Based on the optical transmission theory of multi-layer phase screens, a numerical model including the optical transmission process, layered atmospheric, continuous predicted phase screens, anisoplanatic imaging of the solar extended target was established, then analyzed and verified from the aspects of phase structure function, atmospheric coherent length and anisoplanatic angle. Under H-V 5/7 and H-V 10/10 turbulence models, the absolute errors of atmospheric coherent length and anisoplanatic angle are within 0.02 m and 0.3″ respectively. The results show that the statistical characteristics of the numerical model in time and space meet the practical application requirements, which provides a reliable model for the study of the effect of anisoplanatic errors on the solar image stabilization and adaptive optical system.

A strip sub-wavelength radial polarization grating is designed in this paper. It is fabricated by beam direct write lithography, which can convert a rotation of polarization plane into the horizontal displacement of facula directly, so a linear measurement of rotation angle is achieved by locating the facula displacement. The grating consists of 12 000 units are arranged horizontally, the direction of the central unit is 0°, and the right or the left ones are rotated in turn by 30″ in counterclockwise or clockwise directions respectively and finally achieve a measurement range of±50°optical rotation angle. The theoretical model of the grating is established based on the Jones Matrix, and the relationship among the polarization characteristics and the grating ridge height, the period, the duty ratio, the incident light wavelength, the incident angle, and the temperature is analyzed by using the rigorous coupled-wave theory. The experimental and simulation results show that the grating TM wave transmittance is greater than 80%, and the extinction ratio is better than 26 dB. It achieves the optical power independent measurement of the optical rotation angle, which can be employed to build a new type of polarimeter with no mechanical rotating device or optical transducers with no rotary translation converter.

In order to analyze the thermal characteristics of a jet cooling thin-disk composite ceramic laser, the jet cooling device for a composite ceramic thin-disk laser is designed. A systematic simulation model is developed by using the turbulent heat transfer theory and computational fluid dynamics method. Two evaluation parameters are defined for the cooling capacity and uniformity of the designed jet cooling device. The optimal parameters of the jet cooling device are obtained by using the simulation model, and a verification experiment is carried out afterward. In the experiment, a jet plate with 163 holes is adopted, the inlet coolant flow rate and temperature are set to be 0.2 kg/s and 20℃, respectively. When the pump power is raised to 1 200 W, the output power of 359 W has been achieved, and the maximal temperature on the upper surface of the thin-disk composite ceramic detected by a thermal camera has reached to 92℃. It is also demonstrated that there have been approximate positive linear relationships between the pump power and both the output power and the temperature on the upper surface of the thin-disk of composite ceramic, and the experimental temperature value shows good agreement with simulated value.

Aiming at the defect that most polarization-maintaining fiber input beam expander collimators used in cold atom experiments can not accurately adjust the polarization of the input laser beam, a compact polarization-adjustable laser beam expanding collimator with a full length of 135 mm and an effective diameter of 20 mm for the output circular spot is proposed. The polarization axes of the polarization prism and the wave plate in the beam expander collimator can be independently adjusted, and the polarization state of the input beam of the single-mode polarization maintaining fiber can be accurately adjusted and maintained. The developed laser beam expanding collimator has prepared cold atomic groups that meet the requirements of cold atom interference experiment in the cold atom experiment of three-dimensional magneto-optical trap. The atomic number of cold atomic groups was 5×108, the temperature was about 10 μK, and the flight time signal of atomic fountain with the maximum throw-up height of 1.156 m was obtained.

In order to expand the receiving spectrum of the compound eye optical system, a visible light and long wave infrared wide spectrum compound eye optical system was studied. The dual-band ommatidia common image equation was derived, and the matching requirement between ommatidia and the receiving system was established. The ommatidia optical system has working bandwidths of 0.38~0.78 μm and 8~12 μm, a focal length of 5 mm, a relative aperture of 1:3, and a field of view of 10°. The imaging position of the ommatidia system in both the bands is 2.92 mm. The angle between two neighboring center optical axes of the neighboring ommatidia is 4.016°, with 650 ommatidia, and the combined field of view is 90°.The receiving optical system has a focal length of 4 mm, a field of view of 80° and a relative aperture of 1:3. The ommatidia system and receiving system show good image quality, without any thermal effects in the temperature range of -40℃ to 60℃.

