Abstract

We discuss a new technique to generate force gradient in arrays of optical traps. The arrays can be configured in two or three dimensions by means of phase diffractive optical elements displayed on a spatial light modulator. The design of the diffractive optical elements is based on the approach of spherical wave propagation and superposition, which enables to individually control the strength of each optical trap. Computer simulation and experimental results are discussed for two and three dimensional arrays of traps. An example with silica micro-beads trapped with different forces in two different planes is presented to demonstrate the validity of our approach.