基于双折射原理的脉冲间隔连续可调的晶体分束方法

为对飞秒级超快过程进行可调曝光间隔的实时探测,需要获得共线传输的飞秒级脉冲间隔可调的子脉冲串。提出一种基于双折射原理的脉冲间隔连续可调的楔形晶体分束方法,该方法具有子脉冲能量均等、相似度高、分束结构简单紧凑且容易嵌入到光学系统中的优点。数学上推导了子脉冲脉冲间隔与晶体尺寸、结构角及移动距离的精确表达式。在晶体尺寸和结构角确定之后,子脉冲脉冲间隔随晶体移动距离呈线性变化关系。理论分析了误差项和色散等因素对分束结果造成的影响。模拟计算和干涉实验结果验证了基于双折射原理的脉冲间隔连续可调的晶体分束方法的可行性,为实现飞秒级脉冲间隔的多脉冲分束提供了借鉴。

一种基于沃拉斯顿棱镜的多角度激光分束方法

提出一种基于沃拉斯顿棱镜的多角度激光分束方法。利用沃拉斯顿棱镜和双透镜组合,将飞秒激光单脉冲分束为多角度传输、具有飞秒或者更长时间间隔的多个激光脉冲;分束角度调节灵活,能量利用率高,结构简单。采用本文方法搭建了飞秒激光超快全息记录系统,并记录了4路复用的干涉条纹。实验结果表明,本文所提出的分束系统可以应用于超快全息记录系统。

Multichannel deconvolution with spatial refl ection regularization

Seismic deconvolution plays an important role in the seismic characterization of thin-layer structures and seismic resolution enhancement.However,the trace-by-trace processing strategy is applied and ignores the spatial connection along seismic traces,which gives the deconvolved result strong ambiguity and poor spatial continuity.To alleviate this issue,we developed a structurally constrained deconvolution algorithm.The proposed method extracts the refl ection structure characterization from the raw seismic data and introduces it to the multichannel deconvolution algorithm as a spatial refl ection regularization.Benefi ting from the introduction of the reflection regularization,the proposed method enhances the stability and spatial continuity of conventional deconvolution methods.Synthetic and field data examples confi rm the correctness and feasibility of the proposed method.

Switchable Optical Ultra-Wideband Pulse Generator Based on Polarization Modulator

In order to generate optical Ultra- Wideband （UWB） pulse train with a switchable shape, a novel method based on a Polarization Modulator （PolM）, a Polarization Controller （PC） and a delay line, is proposed and experimentally demonstrated. Experimental results show that when a Gaussian pulse is applied to the PolM, under different phase shifts introduced by the PC, a gauss or gauss doublet pulse will be generated at the output of the Polarization Beam Splitter （PBS）. If the two- path signals after PBS are properly delayed, Gaussian monocycles or third-order gauss pulses will be generated at the output of the Polarization Beam Combiner （PBC）.

Comparison between several seismic inversion methods and their application in mountainous coal fields of western China

With the objective of establishing the necessary conditions for 3D seismic data from mountainous areas in western China, we compared the application results of wave impedance technology in the lithology and exploration of coal fields. First, we introduce principles and features of three kinds of inversion methods. i.e., Model-Based Inversion, Constrained Sparse Spike Inversion (CSSI) and Geology-Seismic Feature Inversion. Secondly, these inversion methods are contrasted in their application to 3D seismic data from some coalfields in western China. The main information provided by the research includes: improving the vertical resolution of coal deposit strata, inferring lateral variation of the lithology and predicting coal seams and their roof lithology. Finally, the comparison between the three methods shows that the model-based inversion has the higher resolution, while CSSI inversion has better waveform continuity. The geology-seismic feature inversion requires information from a large number of wells and many types of logging curves of good quality. All three methods can meet the requirements of seismic exploration for lithological exploration in coal fields.

Phenomena of the Cold Pulse Propagation during Pulsed Molecular Beam Injection

As an advanced fuelling method on tokamak, molecular beam injection （MBI） has successfully been developed in HL-1M firstly and applied to HL-2A later. Many advantages such as peaked density profile and the energy confinement time increasing have been found in the MBI experiments. Some interesting phenomena have been observed in the previous MBI experiments. But up to now the mechanism of the MBI seems not very clear.