Tunable microscopy illuminator by using polymer dispersed liquid crystals

The condenser is one of the most important components in many transmitted light compound microscopes. In this Letter, was shown that such a condenser can be replaced by a solution of liquid crystal in a polymer matrix (PDLC) and back light lamp to achieve greater imaging flexibility and functionality. By changing the voltage applying to the PDLC, we change the amplitude ratio of the non-scattered and the singly forward scattered interfering components significantly affects the spatial-frequency filtering by PDLC. Without mechanically scanning the sample or changing the microscope setup, the proposed approach can be used for dark-field imaging, bright-field imaging, microscopy sectioning, and digital refocusing. Images of a starfish embryo were acquired by using such an approach for demonstration.