Optics express 2019
We present a method to create light field display using a single projector and an array of plane mirrors. Mirrors can reproduce densely arranged virtual projectors regardless of the physical size of the real projector, thus producing a light field display of competitive ray density. We propose an ellipsoidal geometric framework and a design pipeline, and use parametric modelling technique to automatically generate the display configurations satisfying target design parameters. Three units of mirror array light field display systems have been implemented to evaluate the proposed methodologies. More importantly, we have experimentally verified that the high-density light field produced by our method can naturally evoke accommodation of the eyes, thereby reducing the vergence-accommodation conflict. The mirror array approach allows flexible trading between the spatial and angular resolutions for accommodating different applications, thus providing a practical solution to realize projection-based light field display.
Three prototypes including 5x3 (mirror array columns x rows), 7x5, and 11x7 setups. The first row of figure above shows three simulations, second row the real setups. The last row show the ray density in unit rays/mm. The 5x3 setup has the most uniform ray density, the 7x5 setup has the largest viewing angle, and the 11x7 setup has the largest ray density but smallest viewing angle.
The high-density light field produced by our system can naturally evoke accommodation of the eyes, thereby solving the vergence-accommodation conflict (VAC) problem. We used Lytro Illum to capture the displayed light field on screen. As shown in the figure above, the captured light field can be refocused on different depth!
A user study is conducted to demonstrate the accommodation changing of human eyes when focusing on objects on different depth. The participant visually tracked a target oscillating stepwisely while their accommodation responses were measured. The figure above demonstrates the average response of participants matches the ground-truth well.