A wireless optical transmission experiment with a link length of 610m was carried out at night in Lanzhou area to investigate the statistical characteristics of light intensity fluctuation in sunny, overcast, sleet and dust days. The atmospheric structure constant of refractive index C2n in different meteorological conditions were measured by using the scintillation method. The measured maximum, minimum and mean value and the standard deviation of C2n indicate that the range of C2n is 1.06×10－15 m－2/3~1.05×10－13 m－2/3 of the experimental period, which belongs to moderate turbulence. Moreover, it also indicates that the fluctuation of C2n in sunny day and sleet day are greater than overcast day and dust day. Furthermore, Rytov variance is analyzed by using the measured light intensity values. The results show that in sunny day, sleet day and dust day, the light intensity fluctuation belongs to weak fluctuation at most of the time and there is a small part of the time it belongs to moderate fluctuation. However, the light intensity fluctuation in overcast day belongs to weak fluctuation in all time. The light intensity fluctuation in sunny day and sleep day are greater than overcast day and dust day. We can conclude that the probability distribution of light intensity in different meteorological conditions is closest to the exponential weibull distribution by comparing the nonlinear fitting results of the logarithmic normal, Gamma-Gamma and exponential Weibull distribution. The goodness of exponential Weibull distribution is greater than 0.989 95. In the weak to medium fluctuation region, the Gamma-Gamma distribution fits better than the lognormal distribution.

In order to solve the problems that the single-baseline transmissometer is a single sampling volume device and effected by noise seriously, a mobile variable baselines visibility detection device is designed and produced. Four modules of emission, receiver, transfer and processor constitute the entire system. The emission sources is 532 nm laser. The trolley is set on the sliding track, receiving the signals in a state of continuous movement. Applying this approach, the multiple baseline visibility detection is realized. Then, the time averaging combing with least squares method is employed to compute the ultimate atmosphere visibility. This equipment only makes the use of single receiver to operate, which can eliminate the error caused by the optical system contamination in theory. By the error theoretical analysis, the detection variance and baseline sampling points models on the proposed system are exhibited, and the anti-noise performance is proved through adding noise simulations on the system. Finally, the entire device is tested in the real atmosphere, it is turned to be reliable by comparing the actual data.

In order to achieve the water vapor measurement in day and night time, the quadruple frequency of Nd∶YAG pulsed laser is selected as the transmitter in the construction of solar-blind Raman lidar. Due to the Ozone pollution in the lower atmosphere, besides the detection of the vibrational Raman signals of nitrogen and water vapor, exmaination of the vibrational Raman signal of oxygen is necessary for retrieving the Ozone concentraiton from the ground to the height of interest, which can be used as the solution for correcting the Raman lidar equation. Meanwhile, the high-resolution grating and tunable laser mirrors are selected to construct the grating spectormeter for the separation of the vibrational Raman signals of oxygen, nitrogen and water vapor. The simulation results show that the vibrational Raman siganls of oxygen, nitorgen and water vapor can be extracted finely when the incident angle of the grating spectrometer is set to be 10 deg, and the solar blind Raman lidar can achieve the water vapor measurement up to the height of 2 km.

Experiments to study the optical response characteristics of plastic optical fibers under shear and torsion conditions are conducted respectively which are correspond to the conditions when sliding type and tearing type cracks occurred in structures. Results indicate that during the process when the shear displacement increase from 0 to 0.5 mm, the optical loss and Fresnel reflection are linear related to the shear displacement, and the sensitivity of which are 15.6 dB/mm and 5.9 dB/mm respectively, indicating that plastic optical fibers have better optical sensibility to cracks under shear loading conditions, while the sensitivity is low under torsion loading, the optical loss of which is about 1 dB. It can be concluded that plastic optical fibers have the same optical response characteristics when sliding mode or tearing mode cracks occurred in structures. Both Fresnel reflection and optical loss can be used as crack monitoring index among which optical loss is considered to be more sensitive.

