摘要：为了实现扫描电子显微镜(SEM)对纳米颗粒粒径的准确测量,研究了一种SEM放大倍数校准和光栅间距测量的方法;在SEM的不同放大倍数下对光栅纳米结构样板成像,运用MATLAB软件对显微镜图像进行灰度处理并读取灰度图像的亮度值数据,通过确定顶线、基线、底线位置,有效消除成像质量及数据处理等的误差,准确确定质心横坐标,采用质心算法求取平均光栅间距,通过与光栅间距标称值比较计算校准系数和校准误差;为验证放大倍率校准结果的可靠性,对纳米颗粒粒度标准物质进行测量。实际测量的平均粒径与标准值一致,表明该校准方法准确可靠,可有效避免图像质量和人为因素对测量结果的影响,达到对纳米和亚微米颗粒粒径准确测量的目的。

关键词：扫描电子显微镜；放大倍率校准；质心法；颗粒粒径

Abstract：For the purpose of accurately measuring nanoparticle size by scanning electron microscope(SEM) method, SEM magnification calibration method and micrometers spacing measurement method were developed. SEM digital images of micrometers were firstly captured and obtained, and MATLAB software was used to convert digital images into grayscale images automatically, and then the brightness data of grayscale images could be obtained. Based on this work, after the determination of the top line, baseline, the bottom line position of peak structure in the grayscale images, centroid position could be accurately obtained and the potential error of imaging and data processing could be effectively eliminated. The average micrometers spacing were calculated by using the centroid algorithm, and finally, the calibration coefficient and calibration error of SEM magnification could be calculated by comparing with the certified value of micrometer spacing. The reliability of the SEM calibration results were verified by measuring a particle size certified reference materials(CRMs) using calibrated SEM, and a consistent results finally be obtained with the certified value of CRMs. So from the result, a conclusion can be drawn that our developed SEM magnification calibration method and micrometers spacing measurement method are effective and reliable, which can effectively avoid the influence of poor image quality and artificial factors on the measurement results to obtain accurate particle size results.

Keywords: scanning electron microscope；magnification；calibration；centroid method；particle size