ABSTRACT
A more interesting approach for multiple optical trapping has emerged with the use of diffractive optical elements (DOEs). This chapter explores how to implement DOEs for optical tweezers applications. The simplest optical tweezers system consists in a high numerical aperture (NA) microscope objective that focuses an incoming laser beam to a tight spot in order to optimize the gradient force. A Spatial Light Modulator (SLM) is a device capable of modifying the amplitude, phase, or polarization of an optical wavefront in response to information-bearing control signals. SLMs can be classified in two general types according to their addressing mechanism: electrical and optical. The chapter also introduces a special case of DOEs, where the amplitude and phase are encoded in a phase holograms. This DOEs are called synthetic phase holograms (SPHs). The chapter discusses few classes of SPHs, which allow encoding arbitrary scalar complex beams.
