Optical trapping of fluorescent beads

Optical tweezers have been successfully used to trap a variety of particles and biological specimens for numerous applications. Particles which are reflective as well as absorbing could be trapped using beams such as optical vortex. Here we give the details of our efforts to trap fluorescent microparticles. We have set up an optical trap for these fluorescent microparticles using holographic optical tweezers; we observe that it is not possible to trap fluorescent microparticles with a Gaussian laser beam or a hollow beam. However, as the fluorescence of these particles gets degraded they could be trapped in custom-made holographic tweezers. Moreover, when a fluorescent particle is brought in the trap containing stably trapped non-fluorescent particle, the stably trapped non-fluorescent particle also escapes from the trap.