Passive Mid-air Display

We propose a passive mid-air display in which an image is made visible by illuminating an empty space with a flashlight. In this study, we design an optical configuration that reacts to the light source of the user. This design has an inconsistency of illumination that surprises the user. We confirm the basic operational principle and measure the brightness. We also observe user behavior to consider the possibility of this technique for entertainment. With this work, we make three research contributions. First, we design a passive mid-air display that can be used for entertainment displays. Second, we confirm its operational principle and measure the brightness. Third, we observe user behavior. We also summarize the advantages of our display as well as the issues that remain.