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A frequency-shift interference fringe locking system was established to enhance the contrast of holographic grating profile and to decrease the phase shift of exposure interference fringe caused by the external environment. According to the composition and the working principle of the system, the moire pattern occurrence condition in the measuring system and its dependence on the phase change of interference fringe were analyzed and the selection method for photodetectors was given. On the basis of the system accuracy, the digital control system was self-designed including A/D conversion digit. A optical frequency shifting method was used to regulate the fringe phase, and an acousto-optic modulator was taken to correct the frequency shifter of the interference fringe movement in real time. The experimental results illustrate that the system can offer a sampling frequency of 5 kHz and can restrain the interference fringe drift and low-frequency moving below 10 Hz. The 3 value of the phase shift is below 0.12 rad, which means its phase is within 0.02 interference fringe period. The system can lock the phase of the exposure interference fringe effectively in real time, and can satisfy the requirements of the holographic grating lithography better.

On the basis of the UMHexagonS algorithm used in the Joint Model(JM) for H.264,a new fast algorithm on integer pixel motion estimation was proposed to improve the video encoding characteristics.A new order of checking predicted Motion Vector(MV) was proposed in the predicting starting search point to promote the accuracy of starting search point.Then,a self-adaptive global search method was proposed for the global search,by which the unsymmetrical-cross search and uneven multi-hexagon-grid search could be skipped based on the relationship between two predicted MVs with highest accuracy,and the feasibility and accuracy of this judging method was verified through tests on a number of different sequences.Meanwhile,an improved 5×5 search method was presented according to the distribution of best MV relative to the starting search point and a new early termination technique for sub-macroblock was added to further reduce the cost of motion estimation without additional computation.According to the experiment results,the proposed algorithm reduces the total number of search points by 83.80% and the Peak Signal to Noise Ratio(PSNR) about 0.021 dB on average and increases an average increment of 0.46% on equivalent bitrates as compared with that of original UMHexagonS algorithm.With a negligible performance degradation,the proposed algorithm reduces the computation of motion estimation effectively and offers a well-distributed effect on sequences with different motion intensities.

The party Alice in a cryptograph system transmits coherent quantum signals to the party Bob,obtaining a series of correlated continuous Gaussian variables.The process to distill a binary key out of the correlated Gaussian variables that they share is called continuous-variable quantum key distribution(CVQKD).Reconciliation in CVQKD,i.e.,to correct differences between the correlated variables,is the key issue discussed in the paper.Based on both sliced error correction(SEC) protocol and multilevel coding/multistage decoding(MLC/MSD),reconciliation is implemented by LDPC code-based Slepian-Wolf CODEC.According to the proposed multilevel Tanner graph which depicts message transition of information,multistage iterative intrinsic and extrinsic information belief-propagation(LLR-BP) update formulae are derived.Three decoding modes of MSD are compared experimentally in convergence and performance.Simulation results show that the proposed algorithm can reconcile reliably 10000 continuous quantum variables with efficiency of 92.3% when SNR of the channel is above 2.5 dB.

Two legitimate users of an encryption system,Alice and Bob,want to acquire the key from the related Gaussian continuous variables X and Y transferred through a quantum channel,by exchanging parts of information through an ideal public authorized channel,and they get consistent binary keys from the inconsistent X and Y.This process is referred to reconciliation.This paper builds a reconciliation scheme for continuous-variables quantum key distribution using Turbo codes as the primitive code,on the basis of Sliced Error Correction(SEC) and Multi Level coding/Multi Stage Decoding(MLC/MSD).Parity bits of Turbo code are employed as the redundant information in the Slepian-Wolf encoding and decoding scheme.The simulation results show that the reconciliation convergences when the SNR is 7dB above whilst the block size is 20000.

SPIHT and NLS(Not List SPIHT) are efficient image compression algorithms,but the algorithms application is limited by the shortcomings of the poor error resistance and slow compression speed in the aviation areas.In this paper,the error resilience and the compression speed were improved.The remote sensing images were decomposed by Le Gall5/3 wavelet,and wavelet coefficients were indexed,scanned and allocated by the means of family blocks.The bit-plane importance was predicted by bitwise OR,so the N bit-planes can be encoded at the same time.Compared with the SPIHT algorithm,this modified algorithm is easy implemented by hardware.The experiments results show that the PSNR of reconstructed images was increased about 0.2 to 0.6 db and the speed was 4~6 times faster than the SPIHT encoding process.The speed can be further improved via virtue of the parallelism and pipelining,when it is implemented by the hardware.

A measuring method of polarization aberration based on aerial image of alternating phase-shift mask is proposed.The polarization aberration is represented by Pauli-Zernike coefficients.The image placement error and best focus shift are measured by image sensor at multiple illumination settings,combined with X and Ylinearly polarized illuminating light.The Pauli-Zernike coefficients are retrieved using the calibrated sensitivity matrix of polarization aberration.The validity of this proposed method is verified by numerical simulations,and the results indicate that the measuring accuracy is less than 3.07 mlambda.