Dynamic interactive bitwise meta-holography with ultra-high computational and display frame rates

System architecture diagram of an interactive holographic Tetris game implemented with bitwise dynamic metasurface holography. Source: Compuscript Ltd

Computer-generated holography (CGH) represents a cutting-edge technology that uses computer algorithms to dynamically reconstruct virtual objects. This technology has found many applications in various fields such as three-dimensional display, storage and processing of optical information, entertainment, and encryption.

Despite the broad application spectrum of CGH, contemporary techniques rely on projection devices such as spatial light modulators (SLMs) and digital micromirror devices (DMDs). These devices inherently face limitations in display capabilities, often resulting in narrow field-of-view and multilevel diffraction in projected images.

In recent developments, metasurfaces composed of an array of subwavelength nanostructures have shown unique capabilities in modulating electromagnetic waves. By introducing sudden changes in fundamental wave properties such as amplitude and phase through nanostructuring at subwavelength scales, metasurfaces enable modulation effects that are challenging to achieve using traditional tools.

Advances in metasurface-based holography have led to significant achievements such as large viewing angles, achromatic imaging, full-color displays, increased information capacity, and multidimensional multiplexing, making them which are powerful tools for dynamic holographic displays.

However, dynamic metasurface holography, still faces many challenges in realizing the real-time, highly fluid dynamic display effects required for advanced performances such as advanced human interaction- computer. The key to fluid metasurface holographic displays lies in achieving high computational and display frame rates. Computational frame rate refers to the speed at which data is calculated, processed, and prepared for display, ensuring that the system can compute the required content in real time.

Most current holographic display solutions rely heavily on performing fast Fourier transforms (FFTs) multiple times, often requiring dedicated computing units such as graphics processing units (GPUs) to meet the demands for high refresh rates, making computing power and energy consumption critical bottlenecks for widespread applications.

On the other hand, the display frame rate, the speed at which display devices refresh and present new content, is important for the smoothness of the visual content. Currently, most dynamic holographic display strategies based on metasurfaces struggle to achieve high display frame rates, which hinders their ability to deliver a fluid visual experience.

To address these challenges, a team led by Professor Xiong Wei and Associate Professor Gao Hui from Wuhan National Laboratory for Optoelectronics at Huazhong University of Science and Technology introduced a dynamic interactive bitwise metasurface holography (Bit-MH) technique with high computational and display frame rates. They built the world’s first practical interactive metasurface holographic display system.

In their study, published in Opto-Electronic Advances, the team divided the display functionality of metasurfaces into separate spatial regions or channels, each of which is capable of projecting a reconstructed sub-holographic pattern. Using optical addressing for spatial channel multiplexing, they map the on/off states of all channels to a set of bit values, thus changing the dynamic process of updating holography to the manipulation of these bit values ​​for control. the corresponding channels.

This approach greatly improves computational efficiency by using bitwise map operations instead of relying on constant FFT calculations required in traditional dynamic update holography, resulting in efficient dynamic refresh.

The researchers conducted benchmark tests of the core algorithm for bitwise dynamic holography on a low-power Raspberry Pi computing platform, revealing that the maximum computational frame rate of the bitwise dynamic holography approach can reach 800 kHz. In addition, by using a high-speed DMD optical addressing device, they achieve a maximum display frame rate of 23 kHz.

To demonstrate the concept, the research team built an interactive holographic gaming system for playing Tetris within the visible light spectrum. The core components of the system include a spatially segmented metasurface device, DMD, Raspberry Pi controller, gaming controller, and necessary optical components.

The proposed design for bitwise dynamic holography allows for efficient updating of holographic images and real-time interaction with external input devices. This efficient and programmable Bit-MH method is expected to pave the way for future smooth and efficient metasurface holographic display systems.

More information:
Yuncheng Liu et al, Dynamic interactive bitwise meta-holography with ultra-high computational and display frame rates, Opto-Electronic Advances (2023). DOI: 10.29026/oea.2024.230108

Provided by Compuscript Ltd

Citation: Dynamic interactive bitwise meta-holography with ultra-high computational and display frame rates (2023, December 21) retrieved on December 22, 2023 from https://phys.org/news/2023-12-dynamic-interactive- bitwise-meta-holography -ultra-high.html

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