We propose a convenient method for generating optical traps based on a spatially structured beam. The proposed method of optical trap shaping utilizes interference of few Gaussian beams which waists, inclination angles and beam number are chosen for controllable trapping of micron-sized particles in three-dimensional space. In addition to implementing non-contact trapping, optical visualization in all planes was performed with digital holographic microscopy. This method contributes to the accurate localization of the studied specimens inside the cuvette over whole volume.

The design and construction of optical tweezers based on uniaxial crystal anisotropy for generation of adjustable “bottle” beam trap carrying optical vortex with orbital angular momentum is considered. In coupling with digital holographic microscopy, optical trapping becomes a high precision instrument for visualization, shape definition and refractivity measurements of isolated micro structures and biological objects in-situ. The non-destructive and sterile non-contact tweezing of specimens or their parts in localized intensity minima of coherent vortex beam was performed with using of 200 mW semiconductor 532 nm trapping laser and LiNbO3 crystal. Visualization and position control of trapped marine centric diatoms was performed by a lens-free axial digital holographic microscopy in liquid medium.