An Autostereoscopic Display Structure Based on Blazed Grating and Liquid Crystal Optical Elements
Date Issued
2016
Date
2016
Author(s)
Hsu, Chiao-Wei
Abstract
In the recent years, autostereoscopic （AS3D） display has grown increasingly common, in both private settings such as homes, and public settings such as shops and store fronts. However, in the two main types of AS3D systems, namely the parallax barrier method and lenticular method, major undesirable defects exist such as lack of power efficiency for the barrier method, and image crosstalk and heavy weight for the lenticular method. In 2010, Chen et al. proposed an alternative method to achieve AS3D using diffractive optical elements （DOEs）. A blazed grating is adhered directly to the screen surface as the AS3D image splitter, to avoid the efficiency loss posed by the barrier method and strongly decrease the weight, providing a lot of potential on mobile autostereoscopic technology. However, the use of grating introduced chromatic aberration into the system, as the diffracted ray angle is wavelength dependent. Further developments by Chen resulted in a complex panel of blazed grating of three different pitch periods, for the purpose of correcting the chromatic aberration. Besides, there is not much research on the viewing zone of this new structure. Instead of following behind Chen''s footstep in increasing the grating complexity, this paper proposes a new AS3D system structure based on a blazed grating of a single period, with the addition of a liquid crystal （LC） refractive element to correct the chromatic aberration. This research simulatedly shows the result of no chromatic aberration and the efficiency as high as 76.4% with the 4-level blazed grating based on a linewidth of 2 μm of a well-known mass production, roll-to-roll nanoimprint lithography (R2RNIL). Furthermore, since the refractive index of the LC can be varied with applied external electric field, the new structure proposed also provides a potential solution to AS3D displays with controllable optimal viewing distance. A viewing distance ranging from 38 cm to 84 cm was achieved by the simulation in iPad Retina Display as our reference model. Finally with the design of the adhered diffuser for the purpose of widening the viewing zone, the viewing zone of the crosstalk below 0.1 was shown successfully and a design rule was deducted.
Subjects
autostereoscopic display
stereoscopic display
grating
liquid crystal
LC
Type
thesis
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