Numerical analysis for single-beam fiber optic trap

Summary form only given. The laser beam trapping method is considered to be useful for manipulation of microscopic objects and biological cells because of noninvasive technology. Its operation principle is based upon the electromagnetic momentum preservation. Generally, the force on a micro-sphere divides itself naturally into two components which always act through the center of the sphere. The same phenomenon could be seen in our trapping experiments using a tapered hemispherically lensed optical fiber. A sphere was always pushed in the direction of the beam away from the fiber end independent of the distance between the fiber end and sphere, because the beam emerging from optical fiber end could not be strongly focused In the fiber trapping system, the focused spot size at the beam waist was -6 /spl mu/m in ethanol solution, which was measured using an IR camera.