Improvements in both hardware and software could make holographic display more viable for VR and AR applications. To this end, researchers have developed a novel approach that effectively enhances the image quality and contrast of holographic displays. This innovative technology could reportedly help advance near-eye display technology used for augmented and virtual reality applications.
Transformative impact
Jonghyun Kim from Stanford University and NVIDIA technology company, who is also a notable research team member of the said project, said that AR and VR systems are significantly poised to bring a transformative impact on society. This will be achieved by enabling a smooth interface between the digital world and the user. He further remarked that holographic displays could overcome several major challenges existing in these systems by developing more compact devices and providing improved user experience.
The paper was published in Optica, The Optical Society’s journal for high impact research. In the paper, the research team described the innovative holographic display technology as Michaelson holography. The new approach, as stated by the researchers, combines new software development with an optical setup motivated by Michaelson interferometry. This setup produces the interference patterns essential for creating digital holograms.
Outperform
Enhanced holographic displays can potentially outperform all the other 3D display technologies that are conventionally used for AR and VR technology. Holographic technology enables more compact displays and improves the user’s ability to focus on objects at different distances. This allows users with corrective lenses to adjust their vision in AR and VR systems. But the said technology is yet to achieve the desired image quality that can be used in conventional technology.
SLM
Image quality in holographic displays is limited by a component called a phase-only spatial light modulator (SLM). This component generates the diffracted light that creates the interference pattern required to form visible 3D images. The phase-only SLMs used for holography, however, exhibit a notably low diffraction efficiency that degrades the overall image quality, particularly image contrast.
Since it is not easy to increase the diffraction efficiency of these SLMs, the research team has designed a new optical architecture to make holographic images. Instead of a single-phase-only setup, the Michaelson holography approach incorporates two-phase only SLMs. Kim explained that this novel setup is designed to effectively interfere with the diffracted light of one SLM with the non-diffracted light of the other one, so that the non-diffracted light can seamlessly contribute to making a better quality image, instead of forming speckles and other obstructions.
The perfect combination
To optimize the image, the researchers have combined a camera-in-the-loop (CITL) procedure with the new hardware arrangement. This allowed them to incorporate a camera that can capture an array of displayed images. Through this camera, every minute misalignment of the optical system can be corrected without requiring any precise or high-end measuring device.
Michaelson holography architecture was tested using a benchtop optical setup. However, to make the new system viable, it would need to translate the benchtop setup into a smaller system that can be incorporated into a wearable virtual or augmented reality system. To this end, the research team expressed that their approach of combining software and hardware would be useful for enhancing computational imaging in general.
