Fig. 3. Two-dimensional colour plots of the surface profiles of the test surfaces
used in experiment 1. The plots were obtained using an optical surface
profiler. The surface topographies can be inferred from the colour profiles
and the Ra values (i.e. the means of the profile ordinates). Values
of Ra (arithmetic means ± S.D.; N=3) are as follows:
(A) glass microscope slide (Ra=0.034±0.002 µm), (B)
photographic paper (Ra=1.09±0.2 µm), (C) dry leaf of
Phragmites communis (Ra=7.95±0.4 µm) and (D)
filter paper (Ra=8.96±0.6 µm). The dimensions (length and
width) of the measured surface areas can be read off the x- and
y-axes.
