North Carolina State University (NCSU) researchers have developed techniques that can be used to create ideal geometric phase holograms for any kind of optical pattern.
The researchers note the holograms can be used to make new types of displays, imaging systems, telecommunications technology, and astronomical instruments.
Light moves as a wave, creating peaks and troughs along the way; when it passes through a geometric phase hologram, the relationship between those peaks and troughs changes. The new techniques control the changes, enabling the hologram to focus, disperse, reorient, or otherwise modify the light.
Ideal geometric phase holograms can produce three different, well-defined "wavefronts," or transformed versions of the light that passes through the thin film. First, the researchers use lasers to create a high-fidelity light pattern, either by utilizing how waves of light interfere with each other or by using a tightly focused laser to scan through a pattern. A photoreactive substrate then records the light pattern, with each molecule of the substrate orienting itself depending on the polarization of the light to which it was exposed. The recorded pattern serves as a template for a liquid crystal layer that forms the finished hologram.
"Using these techniques, we're able to create ideal geometric phase holograms in nearly any pattern," says NCSU professor Michael Escuti.
From NCSU News
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