A volumetric display generates three-dimensional (3D) graphics consisting of voxels in real space. It is a promising scheme of the volumetric displays to draw the voxels by 3D scanning of laser focusing points. The laser drawing method supports a wide viewing angle because these is no physical wiring between drawing space and the graphics forming system. The graphics size was ~ 1 cm3 in our previous research. In order to enlarge the volumetric bubble displays, the scan range should be increase with an objective lens with a long focal length. However, the increase gives an increase of the focusing diameter that requires an increase of the excitation energy. It is demonstrated that the use of gold nanoparticles was to decrease the excitation energy of the microbubbles.
Much attention has been paid to the development of three-dimensional volumetric displays in the fields of optics and computer graphics, and it is a dream of we display researchers. However, full-color volumetric displays are challenging because many voxels with different colors have to be formed to render volumetric graphics in real three-dimensional space. Here, we show a new volumetric display in which microbubble voxels are three-dimensionally generated in a liquid by focused femtosecond laser pulses. Use of a high-viscosity liquid, which is the key idea of this system, slows down the movement of the microbubbles, and as a result, volumetric graphics can be displayed. This “volumetric bubble display” has a wide viewing angle and simple refresh and requires no addressing wires because it involves optical access to transparent liquid and achieves full-color graphics composed on light-scattering voxels controlled by illumination light sources. In addition, a bursting of bubble graphics system using an ultrasonic vibrator also has been demonstrated. This technology will open up a wide range of applications in three-dimensional displays, augmented reality and computer graphics.
We developed a volumetric display with holographic two- and multi-photon excitations using a computer-generated hologram displayed on a liquid crystal spatial light modulator. The holographic technique has advantages of increasing the number of voxels of the volumetric graphics per unit time, increasing the total input energy to the volumetric display because the maximum energy incident at a point in the display material is limited by the damage threshold, and controlling the size, shape and spatial position of voxels. We demonstrated a volumetric display with stacked multi-color fluorescence plates.