The moving and jitter of the target will lead to the rotation of the center of rotation in the process of laser reflection tomography. This will lead to reconstruction image dislocation and artifact, a modified error reduction algorithm based on phase recovery technology was proposed. Firstly, the phase information of reconstructed target was obtained through iterative iteration of light intensity. In addition, the convergence of algorithm was also effectively improved by increasing the initial constraints and the constraints in the spatial and frequency domains. This method can effectively improve the easy to fall into the local minima problem and phase recovery method for image reconstruction optimization is obtained. The simulation experiments show that the mean square error of the three sets of reconstructed images is reduced from 0.774 to 0.551, and the image reconstruction artifact can be effectively eliminated. The experimental results also show that the resolution of the laser reflective tomography system is improved.

Aiming at the limitation of the original non-interfering phase retrieval technique based on the Transport of Intensity Equation(TIE) which is only suitable for the short distance regions propagation under single wavelength condition, a phase retrieval algorithm based on TIE method under a two wavelength illumination condition is proposed. The algorithm takes into account the correlation constraints between the two phases under two separate wavelength and the concept of synthetic wavelength is introduced. Meanwhile, considering the limitation of phase retrieval accuracy at longer distance transmission, a two wavelength hybrid iterative algorithm is proposed by combining the aforementioned algorithm with the angular iterative algorithm. The experimental results show that the error of phase diagram retrieved by the two-wavelength TIE algorithm is reduced to 0.191 2 on average; the error of phase diagram retrieved by the proposed two wavelength hybrid iterative algorithm is reduced to 0.220 2 on average. The proposed algorithm can effectively recover the phase information under two wavelength illuminations and is not limited by the distance.

A near-infrared image simulation method based on spectral correlation is proposed. The remote sensing image-link model, and spectral correlation between visible multispectral and panchromatic for satellite sensors were analyzed, and the spectral correlation coefficient was calculated. Thus the simulation near-infrared image was generated based on the spectral correlation coefficient. In order to improve the speed of near-infrared image generation, the SIFT algorithm based on GPU was used. The proposed method utilized the data of Jilin-1A optical sensor to generate the simulation near-infrared images. The computation time of individual image was better than 3 s, and the simulation image had better effects for synthesis of true color image and removal of cloud and haze.

The output video of the low-light-level solid-state imaging devices are always gray. For better low-light-level imaging applications, a natural-appearance colorization and enhancement method named Luminance Stretching Color Transfer (LSCT) for grayscale video images using color transfer is proposed. A two-channel natural-appearance color fusion method is refered to in the LSCT method. In order to achieve the natural-appearance colorization and enhancement, firstly, the pre-colorized image is obtained by combining the grayscale image with its negative image. Following this, an adaptive luminance stretching is performed and color of the reference image is transferred in the YUV color space. As compared with other methods based on color transfer, the LSCT method is less affected by the degree of similarity between the reference image and the original grayscale image. It means that relatively good results may be achieved for most scenes with an appropriate reference image. Thus, the LSCT method has better environmental adaptability. The comparisons reveal that the LSCT method is high efficient and its colorized results appear more natural in respect to human perception with better contrast and color harmony. Moreover, the LSCT method has been implemented in real time on hardware platforms.Therefore, it can effectively improve the effect of human observation to apply our method in the low-light-level imaging without increasing any hardware costs.

This paper presents a method of single low dynamic range image exposure correction, which enhances details in over-/ under-exposed areas. Firstly, over-exposed areas and under-exposed areas are corrected respectively. In the under-exposed area, WLS filter is used to decompose the images into illumination map and reflection map, which enhances the brightness and contrast; In the over-exposed area, dark brightness is proposed to characterize the degree of over exposure and the Retinex model is extend to compress the brightness and to enhance details. After the corrected images are fused using the proposed fusion algorithm based on saliency, the multi-region enhancement image is obtained. The results of several methods are compared by using two common image quality evaluation indexes. Experiments show that the indexes of our results are superior to other results. In addition, in the comparison of visual effects, the proposed method can obtain the correction image with rich details and high color reproduction.