The adjustment of the parallel plate dual-path lateral-shearing interferometer was investigated and a method to correct the angle error of the parallel plate was proposed. The wavefront of the laser is fitted with the Zernike polynomial. Based on theoretical derivation, it is found that the difference between oblique astigmatism of wavefront in two directions has a linear relationship with the angle error of the parallel plate. Therefore, the difference between oblique astigmatism of wavefront in two directions can be used as a feedback to adjust the angle error of the parallel plate. The angle error of two parallel plates can approach zero by making the difference between oblique astigmatism of wavefront in two directions is equal to zero during adjusting the parallel plate lateral-shearing interferometer. The linear relationship was further proved by experiments. When defocus aberration is -3.224 7±0.001 8 and the fluctuation range of the difference between oblique astigmatism of wavefront in two directionsis±2.0×10-3, the experimental angle error of two parallel plates for our experimental system can be controlled within 8.82″.The effect of higher-order aberrations on the accuracy of angle error adjustment is approximately 1.63″.This method has the advantages of easy adjustment, high accuracy, and easy process operation.

An optical switch based on polarization state control is designed by using a rectangular-like nanorods tetramer composed of four Au nanorods. The finite element method is used to study the response characteristics of the structure to incident light polarization. It is found that the transmission spectrum of the structure dependent strongly on the polarization direction of the incident light. When the polarization angle of the incident light changes by π/2, the switching ratio of the characteristic peaks can reach 27.81 dB and 21.65 dB, respectively. The analysis shows that the switching effect is mainly caused by the different near-field coupling strength between the horizontal double rod and the vertical double rod at the different polarization states. The relationship between the transmittance and the polarization angle of the structure obeys the Malus law. In addition, the influence of structural parameters on the response characteristics of optical switches is studied by changing the structural parameters of the rectangular-like nanorod array. On this basis, the influence of the periodic parameters on the transmission spectrum of the unit structure under the horizontal and vertical polarization of the incidence light is studied by changing the period parameters of the array. These results can provide a theoretical basis for the design of tunable dual-wavelength polarization-controlled optical switch.

Observation of the total columns of H2O, CO2, CH4, and CO in Hefei is presented based on ground-based Fourier transform infrared spectrometer (EM27/SUN). The results show that, the XH2O and XCO2 vary greatly during the measurement period while the XCH4 and XCO vary slightly. The range of H2O and CO2 are 1 353.17~5 289.43 ppm and 409.22~415.05 ppm, at the same time, the standard deviation of XCH4 and XCO are in the order of 10-2. The average values of XH2O, XCO2, XCH4 and XCO are 2 109.10 ppm, 411.59 ppm, 1.87 ppm and 0.13 ppm respectively. The measured XCO2 and XCH4 are compared with the WACCM model and GOSAT satellite data, respectively. The comparison results show that the XCO2 and XCH4 calculated by WACCM model are relatively stable, with only slight changes near the average value. The GOSAT observations are slightly lower than those of EM27/SUN observations, with the relative deviations of XCO2 and XCH4 are 0.45% and 0.34%, respectively. The time series of the total column of XCO2 and XCH4 from 2010 to 2018 are analyzed by the GOSAT satellite data. It is found that the value of XCO2 increases from 390.83 ppm to 410.30 ppm, with a relative growth rate of 4.9%; the value of XCH4 increases from 1.802 ppm to 1.869 ppm, with a relative growth rate of 3.7%. The results may provide the theoretical basis for tracking the sources and sinks of greenhouse gases in Hefei and its surrounding areas.

