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In this paper, geometric-phase lenses, which can not only correct wavefront aberrations but also magnify an aerial image, have been proposed for use in an aerial display system composed of a retroreflector array, an orthogonal-circular polarization grating, a right-angle prism, and a quarter-wave plate. The geometric-phase lenses were demonstrated both experimentally and computationally by arranging them in the aerial display configuration and observing aerial images. We also investigated the relationship between the magnification and the field of view of an aerial image, and it has been found that there is the trade-off relationship between them.

The incident angle dependence of the diffraction properties of orthogonal-circular polarization gratings (OCPGs) fabricated using a polymer liquid crystal exhibiting biaxial anisotropy have been investigated. It was found that a specific biaxial anisotropy reduces the incident angle dependence of optically thin OCPGs against the wavelength of an incident light.

A polarized laser beam steering system using multiply cascaded rotating polarization gratings (PGs) is presented. The rotating PGs steer incident circularly polarized beams with high optical throughput because the theoretical limitation of the PG diffraction efficiency is 100%. The system also offers more rapid rotation when compared with wedge prism pairs because of the weight of the PGs. The beam steering performance was analyzed theoretically for schemes using two and four rotating PGs. The system’s feasibility was demonstrated experimentally by projecting Lissajous and raster patterns using PGs fabricated from photocrosslinkable polymer liquid crystal films via a photo-alignment technique. The steered beam’s diffraction efficiency and ellipticity were maintained at 83 ∼ 89 % and 96 ∼ 99 % , respectively, during PG rotation. This beam steering system will be applicable to light detection and ranging, optical imaging, and laser displays.

A theoretical framework for determining biaxial anisotropy suitable for reducing the incident angle dependence of a polarization grating is proposed. The principal refractive indices are uniquely given by quantifying the biaxial anisotropy through the N z coefficient. The numerical analysis based on the finite-difference time-domain method reveals that the incident angle dependences of the diffraction efficiency and the polarization ellipticity of the diffracted light are significantly reduced when N z = 0.5 . This result is expected to contribute to the design of polarization diffractive optical elements and the development of anisotropic materials and structures.

The incident angle dependences of the diffraction properties of orthogonal-circular polarization gratings (OCPGs) fabricated using a polymer liquid crystal exhibiting biaxial anisotropy have been investigated. The investigations were conducted with the plane orthogonal to the surface of the OCPGs as the plane of incidence. It was found that a specific biaxial anisotropy reduces the incident angle dependence of optically thin OCPGs against the wavelength of the incident light, and is less effective on thick OCPGs. In addition, a method also has been proposed to determine the biaxial anisotropic shape that most reduces the incident angle dependence in thin OCPGs.

A hybrid polarization grating that can spatially separate orthogonal states of a vector beam with the same polarization topological charge is presented. The hybrid polarization grating is assembled using a fork-shaped polarization grating and a quarter-wave polarization grating and acts as a common pass interferometer for right- and left-circular polarization components of incident vector beams. The hybrid polarization grating can separate two vector beam states that have a 90 ° relative polarization azimuth angle difference. The number of detectable vector beams can be increased by replacing the hybrid polarization grating with a crossed-hybrid polarization grating. Device feasibility was demonstrated experimentally using hybrid polarization grating and crossed-hybrid polarization grating fabricated using the photoalignment method for photoreactive liquid crystals. This approach has the potential to demultiplex several vector beams stably and simultaneously using a compact optical system and should be applicable to vector beam division multiplexing and other applications requiring vector beam detection.

We propose two types of wavefront aberration correction in geometric-phase lenses (GPLs). First, in situations in which the incident light on a GPL has a wavefront aberration represented by the Zernike polynomial, the wavefront aberration is eliminated by setting a phase distribution that cancels the phase distribution of the incident light to GPL. Second, the aberration that occurs when a light wave is obliquely incident on the GPL is compensated for by a correction method that incorporates an optimization design using a genetic algorithm. These methods have been demonstrated not only by theory but also by experiments using imaging systems in which the designed and fabricated GPLs are utilized. These wavefront aberration correction methods can be expected to overcome wavefront aberration caused by the arrangement of optical elements in an optical system and contribute to expanding the application range of GPLs.

An aerial display scheme consisting of an orthogonal circular polarization grating (OCPG), a waveplate, a retroreflector array (RRA), and a right-angle prism (RAP) was developed. Because of the OCPG’s functionality, retroreflected light from the RRA is transmitted through the RAP boundary surface by avoiding the total reflection condition. The proposed system can potentially increase optical throughput to 100% by designing the boundary surface incidence angle to be Brewster’s angle. The scheme’s feasibility was demonstrated experimentally using an OCPG and waveplate that were fabricated from polymer liquid crystal with optical anisotropy using a photoalignment technique. The scheme should be used as a type of aerial display that is compatible with polarization-diffractive elements called Pancharatnam–Berry phase elements.

