The modulation of incident coherent beams is limited much less than 1 to linearize the equations easily in the study of the photorefractive effect with band transport model. The linearization can get good precision if the light modulation is small. However,in most cases the modulation approximates to 1 and the linear theory is not available any more. A new solution based on FlexPDE is put forward to solve the problem at large modulation depth. The photorefractive equations are rigorously solved based on the algorithm of finite element method. The forming of holographic grating in paraelectric KTN crystals at large modulation depth is researched. The distributions and time evolvement curves of space charge filed,light excitated electrons,ionized donors,and crystal refractive index are shown. Calculation indicates that the FlexPDE can reduce the difficulty of solving the photorefractive equations,and display the forming process with visualization of holographic grating dynamically on real time.

In tricolor grating color photography,the digital frequency fs is a key parameter,which affects the decoding speed and the quality of the decoded image. Therefore,the value of fs should be determined. The triangle relation among digital frequency fs,gratings frequency fg and gratings sampling frequency fgs is analyzed in accordance with the Nyquist sampling theorem. The method to determne the optimum value of parameter fs is obtained. The result shows that fs should be 2032 d/i when fg is 20 line/mm. It has not only kept the original encoded image information completely but also improved the decoding speed to 3 times. It is of great benefit to the development of tricolor grating digital color photography and its further application in the future.

All-fiber add/drop filters are the key components in fiber communication systems. The Bragg grating assisted mismatched coupler for add/drop filter is not interferometric,easy to fabricate and works stable. The filter is based on 248 nm ultraviolet-written Bragg grating in 2×2 coupler fused with a standard single mode fiber and a self-made high germanium doped photosensitive fiber. The filter with maximum reflectivity about 20 dB,bandwidth about 2 nm is obtained. Filters with big maximum reflectivity and long bandwidth can be obtained by writing chirped Bragg grating on the uniform region of the coupler or writing Bragg grating on the non-uniform region of the coupler.

Based on therotical analysis and experimental demonstration,three commonly used reconstruction algorithms in digital holographic microscopy,Fresnel transform algorithm,angular spectrum algorithm,and convolution algorithm,are investigated. It shows that the lensless Fourier transform digital hologram can be reconstructed at any distance by Fresnel transform algorithm. For convolution algorithm,the whole reconstructed image with high resolution can be acquired in an optimal reconstruction range or a small area around it. When the reconstruction distance is slightly smaller or larger than the optimal one,a high quality image can also be obtained by using angular spectrum algorithm. Angular spectrum algorithm is better than convolution algorithm as a whole. The Fresnel transform algorithm is time-efficient and simpler than the other two.

The applications of digital holography and image processing technology in reconstructing,identificating and extracting hologram of underwater bubble field in the underwater environment are mainly discussed. First,the recording and reconstructing program is completed and used for recording the hologram of underwater bubbles field,and the hologram is denoised and reconstructed. Using edge detection techniques the bubbles are identified and their size are calculated. At last,using neighborhood reconstructing method the number of bubbles in the hologram is figured out. The project is proved practicable by the experiment.

In order to overcome the disadvantage of slow mechanical scan of optical coherence tomography (OCT), a non-mechanical scan frequency-domain OCT system with imaging spectrometer and Michelson interferometer was set up. The tungsten lamp was used as a non-coherent broadband light source. The focused line was obtained by using cylinder lens. The system structure and work principle were introduced respectively. The experiment to get optical tomography imaging of a sample was carried out. The imaging characteristic of the system was analyzed. The background noise is reduced by using the method of median filtering average. The result shows that the data collecting speed of the system is one hundred times as fast as that of time-domain tomography imaging in scope of 8mm, although the image quality is not as good as that of time-domain OCT due to the light source.

