. With band gap correction, the optical linear response functions of c-HfO2 as a function of photon energy were derived including the complex dielectric functions, reflectivity, complex refractive index and optical absorption coefficient. The relationships between optical properties and electronic structures of c-HfO2 were investigated. The calculated results are in agreement with the experimental value and other theoretical results, offering theoretical data for the design and application of optoelectronic materials of c-HfO2. It is also indicated that using DFT generalized gradient approximation (GGA) approach to calculate and predict the electronic structure as well as the optical properties of c-HfO2 is reliable.

With single pump beam incident in CeKNSBN, the temporal evolution of transmission intensity of pumping beam in CeKNSBN crystal is experimentally studied by altering the angle φ between the polarizing orientation of the pump beam and c axis of the crystal. The experiment is carried out on crystal two-wave-coupling experimental setup with non-synchronous readout. The results show that the beam fanning noise is little at φ≤30°. The two-wave coupling is investigated in CeKNSBN crystal with orthogonally polarized waves. Compared with the situation of extraordinary polarization, the beam fanning noise is effectively suppressed, and the diffraction efficiency of volume grating is greatly improved.

The forming mechanism, diffraction efficiency and polarization characteristic of phase gratings written in cross-linked azobenzene copolymer films under different holography modes were studied. Jones vector was utilized to express interference field, involving orthogonal linear polarization interference mode (SP) and parallel linear polarization interference mode (SS). Based on SP and SS modes, pure refractive index grating (PRIG) without surface topology and surface relief grating (SRG) with unnegligible surface relief were fabricated respectively. Periodic refractive index distribution of PRIG induced under SP mode was observed in polarization optical microscope (POM). Quantitative topographic measurement in near-field optical scanning microscope (SNOM) indicates that SRG has a surface relief at 85.23 nm, but PRIG less than 5 nm. When reconstructed light is set to horizontal polarization, diffraction efficiency of PRIG reaches 22.2%, while SRG reaches only 1.65%. The zero-and first-order diffraction beams of PRIG are horizontally and vertically polarized, with polarization degree at 0.9969 and 0.9963. Diffraction beams of SRG are both horizontally polarized.

The spectral fine structure, zero-field splitting parameters (D, a-F), crystal structure in Al2O3∶Fe3+ crystals were studied with the 252 ranks completely diagonalized Hamiltonian matrix of the 3d5 configuration in trigonal symmetry with irreducible algorithm and group theory. The results show that the contribution of spin quartet state on the ground-state energy levels is the most important, and the contribution of spin doublet state is small but cannot be neglected. The calculated results are in good agreement with the experimental results. The influences of spin-orbit interaction and spin-spin interaction on the spectra fine structure and zero-field splitting parameters were further studied, and the influence of spin-orbit interaction is dominant, but the influence of spin-spin interaction cannot be neglected.

Quantum well intermixing induced by impurity diffusion has been used in fabricating nonabsorbing windows in the cavity facets to improve the output power of high-power laser diodes. A series of experiments on quantum well intermixing induced by Zn impurity diffusion were done on 650 nm laser diode wafers at 550 ℃. Zn was diffused using a closed ampoule method with Zn3As2 as source material. Blue shifts of photoluminescence (PL) spectra taken on the sample increase with the increasing of diffusion time, and the maximum PL blue shift is 53 nm. When the diffusion time was above 60 min, PL red shift occurred with a PL blue shift on the samples and the maximum PL red shift is 32 nm. It is concluded that the PL blue shifts come from the inter-diffusion of Al and Ga atoms between GaInP wells and AlGaInP barrier layers, while the PL red shifts come from the Ga0.51In0.49P buffer layer, and they are both induced by the Zn impurity diffusion into the sample. Additionally, the effects of the diffusion time and temperature on the crystal quality of the sample were studied, and the Al-Ga diffusion coefficient was calculated.