Thermally enhanced photoinduced in-plane molecular reorientation in new photo-cross-linkable polymer liquid crystalline (PPLC) films comprising 4-[ω-(4-methoxycinnamoyloxy)alkyloxy]biphenyl side groups is explored using linearly polarized ultraviolet (LPUV) light exposure and subsequent annealing. The influence of the alkylene spacer length between the photo-cross-linkable group and the biphenyl mesogenic moiety is investigated. The straight-line characteristics of the photoreactive mesogenic side group and the 4-methoxycinnamoyl group play important roles in the high photoreactivity and the large thermally enhanced molecular reorientation, where the in-plane order and the birefringence of the reoriented film are 0.61 and 0.18 are obtained. Finally, cooperative molecular reorientation of dichroic dyes doped in PPLC films is also achieved to fabricate a linear polarizer. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4712–4718, 2008

Thermally enhanced photoinduced reorientation in a photo-cross-linkable liquid crystalline polymethacrylate comprised of 4-(ω-cinnamoyloxyalkyloxy)biphenyl side groups is investigated by irradiating with linearly polarized ultraviolet (LPUV) light and subsequent annealing at elevated temperatures. An odd−even effect of the alkylene spacer length between the cinnamate end group and biphenyl group on the transition temperatures of the polymer, photoinduced optical anisotropy, and thermal amplification of the in-plane molecular reorientation of thin films are observed. Because of the higher straight-line characteristics of the mesogenic side groups with an odd number alkylene spacer, the axis-selectivity of the anisotropic photoreaction of the photoreactive groups is greater than that with an even number, which leads to a larger photoinduced optical anisotropy and effective molecular reorientation. Finally, the cooperative reorientation in composites of the polymer and nonliquid crystalline monomer is explor...

Polarization-selective photosensitization and molecular reorientation in photo-crosslinkable polymer liquid crystal (PMCB6M) films, based on polarization-selective triplet energy transfer using LP-365 nm and LP-405 nm light with different photosensitizers, are described. A dramatic improvement in the photoreactivity of the film was observed with a small amount of photosensitizer; and a high degree of molecular reorientation and slantwise reorientation were generated when annealing the resulting films at elevated temperatures. The efficiency of reorientation depended on the photoinduced dichroism of the film.

光架橋性高分子液晶とビフェニル基を有する低分子化合物からなる複合体フィルムに直線偏光紫外 (LPUV) 光を照射しfその後の熱処理によって誘起される1軸分子配向挙動について調べた. フィルムは高分子液晶部の軸選択的光反応をトリガーにして, 低分子化合物の配向を誘起するだけでなく高分子液晶メソゲンの配向も協調的に増幅した. 作製された複合体フィルムは可視光域において透明であり, 膜厚が1μm以上の光学位相差フィルムが作製できた. さらに, 斜めLPUV光照射により傾斜配向を実現した.

Cooperative reorientation of rodlike groups in amorphous composite films consisting of photo-crosslinkable polymer liquid crystal (PLC) and non-liquid crystalline (non-LC) monomer comprising a rodlike biphenyl group was investigated by irradiation with linearly polarized ultraviolet (LPUV) light and subsequent annealing. Absorption measurements revealed that biphenyl groups of both non-LC monomer and mesogenic side groups of the PLC reorient thermally, along the photo-crosslinked mesogenic groups in the PLC. The reoriented composite film is transparent and the induced birefringence is 0.105. Achieving a three-dimensional reorientation of the rodlike groups is feasible by means of slantwise LPUV light exposure.

New optical birefringent film for liquid crystal display (LCD) is described using composite materials consisting of photo-cross-linkable polymer liquid crystal (PLC) and photoreactive bifunctional monomers. The alignment of mesogenic groups in both PLC and monomers was achieved by irradiation with linearly polarized ultraviolet (LPUV) light and subsequent annealing. Axis-selective photo-cross-linking reaction of the mesogenic group in the PLC occurred by exposure with LPUV light, although the induced birefringence was very small. The annealing process generates a thermal reorientation of monomers in a direction parallel to the photo-cross-linked mesogenic groups, resulting in a reversion of the orientation direction and thermal enhancement of the alignment of the film. Since the orientation direction is parallel to the polarization direction of LPUV light, three-dimensional orientation can be feasible by oblique irradiation with LPUV light, and the angle of the molecular orientation is controlled by changing the exposure angle. By the use of this optical birefringent film, the improvement of the viewing characteristics of twisted-nematic (TN) LCD is demonstrated.