Hong Kong University for Science and Technology (HKUST) published the result of its research, originally shown in a paper at SID, into an optically rewritable 3D LCD.
The display is basically a normal LCD without drive electronics. In a normal LCD, the LCD molecules are aligned by applying a voltage between the front and the backplane. Depending on the voltage, the LC molecules twist and change the polarization plane of the transmitted light. Since the LCD also has polarization filters, the LC twist will create a change in the brightness of the transmitted light.
In the HKUST, approach the electrodes are left out and the image is written by light pulse into the display array. This creates a gray scale image that is viewable with the naked eye. Because of the bistability of the molecules, the image does not need to be refreshed.
HKUST uses masks to write two images in the display. The two images are written with a 90 degree difference in the polarization plane, so that when viewed through 3D passive glasses the right eye sees one image, while the left eye sees the other. This creates a stereoscopic image.
So far the image is in black and white only and contains only static images, with no video. However, the display will work without any power to maintain the image, which may indicate some potential applications in digital signage and the like. Since the image can only be changed by a light impulse the uses may be somewhat limited. – Norbert Hildebrand
