Supplemental material to 'Video aided extinction measurement: A competitive method for dust density diagnostics'

In the following a set of experimental data (excerpt) of a monitored a:C-H nanoparticle growth cycle in a low temperature, capacitively coupled argon discharge is provided . This is a demonstration of the 'Video aided extinction measurement'. MATLAB analysis scripts can be used, to calculate particle densities. The resulting images are packaged into videos and display particle density and uncertainty in different ways. shows the density with fixed axis limits and one example of a low pass filtering approach is given in . Because displaying fixed axis limits leads to limited color resolution, contains the same data, but rescales the colorbar while the overall density changes. This gives a better understanding of the relative local density variation. finally shows an estimate of the time and spatially resolved uncertainty of the method, calculated from the experimental data. As intensities are very low, the relative error is correspondingly very high (the axis \Delta nd / nd is capped at 2, which equals 200% uncertainty). For higher laser light extinction, the uncertainty of the data within the cloud approaches 25%, which is the limit due to uncertainty of the particle size measurement. Outside of the cloud the uncertainty stays high, because there are no particles to scatter light and provide a measureable signal.

下文提供了一套低温容性耦合氩气放电环境中，经实时监测的氢化非晶碳（a:C-H）纳米颗粒生长周期的实验数据（节选）。本数据集为"视频辅助消光测量"方法的演示案例。可使用MATLAB分析脚本计算颗粒数密度。所得图像被封装为视频片段，以多种形式展示颗粒数密度及其测量不确定度。第一组图像展示了采用固定轴限绘制的颗粒数密度分布，并给出了低通滤波方法的一例应用。由于固定轴限会导致色彩分辨率受限，第二组图像展示了相同的数据集，但会随整体数密度的变化自动调整色标范围，这一设置可更清晰地展现局部数密度的相对变化情况。第三组图像则展示了基于实验数据计算得到的、具备时间与空间分辨能力的该方法测量不确定度评估结果。由于信号强度极低，对应的相对不确定度水平较高（轴Δnd/nd的上限被设置为2，对应200%的不确定度）。当激光消光程度较高时，颗粒云内部数据的不确定度可趋近于25%，这一极限由颗粒尺寸测量的不确定度所决定。而在颗粒云外部，不确定度始终处于较高水平，这是因为此处没有颗粒能够散射光线并产生可被检测的信号。