Computational Multilayer Light Field Displays- Systematic Analysis and Evaluation Method

Abstract

A computational multilayer light field (MLLF) 3D display, which recreates multiple directional views of a reference light field by a stack of spatial light modulators, is one of the promising approaches that could potentially solve the vergence-accommodation cue conflict problem plaguing conventional stereoscopic 3D display systems. Those multiple angular samples of light rays enter the eye pupil simultaneously to drive the eye to accommodate at the rendered depth rather than the depth of the display surface. Even though several pioneering works have been conducted to analyze the MLLF 3D display performance and different types of MLLF 3D display prototypes have been built, there still lacks a systemic analysis method for MLLF displays, which takes the display factors, ocular factors as well as diffraction into consideration. Meanwhile, the conventional evaluation method based on the pixel-to-pixel remapping relationship is inadequate for MLLF 3D displays. Therefore a new evaluation metric that takes the multiple view integration into account is required for the MLLF 3D display evaluation. Furthermore, there lacks the investigation of the impacts of engineering parameters on a MLLF displays system to furtheroptimization to improve the display performance. To overcome those problems mentioned above, in this work, an analytical eye model, a systematic analysis method, an evaluation method, as well as the investigation of the impacts of display parameters are illustrated and the simulation is validated through experiments. The analytical eye model describes a generalized framework to form the perceived retinal image for various 3D displays, which can model the display aberration, eye aberration, accommodation, as well as the eye refractive errors. We then apply this analytical model to a MLLF 3D display system to develop the systematic analysis method, which can model the effects of the display factors, the view dependency of the reference LF, as well as the diffraction effect, to characterize the perceived retinal image and investigate the accommodative response for a MLLF 3D display system. Furthermore, several new evaluation metrics are proposed, including a subjective evaluation method based on typical reconstruction defects as well as an objective evaluation method which uses the slope difference of the reconstruction light field as the objective criteria to represent contrast drop (MTF), shape deformation (SN), and phase shift (PS). Moreover, to study the impact of engineering parameters on future optimization, the pixel pitch and the layer separation are investigated for their impacts on the perceived retinal image through reconstruction and diffraction. Then an experimental prototype based on a dual-layer LCoS reflection setup is implemented to validate the simulation prediction for evaluation result and parameter impacts. The experiment results match well with the simulation prediction.