Coherence properties of different light sources and how they affect the image quality of holographic display are investigated. Temporal coherence is related to the intrinsic spectrum bandwidth of the light source, while spatial coherence can be affected by the size of the light source and propagation distance in use. These two coherence properties are measured for various light sources of diode-pumped solid-state (DPSS) laser, laser diode (LD), light emitting diode (LED), super luminescent light emitting diode (sLED) and micro light emitting diode (mLED) in different settings, together with the quality of the holographic reconstructed images. Although the image sharpness and speckle are related to both coherence parameters, our results and subsequent analysis show that the spatial coherence can be linked directly to the image sharpness and the temporal coherence to the speckle. This will provide a quantitative way not only to optimize the image quality between uniformity and sharpness but also to determine the safety power level for different light sources when viewing the produced images by human eyes directly.

The use of pixel-level tunable liquid crystal (LC) lenses to steer the images shown on a flat panel display in full resolution for auto-stereoscopic applications was proposed. Micro lenticular LC lenses of different full widths ranging from 40 to 140 µm were designed and fabricated with laser patterned transparent ITO electrodes as narrow as 10 µm in width and two LC materials of high birefringence. Optical characterization of the lenses showed consistent parabolic phase profiles closely matched to that of ideal lenses. A proof-of-concept device with an array of tunable micro LC lenses each covers two sub-pixels of different colors was fabricated and applied on a standard computer monitor to confirm its capability of sub-pixel-level image steering.

A phase-only hologram modulates the phase of the incident light and diffracts it efficiently with low energy loss because of the minimum absorption. Much research attention has been focused on how to generate phase-only holograms, and little work has been done to understand the effect and limitation of their partial implementation, possibly due to physical defects and constraints, in particular as in the practical situations where a phase-only hologram is confined or needs to be sliced or tiled. The present study simulates the effect of masking phase-only holograms on the quality of reconstructed images in three different scenarios with different filling factors, filling positions, and illumination intensity profiles. Quantitative analysis confirms that the width of the image point spread function becomes wider and the image quality decreases, as expected, when the filling factor decreases, and the image quality remains the same for different filling positions as well. The width of the image point spread function as derived from different filling factors shows a consistent behavior to that as measured directly from the reconstructed image, especially as the filling factor becomes small. Finally, mask profiles of different shapes and intensity distributions are shown to have more complicated effects on the image point spread function, which in turn affects the quality and textures of the reconstructed image.

A full resolution auto-stereoscopic display for mobile phones is demonstrated. It is based on the sub-pixel level phase modulation of a switchable liquid crystal (LC) micro-lens array, which can be switched back to a conventional two-dimensional (2D) display. The full scale (4 inch) device aligns with the display panel perfectly at sub-pixel level and switches the entire display area uniformly with no distortion and no colour separation. The steering angle and crosstalk of the auto-stereoscopic display are evaluated by both simulation and experiment. The results show that satisfactory performance can be achieved by further reduction of the separation distance between the colour filter (CF) layer and the LC lens layer and close match it to the effective focal length of the LC lens.

Self-assembly of patterned nanostructures in solution-processed thin films with single phase polymers is successful.