Laser Written Liquid Crystal Devices for AR and VR Technology

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The aim of this project is to develop novel optical technology for Augmented Reality and Virtual Reality (VR/AR) applications by precisely machining polymer structures into liquid crystal (LC) devices. Two Photon Polymerisation Direct Laser Writing (2PP-DLW) is a laser processing technique that can be used to manufacture 3D structures in polymerizable resins at the micro/nanoscale. Traditionally, 2PP-DLW produces isotropic polymer structures where the properties of the material are dictated by the geometry of the structure. Instead, in this work a polymerizable liquid crystalline mixture will be used because the orientation of the LC molecules can be controlled by applying external electric fields, which can then be locked-in using the 2PP-DLW process. The laser writing technique will be used in this project to develop switchable optical devices such as diffractive elements. In VR/AR headsets, for example, diffraction gratings can be used to project images onto the eye. Switchable diffractive elements will allow small sections of the projected image to be turned on and off. This will improve the quality and tunability of the projected images, with a minimal effect on weight. This advancement is desired by industry leaders as it is a small, lightweight means of improving projection systems. Aberrations present a problem when performing the laser writing process in an LC device. Due to the refractive index mismatch between different layers of the device, the wavefront of the fabrication beam can become distorted, which changes the shape of the focal volume. In general, fabrication is limited to LC materials without any top substrates. However, this project will use spatial light modulator technology to fabricate intricate structures within LC devices thus enabling higher precision. This project falls under the EPSRC's Engineering and Manufacturing the Future themes, and most closely aligns with the Photonic Materials, Light Matter Interaction and Optical Phenomena, Optoelectronic Devices and Circuits, and Optical Devices and Subsystems subthemes. The work will be undertaken with the support of Merck.