Scientists discover technique to improve depth control for holographic projection

Scientists discover technique to improve depth control for holographic projection
Scientists have found a way to address the two long-standing problems that have historically prevented the fine depth control of holograms and limited the quality of 3D displays of objects.

According to an article in Laser Focus World, researchers in China and Singapore have teamed up to shape arbitrary light fields and came up with a new way to break the depth-control limit to create dynamic ultrahigh-density 3D holographic projections.

Lei Gong's research group from the Department of Optics and Optical Engineering, University of Science and Technology of China (USTC), together with Prof. QIU Chengwei from the National University of Singapore (NUS), and Prof. LIANG Jinyang from the National Academy of Sciences of the University of Quebec in Canada, have  proposed a new method of ultrahigh-density 3D holographic projection to solve those key problems.

Light scattering “is usually perceived as a destructive effect in holography, but our work shows disordered scattering can be exploited to break the limitations in holographic projections,” says Lei Gong, a professor of optics at the University of Science and Technology of China, whose group worked on the project with Professor Chengwei Qiu’s group at the National University of Singapore. “It’s why we call our method ‘3D scattering-assisted dynamic holography.’”

Panpan Yu (left) and Lei Gong in the lab, working on their 3D-SDH project, observe the speckle light field behind a scattering medium. The speckle field helps break the depth-control limit of holographic projection.

 

Spatial light modulators (SLMs) are commonly used for dynamic holographic projection, but a serious drawback is that very few images can be projected onto separable planes and they’re at a low depth resolution.

The team outmaneuvered this with their three-dimensional scattering-assisted dynamic holography (3D-SDH) method, which combines a SLM with a diffuser. “It enables multiple images to be separated by a much smaller depth of focus (DoF)—without being limited by SLM pixel pitch or pixel number,” explains Gong. “Interplane crosstalk is suppressed by introducing random phase and orthogonality of random fields, so our method simultaneously reduces the DoF of image planes and suppresses interplane crosstalk to power up ultrahigh-density 3D holographic projection.”

The team’s work is “a new paradigm toward realistic 3D holograms that can deliver exceptional representation of the 3D world around us,” says Gong. “We leverage disordered scattering by a diffuser for ultrafine 3D light field projection—and our approach breaks the depth-control limit of current state-of-the-art methods in multiplane holographic projection.”






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