Dependence of optical trapping efficiency on the beam radius-to-aperture radius ratio

다국어 초록 (Multilingual Abstract)

Microparticles were optically trapped and manipulated by using
optical tweezers. The optical trapping efficiency on a 5
$\mu$m-sized microsphere was measured as a function of the ratio
of the beam radius-to-the aperture radius ($W_0 / R$). The optical
trapping efficiency increased with the ratio of the beam
radius-to-the aperture radius and became constant over the region
$W_0 / R > 1.5$. We analyzed this behavior of the optical trapping
efficiency by using the ray optics model. From the experimental
results, we confirmed that the ratio could be a factor causing
wide variability of the reported experimental data concerning
force or efficiency measurements. Also, these results may be
helpful in reducing the optical damage in trapping of biological
cells.