Regulating trapping energy for multi-object manipulation by random phase encoding

As known to all, optical tweezers depend intensely on trapping laser power. Therefore, the ability to separately regulate trapping power for each optical trap under multi-object manipulation task empowers researchers more flexibility and possibilities. Here, we introduce a simple strategy using complementary random binary phase design to achieve trapping energy assignment. Trap energy ratio can be expediently regulated by effective pixel numbers of the phase mask. We demonstrated the effectiveness and functionality of this approach by calibrating trap stiffness and directly measuring trapping power of each optical trap. In addition, we show the capability of rotating micro-beads with controlled speed and direction by decorating vortex beams with different energy ratio at specified positions. Our results imply that regulating trap energy ratio will be of great significance in various applications, such as optical sorting and microfluidic scenarios.