Third Day Poster Session, 17 June 2010 - NanoTR-VI

P
Erkan
Poster Session, Thursday, June 17
Theme F686 - N1123
Nanoscale Surface Characterization of Materials by SEM Stereoscopic Imaging
1
1
UOrkun ErsoyUP P* andP P AydarP
1
PDepartment of Geological Engineering, Hacettepe University, Ankara 06800, Turkey
Abstract-Surface texture of different type materials were quantified using digital elevation models (DEM) reconstructed from stereoscopic
images acquired from different angles by scanning electron microscope (SEM). Nanoscale roughness parameters were measured on DEMs of
volcanic ash, sphalerite, polymer beads with different surface textures. The implemented method presented in this study offers new insight for
surface characterization of different materials on nanoscale regions.
Three-dimensional reconstruction from stereoscopic images
(acquired at varying specimen tilt angles) is based on the
measurement of the disparity (parallax), which is the shift (in
pixels) of the specimen features from one image to the other
[1]. The resolution of the result is the same as the resolution of
the SEM images. The parallax method for elevation
measurement from stereo pairs consists of imaging the same
object from two viewpoints at the same plane, so the parallax,
or the object point displacement along an axis parallel to the
straight line through these viewpoints contained on the
viewer's plane is proportional to the distance between the
selected point and the viewer's plane, i.e. the local elevation is
proportional to the local parallax.
Detailed information about the method and surface
characterization of volcanic ash particles can be found in [2].
In this study, we measured roughness parameters of surfaces
on profiles (ISO 4287; ISO 11562; ASME B46.1-2002
standards) set in images. Volcanic ash particles and sphalerite
spheres are coarser than polymer beads and have higher values
of roughness parameters (Figure 1).
Mean peak to valley height of roughness profile for finer and
coarser beads are approx. 2 and 5 nm, respectively.
Beside roughness measurements on nanoscale regions, it is
also possible to measure elements such as distance, height
steps, angles etc. on reconstructed 3D models Here, we show
DEM of a broken bead and step height between two different
layers in polymer bead (Figure 2).
Figure 2. Reconstructed model of a broken polymer bead. The height
step measurement between two levels on bead surface gives approx.
7 microns.
In summary, SEM stereoscopic imaging offers new insights
for surface characterization of particles on nano- and macroregions.
After reconstruction of the 3D models of surfaces by
the implemented method, it is possible to quantify surface
parameters of particles which become highly informative and
valuable in characterizing particle structure details.
This work was partially supported by TUBITAK under
Project No. 108Y063 and by Hacettepe University Research
Foundation under Project No. 0701602009. We thank Prof.
Dr. Ali Tuncel for providing polymer beads.
*Corresponding author: oersoy@hacettepe.edu.tr
[1] J.L. Pouchou et al, Microchimica Acta 139, 135 (2002).
[2] O. Ersoy, J.Volc.Geotherm.Res. 190, 290 (2010).
Figure 1. Reconstructed model of a volcanic ash particle and polymer
beads (from [2]).
The average profile roughness values for volcanic ash and
sphalerite spheres are approx. 65 and 14 nm, respectively.
Volcanic ash particles have a mean peak to valley height of
roughness profile of approx. 550 nm while sphalerite has a
value of approx. 105 nm. Polymer beads with different sizes
and surface textures were analyzed. Finer beads have average
profile roughness value of approx. 0.280 nm. Coarser beads
have average profile roughness value of approx. 0.600 nm.
6th Nanoscience and Nanotechnology Conference, zmir, 2010 658