WiMi Hologram Unveils Groundbreaking LCoS Technology for Augmented Reality Displays

Posted  by GoPhotonics


WiMi Hologram Cloud, a leading global Hologram Augmented Reality ("AR") Technology provider, announced that it has developed a liquid crystal on silicon (LCoS) technology solution that will revolutionize augmented reality (AR) displays.

Liquid crystals are optically responsive substances whose molecular arrangement can be altered by an electric field. Liquid crystal displays (LCDs) employ liquid crystals as optical switches to modulate the degree of light transmission by controlling the electric field, thus enabling the control of pixel points. This provides the basis for the development of LCoS. With the rapid development of semiconductor and integrated circuit technology, complementary metal oxide semiconductor (CMOS) technology has emerged in the semiconductor industry. CMOS has the advantages of low power consumption, high integration, and cost-effectiveness, which makes it a highly suitable backplane technology for optoelectronic devices. Advances in CMOS have provided a highly integrative backplane platform for the development of LCoS, which has improved the LCoS performance.

WiMi's LCoS technology for AR displays creatively combines liquid crystals with semiconductor substrates to realize optically addressable liquid crystal light valves. WiMi has developed a principle of LCoS technology for AR displays whereby liquid crystals can be used for optical addressability, which means that light can be propagated multiple times through the liquid crystal layer, each time modulating the phase or polarization state, providing a direction for realizing high resolution, high-performance optical valves. The rise of LCoS technology is closely related to the needs of the high-resolution and holographic imaging fields. High-resolution displays and imaging are critical for applications such as AR, virtual reality (VR), and head-mounted displays (HMDs).

However, LCoS technology faces several technical problems in practice, one of the main ones being the edge field effect, which can lead to a degradation of display performance. The performance of edge pixels tends to be less stable than that of center pixels, which can degrade the display quality. Therefore, solving this problem becomes a key prerequisite for the development of LCoS. In order to solve the problem of the edge field effect, WiMi proposes innovative solutions, including optimizing the pixel structure, adjusting the pre-tilt angle of the liquid crystal and improving the phase modulation algorithm. The technique divides the pixel area into two zones with a border width based on an initially determined phase delay curve. By this method, the pre-tilt angles of the inner and outer regions are optimized, thereby reducing the overall phase delay error. The goal of this optimization process is to achieve more accurate phase modulation, resulting in improved image quality and display performance. In addition, this approach makes it possible to design pre-tilt angle patterns with opposite characteristics, thus providing greater flexibility for different applications.

Panel composition of WiMi's LCoS technology for AR displays:

Liquid crystal(LC): The liquid crystal is the core component of LCoS, which is composed of liquid crystal molecules that can be adjusted in their arrangement by an electric field. In LCoS, the liquid crystal is usually located between two pieces of glass or wafers.

CMOS backplane: The CMOS backplane provides pixel-level control of the electric field used to manipulate the liquid crystal molecules in the liquid crystal layer. Each pixel point has a corresponding electrode that controls the voltage through CMOS circuitry, which changes the alignment of the liquid crystal molecules and adjusts the phase or polarization state.

Orientation layers: Typically, two thin polyimides (PI) orientation layers are located at the top and bottom of the liquid crystal layer, which determines the alignment direction of the liquid crystal molecules and ensures the consistency of the liquid crystal alignment.

One of the core features of WiMi's LCoS for AR displays is phase modulation. When incident light passes through a liquid crystal layer twice, its phase is modulated according to the arrangement pattern of the liquid crystal molecules. This phase modulation is achieved by controlling electrodes on the CMOS backplane, where different voltages result in different arrangements of the liquid crystal molecules, thus changing the phase of the light. In addition to phase modulation, LCoS can also be used for polarization modulation. By adjusting the arrangement of the liquid crystal molecules, LCoS can change the polarization of the incident light so that it becomes linear, circularly polarized, or other specific polarization states, which is very important for certain applications. In addition, the electrodes on the CMOS backplane are typically pixelated, meaning that each pixel point can be controlled independently. This pixelated layout allows for the creation of high-resolution images or light fields across the entire LCoS panel.

In order to improve the display performance, especially to address the fringe field effect, the solution employs phase delay optimization. This includes dividing the pixel area into inner and outer zones, as well as precisely adjusting the pre-tilt angle to minimize phase delay errors. The solution is dedicated to realizing high-resolution and small-pitch LCoS panels to provide sharper, brighter and more realistic AR displays.

WiMi's LCoS technology for AR displays is expected to bring higher performance, better user experience, and a wider range of applications to augmented reality technology. Through optically addressed liquid crystal light valves, LCoS can precisely modulate the phase and polarization state of light to achieve highly controllable optical effects, which opens up new possibilities for the development of AR fields such as virtual simulation, healthcare, education and entertainment. The technology enables users to experience a more realistic overlay of virtual information. This results in a more realistic, brighter and clearer display in AR. Not only that, LCoS has lowered the threshold of the AR market, attracting more manufacturers and developers and driving continuous innovation and development of the technology. The application of this technology will help drive the popularization and innovation of AR technology, bringing more possibilities to our daily lives and professional fields.

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