A printer that halves the time it takes to produce digital 3D holograms with pulsed lasers could lead to high-resolution holographic displays with unprecedented levels of detail.
It is claimed the new printer could be used to make high-resolution colour recreations of objects or scenes for museum displays, architectural models, fine art or advertisements that do not require glasses or special viewing aids.
“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 colours,” said research team leader Yves Gentet from Ultimate Holography in France. “We accomplished this by creating the CHIMERA printer, which uses low-cost commercial lasers and high-speed printing to produce holograms with high-quality colour that spans a large dynamic range.”
In Applied Optics, the researchers describe the new printer, which is said to create holograms with wide fields of view and full parallax on a special photographic material designed in-house. Full parallax holograms reconstruct an object so that it is viewable in all directions, in this case with a field of view spanning 120 degrees.
According to the team, the printer can create holograms from 3D computer generated models or from scans acquired with a dedicated scanner developed by the researchers.
To develop the new hologram printer, the researchers studied two previously developed printer technologies to understand their advantages and drawbacks.
“The companies involved in developing the first two generations of printers eventually faced technical limitations and closed,” Gentet said in a statement. “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.”
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 milliseconds. The researchers also created an anti-vibrating mechanical system to keep the holographic plate from moving during the recording.
Holograms are created by recording small holographic elements called hogels, one after another using three spatial light modulators and a custom designed full-colour optical printing head that enables the 120-degree parallax. After printing, the holograms are developed in chemical baths and sealed.
The hogel size can be switched between 250 and 500μm and the printing rate adjusted from 1 to 50Hz. If a hogel size of 250μm is used, the maximum printing speed is 50Hz. At this speed it would take 11 hours to print a hologram measuring 30 by 40cm, or about half of the time it would take using previous systems based on pulsed lasers.
The researchers used the new technology to print holograms that measured up to 60 by 80cm showing various colour objects including toys, a butterfly and a museum object.
“The new system offers a much wider field of view, higher resolution and noticeably better colour rendition and dynamic range than previous systems,” said Gentet. “The full-colour holographic material we developed provides improved brightness and clarity while the low-power, continuous wave lasers make the system easy to use.”