A novel design of dynamic holographic stereogram with a curved array of spatial light modulators (SLMs) is proposed. In general, it is difficult to simultaneously achieve a wide viewing angle and an available width for the digital holographic display. Moreover, the wide viewing angle of a display system needs a large optical numerical aperture where the paraxial approximation fails, and thus an extremely large planar SLM is necessary in using previous methods. To solve this problem, our proposed display system is composed of a curved array of SLMs to obtain a large number of data points and reduce the spatial bandwidth in SLMs. In the curved array of SLMs, each SLM is individually transformed to display local angular spectra of object wave, which is based on a fundamental idea of holographic stereogram. To embody the dynamic holographic stereogram with SLMs, each SLM is effectively reformed for simplifying the optical structure and reducing the light power loss. In detail, spatially modulated wave is optically divided and transformed, as if each SLM were composed of three sub-SLMs. This design improves the scalability in viewing angle of holographic display and the loss of light power is significantly reduced. With this method, we can achieve the digital holographic display with 22.8 degrees viewing angle.
The authors propose a method for the off-axis directional beaming of optical field diffracted by a single subwavelength metal slit with dielectric surface gratings. In the proposed method, dielectric gratings are optimally designed to directionally couple the surface plasmon polariton modes induced by the metal slit into surrounding medium along a specific off-axis direction. Design of the gratings and the analysis are conducted based on the rigorous coupled wave analysis method. Their simulation shows the off-axis directional beaming of the oblique angle, 20.2°, with respect to the on axis by the proposed method. The beaming angle can be changed by adjusting the grating periods.
A method for optical beam focusing by a single subwavelength metal slit surrounded by surface gratings is proposed. In our proposed method, the period of each surface grating is chirped so that the radiation fields of surface plasmon polaritons can be controlled to make a beam spot at the desired focal length. Through our proposed method, it is numerically shown that we can make a beam spot which is located at the several times of wavelength distance from the slit, and its focal length can be controlled.
Optical Fourier surfaces (OFSs) are used for various applications, from diffractive optics to augmented reality (AR). However, the current methods of fabricating OFSs primarily rely on lithographic photochemical reactions and etching. These methods are likely to fabricate digitalized binary reliefs, which cannot match the ideal surface profile of OFSs. Such a profile is the sum of sinusoidal surfaces with various spatial frequencies. As an exception, scanning probe lithography (SPL) is found to be compatible with OFSs. However, the accessible pattern area of the OFSs created via SPL is relatively small owing to the serial feature of the fabrication, which in turn results in an undesired and complicated Fourier spectrum. In this article, the holographic inscription is redesigned for the low‐cost, large‐area, and rapid prototyping of customized OFSs. To this end, an integrative pipeline is established across numerical design, material optimization, and the pragmatic considerations of optical processing. Then, a soft molding strategy is suggested for optically transparent and flexible OFSs and its use for easy‐to‐craft AR devices. Overall, this intuitive framework not only expands the scope of Fourier optics but also acts as a field guide to azopolymeric OFSs and AR technology for experts and newcomers alike.
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