Holographic printers can make 3D recreations of things. For example, you could think of making a holographic replica of a sculpture at a museum to keep at home. This technology has been existing for already a few years now but printing was very slow and expensive lasers were used. Engineers have been trying to make these printers inexpensive and fast.
Engineers have developed a new printer that creates digital 3D holograms with an unprecedented level of detail and realistic colour. This new printer could be used to make high-resolution colour recreations of objects or scenes for museum displays, architectural models, fine art or advertisements. These holograms do not require glasses or special viewing aids.
In the journal Applied Optics, the researchers describe the new printer, which creates holograms with wide fields of view and full parallax on a special photographic material they designed. Full parallax holograms reconstruct an object so that it is view-able in all directions, in this case with a field of view spanning 120 degrees (1).
The printer can create holograms from 3D computer generated models or from scans acquired with a dedicated scanner developed by the researchers. The high-quality holograms can even be used as masters to produce holographic copies.
Bettering the current hologram printing technology
When developing the new hologram printer, the researchers carefully studied two previously developed holographic 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,” said Gentet. “Our small, self-funded group found that it was key to develop a highly sensitive photo-material 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 a matter of milliseconds. The researchers also created a special anti-vibrating mechanical system to keep the holographic plate from moving during the recording.
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 50 hertz (Hz). 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 centimeters, about half of the time it would take using previous systems based on pulsed lasers.
Printing with high brightness and clarity
The researchers used the new technology to print holograms that measured up to 60 by 80 centimeters showing various color objects including toys, a butterfly and a museum object.
“The new system offers a much wider field of view, higher resolution and noticeably better color rendition and dynamic range than previous systems,” said Gentet. “The full-color holographic material we developed provides improved brightness and clarity while the low-power, continuous wave lasers make the system easy to use.”
The researchers say that as technology improves, especially 3D software, it may be possible to expand their hologram printing approach to medical or other advanced applications.
- 1.Y. Gentet, P. Gentet, CHIMERA, a new holoprinter technology combining low-power continuous lasers and fast printing. Appl. Opt., G226 (2019).