See the main Beta Pictoris page for full details: http://www.pbase.com/rolfolsen/beta_pictoris

Line profiles taken with MaximDL both through the debris disc plane and perpendicular to it. The horizontal scale is Astronomical Units and the area saturated by Beta itself is highlighted on the plots:
The visible part of the debris disc seems to extend to roughly 250-300AU before it falls below the background noise levels.