How To hide the Plane use for Light while retaining the light ?

http://i.imgur.com/av2SYl7.jpg

Hi im still new to blender and im now experimenting at cycles but i came across a problem
Q> how do i hide the 2 planes while the light is retained when doing raytrace render or render

Select the object and in the Ray Visibility settings disable Camera so the camera doesn’t see it


thank you very much