Aiming at the problem of the stress and the displacement of the fiber embedded in the flexible optoelectronic substrate can change, which affects the coupling efficiency of the optical path and the effective refractive index of the fiber which can result in the transmission performance to change under lamination process, he finite element method software was adopted to conduct coupling analysis of stress modules, heat transfer and electromagnetic field of fiber embedded flexible substrate. Simulation results show that the maximum stress of the fiber embedded in the trapezoidal groove flexible optoelectronic substrate was 68.336 7 MPa. The fiber displacement embedded in trapezoidal groove is 1.430 4 μm largest among the three types grooves. The maximum stress of the fiber increases from 52.667 MPa to 71.907 MPa with the increasing of groove width. The maximum stress of the fiber increased from 51.589 MPa to 53.567 MPa as groove spacing increases. The maximum fiber stress decreases from 52.667 MPa to 47.793 8 MPa firstly and then increases to 67.349 6 MPa with the increase of groove depth. With the increase of temperature and pressure, the effective refractive index of single-mode fiber in the X direction increased from 1.446 249 977 to 1.446 259 084 and increased from 1.446 326 398 to 1.446 393 041 in the Y direction. The difference of effective refractive index increases with the increas of temperature and decreases as the pressure increases. With the effective refractive index increases, the fiber core's ability to limit light energy increases which can better reduce the radiation of light energy and the bending loss of the fiber. The research conclusion has certain reference value and guiding significance for designing the embedded structure of flexible optoelectronic printed circuit boards.

A double square wave and B-spline wavelet for demodulation of a Weak Fiber Bragg Grating (WFBG) was proposed and demonstrated. A period of single square wave is set as the round trip time of laser transmission in the fiber between two adjacent WFBGs. The burst operation is conducted to the single square wave to form a double square wave, for which the rear square wave reflected by former WFBG and the front square wave reflected by latter WFBG overlap and interfere. B-spline wavelet transform is used to reduce the noise of interference signal. Hilbert transform is applied to produce π/2 phase-shift of the interference signal. Arc tangent operation is conducted to the ratio of the interference signal with the phase-shifted signal to obtain the phase signal of the interference signal. A 5-WFBG array with 50 meters equispaced length is put on a wooden platform, and received sinusoidal sounds with different amplitudes and frequencies respectively. The experimental results can reflect the information of the sounds well. The advantage of the proposed demodulation method is that the optical structure and data processing is simple.

In order to solve the problem that the accuracy of scale factor measurement of Resonance Fiber Optic Gyroscope (RFOG) is limited by the performance of turntable, a new method based on sawtooth equivalent input was proposed. By adding sawtooth wave to the RFOG's phase modulator, which works as equivalent input angular velocity, the RFOG closed-loop transfer functions under turntable input and equivalent input were analyzed, relationship between the parameter of sawtooth and equivalent input angular velocity was given, the scale factor and non-linearity were obtained by the scale factor test system. The scale factor is basically identical to the test result on the turntable, and the non-linearity is also improved from 0.42% to 0.26%. The test results demostrate that the scale factor test system based on sawtooth equivalent input can accurately measure the scale factor of RFOG, and effectively eliminate the measurement errors due to the vibration and imperfect precision of the turntable.

In this paper, a novel photonic analog-to-digital conversion scheme with differential encoding based on vector superposition is proposed and demonstrated. Two pulse sources with different center wavelengths are employed to modulate the input signal by a phase modulator, the modulated signal is sent to a delay-line interferometer to achieve two differential modulated signals with a specific phase difference. By adjusting and combining the intensity of two differential modulated signals with a vector superposition module, the desired phase shifts among different transfer functions can be obtained. Compared with most existing photonic analog-to-digital conversion schemes, the proposed scheme can differentially encode the input signal with improved bit resolution; furthermore, this scheme features its relative simpler configuration, because only one phase modulator, one delay-line interferometer and a vector superposition module are required; in addition, since the desired phase shifts of transfer functions are realized by attenuating the signal intensities, the proposed scheme can effectively alleviate the problem of phase bias-drift induced by modulators. Proof-of-concept experiment of a 4-bit photonic analog-to-digital conversion system based on the proposed scheme is successfully carried out, which demonstrates the feasibility of the approach.

