Optical System for trapping and illumination in a digital holographic microscope

We present a new optical trapping and illumination system for simultaneously trapping and digital holography visualization of particle flows in microfluidic systems. The free-form trapping system was fabricated in PMMA and has a single aspherical surface. Its peripheral annular region produces an optimized high NA (0.81) converging trapping beam for trapping of a single particle while coherent holographic illumination is being carried out through the plane central region. The developed system combines simplicity, application of low cost components including the low NA imaging microscope objective and complex functionality. In our contribution we present the optical design, experimental characterization as well as successfully trapping and 3D reconstruction particle movements.