A method of treating a substrate comprises, in one aspect, placing a substrate having material on a surface thereof in a treatment chamber; directing a stream of a liquid treatment composition to impinge the substrate surface; and directing a stream of water vapor to impinge the substrate surface andor to impinge the liquid treatment composition. acquisition of a map of the radiation coming from the surface of the portion of space within or behind the object to be sensed at least at a first time t1 and a second time t2, such times being successive to each other; B. The blade includes a body, first transition section, second transition section, first blade wing and second blade wing. The substrate pad is disposed on the surface of the substrate body.