Dual Transverse Electro-Optic Effect Enables Heterodyne Differential Interference Contrast Imaging

Differential interference contrast (DIC) technique has emerged as a widely utilized tool in the field of biomedical science for label-free imaging of transparent biological samples. Its distinct advantage lies in the avoidance of contrast agents, effectively mitigating concerns related to photobleaching and phototoxicity. However, a fundamental limitation of DIC stems from its qualitative nature and nonlinear response to phase gradients. To address this issue, we present quantitative DIC with our newly established dual transverse electro-optic phase modulation. Our method serves as an add-on module for existing commercial DIC systems, exhibiting compatibility with standard commercial cameras in terms of frame rate, while also eliminating the moving units. By leveraging the dual transverse electro-optic effect, we enable the application of the heterodyne technique for precise phase retrieval within quantitative DIC. Initial experiments demonstrate the quantitative imaging capabilities of our technique on both artificial and biological samples, without the requirement for any exogenous labeling.