Scientists from the Missouri University of Science and Technology developing a novel approach to reconstruct 3-D full-color holographic images. For this, they are using only one layer of nanoscale aluminium film.
Scientists have reproduced several full-color holographic images through nanoscale aluminium thin foils. Scientists use metallic films with metasurfaces that control the wavefront of light. The metasurface hologram was just one 35-nanometer thick aluminium film.
Scientists then drilling out tiny rectangular slits with various orientation angles through the aluminium thin layer. This film was cut through tiny rectangular holes of 160 nanometers by 80 nanometers by a microfabrication process known as focused ion beam milling. This hologram looks like a needlepoint pattern during scanning under an electron microscope.
The experiment was done with laser light with the red, green and blue light on the metasurface structures. Through this, scientists found clean and vivid full-color holographic images with high resolution and low noise. Thus, the three primary colours- red, green and blue were produced. The secondary colours of cyan, magenta, yellow and white also were produced.
Scientists then demonstrate CMYW letters to explain their holographic image. CMYW letters are an apple and a Rubik cube. According to scientists, the metasurface hologram holds promise for future applications. For example, it can be used in credit card security marking, biomedical imaging, 3-D floating displays and big-data storage.
Dr. Xiaodong Yang, said, “By adjusting the orientation angle of the nanoscale slits, we are able to fully tune the phase delay through the slit for realising the phase modulation within the entire visible colour range. In addition, the amplitude modulation is gain by simply including or not including the slit. Our holograms contain both amplitude and phase modulations at the nanometer scale. Thus high resolution and low noise holographic images can be reconstructed.”
Gao, co-author of the paper said, “It is different from the currently existing metasurface holograms. Generally, they redesign for limited colours. Our wavelength multiplexed method by encoding additional phase shifts into the holograms and introducing tilted incident angle illumination of laser light. This results in the successful reconstruction of almost all visible colours.”