To solve the low contrast and color distortion problem of deep sea image caused by active light scattering and absorption effects in the underwater environment, an underwater image enhancement method is proposed. Different from the previous methods, which estimate the background light with the brightest pixels, background light is estimated based on the non-correlation of the object and the background light, to alleviate the disturbance of the pixels in the white objects or the illuminated foreground region, while keeping its accuracy in removing scattering, and improve the underwater image contrast. Aiming at the color distortion caused by the color gain of artificial light source color and the optical attenuation, the grey pixels, which are close to the light source, are picked in the dehazed image. Then the light intensity can be derived with the detected pixels according to the sensitivity to the source. With the estimated light intensity, the light source color is achievable. At last, color distortion can be corrected by removing the source color while compensating for the optical attenuation. Experimental results demonstrate the proposed method can effectively remove haze, recover the relatively genuine color, and further obtain the enhanced image. The information entropy and the underwater image quality evaluation values of the proposed method are higher than that of the existing methods, which indicates that the proposed method can improve the underwater image quality significantly while preserving the efficient information.

In order to overcome the limitations of the existing optical encryption methods on high encryption system requirements, limited device performance, low encryption efficiency, and easy distortion of decrypted images, a multi-image encryption method based on the light field imaging principle and chaotic system was proposed. The method first generates random numbers through a chaotic system, and these numbers are used as the number of the light field imaging systems and the parameters of each system. Then multiple light field imaging systems are built according to the generated numbers in the computer. The images to be encrypted are spliced to a big image, and placed into the constructed light field imaging systems sequentially to obtain the corresponding light field images. By extracting and splicing the sub-aperture images of each light field image, the encryption of multiple images are achieved fast. The decryption process is the reverse of the encryption. The proposed method introduces the computing imaging technology into the encryption, which can avoid the limitation of real optical decives, and is easy to be achieved. The experimental results show that the proposed algorithm has low complexity of secure keys which can be transmitted easily. And it has good robustness to noise, large key space and high sensitivity of keys, which can provide high security. It also has high efficiency. The proposed method has widely potential uses in the fields of requiring plenty of images transmission with security.

Aiming at the problems of color distortion, uneven illumination and low contrast of underwater optical image, an underwater optical image enhancement algorithm based on the fusion of dominant feature image was proposed. Firstly, an improved dark channel prior algorithm was proposed to remove the uneven turbidity and balance the color in the degraded image. Secondly, the adaptive gamma correction algorithm based on weighted distribution and the contrast limited adaptive histogram equalization-homomorphic filtering algorithm were used to enhance the contrast of color correction image and make its brightness distribution uniform. Finally, the associated weight maps of the three fused images namely the color-corrected image, the brightness-balanced image and the contrast-enhanced image were defined, and the fused images were obtained by the multi-scale fusion algorithm. Compared with single preprocessing algorithm which can only solve the corresponding degradation phenomenon, the algorithm processes single degraded image with multiple algorithms and obtains three dominant feature images, the combination of different weights can combine the dominant features to the greatest extent, and the comprehensive effect is far beyond the optimization effect of each single algorithm, and is no longer limited to solving single problems such as color distortion. The algorithm in this paper is compared with existing algorithms in subjective evaluation and objective evaluation. The results show that the algorithm can effectively balance the chroma, saturation and sharpness of underwater images, and the visual effect is close to the images in natural scenes.

A mode converter is prepared through fusion taper coupling a single mode fiber and a few mode fiber, and then a multi-walled carbon nanotube film is used as a saturable absorber to cover the cone of the converter to form a saturable absorber cylindrical vector optical device. Combined the advantages of Q-switched fiber laser and mode conversion device, the pulse cylindrical vector beam can be generated simply and efficiently, and a pulsed high-order mode laser output with high peak power and high mode purity can be obtained. The experiment successfully achieves a stable Q-switched pulse output with a center wavelength of 1 560 nm, a maximum single pulse energy and a maximum peak power of 116 nJ and 57 mW, respectively. The output of the Q-switched laser with radially and azimuthally polarized beams can be achieved by adjusting the polarization controller in the optical path.

