Mingjie ZHENG, Yusuke OGURA, and Jun TANIDA

Department of Information and Physical Sciences, Graduate School of Information Science and Technology, Osaka University, 2-1 Yamadaoka, Suita 565-0871, Japan

(Received October 12, 2007; Accepted December 27, 2007)

Since the introduction of computer-controlled spatial light modulators (SLMs), holographic optical tweezers have become an important tool for dynamic parallel optical manipulation. In this paper we clarify the usefulness of a new configuration for optical trapping that creates light patterns using the combination of a diffractive optical element (DOE) and an SLM. This configuration not only enables the use of the higher part of the SLM's diffraction efficiency curve, because a simple hologram can be chosen for the SLM, but also achieves three-dimensional dynamic optical manipulation over a large spatial range. By switching blaze-like holograms displayed on the SLM, we demonstrated simultaneous transportation of three 6-μm-diameter polystyrene beads over a range of 90 μm in the vertical direction and 37.5 μm in the horizontal direction. Compared with the same manipulation executed using only the SLM, the range of this method is extended four-fold in the vertical direction and three-fold in the horizontal direction.

Key words: spatial light modulator, diffractive optical element, blaze-like hologram, optical manipulation, holographic optical tweezers, diffractive efficiency, transportation