[Paper Review] TomoReal: Tomographic Displays

Seungjae Lee, Youngjin Jo+4 more|arXiv (Cornell University)|Mar 22, 2018

Advanced Optical Imaging Technologies28 references3 citations

TL;DR

TomoReal introduces tomographic displays, a novel 3D display technology that combines focus-tunable optics, a 2D display panel, and a fast spatially adjustable backlight (FSAB) to enable quasi-continuous accommodation, wide depth of field, and omni-directional motion parallax while preserving full resolution and frame rate. The prototype achieves 60Hz operation, 450×450 resolution, 7.5mm eye-box, and 30° field of view with 80 tomographic layers across 5.5D to 0.0D depth.

ABSTRACT

Since the history of display technologies began, people have dreamed an ultimate 3D display system. In order to get close to the dream, 3D displays should provide both of psychological and physiological cues for recognition of depth information. However, it is challenging to satisfy the essential features without sacrifice in conventional technical values including resolution, frame rate, and eye-box. Here, we present a new type of 3D displays: tomographic displays. We claim that tomographic displays may support extremely wide depth of field, quasi-continuous accommodation, omni-directional motion parallax, preserved resolution, full frame, and moderate field of view within enough eye-box. Tomographic displays consist of focus-tunable optics, 2D display panel, and fast spatially adjustable backlight. The synchronization of the focus-tunable optics and the backlight enables the 2D display panel to express the depth information. Tomographic displays have various applications including tabletop 3D displays, head-up displays, and near-eye stereoscopes. In this study, we implement a near-eye display named TomoReal, which is one of the most promising application of tomographic displays. We conclude with the detailed analysis and thorough discussion for tomographic displays, which would open a new research field.

Motivation & Objective

• To address the long-standing challenge of providing realistic 3D visual cues without sacrificing resolution, frame rate, or eye-box size in conventional 3D displays.
• To overcome the limitations of existing 3D display technologies such as light field displays, stereoscopes with focus cues, and holographic displays, which often involve trade-offs in performance metrics.
• To develop a new display architecture that supports physiological depth cues—accommodation, convergence, and motion parallax—while maintaining high spatial and temporal resolution.
• To demonstrate a near-eye prototype, TomoReal, that realizes the theoretical advantages of tomographic displays in practice.

Proposed method

• The system uses a focus-tunable lens as the primary optical element to dynamically adjust the focal plane of the 2D display image.
• A digital micromirror device (DMD) serves as the fast spatially adjustable backlight (FSAB), enabling selective illumination of specific pixels on the display panel based on depth layer.
• Synchronization between the focus-tunable lens and the DMD is achieved via a DAQ board and LabVIEW, generating a 60Hz triangle wave for lens tuning and a 4,800Hz square wave for DMD frame updates.
• Tomographic layer images are rendered using a 2D projected image and depth map, with optimal backlight operation derived by solving a least squares problem to minimize DC noise.
• Pre-compensation for optical aberrations such as curvature of field is applied using Seidel coefficients in the rendering pipeline to improve image quality.
• The system employs a 4f relay optical setup with two 50mm camera lenses to project the DMD image onto the display screen with 2× magnification.

Experimental results

Research questions

• RQ1 Can a 3D display system achieve quasi-continuous accommodation and wide depth of field without compromising spatial resolution or frame rate?
• RQ2 How can the synchronization between focus-tunable optics and a fast spatially adjustable backlight be achieved to enable volumetric 3D rendering?
• RQ3 To what extent can optical aberrations such as curvature of field be mitigated through pre-compensated rendering in a tomographic display system?
• RQ4 Can tomographic displays support high dynamic range (HDR) imaging, and how does the architecture enable this capability?
• RQ5 What are the practical limitations of tomographic displays in terms of occlusion realism, brightness, form factor, and cost?

Key findings

• The TomoReal prototype successfully demonstrates 60Hz operation with 450×450 spatial resolution and a 7.5mm eye-box, supporting 80 tomographic layers across a 5.5D to 0.0D depth range.
• The system achieves a DC noise level of 0.05 through optimized illumination time (10/480 seconds), corresponding to 10 sequential illuminations per cycle.
• The use of a DMD-based FSAB enables precise, high-speed control of backlight patterns, allowing accurate depth-layer reconstruction.
• Pre-compensation based on Seidel coefficients effectively mitigates curvature of field aberration, improving image quality across the depth field.
• The system supports a 30° field of view and maintains full-frame, full-resolution operation without spatial or temporal multiplexing.
• The implementation confirms the feasibility of tomographic displays as a competitive, cost-effective alternative to existing 3D display technologies, particularly for near-eye and tabletop applications.