A super-resolution algorithm via tiny recurrent convolutional neural network was proposed on the basis of the principles of image degradation. The proposed model has very few parameters when compared to super-resolution algorithms based on naive statistical learning. Model parameters of the proposed model have their specific physical meanings because corresponding image degradation model is introduced and regularizes the proposed model implicitly. This paper also provides an inner view of the related parameters of the algorithm and how these parameters influence the performance of the algorithm. As a result, the proposed model can achieve better performance in terms of running speed and peak signal noise ratio, comparing to current iterative backprojection algorithm. The result illustrates that the proposed algorithm only takes about 75% time consumpion, but improves the peak signal noise ratio by 0.2 dB comparing to conventional backprojection algorithm and 1.2 dB improvement comparing to bilinear interpolation respectively.

In order to acquire the geographic location information of the target zone accurately and quickly, the location algorithm was developed for width area-array aerial camera processing passive target location. The paper uses camera′s position and attitude information measured by position and orientation system which was rigidly connected with camera to regain beam′s space position. Then paper chooses the suitable object coordinate system and builds collinearity equation by coordinate transformation to calculate the location information by single photo and target elevation information. Error model is built and simulated by total differential method and Monte-Carlo method respectively. The geo-location algorithm is verified by the flight test, when the plane flies at an altitude of 5 000 m, the location error is less than 30 m, which meets the requirement of the project.

A calibration method of intrinsic parameters was proposed, which aimed at optimizing both the flatness and the area of planar patches detected from the point cloud. Either region growing algorithm or improved Random Sample Consensus (RANSAC) algorithm was chosen to extract planes according to different cases. A hybrid optimization algorithm (i.e. NMS-ABC) integrating the Nelder-Mead Simplex algorithm with the Artificial Bees Colony algorithm was proposed to calculate parameters, by means of which the intrinsic calibration of the DIY system was successfully implemented. Simulation experiments were performed using synthetic data based on known intrinsic parameters, which demonstrated the efficiency of NMS-ABC hybrid algorithm. Actual calibration experiments were conducted with multiple groups of point cloud data acquired in different scenes. Results indicate that both the percentage of planar inliers and the total flatness are improved after calibration. Besides, the calibration results will be more stable and reliable when the number of detected planes is not less than 3. Position precision test was conducted, and position precision of the DIY scanner was improved to the level of 3 mm@4 m after calibration. By increasing installation errors artificially and then contrasting point coulds as well as extracted planes before and after calibration, it is visually validated that the proposed calibration method is correct and effective.

This paper presents a novel laser Doppler shift measurement method. The propoed method uses the amplitude and phase of the phase-modulated beat signal as independent variables to define a new function and uses the function as a Doppler-shifted frequency-discriminating parameter. The purpose of the proposed method is to combine the two phase-modulated laser Doppler frequency shift measurement methods. In theory, the frequency-discriminating curve, the sensitivity curve and the error curve of the proposed method are respectively compared with the corresponding curves of the two types of phase-modulated methods. It is found that the propoed method not only inherits the working mode of the phase-modulated beat frequency signal amplitude method to measure the small frequency shift amount, but also absorbs the measurement ability of the phase-modulated beat frequency signal phase method to obtain higher measurement sensitivity and dynamic range. The hard-target reflected frequency-shifted controllable signal light is measured. The experimental results not only prove the correctness of the theory, but also prove that by adjusting the translation parameters, the dynamic range of the new method can be improved by about 26.8%, which is more suitable for measuring the high Doppler frequency shift.

In order to satisfy the application requirements of high-speed free-space coherent optical communication, the high stability four-lane integrated laser module with different frequency in the same spectrum was fabricated. The method of the gradient feedback control was proposed and it distinguish control cases with five levels which were set by the feedback values of temperature. The current and temperature of each lane are controlled step by step based on the priority order in this method and that will reduce the temperature drift, the current jitter and the influence of servo system on the linewidth of lasers. This method was applied to the module and it needed the more accurate feedback values of the temperature. Hence, the passive feedback amplifying circuit of the temperature was adopted and it can eliminate the deviation caused by the current component. The temperature drift and the current jitter which were less than 0.001 ℃ and 0.6 μA, respectively, were tested. After being integrated into the module, the Lorentzian linewidth of four external cavity diode lasers were 4.5-7.5 kHz and the Allan variances were all less than 4×10－9. In the Free-Space Optical (FSO) communication, the bit error rates of four modulation formats were tested with four lasers in the module and the ultra-high speed free-space coherent optical communication with 4×50 Gb/s 16QAM was demonstrated. The experimental results show that the four-lane integrated module has a wide application prospect in the FSO communication.