3D object cut length measurement using light-knife is deeply researched based on laser triangulation,and the measurement principle and calibration method are studied in detail. The object-image relationships in height direction and light-knife direction are analyzed through coordinate transformation method,and the calculation formula of 3D object cut length measurement using light-knife is derived. A new linear calibration method is proposed based on the object-image relationships. An experiment of finger’s length measurement has been done and the results are precise. In the height direction the inverse of object’s relative height is linear with the that of image’s relative height. In the light-knife direction the ratio of object’s length to image’s length is linear with the object’s relative height. The new linear calibration method is very precise and simple. The advantages of 3D object cut length measurement using light-knife are of high accuracy,low cost,and high processing speed.

A modified grating light modulator (GLM) device applied to novel micro-spectrometer is proposed,which consists of an upper movable grating and a bottom reflector. When the GLM array is actuated by different voltages,the movable gratings are pulled down to different height,which can modulate lights of different wavelengths. The operating principle,device architecture and fabricated process are introduced,and the device is modeled by using Coventor ware. The electromechanical coupling characteristic is analyzed by the finite element simulation method,the pull-in voltage and response frequency are deduced,and the influence relationship between device architecture and flatness of grating is discussed. The result indicates that flatness of grating can be optimized effectively to achieve better switching modulation feature by increasing the thickness,improving bottom electrode distribution and adopting thinning-folded-beam.

The ultrasonic cleaning technology of uncoated optics with high cleanliness requirement is studied. The effects of ultrasonic cleaner,cleaning temperature,cleaning time and other parameters on optics have been carried out. An effective ultrasonic cleaning technology without damage to the surface of optics is achieved. It is found that the standing time of the optics will affect the cleanliness;the freshly polished optics has better cleanliness and shorter cleaning time.

A circuit of high-resolution digital video camera,supporting 1.4 mega pixels and 7.5 frames per second was presented. ICX205AK is used as CCD sensor,AD9923A is used as the analog front end,and other chips include XC3S1200E and TE3310RPF. The AD9923A converts CCD analog signal to digital signal,and the digital signals are sent to XC3S1200E which converts Bayer signals to YUV signals. The YUV signals are input to TE3310RPF to generate JPEG data. AT91RM9200 sends the JPEG data to network. The testing results show that image can be collected,compressed,and transmitted with 1.4 mega pixels image 7.5 frames per second by this design.

The system design in fiber cavity ring-down spectroscopy (CRDS) and liquid sensing are studied in general. Firstly,the technique principle of CRDS is introduced. Secondly,the typical fiber ring-down cavity structures are classified. Thirdly,the design methods of CRDS system are proposed and our recent progress of the liquid sensing study in application of CRDS technique is briefly introduced. Finally,the development of the CRDS technique is presented,and study idea and project suggestion are proposed.

Wide bandwidth,high dimension chaotic carriers can be generated by lasers. It is hopeful to establish chaotic optical secure communication channel. Combined with the research both at home and abroad,the security performance of chaotic optical communication is demonstrated according to the cryptanalysis. The research progress in security analysis of chaotic optical communication is introduced. The advantages and disadvantages of several currently reported methods of enhancing the security of chaotic optical communication are analyzed in detail. Meanwhile,some other spare measures are proposed.

Based on analysing development of radiation measurement technology,new metrology research directions after into 21 century are introduced,including new method of radiation metrology transfer and high energy laser limit measurement. Blackbody radiation,cryonic radiometer,and synchrotron radiation ultraviolet value transfer system are described in value transfer methods. In laser limit measurement,measuring high-energy laser power with different methods is of great importance. Then some radiation measurement work in the First Scale Optical Metrology Station of the Commission of Science,Technology and Industry for National Defense is introduced,including spectral irradiance and radiance standard,blackbody radiation source standard,extended area blackbody calibration device,and spectral response measurement device of radiation detector,etc..

The tip-enhanced Raman spectroscopy (TERS) has drawn much attention from the academic community due to its high spatial resolution and detection sensitivity in the last decade. The TERS method provides a powerful tool for the nano-material science and life science. It makes nano- spectroscopy come true. The basic principles of TERS are briefly described,and the configuration,design method and evaluation criterion of TERS systems are discussed. The new applications and research of TERS are introduced,and the frontier topics,key technical issues are analyzed.