Oho Eisaku, Suzuki Kazuhiko, Yamazaki Sadao
Department of Electrical Engineering, Kogakuin University, Tokyo, Japan.
Scanning. 2007 Sep-Oct;29(5):225-9. doi: 10.1002/sca.20063.
The quality of the image signal obtained from the environmental secondary electron detector (ESED) employed in a variable pressure (VP) SEM can be dramatically improved by using helium gas. The signal-to-noise ratio (SNR) increases gradually in the range of the pressures that can be used in our modified SEM. This method is especially useful in low-voltage VP SEM as well as in a variety of SEM operating conditions, because helium gas can more or less maintain the amount of unscattered primary electrons. In order to measure the SNR precisely, a digital scan generator system for obtaining two images with identical views is employed as a precondition.
通过使用氦气，可显著提高在可变压力（VP）扫描电子显微镜（SEM）中使用的环境二次电子探测器（ESED）所获得的图像信号质量。在我们改进的扫描电子显微镜可用的压力范围内，信噪比（SNR）会逐渐增加。该方法在低电压VP SEM以及各种扫描电子显微镜操作条件下都特别有用，因为氦气或多或少可以保持未散射初级电子的数量。为了精确测量信噪比，作为前提条件，采用了一个数字扫描发生器系统来获取具有相同视图的两幅图像。