A frequency stabilized laser used in optically pumped cesium beam clocks is designed. The concise saturated absorption frequency stabilization system, in which the polarization direction of pumping laser is perpendicular to the polarization direction of probing laser, is utilized to lock laser frequency. The transition probability of the cesium atom is improved by the adjustment of the polarization direction of pumping laser. The amplitude of reference signal produced by the proposed system is higher than the signal produced by the simplified saturated absorption frequency stabilization system. When laser is locked at the frequency of the cycling transition 6S1/2, F=4→6P3/2, F=5 of cesium, the frequency stability is measured as 1.88×10－11 at 100 s. The setup of the system is compact, which is beneficial to the miniaturization and engineering of the optically pumped cesium beam clocks.

The scalar diffraction theory has carried on the analysis to eliminate the axial chromatic aberration and the conditions of magnification chromatism. Using the programmable control features of phase-only liquid spatial light modulator, the Fresnel lenses with three colors of red, green and blue are inlaid with blazed gratings and programmed on a liquid crystal spatial light modulator by random equal probability multiplexing. So that a common focal length of the three-color optical multiplexing lens is achieved, and the axial chromatic aberration eliminated. At the same time, through the constraint of the red, green, blue three-color light-modulated Fresnel lens aperture, the three-color light has the same size and intensity of the focal spot radius at the focal plane, and the magnification chromatic aberration is eliminated. The experimental results show that the axial chromatic aberration and the chromatic aberration of the multiplexing lens are effectively corrected by this method, at three-color light, the Airy′s radius is 67 pixels, which is close to the Airy's patch radius of 65 pixels produced by a monochromatic lens with the same focal length and resolution.

For weakening or eliminating the effect on uniformity, the method of uniform light accumulation based on fly-eye lens was presented. At first, illumination uniformity is designed for one LED. Then the same uniform light spot can be generated on the target surface from every LED, according to the study of LED position error. Next, An exposure light source is designed by a simulation optimization software. The maximum illuminance is 18.2 mW/cm2 while the uniformity is 86.9%, which meeting the exposure requirements fully. At last, an experiment is made to test the illumination uniformity with the method of blocking LEDs. The result shows that a few invalid LEDs cause less than 1% decease of uniformity. Even half of invalid LEDs lead to a result that uniformity declines by less than 5%. Thus, this method better suits actual manufacture than others by maintaining illumination uniformity for a long period.

The classical restoration algorithm can not effectively recover the full frequency domain information of the object, which leads to the serious optical sidelobes. In this paper, the application of metal nano arrays in structured light illumination is studied, and the problem of optical sidelobes in plasmonic structured illumination microscopy is solved using Maximum A Posteriori (MAP) estimation. The research shows that the MAP estimation method can effectively restore the high spatial frequency information, and through the reasonable selection of optimization parameters to achieve the purpose of suppressing optical sidelobes. At the wavelength of 520 nm, 1.3 numerical aperture, the lateral resolution can be obtained at FWHM of 65 nm, which is about 3.6 times of the traditional fluorescence microscope. This technology has potential application application in the field of life science.

In order to improve imaging quality of the space camera, a thermally driven focusing structure is designed to compensate the offset. Firstly, the focusing method is chosen according to the optical system, and the focusing structure is designed by driving the secondary mirror to move along the direction of the optical axis which occupies small space and is light in quality. Then, according to the demand of focusing, the aluminum with higher thermal expansion coefficient is selected as the main material. To ensure the secondary mirror works at constant temperature, some heating films are attached to the back of the mirror seat. And the performance of the focusing structure is simulated by the finite element method. Finally, the working state of the focusing structure is analyzed, and the deformation of the mirror caused by the temperature change is fitted by Zernike polynomial, and the fitting coefficients are input into the Zemax. As the measurement of imaging quality, the modulation transfer function is used to reflect the impact of the deformation of the sub-mirror on the optical performance of the space camera. The result shows that the focusing structure meets the design specifications and the impact of deformation belonging to the sub-mirror on the imaging quality of optical system can be neglected when the focusing structure is working. Compared with traditional focusing structures, the thermally driven focusing structure has the advantages of light weight and simple structure.

