Researchers from Nanjing University have developed a portable, inexpensive, and easy-to-use microlens to acquire 4D images. 4D imaging provides 3D resolution as well as polarization information. Wei Hu, Yan Qing Lu, and colleagues used liquid crystals, materials found in most electronic displays. With a self-assembly process, they patterned arrays of liquid crystal microlenses into concentric circles. A concentric array of liquid crystal microlenses provides 4D information about objects. Scale bar, 20 μm. Courtesy of ACS Nano 2019, DOI: 10.1021/acsnano.9b07104. The researchers used a polarized optical microscope to image objects, such as a cross or the letter “E,” under different directions of linearly polarized light. Microlenses in the array imaged the object differently, depending on their distance from the object (depth) and the direction of polarized light, producing 4D information. Light can become polarized by reflecting off objects that cause the lightwaves to undulate in a single plane. Unpolarized light, such as that from the sun, contains waves that move in every direction. Detecting polarized light can reveal information; for example, cancer cells can reflect polarized light differently than healthy tissues. Although the resolution needs to be improved, the technique could someday be used in applications such as medical imaging, communications, displays, information encryption, and remote sensing, the researchers said. The research was published in ACS Nano (www.doi.org/10.1021/acsnano.9b07104).