In order to study the thermo-optic effect of the optical microsphere cavity, two kinds of pump sources, 1 550 nm band tunable laser and broadband light source, were used to measure the change of the resonance peak wavelength of silica, tellurite glass microsphere and rare earth ion doped microsphere when the excitation light power and environment temperature change. The excitation power sensitivity of the silica microspheres was 32.4 pm/mW and the temperature sensitivity was 13.4 pm/℃. For the thulium ions doped silica microsphere, the sensitivity of excitation power was 48.7 pm/mw and the sensitivity of the environment temperature was 15.2 pm/℃. The excitation power sensitivity of the tellurite microsphere was 71.1 pm/mw, and the temperature sensitivity was 0.019 1 nm/℃, which was nearly one times higher than that of the FBG temperature sensor (10 pm/℃). If the rare earth ions were doped, the sensitivity was 1.1 times higher. The results have reference significance for the microcavity applications of the temperature sensor.

The application of luminescent nanomaterials combined with organic dyes in multi-sensing is studied in this paper. The luminescent nanomaterial CdSe/ZnS and the organic dye Pt(Ⅱ)meso-Tetra(pentafluorophenyl)porphine are embedded in polyurethane hydrogel D4, so a solid film is obtained through hydrolysis and condensation to achieve simultaneous detection of oxygen concentration and temperature. Among them, CdSe/ZnS luminescent nanomaterials with an emission peak at 524 nm are used to provide temperature sensing, and oxygen sensing is based on the dynamic quenching of Pt(Ⅱ)meso-Tetra(pentafluorophenyl)porphine with an emission peak at 650 nm. The prepared thin film has good optical stability and is excited by 405 nm violet light to obtain a spectrum in which the two emission peaks do not overlap with each other. The experimental results show that the sensing membrane can be well applied to the oxygen and temperature dual sensing systems. Under the oxygen concentration (0~30%) and temperature (15~67℃), the sensitivity coefficient of oxygen sensor is 9.69×10-4 and the sensing coefficient of temperature is -0.003 5 (with an error of±0.000 2). This technology provides a possibility for new portable multi-sensors.

Monolayer molybdenum disulfide (MoS2) was prepared on the SiO2/Si substrate by Chemical Vapor Deposition (CVD) method, and then treated with sulfur vapor at 300℃ after the monolayer MoS2 transferred to desired substrate by polymethyl methacrylate. The morphology and photoluminescence properties of the samples were characterized by Atomic Force Microscopy (AFM), vacuum fluorescence detection and Raman spectroscopy. The results show that the photoluminescence intensity of the transferred monolayer MoS2 after sulfur vapor treatment is about 5 times higher than that of the untreated monolayer MoS2 prepared by CVD. This photoluminescence enhancement effect is due to that part of the sulfur vacancies of the monolayer MoS2 are filled by the sulfur atom nanoclusters during the sulfur vapor treatment, thereby improving the photoluminescence efficiency. In addition, similar photoluminescence enhancement is observed after sulfur treatment were observed in the monolayer MoS2 transferred to SiO2/Si substrate, quartz, alumina, and magnesium fluoride substrates, respectively.

BaAl2Si2O8:Cr3+, Er3+ series phosphors were synthesized by high-temperature solid-phase method. The effects of Cr3+ and Er3+ doping on the light-emitting properties of BaAl2Si2O8 materials were studied. The BaAl2Si2O8:Er3+ fluorescence sample exhibited only green fluorescence with a peak value of 550 nm at an excitation wavelength of 393 nm, which is derived from the superposition of 2H11/2→4I15/2 and 4S3/2→4I15/2 transitions. The BaAl2Si2O8:Cr3+ fluorescence sample exhibits red fluorescence with a peak value of 694 nm at an excitation wavelength of 550 nm, which is derived from the 2E→4A2 transition. In the co-doped samples BaAl2Si2O8:Cr3+, Er3+, 380 nm is used as the excitation light at the groove of the Cr3+ excitation peak, and the obtained emission peaks include not only the emission peak position of Er3+, but also the emission peak position of Cr3+, which indicates that there may be radiant energy transfer between them; the fluorescence spectra of the co-doped BaAl2Si2O8:1% Cr3+, x% Er3+ samples were tested. With the increase of x, the intensity of the excitation and emission spectra of Cr3+ increased, and when x=0.5, the spectral intensity is 4 times the original. In addition, when the concentration of Cr3+ is fixed, the fluorescence lifetime of Cr3+ gradually increases as the concentration of Er3+ increases; when the concentration of Er3+ is fixed, the fluorescence lifetime of Er3+ decreases gradually as the concentration of Cr3+ increases. These phenomena indicate the existence of resonance energy transfer between Er3+ and Cr3+. The critical energy distance between Er3+ and Cr3+ is 4.5 nm, which is an electric dipole-dipole (d-d) interaction.

