Laser Written Liquid Crystal Devices for AR and VR Technology

该项目的目的是通过将聚合物结构精密加工成液晶（LC）器件，开发用于增强现实和虚拟现实（VR/AR）应用的新型光学技术。双光子聚合直接激光写入（2 PP-DLW）是一种激光加工技术，可用于在微/纳米级的可聚合树脂中制造3D结构。传统上，2 PP-DLW产生各向同性聚合物结构，其中材料的性质由结构的几何形状决定。相反，在这项工作中，将使用可聚合的液晶混合物，因为LC分子的取向可以通过施加外部电场来控制，然后可以使用2 PP-DLW工艺锁定。激光写入技术将在本项目中用于开发可切换的光学器件，如衍射元件。例如，在VR/AR头显中，衍射光栅可用于将图像投射到眼睛上。可切换的衍射元件将允许投影图像的小部分被打开和关闭。这将提高投影图像的质量和可调性，对重量的影响最小。这种进步是行业领导者所期望的，因为它是改进投影系统的小而轻的手段。当在LC器件中执行激光写入过程时，像差存在问题。由于装置的不同层之间的折射率失配，制造光束的波前可能变得失真，这改变了聚焦体积的形状。通常，制造限于没有任何顶部基板的LC材料。然而，该项目将使用空间光调制器技术来制造LC器件内的复杂结构，从而实现更高的精度。该项目福尔斯属于EPSRC的工程和制造未来的主题，并最密切地配合光子材料，光物质相互作用和光学现象，光电器件和电路，光学器件和子系统的子主题。这项工作将在默克的支持下进行。

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.