PMC

Concept of orbital tracking. The laser (green) is scanned laterally in a circular pattern around a particle (orange dot). (A) When a particle deviates from the center of the orbital scan, the fluorescence intensity (, red curve in the low panel) of the particle is modulated at the same frequency as the laser scan. The phase () and intensity () are extracted via FFT or lock-in amplifier and used to calculate the position of the particle within the orbit. The calculated position is used to relocate the particle so that the modulation of intensity is minimized. (B) When a particle is located in the center of the orbital scan, the fluorescence intensity of the particle remains stable with time.

Positional trajectory of a prolate spheroid within a linear shear field termed a Jeffery orbit []. This schematic shows two positions of the spheroid with the Jeffery orbit. The spacing of the black dots around the orbit represent the particle speed, with larger spacings indicating higher speed

RCS of a single spherical particle with a diameter of 20 mm and relative permittivity of for an elevation angle of and full azimuth orbit.

Effective potentials χ of the a non-crossing (NC) orbit class, b double-well orbit class with a negative time-averaged velocity (; DW−), c double-well orbit class with a positive time-averaged velocity (; DW+), and d meandering (M) orbit class. e–h Particle orbits in the plane respectively belong to the four classes in a–d. The strength of the out-of-plane magnetic field B_y is represented by the magenta and green colors. Three particles are plotted for each class and are labeled by the blue, cyan, and red colors. Each particle’s energy is represented by its corresponding color in a–d. The blue particles in f and g, respectively, belong to NC and DW− but are plotted to show the NC→DW− and DW−→DW+ transitions.