Dual-mode holographic microscopy imaging platform.

We report on a novel layout capable of dual-mode imaging in real time with different magnifications and resolution capabilities in lensless microscopy. The concept is based on wavelength multiplexing for providing two illuminations with different wavefront curvatures: one is collimated, allowing a large field of view (FOV) with a poor resolution limit, and the other is divergent, to achieve a better resolution limit (micron range) over a small FOV. Moreover, our recently reported concept of MISHELF microscopy [M. Sanz, J. Á. Picazo-Bueno, L. Granero, J. García and V. Micó, Sci. Rep., 2017, 7, 43291] is applied to the divergent illumination case, improving the image quality by noise averaging and twin image minimization. The performance of this novel dual-mode lensless microscopy imaging platform is validated through experiments using both static amplitude (resolution test targets) and dynamic complex (flowing microbeads and live sperm cells) samples. The proposed imaging platform represents the background technology for a new generation of lensless microscopes with improved performance and capabilities.