近轴光线追迹，也就是一阶光线追迹。

可以通过这个功能，详细的列出一阶光学的参数。

To generate a list of first-order properties, choose the prescript data from the report menu. There is a item you can choose to display the first order data.

如果要生成一阶光学参数，可以从“报告”菜单中选择“指令数据”，这里有一个选项，你可以显示一阶光学数据。

To perform a first-order ray trace, choose the Analysis > Diagnostics > Paraxial Ray Trace menu. The Paraxial Ray Trace dialog box is displayed.

要显示一阶光线追迹，选择“分析”-“选项”-近轴光线追迹，对话框将会显示。

YUI equations are used to trace a ray through a surface, the quantity i is needed to calculate the aberration contributions of the surface, so the additional labor produces useful data. In fact, if the aberrations of the system are to be calculated, the YUI method is actually more efficient than the YNU method. The YNU method is used in CAXCAD for paraxial ray tracing and provides a additional item for i parameter.

YUI方程被用来计算每个面，实际上YUI的方法比YNU的方法要更加精确，在CAXCAD中YNU方法被用来进行计算近轴光线追迹，同时提供了一个i变量的附加参数。