Ultracompact optical microscopes made of liquid crystal Pancharatnam–Berry optical elements

Ultracompact optical systems are increasingly sought after for applications such as consumer electronics and medical imaging. Here, we present a design and manufacturing approach for ultracompact bright- and dark-field optical microscopes entirely made of flat liquid crystal optical elements. Both systems utilize liquid crystal PB lenses as objective and tube lenses, while the dark-field optical microscope incorporates an additional Q -plate with a +1 topological defect to filter zero-order light. We demonstrate two optical microscopic systems with a numerical aperture of 0.25 and overall thickness of just 5 mm. The system can achieve high imaging performance with a resolution better than 7 µm. We further demonstrate an exemplary application in biological imaging to effectively enhance edge contrast in imaging onion epidermal cells. This work presents an example in exploiting the flatness and high quality of liquid crystal optical elements to achieve compactness and high-quality imaging promising for various applications.