共查询到18条相似文献,搜索用时 234 毫秒
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根据动态光散射装置测量纳米粒径原理,开发了一套基于现场可编程门阵列(FPGA)的纳米粒径测量系统。该系统通过光电倍增管(PMT)输出光子脉冲信号,利用FPGA实现高速脉冲采集及自相关运算,采用双脉冲计数器实现高精度可控的连续计数,并实现DDR3异步存储以及USB通信交互等接口功能。自研板卡既可实现自相关函数实时采集运算,又可无丢失地保存海量原始数据信号。采用该系统对200nm聚苯乙烯颗粒进行了测量,分析了不同采样时间及延迟时间等参数对粒径测量结果的影响。实验结果表明:自研FPGA采集板卡测量重复性为1.2%,具有很好的稳定性和重复性。 相似文献
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为提高多角度动态光散射(MDLS)实验的测试效率与测量精度,开发了一种基于现场可编程门阵列(FPGA)的多通道动态光散射自相关器。该自相关器利用FPGA同时采集4个散射角度的光子脉冲信号,实现高频脉冲计数和自相关计算;设计双计数器模块保证高频无丢失计数,结合片内环形寄存区与片外DDR3芯片实现动态存储数据;提出multi-tau相关器结构设计自相关器的相关计算模块,通过USB通信模块传输自相关计算结果。该自相关器利用有限的FPGA内部硬件资源,实现了多通道自相关运算,解决了大量计数数据的存储问题,提高了MDLS实验的测试效率。利用自相关器对50~200 nm的聚苯乙烯颗粒进行MDLS实验,实验结果与样品的标称粒径表现出良好的一致性,表明该设计能有效地表征颗粒粒径信息。 相似文献
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测量下限是光散射颗粒测试技术的关键问题。本文通过理论分析、比较归一化散射光强的分布图和构造方差函数F(d)对颗粒散射光的光强分布进行了定性和定量的讨论,对Mie散射向Rayleigh散射趋近的情况进行了分析,讨论了散射光光强大小的分布,分析了测量不同粒径的颗粒的可行性,最终得到在入射光源是波长为0.6328μm的He-Ne激光器的情况下,当粒径d取200nm以上时,不同粒径颗粒的M ie散射光强分布有较大差别,适合用静态光散射的方法来判断颗粒粒径。 相似文献
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研究了基于图像的光散射颗粒粒度测量系统。结合图像处理技术,提出一种最小二乘原理圆拟合光环定中方法,设计CCD探测器光环尺寸与颗粒粒级划分数目。搭建了颗粒光散射图像测量硬件系统,利用非独立模式差分进化算法反演出颗粒粒度。通过8种聚苯乙烯乳胶球标准颗粒实验对测量系统准确性进行验证,测量误差在3%之内;对2种不同体积分数的大豆蛋白乳液进行了测量,与图像粒度仪对比偏差在5%之内。实验结果表明:采用最小二乘原理圆拟合方法定中提取到的散射光能与理论分布更加吻合,35环的光环划分方式有利于获得相对良态特性的光能系数矩阵,该测量方法为颗粒粒度测量提供了一种光散射法有效改进方式。 相似文献
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The charging behavior of PS (polystyrene) particles dispersed in nonpolar solvent containing surfactant AOT (sodium di-2-ethylhexylsulfosuccinate) was researched by phase angle light scattering (PALS). The effects of the AOT concentration, the particle concentration and the particle size on the zeta potential of the particles were analyzed systemically. The results showed, at different particle concentrations (expressed in the volume fraction of 10(-5)-10(-3)), that the zeta potential could be adjusted by surfactant AOT over a wide concentration range of 0.001-100 mM. An obvious difference of zeta potential on particle concentration was revealed between the high AOT concentrations (beyond 10 mM) and the low ones (below 1 mM). Meantime, it was found that the relationship of particle size to zeta potential showed a great discrepancy between the dilute particle concentrations (below 10(-4)) and the concentrated ones (beyond 6 × 10(-4)). These findings were consistent with the mechanism of preferential adsorption of the charged micelles in nonpolar solvent. 相似文献
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H. M. Anderson S. B. Radovanov 《Journal of research of the National Institute of Standards and Technology》1995,100(4):449-462
Particle “dust” in processing plasmas is of critical concern to the semiconductor industry because of the threat particles pose to device yield. A number of important investigations into the formation, growth, charging, transport and consequences of particulate dust in plasmas have been made using the Gaseous Electronics Conference Reference Cell as the reactor test-bed. The greatest amount of work to date has been directed toward a better understanding of the role that electrostatic, ion drag, neutral fluid drag and gravitational forces play in governing the dynamic behavior of particle cloud motion. This has been accomplished by using laser light scattering (LLS) techniques to track the motion of suspended particle clouds in rf discharges. Also, statistical correlation’s in the fluctuation of scattered laser light intensity [dynamic laser light scattering (DLLS)] can be used to determine information about particle size, motion, and growth dynamics. These results are reviewed, along with recent work demonstrating that charged dust particles in a plasma can form a strongly coupled Coulomb liquid or solid. New results from DLSS experiments performed in the Reference Cell are presented that show process-induced dust particles confined in an electrostatic trap exhibit low-frequency oscillatory motion consistent with charge density wave (CDW) motion predicted for strongly coupled Coulomb liquids. 相似文献
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