Man Chun Tseng

Tunable lens by spatially varying liquid crystal pretilt angles

We report a method of obtaining controllable spatially varying liquid crystal pretilt angles using a stacked alignment layer. The stacked alignment layer consists of nano-domains of horizontal and vertical alignment materials. The pretilt angle is controlled by varying the domain ratio of the two layers. By using photoalignment material as the top layer, the pretilt angle can be controlled by varying the UV light dosage. A spatially variable UV light beam can be used to control the pretilt angle spatially. An electrically tunable-focus liquid crystal lens is obtained using this method.

32.3: Simple Single‐Layer Multi‐Touch Projected Capacitive Touch Panel

A simple projected capacitive touch panel is developed. This touch panel is capable of detecting multi-point touch events. The device consists of a single piece of patterned transparent ITO glass and a sensing circuit. The applied driving signal is projected onto the sensing node in the form of an electric field. A charge sensing circuit is used to monitor the mutual capacitance between the driving and sensing nodes. This approach provides a simple and low cost alternative to current capacitive multi-touch panel design.

Low voltage tunable liquid crystal lens

In this Letter, we report a method to prepare a liquid crystal (LC) lens based on a variable pretilt angle of a photoalignment (PA) layer. With precise control of the irradiance, such PA provides good control on the pretilt angle that can be tuned in the range of 1°-89°. Therefore, the precise control of the irradiance generates a spatially varying pretilt angle with any desired pretilt angle profile. Thus, the tunable LC lenses have been fabricated and characterized. With low voltage operations, easy fabrication, and relatively high switching speed, such lenses can be applied in many modern optical and photonic devices.

Strengthening of liquid crystal photoalignment on azo dye films: passivation by reactive mesogens

Disazo dyes form a highly effective class of liquid crystal (LC) photo-aligning materials whose molecules undergo fast orientation or reorientation under exceptionally low irradiation doses. These properties make these materials irreplaceable for application in all-optical LC devices. At the same time, the high sensitivity of the photo-orientation prevents the extension of this method to electro-optical elements such as LC displays and photonic devices. To stabilize LC alignment on dye films, several approaches have been developed which employ reactive mesogens (RMs) capable of photopolymerization. This article comprehensively describes the approach associated with the passivation of photoaligning films by thin layers of RMs. It is shown that continuous RM films with a thickness ≥5 nm provide highly uniform, thermally and photo-stable LC alignment. This approach also provides a VHR of more than 99%, RDC voltage less than 5 mV, and image sticking parameter about 1.002, which are the same as for rubbed polyimide films. Together with the low pre-tilt angle, high anchoring energy and ability of alignment patterning, this makes the proposed approach promising for application in a range of electro-optical devices, particularly those requiring active matrix driving and multi-domain alignment.

Light-Driven Liquid Crystal Circular Dammann Grating Fabricated by a Micro-Patterned Liquid Crystal Polymer Phase Mask

As one of the diffractive optical elements, circular Dammann grating has shown its excellent versatility in practical applications. The electrically switchable Dammann grating has been extensively investigated; however, the research on the optically tunable circular Dammann grating has received less attention and reports on this subject have been insufficient in the past decade. In this paper, three-order and eight-order binary-phase liquid crystal circular Dammann gratings with two mutually orthogonal photo-induced alignments in every two adjacent alignment domains, fabricated by a micro-patterned liquid crystal polymer phase mask, are proposed to generate annular uniform-intensity patterns in the far field. A simple maskless optical tuning of an eight-order liquid crystal circular Dammann grating is demonstrated by controlling the polarization of an ultraviolet light as well as the energy dose. The proposed liquid crystal circular Dammann gratings with high efficiencies and desirable uniformities exhibit outstanding optical as well as electrical tunabilities, enabling the widespread prospective applications in adaptive photonic chips stimulated flexibly by only light or by the combination of light and electric field.

P-150: Tunable Liquid Crystal Lens by Spatially Controlling of Pretilt Angle

Stacked alignment layer (SAL) with both vertical and horizontal alignment materials are used to control the liquid crystal (LC) pretilt angle. When one alignment material in SAL is photoalignable, the pretilt angle can be controlled by UV exposure dosage. A tunable LC lens is achieved by exposing the SAL under UV laser.

P-124: Study of stacked alignment layers on a single substrate with spatial liquid crystal pretilt angles and its applications

In this paper, we report recent developments in stacked alignment to generate spatially varying liquid crystal pretilt angles. This is a nanostructure alignment surface that can be produces any pretilt angle on a single substrate. The pretilt angles profile can be controlled. An electrically tunable liquid crystal lens using such nanostructure alignment surface is demonstrated

Stereoscopic three-dimensional display with a fast-response liquid crystal polarization rotator

A stereoscopic three-dimensional (3D) system using a polarization rotator is proposed. The polarization rotator converts the polarizations of images from different eyes in temporal multiplexing. A novel fast nematic liquid crystal mode is also proposed. The new liquid crystal mode has a fast response time and a high contrast, and is thus a good candidate as a polarization rotator. The proposed 3D system uses only passive polarized glasses, which are more convenient, lightweight, and low-cost than what? In addition, the polarization rotator can be applied to current two-dimensional displays and can become 3D-capable displays.

41.4: Discontinuous alignment thin-film formation by self-organized dewetting

A new discontinuous alignment layer is developed. The formation of such discontinuous structure is created by self-organized dewetting. Different dewetting mechanisms have been investigated. Such a discontinuous alignment layer can be fabricated on top of a continuous alignment layer. This heterogeneous surface for liquid crystal alignment can be used to produce arbitrary pretilt angles for the liquid crystal cell. Experiments using photo-aligned polymer have been done to verify the dewetting theory. The alignment layers thus produced are proved to be robust. Moreover, the dewetting step is a fully controllable process and is compatible with existing manufacturing techniques.