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A variable-focus lens using a combination of liquid crystals and ultrasound is discussed. The lens uses a technique based on ultrasound vibration to control the molecular orientation of the liquid crystal. The lens structure is simple, with no mechanical moving parts and no transparent electrodes, which is helpful for device downsizing; the structure consists of a liquid crystal layer sandwiched between two glass substrates with a piezoelectric ring. The tens-of-kHz ultrasonic resonance flexural vibration used to excite the lens generates an acoustic radiation force on the liquid crystal layer to induce changes in the molecular orientation of the liquid crystal. The orientations of the liquid crystal molecules and the optical characteristics of the lens were investigated under ultrasound excitation. Clear optical images were observed through the lens, and the focal point could be controlled using the input voltage to the piezoelectric ring to give the lens its variable-focus action.

Methods for controlling the periodic molecular orientation of liquid crystals using ultrasound vibrations and estimating the orientational direction are proposed. An ultrasonic liquid crystal cell was used, consisting of a liquid crystal layer sandwiched by two glass plates fitted with piezoelectric ultrasound transducers. The transmitted light intensity distribution through the cell was measured by changing the polarization direction to investigate the orientation direction of the liquid crystal molecules. The transmitted light distributions changed periodically owing to the flexural vibration of the cell at resonance frequencies of 43.9 and 70.7 kHz. The orientational direction of the liquid crystal molecules correlated with the vibrational distribution of the glass substrates, and the molecular orientation was changed periodically by the acoustic radiation force. The interval and intensity of the transmitted light could be controlled by the driving frequency and voltage amplitude, respectively.

We propose a technique to control the orientation of nematic liquid crystals using ultrasound and investigate the optical characteristics of the oriented samples. An ultrasonic liquid crystal cell with a thickness of 5–25 μm and two ultrasonic lead zirconate titanate transducers was fabricated. By exciting the ultrasonic transducers, the flexural vibration modes were generated on the cell. An acoustic radiation force to the liquid crystal layer was generated, changing the molecular orientation and thus the light transmission. By modulating the ultrasonic driving frequency and voltage, the spatial distribution of the molecular orientation of the liquid crystals could be controlled. The distribution of the transmitted light intensity depends on the thickness of the liquid crystal layer because the acoustic field in the liquid crystal layer is changed by the orientational film.

Optical phase gratings have been prepared in a photo-cross-linkable polymer liquid crystal substituted with a 4-methoxycinnamoyloxybiphenyl side group by the use of linearly polarized ultraviolet interference light and subsequent annealing. The diffraction was almost invisible after irradiation, and was successfully enhanced during the subsequent annealing. Recorded phase grating involves both linear birefringence and surface-relief modulation, which is generated by thermally enhanced reorientation of the mesogenic groups and molecular migration. The sign of the induced birefringence was dependent on the degree of photoreaction and the reversion of the reorientation direction of mesogenic groups has been observed.

We demonstrate tailored assembly of colloidal particles in a glass cell. Photonic crystal or photonic glass is alternatively formed by changing the growth rate. The growth rate was controlled via the surrounding humidity. Thus, the two phases (photonic crystal and photonic glass) are formed adjacently and repetitively. Photonic characteristics specific to each phase are also obtained from the cell. The sequential formation process yields a system with unique properties suitable for functionalized optical device applications.

We present a highly functionalized photorefractive device consisting of fullerene (C60)-doped nematic liquid crystals (NLCs) on silver sulfide thin films. Either stable holograms or real-time holography is possible depending on the polarity of an external electric field. When certain direction of external field is applied to the device under irradiation by interference field, photoexcited charges are recombined with silver ions at the boundary between the silver sulfide and NLCs. The resulting interface structures reorient the NLC molecules and holographic gratings are stably memorized. When the polarity of the external field is reversed, normal photorefractive holographic gratings are formed.

We have demonstrated the vector holograms using the radially polarized light. The inhomogeneous polarized light well controlled the spatial distribution of the optical anisotropy in the solid state polymeric materials. The theoretical calculation revealed formation mechanism and optical properties of the vector holograms.

Transmission and reflection gratings were simultaneously formed in azo-dye-doped chiral nematic liquid crystals (N∗LCs) with planar alignment. The formation process is based on a phototuning of the Bragg reflection band of the N∗LC. The helical pitch of the photoreactive N∗LC was spatially controlled with intensity variation of interference light. The resultant periodic structure showed both transmissive and reflective diffractions due to the spatially modulated light intensities. The observed dependence of diffraction efficiencies on the polarization states of the probe beam was well explained by considering a spatial modulation of the helical pitch.

Three-dimensional phase gratings with twisted structures were self-organized by photoregulated mesogenic molecules on the surface of photocrosslinkable polymer liquid crystal film. The molecules are selectively photoreacted only at the surface of the film under the polarization holographic illumination, and the resultant photocrosslinked mesogenic molecules induce the three-dimensional twisted gratings in the film during annealing process. The diffraction properties were well explained by means of Jones calculus and diffraction theory.