Overview: Holographic optical tweezing uses tightly focused laser beams to manipulate the 3D position of objects within a field of view. This can be used for research in fundamental physics, biological studies, and cold atom trapping. The SLM is used to modulate the phase of an incident laser beam to create a 3D volume of focal points. Objects with a higher refractive index than the surrounding media are pulled toward the waist of the focal points, allowing the ability to manipulate the position of objects with diameters ranging from 10 nm to 100 μm with micron-scale control.