Open-source implementation of polarisation-resolved single-shot differential phase contrast microscopy (pDPC) on a modular openFrame-based microscope

We recently demonstrated polarisation differential phase contrast microscopy (<i>pDPC</i>) as a robust, low-cost single-shot implementation of (semi)quantitative phase imaging based on differential phase microscopy. <i>pDPC</i> utilises a polarisation-sensitive camera to simultaneously acquire four obliquely transilluminated images from which phase images mapping spatial variation of optical path difference can be calculated. <i>pDPC</i> microscopy can be implemented on existing or bespoke microscopes and can utilise radiation at a wide range of visible to near infrared wavelengths and so is straightforward to integrate with fluorescence microscopy. Here we present a low-cost open-source <i>pDPC</i> module that is designed for use with the modular open-source microscope stand "<i>openFrame</i>". With improved hardware and software, this new <i>pDPC</i> implementation provides a real-time readout of phase across a field of view that facilitates optimisation of system alignment. We also provide protocols for background subtraction and correction of crosstalk.