Using Müller matrix and Stokes parameter, theoretical calculation formulas for characteristic parameters of the quartz optical filter based on optical rotatory dispersion effect were deduced from the filter's transmission equation. The formulas show that the characteristic parameters have direct relationships with the stage number of the filter and the thinnest quartz's thickness. The filter characteristics of the one-, two-, and three-stage quartz optical filter at different main transmission peaks were calculated and proved by experiment. The filter characteristics were compared and the result shows that as the wavelength increases, the filter’s free spectral range and full width at half maximum at different peaks increase, and the full width at half maximum at the same peaks decreases with the filter's stage, number.

Based on the microelectromechanical systems (MEMS) technology, a new microprogrammable grating with tunable blazing angle was designed and fabricated by using the two-layer polysilicon surface micromachining process. The basic operational principle and structural characterizations fabricated grating were briefly introduced and then the maximum blazing angle, the most important optical parameter, was theoretically computed according to the designed structural dimensions and numerically simulated by combining the finite element simulation tool of ANSYS with Matlab's data processing functionality. A simple but efficient optical system was set up for measuring the maximum blazing angle. The results from simulation, calculation and experiments agree very well with each other. The maximum blazing angle of the fabricated micro programmable grating is larger than 5°.

The effect of LED light source on modulation performance of grating light modulator (GLM) is discussed. Based on partially coherent light theory, simulation by MATLAB software shows LED light sources bandwidth will affect the image contrast greatly. If the bandwidth is reduced by filter to 13 nm, the image contrast will be 150, and if the bandwidth decreases to 10 nm, the contrast will be 225. Furthermore, if the ratio of the size of light source and the distance between GLM and light source is less than 0.03, the size of light source will not influence the optical information processing. The research results are testified by experiments. These results prove the feasibility of LED as the light source to GLM.

An optimized algorithm based on simulated annealing and genetic algorithm was provided for designing films of 3-skip-1 filters. Two antireflection layers were added to the exterior of the stack to deminish the ripple of passband. The optimized multilayer film meets the design demand of 3-skip-1 filter of 100 GHz.

N2 spectral in glass capillary by dielectrical barrier discharge at discharge frequency of 20 kHz are measured via concentration modulation spectroscopy. The spectral lines at 357.7 nm of N2 C3∏u-B3∏g and at 391.4 nm N+2 B2∑+u-X2∑+g are recorded to study the effect of discharge voltage and gas pressure. The measurement results show that the intensity increases rapidly with discharge voltage at a lower voltage range, but the speed slows at the higher voltage range, for constant gas pressure of 130 Pa; and the intensity increases backwardly with gas pressure at constant discharge voltage of 6.4 kV. Furthermore, a theoretical model is proposed according to electronic excitation function and ionization function, which can basically interpret the relation between spectral intensity and discharge parameters, fit the experimental data well, and the correlation coefficient is over 0.9. The mechanism of the dependence of the emission spectral intensity on discharge voltage and gas pressure in the plasma discharge was revealed further.

The fluorescent spectra of amaranth and ponceau-4R have been measured by a fluorescence spectrophotometer. The result shows that ponceau 4R excited at 220～400 nm has four obvious fluorescence peaks at 420 nm, 530 nm, 635 nm and 637 nm respectively. Under the same condition, amaranth excited at 220～430 nm has only one obvious fluorescent peak at 654 nm. It is considered that the ponceau-4R′s four obvious fluorescence peaks are resulted from four fluorescent clusters. In order to find the sensitivity of every fluorescent cluster when excited by different-wavelength light, and the relation between the two pigments, the intensity of fluorescent peaks was calculated by matrix operation based on the principle of additive property of fluorescent intensity. The fluorescent peak of amaranth is found to be homologous to the third fluorescent peak of ponceau 4R. Based on this, the influence of four fluorescent clusters on two pigments′ fluorescent spectra was discussed. The origin of different fluorescence spectra was studied from the difference in the structure.