Compact and low-cost instrument for digital holographic microscopy of immobilized micro-particles

A compact and low-cost system capable of Digital Holographic Microscopic (DHM) imaging of immobilized micro-particles is presented. The proposed design, integration, and manufacturing can lead to wider use and increased accessibility of this device for research, education, and biomedical applications. The optical tweezer system for particle immobilization is built using the optical pickup unit taken from a DVD burner. DHM is integrated into the system through the addition of a glass plate which enables one arm of the system to operate as a lateral shearing digital holographic interferometer. The operation of the system is confirmed by trapping, quantitative phase imaging and analysis of polystyrene micro-spheres for which the corner frequency measurements, carried using an in-house developed low-cost Quadrant Photodiode, compare favorably with simulated results. Furthermore, the system is illustrated for trapping and simultaneous quantitative phase imaging of micro-particles, including biological specimen such as red blood cells. The use of a low-cost easily implementable DHM integrated optical tweezer system provides vast information content, which enable in-depth analysis of immobilized micro-particles.