Three-dimensional structured illumination microscopy achieves double the lateral and axial resolution of wide-field
microscopy, using conventional fluorescent dyes, proteins and sample preparation techniques. A three-dimensional
interference-fringe pattern excites the fluorescence, filling in the "missing cone" of the wide field optical transfer
function, thereby enabling axial (z) discrimination. The pattern acts as a spatial carrier frequency that mixes with the
higher spatial frequency components of the image, which usually succumb to the diffraction limit. The fluorescence
image encodes the high frequency content as a down-mixed, moiré-like pattern. A series of images is required, wherein
the 3D pattern is shifted and rotated, providing down-mixed data for a system of linear equations. Super-resolution is
obtained by solving these equations. The speed with which the image series can be obtained can be a problem for the
microscopy of living cells. Challenges include pattern-switching speeds, optical efficiency, wavefront quality and fringe
contrast, fringe pitch optimization, and polarization issues. We will review some recent developments in 3D-SIM
hardware with the goal of super-resolved z-stacks of motile cells.
We report cyclic strain measurements form an experimental Terfenol-D actuated polymer matrix composite. Basic material constitutive response are identified as functions of frequency. Anhysteric theory is used to quantitatively model the behavior of the composite. Insight provided by the analysis is used to suggest material design changes leading to improved composite performance.