Electrically switchable liquid crystal lens for bright-field and spiral phase contrast imaging

Bright-field imaging and phase contrast imaging, as two of the most representative modes in optical imaging, play significant roles in microscopy and optical analog computing, providing complementary and comprehensive morphological information of target objects. The development of devices capable of switching between or simultaneously performing these two modes has become a research focus. However, existing dual-mode imaging devices often suffer from insufficient integration, inflexible switching, and complex fabrication processes. Here, an electrically switchable dual-functional liquid crystal (LC) lens architecture based on laser direct writing is presented. One demonstration of the dual-mode LC lens (DM-LCL) consists of two vertically stacked lenses: a focusing lens for bright-field imaging and a spiral lens for spiral phase contrast imaging. By varying the applied voltage, different lens phase functions can be activated, enabling distinct imaging modes. The fabricated DM-LCL produces focused light fields consistent with theoretical simulations. Additionally, the optical and imaging performance across multiple wavelengths has been experimentally validated. Furthermore, an electrically switchable varifocal LC lens capable of simultaneous dual-mode imaging within the same field of view is demonstrated, validating the adaptability of the proposed architecture. The proposed LC lens exhibits switching speeds on the order of tens of milliseconds. This architecture provides a reliable solution for ultra-compact, fast-switching dual-mode imaging components and enables real-time adaptive imaging, showing significant potential for applications in microscopy, optical analog computing, and biomedicine.