To meet the requirement of mid-infrared gas detection based on continuous Quantum Cascade Laser (QCL), a board-level QCL driver and a lock-in amplifier are developed. High-precision direct-current (DC) bias signal, low-frequency saw-tooth scan signal and high-frequency sine-wave modulation signal are generated by a signal generation circuit to control the laser current and scan/modulate laser output wavelength. The developed lock-in amplifier includes a multiple frequency circuit, an orthogonal conversion circuit, and a data-conversion circuit, which detects the second harmonic (2f) signal from the trace gas absorption signal and gains a high signal-to-noise ratio. In addition, in order to improve the stability and reliability of the system, a linear power supply with high stability and a high-performance protection circuit are designed. A QCL with a wavelength of 4.76 μm developed by the Semiconductor Institute of Chinese Academy of Science is used as a light source, and function verification and gas detection experiments of the electrical system are carried out. The experimental results show that the linearity of laser driver is as high as 0.006 3%, the long-term current stability is 5.0×10-5, and the long-term power stability of QCL is 5.07×10-4. The lock-in amplifier has an average detection error on the first harmonic (1f) signal of less than 2.4% and an error on the 2f signal of less than 5.5%. Low-concentration carbon monoxide (CO) detection is carried out, and there is a high linearity (R2>0.99) between the amplitude of 2f signal and CO gas concentration in the concentration range of 0-100 ppm. These results confirm that the developed electrical system has good stability and reliability, assuring a safe and reliable mid-infrared CO gas detection.

To eliminate the edge breakdown and reduce the dark current of conventional InGaAs/InP avalanche photodiode, a novel avalanche photodiode with triple-mesa structure was proposed. The effects of edge distance, doping concentration and thickness of charge layer and multiplication layer on the device performance were systematically investigated by a commercial simulator. The simulation results shown that the device was possessed of low edge electric field and reasonable device size, when the edge distance was 8 μm. In this design, the high electric field was confined within the center of device and the breakdown voltage was improved. The edge electric field of optimized device was only 2.6×105V/cm, which was a half of central region at 40 V reverse voltage. What’s more, it can reduce dark current to 9.25 pA at 0.9 Vbr, which was only 1/3 for the dark current of traditional double-mesa avalanche photodiode.

A metal-insulator-metal asymmetric structure filter is proposed based on the aperture coupled method, which is composed of two semi-circular cavities, a waveguide and two rectangular apertures connecting the semi-circular cavities and the waveguide. The finite element method is used to simulate and calculate its magnetic field distribution, transmission spectra, bandwidth and edge steepness distribution curves. The results show that the obvious red shift or blue shift phenomenon will be occurred in the transmission curve when the structure parameters are adjusted, and the transmission curve is very smooth. Its pass-band’s transmittance can reach 0.95, its stop-band has the flat characteristics and the transmittance is as low as 0.001. Besides, its pass-band and stop-band all have a wide bandwidth. After optimizing the structure parameters, the filter can realize a similar function of the rectangular filter and the filtering function of channel selection of the three optical communication windows at telecommunication regime. The proposed filter can be well applied in the micro / nano optical integrated devices, especially in optical communication systems.

Aiming at the quantum radar cross section computational problems of missiles, a cone-pillared composite model is used to simulate the missile target geometry. The single-photon wave equation is introduced to derive and improve quantum radar cross section expressions. By interfering with the interaction of atoms and photons on the mirror surface, the intensity of the photons scattered by the target atoms is measured at the detection point to obtain the quantum radar cross section formula of the cone column compound target. The simulation results show that the mainlobe peak of single-photon quantum radar cross section is higher than that of classical radar cross section and the quantum radar cross section sidelobes peak is lower than that of classical radar cross section under different incident angles. The quantum radar cross section decreases with decreasing wavelength, and the incident angles have no influences on quantum radar cross section. It shows that the quantum radar has a high detection and identification ability for small targets and the resolution can reach nanometer level, which provides a basis for missile target identification.

