FIGURE 4. Images from the updatable holographic 3D display.

The display uses a single photorefractive thin-film device with an active area of 4  4 inches. Here, a modified version of the voltage kick-off was used to avoid using patterned electrodes. A constant voltage (9 kV) was applied across the entire polymer. Once recording of all of the hogels was completed, the voltage was reduced to its optimal value of 4 kV. a, A 3D hologram of a sports car was written, displayed, and then erased and a new hologram of a human brain was recorded onto the same area. The images were captured from a distance of 75 cm from different angles to demonstrate the 3D effect using a video camera moving around the display. b, The persistence of the hologram, in this case a 3D model of an ethane molecule, is demonstrated by capturing pictures at different times after recording. c, Erasure of a 3D image, a human skull, using uniform exposure is demonstrated.