Domestic Researchers Develop World's Thinnest 4D Camera

Professor Jeong Ki-hoon’s KAIST Research Team Develops Ultra-Thin Light Field Camera

[Asia Economy Reporter Kim Bong-su] A domestic research team has developed the thinnest existing camera capable of implementing high-resolution 4D imaging.

The Korea Advanced Institute of Science and Technology (KAIST) announced on the 4th that Professor Ki-Hoon Jeong's research team from the Department of Bio and Brain Engineering developed an ultra-thin light field camera capable of high-resolution 4D imaging through a metal nano optical absorption layer.

The 'light field camera' is an advanced type of camera inspired by the visual structure found in insects, combining microlenses and an objective lens. It simultaneously acquires four-dimensional information of light, including both spatial and directional data, from a single two-dimensional shot.

However, existing light field cameras have limitations in resolution degradation due to optical crosstalk in the microlens array and size constraints caused by the position of the objective lens.

The '4D camera' developed by the research team inserted a nano-thickness optical absorption structure between the microlens arrays to enhance contrast and resolution, overcoming the limitations of external light sources and additional sensor attachments found in conventional cameras.

Accordingly, it is expected to be applicable in fields such as medical imaging, biometric recognition, mobile cameras, and various virtual reality and augmented reality cameras.

To eliminate optical crosstalk in the microlens array, the research team placed an optical absorption layer composed of a 200-nanometer (nm) thick metal-dielectric-metal thin film between the lenses and reduced the distance between the objective lens and microlenses to a certain level, successfully developing an ultra-thin light field camera.

The structure (Cr?SiO2?Cr), which stacks chromium (Cr) metal with high optical loss and low dispersion and a glass layer with high transmittance at nanometer thickness, can completely absorb visible light. By placing the nano optical absorption layer between the microlens arrays, it removes optical crosstalk between microlenses and helps acquire high-contrast and high-resolution three-dimensional images.

The research team mass-produced the microlens array with the optical absorption structure through photolithography, lift-off, and thermal reflow processes. To minimize the overall thickness of the light field camera, they arranged the microlenses in the reverse direction of the image sensor and reduced the distance between the objective lens and microlenses to about 2.1 mm, resulting in a total thickness of 5.1 mm. This is the thinnest thickness among light field cameras developed to date.

The raw images recorded on the image sensor by the microlenses with the nano optical absorption structure have higher contrast and resolution compared to images through conventional microlenses. The research team confirmed that when reconstructed into viewpoint images and three-dimensional images through image processing techniques, the accuracy was improved.

Professor Ki-Hoon Jeong said, "We have presented a new method to produce an ultra-thin, high-resolution light field camera. This camera will be integrated into ultra-compact imaging devices requiring multi-view and refocusing, such as biometric recognition, medical endoscopy, and mobile phone cameras, serving as a new platform for ultra-compact 4D cameras."

The research, led by Sang-In Bae, a doctoral researcher in the Department of Bio and Brain Engineering at KAIST, was published on the 20th of last month in the international journal Advanced Optical Materials. This research was conducted as part of the Ministry of Science and ICT's Individual Research Support Project, the Ministry of Trade, Industry and Energy's Technology Innovation Program, and the Ministry of Health and Welfare's Health and Medical Technology R&D Project.

This content was produced with the assistance of AI translation services.