The role of propagation invariant light modes in single and multi-photon imaging

Propagation invariant, 'non-diffracting' beams have found numerous applications in areas as diverse as filamentation, trapping, and photoporation. However, the prominent transverse structure of Bessel beams prevents localized illumination, thus hampering its use for high resolution imaging with an extended focus. We investigate the relationship between axial resolution, contrast, and propagation invariance for single and two-photon fluorescence light sheet microscopy.