In the spectrum diagnostic physics experiment of inertial confinement fusion, the spectral signal is weak due to the X-ray diffraction efficiency with crystal. So a spectral diagnostic instrument with high light collection efficiency and wide spectral range is urgently needed. A multi-curvature bent crystal multi-energy point imaging technique is proposed based on traditional conical crystal structure. It has the characteristics of wide spectral range, strong focusing ability and high spectral resolution. At the same time, it can eliminate imaging aberration in principle due to the rotational symmetry of imaging light. The measuring spectra experiment of multi-curvature bent α-quartz crystal is conducted at a Ti X-ray tube device and the same experiment with plane α-quartz crystal is done to demonstrate the strong focusing ability. The result shows that the intensity of multi-curvature bent α-quartz crystal is 100 times than that of plane crystal, and the energy range of detected X-ray is 4.51~5.14 keV. This device combined with a streak camera at a vertical direction could be used to collect weak X-ray with wide spectral range.

In order to realize the inner focusing and meanwhile ensure the excellent image quality of the wide spectrum system, the position chromatic aberration and secondary spectrum in the wide spectrum optical system are corrected through the reasonable selection of materials, and a kind of design method of the wide spectrum optical system with inner focusing is proposed. The mathematical model of the achromatic with inner focusing is established, and the formulas that the system design needed are deduced. Combined with the proposed mathematical model and the derived formulas, a wide spectrum optical system with a focal length of 90 mm, the F number of 2.8 and the function of inner focusing is taken as an example. The result shows that in the range of 420~900 nm, the system can correct the chromatic aberration of the target at the distance of 0.2~200 km. The correctness of the design method and mathematical model of the inner focusing wide spectrum optical system is verified.

A method is proposed to calculate the photocurrent by measuring the output current and gain of microchannel plate, so as to measure the quantum yield. The quantum yield is measured in the near ultraviolet (200~380 nm) by the proposed method. The measurement results show that the quantum yield of microchannel plate is very low, and decreases rapidly with the increase of wavelength. The quantum yield of 200 nm wavelength is 10-4 order of magnitude; the quantum yield of 320 nm wavelength is 10-8 order of magnitude, and the quantum yield after 340 nm wavelength is very low and almost zero. The imaging device composed of microchannel plate and fluorescent screen can image the flame of alcohol lighter, but the image is sparse, while the image of traditional Cs2 Te photocathode ultraviolet imaging device is dense, which is consistent with the situation of low quantum yield of microchannel plate and high quantum yield of Cs2 Te photocathode. When a 350 nm high pass filter is placed at the front of the imaging device, the detected flame image of the alcohol lighter disappears. When imaging the illuminated target, it can be imaged if the light source is a 254 nm mercury lamp; but it cannot be imaged, if the light source is a 365 nm mercury lamp. The results show that the spectral response of microchannel plate is mainly below 350 nm wavelength, which is consistent with the measurement results of quantum yield. Finally, the resolution of the imaging device is measured as 32 lp/mm, which is the same as that of the traditional Cs2 Te photocathode ultraviolet imaging device. Because the imaging device composed of microchannel plate and fluorescent screen does not use photocathode, it has the advantages of low price, long life and high reliability, so it can be used under the condition of strong ultraviolet signal or short imaging distance.

