Fringe periods of color moirés in contact-type 3-D displays.

A mathematical formula of calculating the fringe periods of the color moirés appearing at the contact-type 3-D displays is derived. It is typical that the color moirés are chirped and the period of the line pattern in viewing zone forming optics is more than two times of that of the pixel pattern in the display panel. These make impossible to calculate the fringe periods of the color moirés with the conventional beat frequency formula. The derived formula work very well for any combination of two line patterns having either a same line period or different line periods. This is experimentally proved. Furthermore, it is also shown that the fringe period can be expressed in terms of the viewing distance and focal length of the viewing zone forming optics.

A floating type holographic display.

A floating image type holographic display which projects an electronically generated holographic image together with a background image displayed on a monitor/TV to enhance the visual effects of the former image is introduced. This display can display a holographic image with a spatial volume floating in the front space of the display with use of PDLC sheets as the focused plane of the image. This display can preserve and enhance the main property of holographic image from a display chip, i.e., a spatial image with a volume. This property had not been appealed by the previous holographic displays due to the much brighter active surface image accompanied with the reconstructed image and the diffuser used for viewing the image.

Holographic display based on a spatial DMD array.

The image space of the reconstructed image from the hologram displayed on a digital micromirror device (DMD) is defined by the diffraction pattern induced by the 2D pixel pattern of the DMD, which works as a 2D blazed grating. Within this space, a reconstructed image of 100 mm × 20 mm is spatially multiplexed by a 2 × 5 DMD array that is aligned on a board, without using any extra optics. Each DMD chip reconstructs an image piece of the size 20 mm (width) × 10 mm (height). The reconstructed image looks somewhat noisy but regenerates the original object image faithfully.

Depth resolution in three-dimensional images.

The depth of field of a camera defines the depth range to be covered by the camera. In 3D images, the resolvable depth range is also determined by the depth of field (DOF). Hence the depth resolution and resolvable number of depth layers obtainable with a given 3D display will be defined within the DOF when the display has the same resolution as the total camera resolution of the array in the horizontal direction. The depth resolution and resolvable number of depth layers are mathematically derived in terms of the circle of confusion. The resolvable number of depth layers is approximately linearly proportional to the camera distance and inversely proportional to the aperture diameter of the camera objective. The accuracies of the derivations are examined experimentally. The results show that the DOF extends slightly and the depth resolution improves up to 20% more than that predicted by theory for the given experimental condition. This means that the depth resolution derived has more than 80% accuracy.