The screen projection principle of AR glasses mainly involves optical imaging technology and display system. Here's a detailed description of how it works:
First of all, the optical imaging system of AR glasses consists of a micro display and optical lenses. This system creates an augmented reality effect by overlaying and blending the images generated by the device with the real world. Specifically, the light beams emitted by the microdisplay are reflected, refracted or diffracted through the optical lens assembly and ultimately projected onto the human retina, allowing the human eye to see virtual images superimposed on the real world.
In AR glasses, common optical display systems include "LCOS + prism", "micro OLED + self-developed curved surface", and "LCOS DLP + optical waveguide". These systems use different types of optics to project images.
Prism solution: The prism solution has mature technology and low cost, but the field of view of AR glasses made of it is relatively small, resulting in a weak AR experience. In addition, the transparent prism does not display well in bright light. To alleviate these issues, some prism solutions use a wrap-around design to ensure that the display is clear enough and not affected by ambient light.
Surface Reflection: Surface reflection is divided into two types: large surface and small surface. The large curved design provides a larger field of view and better imaging results, while the small curved surface sacrifices part of the field of view in exchange for a smaller and lighter appearance, which is easy to wear every day and more cost-effective.
Optical waveguide: An optical waveguide is a more advanced optical component with a variety of subdivisions such as geometrically reflective waveguide, diffraction etching grating waveguide, and holographic grating waveguide. These waveguide technologies differ in processing and mass production capabilities, but they share the same feature of providing a large field of view and high-resolution image display. For example, smart AR glasses such as HoloLens, Magic Leap, and Tian Zhi Hotspot Engine Project all employ diffraction-etched raster waveguide technology to achieve high-quality image projection. It is important to note that the size of the field of view is crucial for AR or VR glasses, as it determines the range of view that a person can see. Generally speaking, the larger the field of view, the better the experience, but there are also trade-offs such as power consumption, technical complexity, and manufacturing costs. In some applications, such as remote assistance in industrial production activities or simple information prompts, a small field of view (e.g. 15-30°) may be sufficient. However, in scenarios where a more immersive experience is desired, a larger field of view is more desirable.
In addition, in order to provide a better digital image experience and reduce the interference of ambient light on low-brightness and low-contrast digital images, many AR products add a dark, transparent material to the outside of the lens to block most of the ambient light. However, this processing may make it difficult for the wearer to see the real world and thus interact with the real world in the case of a weak optical environment. Therefore, these factors need to be weighed when designing AR glasses to provide the best user experience.