Phase modulating micro mirror array for real holographic mixed-reality displays

Project Information

REALHOLO

Grant agreement ID: 101014977

DOI

10.3030/101014977

Project closed

EC signature date 1 December 2020

Start date 1 January 2021

End date 31 December 2025

Funded under

• INDUSTRIAL LEADERSHIP - Leadership in enabling and industrial technologies - Information and Communication Technologies (ICT)

Total cost

€ 5 997 852,50

EU contribution

€ 5 997 852,50

Coordinated by

TECHNIKON FORSCHUNGS- UND PLANUNGSGESELLSCHAFT MBH
Austria

Periodic Reporting for period 3 - REALHOLO (Phase modulating micro mirror array for real holographic mixed-reality displays)

Reporting period: 2023-07-01 to 2024-12-31

Summary of the context and overall objectives of the project

Emerging mixed-reality (MR) applications demand a natural visual experience with an increased depth range from touching distance to the horizon - without physiological side effects like eye fatigue, misjudgement, motion sickness and accommodation-vergence conflict, which are known from alternative and intermediate technologies such as stereoscopic 3D. The required natural visual experience can only be achieved with real holographic displays which have been principally demonstrated on the base of available component technologies. One crucial component, the spatial light modulator (SLM), is currently based on liquid crystal display technology which is the limiting factor on the performance of first generation real holographic projection prototype set-ups.
In REALHOLO we will develop a new type of SLM, for a micro-electro-mechanical system (MEMS)- based reflective micro-display: a micro mirror array component with a unique set of properties which is especially suited for real holographic MR displays but also for many other applications from high value to high volume. The SLM will allow a precise forming of the wave-front of reflected visible light by millions of individually movable mirrors of the piston type at a speed far beyond the human perception and with a quality that is superior to liquid crystal-based equivalents.
The improved quality of the modulated light and its impact on the quality of holographic image generation will be measured and demonstrated with individual SLMs and with integrated validation systems.
The new SLM will, besides the MEMS technology, be based on conventional semiconductor technologies, both digital and analogue, and advanced packaging techniques. The package will provide the electrical, optical, thermal and mechanical interfaces to the holographic system.
The SLM is the key enabling element for real holographic projection systems that are compact, energy efficient, and have unique imaging features and quality - impossible with today’s state-of-the-art. REALHOLO will demonstrate the SLM’s advantages in a real holographic MR application implemented as a head-up display (HUD) module for future vehicles.
Fully featured holographic HUD incorporating a sophisticated new MEMS-based SLM will provide an unique user experience but will be made at higher cost than common standard HUD, which only provide flat 2D information somewhere in front of a driver - at least initially. In order to provide additional options for swift market introduction of the new HUD systems, variants of different complexity and feature specifications will be conceptually designed and investigated.
At the end of the project, the achieved technology readiness level (TRL) will be 5. Our developments aim at producing fully functional demonstration prototypes of the SLM and of a real holographic MR display system. Prototypes will be thoroughly evaluated at different stages during the project. This evaluation will then allow to determine the necessary steps to obtain final versions for product commercialization. The REALHOLO consortium with support of its Industrial (Advisory) Board represent the complete value chain for manufacturing and commercialization in Europe.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

Within the first project period tThe REALHOLO project was successfully started up. Target specifications of key components and demonstration systems were compiled and finalized for use in practical design and manufacture. The specifications were summarized in a deliverable D1.3. A benchmarking against potentially competing and prior art approaches combined with and mass production cost estimation of the device and application systems wereas done.
Project plans were refined and the development work structured accordinglystarted.
The design of the SLM has progressed far into the individual subsystems: the semiconductor part of the SLM, the MEMS micro-mirror-array build-up and the package. Individual manufacturing steps of the MEMS process have been developed and, mostainly successfully, tested. First simplified MEMS-only test devices have been designed and are under fabrication.
Concepts and base designs for the application demonstrations have been created.

The second project period focused on a number of fundamental developments enabling manufacturing of the new MMA component as well as implementation of unique holographic projection systems. Conceptual and extensive design activities were conducted for the underlying CMOS backplane which provides the signal distribution and supplies proper voltages to the micro mirror pixels and for the micro-mirror array, the actual light-modulating pixels, which are integrated with the backplane in the final component. Work included not just computer-aided design and extensive simulation of electrical or mechanical behaviour but also practical development and prototyping down to single mirror level. Simultaneously, development of HUD concepts and optical designs was progressed as well as chip packaging, electronics control and driving. In order to ensure compliance to strict automotive design and manufacturing requirements of future mass-manufacturing, semiconductor design and manufacturing processes and procedures were developed and verified in simulation and practice to validate them accordingly.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

Real holography requires very fast modulation of many pixels with a good phase quality. For technical and economic reasons it is beneficial or even required that these pixels should be as small as possible. The combination of these requirements cannot be achieved with state-of-the-art liquid crystal technology because a viscous liquid does not have a solid state within the individual pixels and secondly because it is harder to control with high speed while still preserving the quality of the modulation. MEMS based reflective micro-displays can achieve all these requirements at the same time and with further technological headroom in regards to speed and bit depth. Compared to other state-of-the-art MEMS-based SLMs, the REALHOLO SLM’s feature set is unique - it is optimized for real holographic applications.
The development of real holographic MR applications will have a revolutionary impact on many fields of our daily life. It may even have a revolutionary impact on society. This results from the unique new ability to integrate any visual content (from a multitude of content sources) into our perception of the world through our normal human visual perception system - without physiological limitations known from inferior intermediate solutions.
The REALHOLO MR use case demonstration of a real holographic HUD will make use of these features and extend the 3D depth range of the displayed information. This unique selling property is expected to have a large potential in the automotive market, especially against the background of gradually shifting of the driver’s role to different levels of assisted, automated or autonomous driving. Real holographic displays can inform, warn and entertain the viewer from arms’ reach to the horizon.

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