基于深度学习的显微离焦图像法颗粒深度测量

显微成像条件下的三维流场测量是微通道流动等研究的基础,其难点在于颗粒深度位置的测量。由于显微镜头景深极小,成像时通道内大部分颗粒处于离焦状态。本文首先基于几何光学原理分析了显微成像前后离焦不对称的特点,随后基于Inception V3卷积神经网络搭建了颗粒深度预测模型,并通过光线追踪方法生成粒径1~10μm的10种颗粒在深度范围-50~50μm内的仿真显微图像,应用深度预测模型对其进行训练及预测,颗粒深度预测结果显示1~3μm颗粒的相对误差在±13%以内,4~10μm颗粒的相对误差小于±5%。最后在微通道中拍摄粒径分别为2.6μm和5μm的聚苯乙烯微球在深度范围-50~50μm内的显微图像,应用同一深度预测模型进行训练及预测,两种颗粒深度预测结果的相对误差分别为小于±15%和±5%。结果表明,所提出的基于深度学习的显微离焦图像法能够有效测量微通道内颗粒深度位置,为图像法流场测量技术增加了新的思路。

Effect of Ce on morphology of a(Al)-Al_2Cu eutectic in Al-Si-Cu alloy

The effect of Ce addition on the morphology of the α（Al）-Al2Cu eutectic in Al-Si-Cu alloy was investigated using thermal analysis, light microscopy, scanning electron microscopy, focused ion beam and energy dispersive analysis. The results show that the eutectic α（Al）-Al2Cu forms within small space between dendrites, silicon and AlSiFeMn plates. Eutectic Al2Cu is not lamellar but degenerated. However, Al2Cu in Ce-modified alloys is more compact. Ce partially dissolves in Al2Cu, which is a viable reason for the formation of coarser Al2Cu. The addition of Ce also increases the microhardness of theα（Al）-Al2Cu eutectic by almost 10%compared with the basic Al-Si-Cu alloy.

Suppression of gold nanoparticle agglomeration and its separation via nylon membranes

Use of ultraporous nylon membrane is one of the most widely employed techniques for removal of hard and soft nanoparticles in the semiconductor industry, and the accurate determination of membrane pore size is necessary in order to avoid manufacturing defects caused by contamination. The gold nanoparticle has several benefits for the evaluation of polymeric membranes; however, the nanoparticles agglomerate easily on the nylon membrane and make it difficult to evaluate the membrane precisely. The properties of 2-amino-2-hydroxymethyl-1,3-propanediol(ADP) ligand in gold nanoparticle solution were systematically investigated, and ADP was utilized for improved evaluation of the nylon membranes. Nylon membrane used in this study was prepared by phase inversion techniques. Ultrathin dense layer on top of the membrane surface and Darcy structures in the microporous membrane support were observed. The gold particle rejection was carried out at various p H values from 4 to14 and higher rejection was observed at p H 4 and 8. The suppression of gold colloid agglomeration using ADP and monodispersity of gold colloids was also analyzed by confocal laser scanning microscopy(CLSM), transmission electron microscopy(TEM), and scanning electron microscopy(SEM). van der Waals interaction energy of the particles was reduced in the addition of ADP. The presence of ADP ligand in the gold solutions prevented the agglomeration of gold nanoparticles and reduced the adsorption of the particles on the nylon membrane surface,leading to precise evaluation of membrane pore sizes.

A micro-scale strain rosette for residual stress measurement by SEM Moiré method

In this paper,a new method combining focused ion beam(FIB)and scanning electron microscope(SEM)Moirétechnique for the measurement of residual stress at micro scale is proposed.The FIB is employed to introduce stress relief like the macro ring-core method and fabricate gratings with a frequency of 5000 lines/mm on the measured area of the sample surface.Three groups of gratings in different radial directions are manufactured in order to form a micro-scale strain rosette.After milling ring-core by FIB,the deformation incurred by relief of the stress will be recorded with the strain rosette.The displacement/strain field can be measured using SEM scanning Moiréwith random phase-shifting algorithm.In this study,the Nickel alloy GH4169 sample(which was processed by laser shock peening)is selected as a study object to determine its residual stress.The results showed that the components of the in-plane principal stresses were-359 MPa and-207 MPa,respectively,which show good agreement with the results obtained from the available literature.

Focused ion beam built-up on scanning electron microscopy with increased milling precision

In this work,a focused ion beam(FIB)-scanning electron microscopy(SEM) dual beam system was successfully built by integrating a FIB column and a graphics generator onto a SEM.Real-time observation can be realized by SEM during the process of FIB milling.All kinds of graphics at nanoscale regime,such as lines,characters,and pictures,were achieved under the control of graphics generator.Moreover,the FIB milling line width can be reduced nearly 27% by the introduction of simultaneous electron beam,and a line width as small as 10 nm was achieved.The numerical analysis indicates that the significant improvement on line width is induced by the Coulomb interaction between the electrons and ions.