J. Eur. Opt. Society-Rapid Publ. 22, 22( 2026) 225
Figure 14.( a) Geometrical configuration of the retro-reflective projection system module,( b) view of the module showing the retroreflective projection of a virtual retro-reflected image at a viewing angle close to 0 °, and( c) side view of the optical module [ 54 ].
Figure 15. Application images of Fairy Lights in Femtoseconds – three-dimensional, aerial, and volumetric graphics displayed in mid-air through the use of femtosecond laser technology [ 57 ].
3.4.6 Floating 3D display of acoustic wave
In 2019, researchers at the University of Sussex in the UK developed a novel technology called the multi-modal acoustic trap display( MATD). Using ultrasonic speakers to manipulate tiny particles, MATD can simultaneously deliver visual, auditory, and tactile content, creating a floating display that changes shape in mid-air [ 58, 59 ]. The manipulation of particle morphing in the air is achieved by a simple device: two slim arrays of 256 tiny speakers that move