Gradient pretilt angle alignment materials with different photosensitivity for tunable polarization‐independent self‐aligned liquid crystal lens

Abstract

Alignment of benzaldehyde materials with different photosensitivity thresholds, capable of changing the pretilt angles of nematic liquid crystal (LC) from 90 to 0 in a controlled manner under UV-B exposure, has been developed. Inhomogeneous exposure of uniform rubbed alignment layers allows the formation of a refractive index gradient inside the LC cell. The concept of tunable polarizationindependent self-aligned LC lens based on gradient pretilt angle alignment materials with different photosensitivity is demonstrated. Self-alignment of two polarization-dependent sub-lens is achieved due to a single exposure act of two alignment layers, which are located on the same piece of glass on both sides, forming one common optical axis for a polarization-independent LC lens. The sublens cells have uniform cell gap and are independently controlled using lowvoltage driving. Devices based on gradient benzaldehyde alignment materials can be used in many modern optical and photonic devices.

Q&A of liquid crystal alignment: theory and practice

“…Such LTAMs, achieved through the careful designing of polymer chemistry (Bezruchenko et al, 2016), can provide gradient alignment conditions tuning from VA to PL through light exposure control. The main application of pretilt angle gradient alignment materials is the fabrication of polarizationindependent liquid crystal lenses (Bezruchenko et al, 2021) and LC lens arrays (Figure 5) (Muravsky et al, 2022).…”

54.3: Invited Paper: Surface Control of LC Alignment for Creation of Liquid Crystal Lenses Arrays

“…The advanced surface control of liquid crystal alignment conditions of novel alignment layers with tunable pretilt angle through light exposure [1] opens up technological process for fabrication of liquid crystal lens system [2] by generation of predefined parabolic gradients of pretilt angle [3]. The photosensitive orienting layer is subjected to local irradiation with a parabolic UV-B radiation intensity distribution profile, forming the lens aperture in the LC layer, by changing the pre-tilt angle on the surface from 90° to 0°.…”

Nematic Structures under Conical Anchoring at Various Director Tilt Angles Specified by Polymethacrylate Compositions

“…For example, electrically-induced switching between twisted and untwisted nematic structures occurs under tilted boundary conditions ( ) ( Figure 1 c) [ 4 ]. The electro-controllable lenses [ 5 , 6 , 7 ] and the phase gratings [ 8 , 9 , 10 , 11 ], the chiral nematic structure with the tilted homogeneous orientation of helicoid axis [ 12 ], Q-plates with different topological characteristics [ 13 ], and other superstructures of cholesteric [ 14 ] are created by the assignment of the specific azimuthal and polar director orientation on the substrates. There are some methods to assign the required boundary conditions.…”