Standing quasi-diffraction-free beams generated by circular Dammann gratings under high-order radially polarized Laguerre-Gaussian incidence

A standing quasi-diffraction-free beam generated by one-order cosine circular Dammann gratings is demonstrated in a single-objective 4Pi focusing system for high-order radially polarized LaguerreGaussian incident beams. Numerical results indicate that, similar to a Bessel beam, this standing quasi-diffraction-free beam can also well reconstruct itself after an obstruction, and the self-healing property implies that such beam should be more resistant to scattering. Furthermore, it is shown that, for a focusing system with a water-immersion NA=1.2 objective, the transverse and axial average sizes are about 0A3-0.54 lambda and 0.36-046 lambda respectively, for those isotropic focus spots within the whole nondiffracting extent It suggests that such standing quasi-diffraction-free beam can provide high resolving power along both transverse and axial directions when it is used as the excitation light in fluorescent microscopy. Therefore, this kind of standing quasi-diffraction-free beams should be of high interest in optical biological imaging and also parallel multiplane optical manipulation. (C)) 2014 Elsevier B.V. All rights reserved