Making volumetric displays out of glycerin-filled tanks

Making volumetric displays out of glycerin-filled tanks

Technology News |
By Julien Happich

Using a glycerine-filled tank as the medium, the researchers then fire femtosecond laser pulses focused at different points in the medium to induce light-scattering microbubbles (via multiphoton absorption). An illumination source then reveals these microbubbles as voxels forming a 3D image in the volume of otherwise transparent glycerin.

The volumetric bubble display, as the researchers describe it in the Optical Society of America (OSA) Optica journal, consists of a light source (the femtosecond laser), a 2D galvanometer mirror combined with a varifocal lens and a LCOS-based light modulator. This optical setup is able to perform 3D beam scanning across the transparent medium to form the voxels in a volume of glycerin which acts as the revealing screen.

Concept of volumetric bubble display.
Various volumetric graphics rendered by bubbles
can be viewed from any direction.

Thanks to its high-viscosity, glycerin slows down the movement of the microbubbles, making the voxels stable enough to accurately display volumetric graphics with surround viewing angles. Other benefits of the optically-addressed glycerin-filled display is its simplicity, with no wiring.

A proof-of-concept experiment was performed at the cubic centimetre scale with a 10x10x100mm3 volume of glycerin sealed in a glass cell, irradiated by 800nm 100fs laser pulses at a repetition rate of 1kHz to form microbubbles of roughly 20μm in diameter.

Volumetric graphics of “Stanford bunny” rendered
by femtosecond laser-induced microbubbles.

The researchers also noted that microbubbles’ length and diameter could be controlled through multi-shot irradiation, altering the contrast of the displayed graphics by changing the number of irradiation pulses. Several patterns and holographic images were successfully rendered in greyscale.

The researchers anticipate that different voxels may scatter different colours if illuminated through a dedicated projector (with spatially focused and temporally controlled illumination light). In the future, they hope to be able to demonstrate an updatable display by adding a bubble bursting system to their invention.

Visit the Center for Optical Research & Education (CORE), Utsunomiya University at

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