The visual system of the mantis shrimp, a marine crustacean whose eyes handle data about both the hue and the polarization of light, has long captivated optical scientists. These capabilities have been the driving force behind several optical devices that extract 3-D spatial and polarization information concurrently. However, cramming both characteristics into a small optical package has proven challenging. A research team has suggested a novel method for recording both kinds of image data simultaneously. The 4D Imaging strategy the team uses is based on a clever concentric arrangement of liquid-crystal (LC) microlenses that enables depth and polarization information to be determined based on which microlens within the array give the sharpest image of the target.
The design is currently only a proof of concept, but the researchers think this 4D Imaging strategy may eventually find use in apps like medical imaging, remote sensing, and information encryption. The fact that the sensing of the two depends on different properties—the spatial refractive-index distribution in the case of depth focusing and characteristics such as birefringence in the case of polarization—is one of the reasons it has been challenging to develop a lens that can process both 3-D depth and polarization information.
LC lenses, which have tunable birefringence and refractive-index distribution, would be a suitable choice for collecting both data types simultaneously. Unfortunately, altering the polarization dependence of LC lenses can reduce their optical performance and image clarity.
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