Compact, low cost, large field-of-view self-referencing digital holographic interference microscope

Abstract

Digital holographic microscopes provide quantitative phase images of transparent objects like biological cells. These phase images can in turn provide a host of parameters based on the object morphology, which could be used for object identification. But one of the biggest challenges in digital holographic microscopy is the design of compact setups with minimal optical elements providing high quality images and nanometer level temporal stability. Self-referencing interferometers in which the reference beam is obtained from the object beam is ideal for implementing compact devices with only few optical components. But they suffer from reduced field of view and has restriction on the sparsity of object distribution. Here we describe the development of a low-cost large field of view self-referencing digital holographic microscope based on wavefront division interferometer utilizing Lloyd’s mirror geometry. The device takes away the restriction on the sparsity of the sample also. The developed device does not have any translation stage and the focusing is achieved post-recording of the holograms. Off the shelf low-cost optics, a laser pointer and a webcam were used in development of the device. The developed device was tested on glass microspheres as well as was used to study human erythrocytes. To the best of our knowledge this is the first time such low-cost configuration using webcam is demonstrated for quantitative phase imaging of cells.