In this paper, the reason of input signal loss caused by input electrode of Microchannel Plate (MCP) is analyzed, and a method of plating insulation layer on input end of MCP is proposed to increase the utilization of input signal of MCP which is verified by experiment. The experimental results show that a layer of 15 nm thick insulating layer is plated on the input end of the MCP, which can increase the utilization of the input signal of the MCP and the gain of the MCP. The higher the secondary electron emission coefficient of the insulating layer is, the higher the utilization ratio of the input signal of the MCP is, and the larger the ratio of the gain increase is. For SiO2 films, the gain can be increased by about 12%. For Al2O3 films, the gain can be increased by about 35%. At the same time, the resolution and MTF of image intensifier will decrease slightly. Similarly, the higher the secondary electron emission coefficient is, the larger the decrease ratio of resolution and MTF is. However, the decrease ratio of resolution and MTF of MCP is much lower than that of gain increase. The method proposed in this paper to increase the utilization rate of input signal of MCP has certain practicability and can be popularized.

The multi-channel Raman imaging system is often affected by the nonlinear factors such as fluorescence background and noise, which reduces the Raman spectral reconstruction accuracy. Therefore, a reconstruction algorithm based on Gaussian kernel principal component analysis was proposed, in which the calibration samples are optimized by similarity factor; Then the calibration samples were mapped to high-dimensional space in a nonlinear form by using kernel function; The basis function was extracted from the mapped data set, and the basis function coefficients were obtained by pseudo-inverse method. Polymethyl methacrylate was used in the experiment and the Raman spectral reconstruction accuracy was evaluated in terms of relative root mean square error. The experimental results show that the proposed algorithm has higher reconstruction accuracy and anti-noise property than the traditional pseudo-inverse and wiener estimation methods. And the proposed algorithm can effectively reduce the impact of bad data and nonlinear factors in the calibration samples and imaging system. Therefore, the proposed algorithm can provide an effective Raman spectral reconstruction algorithm for multi-channel Raman imaging.

To reduce the complex optical path and circuit structure in optical dissolved oxygen concentration detection system, this paper proposes a methodology for detecting dissolved oxygen by frequency-domain fluorescence lifetime. The single-channel light source is used to detect the concentration of dissolved oxygen in water, which simplifies the optical path and circuit structure, improves the dissolved oxygen concentration detection algorithm and enhances the efficiency of inspection process. The effectiveness of the method is evaluated. Comparing with the results from an optical dissolved oxygen analyzer, our proposed method performed better in terms of the detection error (reduced from 0.1 mg/L to 0.04 mg/L in the range of 0~9 mg/L) and the stability (the standard deviation is decreased by 36% to 0.007 mg/L). Leveraging the implementation of a fast Fourier transform-based algorithm, the response time was reduced by an average of 12 seconds as steady state reached 90%, the response speed was increased to the percentage of 40% at the rise of concentration and 28% at the fall of concentration separately. The methodology demonstrated the effectiveness of detection accuracy, stability and response speed.

Aiming at YAG white LED generated by blue-light excitation phosphor, a set of junction temperature measurement system based on characteristic spectral parameters is designed by using conventional visible spectroscopy and temperature control system through analyzing spectral trough characteristics. The measurement process is divided into two parts:the measurement of calibration function and the measurement of arbitrary state. Firstly, the relative luminescence spectra at different junction temperature and normal driving current are measured by spectrometer, and then the relative spectral intensity at the spectral trough is analyzed. Considering practicability and cost reduction, normal working current drive is adopted, but the self-heating effect of LED driven by normal working current can not be neglected in the fixed reaction time of spectrometer. Therefore, the selected reference state method is used to make the difference between the relative luminescence spectral intensity at each temperature and the reference state point by point to get the corresponding difference value. At the same time, in order to reduce the temperature deviation introduced by the temperature control system, the corresponding junction temperature difference is also obtained by making the difference between each temperature and the reference temperature. Experiments show that the calibration functions of junction temperature difference and luminescence spectral intensity difference of LED with high and low color temperature have high linearity, and R2 is above 0.99. Using the calibration function, the junction temperature of LED can be measured at any state. Finally, the junction temperature data of high and low color temperature LED obtained by the proposed method under different conditions are compared with the measurement results by T3Ster instrument of Mentor Graphics Company. The maximum deviation is 2.82%. Within the acceptable error range, it shows that the proposed method is completely feasible and has certain practical value.