See this link on Laser Techonlogies website for TruPulse Setup Guides for TerraSync and ArcPad

Using a laser for GPS Offsets is a great tool when you know you will have a tough time collecting reliable GPS under or near an obstruction such as a tree, parked vehicle over or near your asset causing GPS Mulitpath interference or if you are too close or on the north side of a building.  Also using a laser for GPS Offsets for data collection will allow you to collect good GPS in the open and it can keep you or your field crew safe from harms way by avoiding traffic or animals etc.