Researchers improve holographic printing material, resolution
Disclosed in the Applied Optics journal in a paper titled “CHIMERA, a new holoprinter technology combining low-power continuous lasers and fast printing”, the new technology achieves a printing speed in excess of 25 hogels per second (holographic pixel) for full-color, 120° full-parallax digital reflection holograms. The authors demonstrated printed holographic optical elements up to 60x80cm, with a hogel size ranging from 250 to 500µm.
The CHIMERA printer uses red, green and blue low-power commercially available continuous wave lasers with shutters that adjust the exposure for each laser in a matter of milliseconds. The researchers also created a special anti-vibrating mechanical system to keep the holographic plate from moving during the recording. They also developed a 3D scanner using a 4K video camera, so they could scan real objects from which to print holograms on CHIMERA
They anticipate high-resolution colour holograms could be used to recreate objects or scenes for museum displays, architectural models, fine art or advertisements. As technology improves, especially 3D software, it may be possible to expand this hologram printing approach to medical or other advanced applications.
“Our 15-year research project aimed to build a hologram printer with all the advantages of previous technologies while eliminating known drawbacks such as expensive lasers, slow printing speed, limited field of view and unsaturated colors,” said research team leader Yves Gentet from Ultimate Holography in France.
“The companies involved in developing the first two generations of printers eventually faced technical limitations and closed” added Gentet. “Our small, self-funded group found that it was key to develop a highly sensitive photomaterial with a very fine grain rather than use a commercially available rigid material like previous systems.”
holograms such as the one shown with an unprecedented
level of detail and realistic color. Credit: C Yves Gentet.
Holograms are created by recording small holographic elements known as hogels, one after another using three spatial light modulators and a custom designed full-color optical printing head that enables the 120-degree parallax. After printing, the holograms are developed in chemical baths and sealed for protection. The hogel size can be toggled between 250 and 500 microns and the printing rate adjusted from 1 to 50Hz. For example, if a hogel size of 250 microns is used, the maximum printing speed is 50 Hz. At this speed it would take 11 hours to print a hologram measuring 30 by 40 centimetres, about half of the time it would take using previous systems based on pulsed lasers.
Ultimate Holography – www.ultimate-holography.com
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