Evaluation of a pixelated holographic display concept for a near-eye display: recent results and technological developments

Abstract

The development of an ideal optical system to support Mixed Reality and Augmented Reality (AR) applications has raised a lot of interest in the scientific community in the last decades. The perfect device remains an inaccessible target and researchers have to focus on the optimization of some specific behaviors. Several years ago, we introduced a disruptive display concept to push the device integration to the limit, with the suppression of the optical system. This allows the imaging process to be considered in a different way with a specific monitoring of the field of view. With this ‘smart glass’ concept, the glass is the display, and the image is formed directly onto the retina with a combination of refractive and diffractive effects. This conceptual target allowed us to define a technological roadmap to support our development. Technologies involved in this concept concern principally the field of Photonic Integrated Circuits in the visible range, digital/analogic holography and Liquid Crystal devices. We will present the current state of our research with a particular focus on the holographic display element. Recent results related to analogic pixelated hologram recording validate and question both our technological and conceptual approach. We will show images formed by sparse holographic pixel distributions with controlled angular characteristics that demonstrate the mix of refractive and diffractive effects. The transmission behavior of this holographic device will also be analyzed.

Directional display for AR applications based on holography and photonic integrated circuits

“…It shows two pixels; both have different divergence (β1, β2) and different angular direction (γ1, γ2). This is possible by using holographic pixel [12]. Figure 1(b) displays the principle of operation, based on Photonics Integrated Circuits (PICs).…”

“…We have developed a holographic printer to record a distribution of holographic pixels [13]. This research concerns the development of an integrated near-eye display (NED) where the display engine and the combiner are integrated in the same device [12], [14]. This retinal projection display consists of using a set of holographic pixels adjusted in phase and directivity to form a composite planar wavefront.…”

“…These µ-displays do not allow for control over the emission properties, resulting in low power efficiency in the AR system, or a limited EyeBox (EB) and Field of View (FoV). This paper introduces an innovative display concept that uses photonic integrated circuits (PICs) in the visible range [8], [9], combined with active light extraction components using liquid crystals [10], [11] and pixelated holograms [12], [13]. This new approach aims to offer a more flexible integration with the optical combiner and to increase the energy efficiency of AR glasses.…”