Comment on Influence of non-conservative optical forces on the dynamics   of optically trapped colloidal spheres: The fountain of probability,   arXiv:0804.0730v1
  We demonstrate that the data presented in the manuscript by Y. Roichman et al. are not sufficient to show that the circulation of a trapped particle exists in a static optical trap. 
Rongxin Huang, Pinyu Wu, Ernst-Ludwig Florin