In order to solve the problem on the information utilization and noise reduction of angular weighting methods by Mie scattering calculation for multiangle dynamic light scattering, multiple angle-weighting method was proposed, in which the Mie scattering′s spatial character of all granularities at each angle is as the angular weighting factor and that of each granularity is as the nuclear matrix weighting factor. By using this multiple angle-weighting method, the regularization inversions for both simulated and measured multiangle dynamic light scattering data were carried out. Compared with the inversion results of the light intensity ratio method and the light intensity mean method, the inversion results for multiangle dynamic light scattering are closely related to the angular weighting methods. In the absence of noise, the intensity ratio method and the multiple angle-weighting method can obtain accurate particle size distributions, but the information utilization for the light intensity mean method is not sufficient. With the increase of the noise level, the inversion results of the ratio of light intensity are rapidly getting worse, which shows the lower noise reduction capability. Multiple angle-weighting method, taking the information utilization and noise reduction capability into account, can better show the advantage for increase of information and effectively suppresses the noise influence when the scattering angles are increased. The method significantly improves the accuracy of particle measurement in the multiangle dynamic light scattering, especially for the multi-peak distribution particle system.

Quantum state genetic algorithm was applied into the discrete design of broadband extreme-ultraviolet multilayer to solve the problem of solving accuracy in genetic algorithm. And the discrete design of layer thickness can be achieved in the process of quantum state genetic algorithm. It solves the problem that the layer can be accurately fabricated when the magnetron sputtering system is controlled by the deposition time. According to the results designed by quantum state genetic algorithm, broadband extreme-ultraviolet multilayers have been fabricated by magnetron sputtering system. The measured results show two kinds of multilayers designed by quantum state genetic algorithm were fabricated, one has a reflectivity of more than 45% in the 0°~15° range of incidence angle, and the other reaches the reflectivity of more than 20% for the wavelength range from 13 nm to 15 nm. The relative work shows the potential value of quantum state genetic algorithm and offers another alternative optimizing algorithm in the field of broadband extreme-ultraviolet multilayer design. And then the algorithm can achieve the discrete design of multilayer, which makes fabricated multilayer have better spectral properties.

The high quality Na5Lu9F32 single crystals with different Tm3+ concentrations ranging from 0.5 to 4 mol% were grown successfully by an improved Bridgman method. The fluorescence spectra and decay curves at 1.86 μm were measured under the excitation of 790 nm LD to study the luminescent properties of the crystals and the energy transfer process between Tm3+ ions. The 1.86 μm emission intensity gradually increases to the maximum value when the Tm3+ concentration increases to around 1.95 mol%. Nevertheless, it decreases fleetly with the Tm3+ concentration further increase from 2.0 mol% to 4.0 mol%. The maximum stimulated emission cross section at 1.86 μm is also calculated to 0.80×10－20 cm2. The 1.86 μm fluorescence lifetime of Tm3+∶3F4 level decreases with the increase of Tm3+ doping concentration. The concentration quenching effect of Tm3+ ions and the cross relaxation energy transfer process between Tm3+ ions are mainly in charge of the variety of the 1.86 μm emission.

The 488 nm, 518 nm and 637 nm lasers in visible wavelength band were used to carry out the light reduction experiment on the graphene oxide samples. Meanwhile the transmittance and resistance of reduced graphene oxide were measured in real time to investigate effect of laser with different wavelengths on reduction of graphene oxide. The results show that the transmittance and resistivity of reduced graphene oxide appear different variation under different wavelengths laser irradiation. When 488 nm laser is used, the sample can be reduced though under the condition of low power density, and the reduction process is in accordance with the photochemical reaction. When using 518 nm and 637 nm laser, only when the laser power density is greater than a certain threshold, can the graphene oxide be reduced; longer the laser wavelength, higher the power threshold; and the reduction process conforms to photothermal reaction. The results can pave a way for the improvement of the patterning process of graphene film.