All Done With Mirrors: Microscope Tracks Nanoparticles In 3-D

All Done With Mirrors: Microscope Tracks Nanoparticles In 3-D

Would they consider using our “standard” 3D-PTV software?

One alternative, NIST researchers reported at the annual meeting of
the American Physical Society,* is to use geometry instead of algebra.
Specifically, angled side walls of the microscopic sample well act as
mirrors to reflect side views of the volume up to the microscope at the
same time as the top view. (The typical sample well is 20 microns
square and 15 microns deep.)

The microscope sees each particle twice, one image in the horizontal
plane and one in the vertical. Because the two planes have one
dimension in common, it’s a simple calculation to correlate the two and
figure out each particle’s 3-D path. “Basically, we reduce the problem
of tracking in 3-D to the problem of tracking in 2-D twice,” explains
lead author Matthew McMahon.

The 2-D problem is simpler to solve–several software techniques can
calculate and track 2-D position to better than 10 nanometers.
Measuring the nanoparticle motion at that fine scale–speeds, diffusion
and the like–will allow researchers to calculate the forces acting on
the particles and better understand the basic rules of interaction
between the various components. That in turn will allow better design
and control of nanoparticle assembly processes.

* M. McMahon, A. Berglund, P. Carmichael, J. McClelland and J.A.
Liddle. Orthogonal tracking microscopy for nanofabrication research.
Paper presented on Monday, March 10, 2008, 1:03 p.m., at the 2008 March
Meeting of the American Physical Society, New Orleans, La., March
10-14, 2008.