Succeeded in developing ultra-thin lens 100 times thinner than hair

As the fourth industrial revolution emerges and interest in autonomous driving technologies such as unmanned vehicles and drones increases, technical demand for ultra-small optical sensors such as micro-optical systems, LiDAR, and cameras is increasing. However, the existing optical system has fundamental limitations in reducing the size and weight due to the physical limitations of the refractive lens.

However, a domestic research team succeeded in developing an ultra-thin lens that is 10,000 times thinner than the existing refractive lens, opening a way to drastically reduce the size of the camera used in smartphones.

The Ministry of Science, ICT and Communication, Pohang University of Science and Technology, Department of Mechanical Engineering/Chemical Engineering, Prof. Joon-Seok Noh’s research team, along with Professor Heon Lee’s research team from Korea University’s Department of Materials Science and Engineering, and Seung-Hoon Han’s Master Team, Imaging Device Lab, Samsung Electronics Advanced Institute of Technology, maintain the performance of the existing refractive lens, but the thickness is 10,000 times. It announced on the 2nd that it has developed a thin (100 times thinner level of hair) infrared ultra-thin lens and mass production technology for it.

This is a research achievement that overcomes the limitations of large and heavy existing optical devices, and was published online on January 1, 2021 in ACS Nano, a global academic journal in recognition of its potential to greatly contribute to the commercialization of metamaterials.

Optical devices are devices that can control various characteristics such as amplitude, phase, and frequency of light, and metamaterials refer to new materials made of artificial atoms that mimic atoms existing in nature.

Lenses that collect light are indispensable for the latest electronic devices and optical devices such as smartphones and DSLR cameras, but conventional refractive lenses are large and heavy, and the performance decreases as the volume decreases.

The camera used in the smartphone uses a composite lens consisting of 8 to 9 refractive lenses to reduce image distortion, but since it is difficult to reduce the thickness of the composite lens, the so-called’katucky’ problem that the camera protrudes from the back of the smartphone is caused. Occurs. In addition, in the case of refractive lenses used in DSLR cameras, the demand for thin and light lenses is very high, as they exceed 4kg as they go from 500g to high-performance products.

The researchers studied metamaterial-based lenses to develop lenses with high performance and small volume, and metamaterials can freely control various optical properties such as sound refraction and ultra-high refraction that conventional materials cannot provide. It is a field that is being studied worldwide because it is possible to implement new optical devices such as ultra-thin flat lenses, high-resolution holograms, and transparent cloaks.

However, electron beam lithography (a nano-processing technology that can process nanometer-level patterns by concentrating electron beams through a strong voltage), which was previously used for manufacturing meta-materials, is a meta-material produced through it because the process speed is slow and the cost is very high. The unit cost of the drug was also high, so the existing metamaterial research could not escape the laboratory level.

In order to overcome these limitations, the research team is developing a new nano-molding material based on nanocomposites that has optical properties suitable for metamaterial realization and can be freely formed, and a one-step printing technology that can be formed in a single process. succeded.

On the other hand, the researchers developed a 1-micrometer-thick ultra-thin meta-lens 100 times thinner than the thickness of a hair based on silicon nanocomposites and printing technology, and through this, they succeeded in imaging by combining it with an actual optical system. Verified.

Prof. Joon-Seok Noh said, “Because the ultra-thin metal lens implemented in this study is 10,000 times thinner than the existing infrared refractive lens with the same optical properties, it will be able to solve various problems caused by large and heavy refractive lenses. It is expected that it can be applied to various fields such as fluoroscopy.” He explained the impact of the research.