Multiple optical line traps using a single phase-only rectangular ridge

An optical line trap has the ability to simultaneously trap and align microparticles in line formation due to its intensity profile. In this paper, we demonstrate a straightforward means to generate multiple optical line traps by simply placing a phase-only rectangular ridge in the path of a laser beam. By carefully positioning the rectangular ridge, we were able to control the separation between the optical trapping lines, which were then used to create multiple line formations of trapped particles. The simplicity of the proposed technique lends itself to the realization of a highly efficient optical line trap converter for easy modification of existing optical microscopes.