Hi Zemax,

The problem I am facing is there is only 1 beam spot on detector as what I wish to see is the light scattered from a surface. Below is a little more details on this problem.

What i wanted to observed on Zemax detector (rectangle) is after the light ray reflected from a surface:

1.  What is the light pattern;
2.  What is the intensity of the beam

The object i used:

1. source point (act as a CW laser and placed at a certain angle)
2. rectangle (act as a surface)
   1. beam is reflected and scattered from object 2 (lambertian)
3. detector rectangle (to observed the scattered part)