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本文采用了一种简单的功率监测法,观察了KrF准分子激光对掺锗光纤折射率影响的非线性过程。观察到子纤芯折射率扰动过程中非稳定现象、饱和现象和折射率扰动的非线性。 相似文献
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光纤法布里-珀罗传感器串连复用的傅里叶变换解调方法初探 总被引:6,自引:2,他引:4
光纤法布里—珀罗传感器复用、特别是串连复用的解调十分困难。为解决这个问题,从光纤法布里—珀罗应变传感器的基本原理出发、在仅有两只传感器复用的基本条件下,深人分析了复用系统组合输出光强信号及其分布特性;研究了对其进行傅里叶变换的解调原理及具体实现方法,分析了因复用信号不满足傅里叶变换条件而在变换域产生的畸变,进行了计算机仿真解调。在此基础上,搭建了两只传感器的串连复用实验系统,并用此方法实现了两只复用传感器的解调,且传感器之间的相互影响小于5%。理论与实验表明,虽然传感器的复用信号不满足傅里叶变换的标准条件,且仿真与实验存在一定差异,但所提出的傅里叶变换方法,基本可用于光纤法布里—珀罗传感器的串连复用解调。 相似文献
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Due to X-ray attenuation being approximately proportional to material density,it is possible to measure the inner density through Industrial Computed Tomography(ICT) images accurately. In practice,however,a number of factors including the non-linear effects of beam hardening and diffuse scattered radiation complicate the quantitative measurement of density variations in materials. This paper is based on the linearization method of beam hardening correction,and uses polynomial fitting coecient which is obtained by the curvature of iron polychromatic beam data to fit other materials. Through theoretical deduction,the paper proves that the density measure error is less than 2% if using pre-filters to make the spectrum of linear accelerator range mainly 0.3 MeV to 3 MeV. Experiment had been set up at an ICT system with a 9 MeV electron linear accelerator. The result is satisfactory. This technique makes the beam hardening correction easy and simple,and it is valuable for measuring the ICT density and making use of the CT images to recognize materials. 相似文献
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Based on Sagnac interferometer, a simple distributed optical fiber sensing system with sub-loop is presented to monitor the vibration applied on the sensing fiber. By introducing a sub-loop, three output beams of interference with different delay time are gotten. Location of the vibration is analyzed through mathematical-physical equations. The vibration frequency, amplitude, and location are theoretically simulated. The results agree well with the previous experiments. 相似文献
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Through the use of time and space integrated kiloelectronvolt (keV) spectroscopy, we investigate the thermal emission of plasma, which produces strong line emission from the titanium K shell (He-a at 4.7 keV and H-α at 4.9 keV), created by laser. In order to optimize the conversion efficiency enhancement on titanium foils, the experiment is conducted under a variety of laser-driven intensity conditions. The X-ray emission intensity at 4.7 keV is measured and compared with prediction. The experimental result demonstrates that the solid Ti target laser-produced plasma (LPP) source has X-ray emission at 4.7 keV, which are all generated from electronic transitions in Ti ions at pulse width of 2.1 ns or 30 ps, the crudely evaluated He-α X-ray intensity appears to slightly increase with laser intensity enhancement, and the pre- pulse effect increases the conversion efficiency of the He-α X-ray. In addition, a 90-μm-thick Ti foil as a filter is used to transmit He-α X-ray at near 4.7 keV, creating a quasi-monochromatic transmission and greatly reducing the lower- and higher-energy background. 相似文献
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