According to Qingting. Duke University researchers said in their paper that they can encode color images into 300x300 micron holograms in a two-dimensional optical waveguide structure (very thin for guiding light). When the grating coupler is illuminated by red, green and blue light, the computational hologram will produce complex color holographic images.
Daniel L. Marks, one of the team's researchers, said: "Holograms can be printed directly on the lenses of AR glasses, so that images can be projected directly into people's pupils without bulky optical components, spectrometers or prisms. This technology can also be used to project 3D images on smartphones onto the wall. "
This new manufacturing process needs to encode holograms into materials compatible with integrated photon technology, that is, if the same manufacturing process as computer chips is used, this holographic equipment can be easily mass-produced. The holographic light generating element manufactured by the above technology can be placed in an apparatus having a supporting chip and a light source capable of generating a 3D image.
Solve the problem of single color
The color holographic imaging technology mentioned in this paper is based on computer-generated hologram, which is different from traditional holographic imaging. It does not need real objects and lasers, and can generate interference patterns and holographic images by digital methods.
Computer-generated hologram can generate high-resolution 3D images, but in order to solve the problem of single color, Duke University researchers made a grating, a series of stripes and a binary hologram (embedded in an optical waveguide made of photosensitive materials such as photoresist). They developed a method to integrate red, green and blue interference patterns into binary holographic patterns.
Huang, the first author of the paper, said: "One of the challenges we encounter is how to mix colors to generate color images, and then accurately separate them to generate full-color images. And our method can make the whole process realize on a plane. "
Another challenge they encounter is how to make holographic imaging equipment in optical waveguide structure, because the traditional way (making color computer generated hologram) does not use optical waveguide.
The effect is good enough.
After testing, the holographic imaging method developed by this group of researchers can encode color holographic photos such as apples, flowers and birds, and the generated holographic images are not far from the theoretical prediction. Although they only used 300x300 micron holographic photos in the demonstration, they said that it is not difficult to expand the scale, and this technology can also be combined with existing technologies (such as LCD screen manufacturing process) to generate dynamic pictures.
Next, the researchers will continue to optimize this technology to reduce the light loss caused by the holographic coding structure. They also pointed out that combining this structure with laser-based integrated devices will bring more practical application scenarios. This article is translated from The Duke by Qingting.com.