Often poorly understood, the Terahertz non-ionizing radiation falls under the electromagnetic spectrum and is placed in between infrared and microwave radiation. Owing to its properties, the fields of medical imaging, scientific imaging and defense research can potentially reach new heights. Cheng Sun from the Northwestern University explained that the terahertz radiation bears numerous relevant information that could be studied and modified as per requirement.
A group comprising of Cheng and his colleagues have recently demonstrated a lens created using a meta-material with the help of 3D printing, that can interact with Terahertz frequencies. The single lens is powerful enough to replace the combination of lenses and greatly multiplies the imaging capability. The focal length of a lens is a function of its curvature and refractive index and works as the key component in shaping light. The aforementioned system consists of an error correction component, without which it will produce blurry and grained images.
The design of Sun’s lens with gradient refractive index
The latest version makes use of gradient index, the refractive index dependent on varying space and generates errorless images without requiring any additional error manipulation. Processing of a lens is realized in a two-step process. First and foremost, the lens is manufactured using a novel meta-material which exhibits artificial properties attributed to a small structure supporting the Terahertz radiation.
The lens was engineered using projection micro-stereo-lithography, a technique prevalent in 3D printing. This helps to produce cost-effective and scalable small structures needed for terahertz radiation. As for the printing liquid or filer, the team used a photo-polymer in a liquid, from which after absorbing light, it transforms into a solid. The research can unfold the internal structures of some opaque materials which are still unknown to Science. This research has been published in the Advanced Optical Material Journal and has been funded by the National Science foundation.
Source: Northwestern University