The Talbot effect in self-assembled red blood cells investigated by digital holography

Abstract

The Talbot effect, also known as self-imaging, is a well-established phenomenon observed when a beam of light is transmitted through a periodic pattern and the image of the pattern is reproduced at a regular interval along the optical axis, namely the Talbot length. This effect has been widely investigated and exploited for several applications in different fields. Here we discuss for the first time, to the best of our knowledge, the self-imaging effect due to a self-assembled and quasi-ordered array of live biological cells under illumination by a coherent light beam. In particular, self-assembly of red blood cells (RBCs) provides a monolayer of cells that appear to be quasi-ordered in a trigonal array geometry. Thanks to the recent proof that RBCs can be modeled as a microlens array, the Talbot length can be predicted and the corresponding self-imaging can be observed experimentally. In particular, we investigate the Talbot effect of self-assembled RBC arrays for two different RBC body shapes, i.e. discocytes and spherocytes, by using digital holography as tool for imaging and quantifying this phenomenon. This research could open up a new way to investigate biological material by exploiting its photonics properties.