Overview of the parts. Two mirror, one light source and line of beams designed as 2 seperate part (ray 1 and ray 2).
Go under Motion study tab
Drag the Animation time line to Zero and make both rays invisible.
Now drag the timeline littlebit forward
Right click and Change the orientation to isomatric. If you want to have a 3D view in Animation.
This is the view you get after the last step
Now drag the timeline even further and at this Location Change the ray 1 visibility to 'show'.
Be careful at this step. Do not Forget to drag the starting Point of ray one to shown timeline (marked red) in the Image.
By this step you activate the visibility of ray 1 only after the vie changes to iso. Otherwise the ray will be visible form the beginning of thre Animation.
Next step is going a bit ahead in time line and Change the visibility of ray 2.
Again do not Forget to drag the pink line. This will ensure that ray 2 will be activated only after ray 1 is visible.
Now you can Play the Animation by clicking Play bbutton. If you like what you see, you can click save as and save the Animation.