Strobing the illumination laser allows a better look at a Coulomb crystal. Here the laser is pulsed on briefly every 1/60th of a second, effectively "freezing" the 60-Hz micromotion of the particles. Because the particles have like charges and repel one another, they self-assemble into a lattice-like pattern. The pattern only approximately resembles a hexagonal lattice for a number of reasons: 1) the trap is three-dimensional and the trapping forces push the particles toward the trap center; 2) the photograph projects the 3D pattern onto a 2D image, and 3) the particles do not all have identical charges or masses. Residual micromotion blurs the particle images somewhat.

Electrodynamic Ion Traps