Abstract
In this paper, we propose the viscosity measurement method using laser trapping. We can measure the viscosity of films without contact using this method. Particles of the order of 2 micron in diameter have been trapped using a dry objective lens with large working distance. The principle of the viscosity measurement method is as follows. We investigate the maximum velocity which can capture a particle when optical radiation pressure is equal to viscous resistance. Then, we ask for the viscosity by applying Stokes's law using the velocity. And, it was proved this measuring method using laser trapping by viscosity measurement with glycerin is possible.
