FIG. 3.

(Left) 50 nm Bi on 4 μm Prolene substrate attached to a frame for handling. A column-like structure is clearly visible from a vast number of positions which have been probed by optical laser and FEL. (Center) A target with a 30 × 30 matrix of silicon nitride membranes of 30 nm thickness etched into silicon bulk. The left and bottom half of the windows have been partly shot leaving a destroyed membrane. (Right) Silicon oxide membranes of 200 nm etched into silicon bulk, with a total of 25 281 individual membranes arranged in 3 × 3 sub-matrices of 53 × 53 membranes.