RayCast Problem

can i when i say
if(Physics.Raycast(transform.position , DirRayDo , 0))
Replace the 0 to something Like 1 to 0?

To limit your test to a min/max range, just shift your starting point to the min value, and use a maxDistance of the remaining distance (max-min):

// assuming you have created minDist and maxDist with the values you need
// also assuming your DirRayDo is normalized (if not, normalize it, or you will have to recompute different min/max values
if(Physics.Raycast(transform.position + DirRayDo*minDist, DirRayDo , maxDist-minDist))