Liquid Crystal Technologies for Laser-based Imaging Applications

一个关键目标是为激光成像应用开发新的液晶（LC）技术，包括减少由激光形成的图像中空间变化干扰（散斑）造成的畸变。激光光源相干光的高亮度、方向性和宽色域使其成为许多应用（例如通信和成像）非常理想的资源。然而，这种相干性会产生一些问题，比如在图像中产生空间变化的干扰，这通常被称为散斑。成功去除这种斑点将使激光能够用于一系列生物医学、投影和头视显示技术。减少散斑的最常用方法是通过产生多个统计独立的散斑图案的装置。现有的设备通常使用移动的机械部件（例如磨砂玻璃扩散器）来散射光并产生统计独立的图案。然而，这种方法有尺寸、重量、功率和成本限制，限制了广泛使用。液晶（lc）是对抗散斑的潜在理想材料，因为它们的光学各向异性和对电场的响应的组合意味着它们能够产生部分去相关的散斑图案，而无需任何机械运动部件。这种设备有可能比现有设备小得多，并实现无振动解决方案，因此具有更广泛的商业适用性。该项目的一个目标是开发新的LC设备，以减少激光散斑在一系列不同应用中的出现，包括激光投影、生物医学成像和头视显示技术。对于确定的每个应用，将开发测试平台，并将最成功的LC设备纳入其中，以突出其商业影响。由来自Hadamard矩阵的相位掩模组成的优化设计将被认为是通过应用电场实现统计独立散斑图案的一种手段。该项目旨在使用激光书写的增材制造工艺在LC设备的不同层生产一系列不同的相位掩模，消除了移动机械部件的需要，因为不同的相位掩模将通过施加各种电场来访问。这种激光书写制造技术将用于探索和创造其他基于激光的光子学应用的潜在应用的替代LC器件。该项目属于EPSRC工程主题，并与光子材料，光物质相互作用和现象，光学器件和子系统，光电器件和电路子主题密切相关。

A key objective is to develop new liquid crystal (LC) technologies for laser-based imaging applications, including reducing distortion from spatially varying interference in images formed with lasers (speckle). The high brightness, directionality, and wide colour gamut of coherent light from laser sources makes it a very desirable resource for many applications (e.g., communications and imaging). However, this coherence can generate problems, such as a spatially varying interference in an image, which is commonly known as speckle. Successful removal of this speckle would enable lasers to be used in a range of biomedical, projection and head-up display technologies. The most common method to reduce speckle is via a device producing multiple statistically independent speckle patterns. Existing devices typically use moving mechanical parts, (e.g., ground glass diffusers) to scatter the light and produce the statistically independent patterns. However, such approaches have size, weight, power, and cost limitations that constrain widespread use. Liquid crystals (LCs) are potentially desirable materials to combat speckle as their combination of optical anisotropy and response to electric fields means that they are able to produce partially decorrelated speckle patterns without having any mechanically moving parts. Such devices have the potential to be much smaller than existing devices and achieve a vibration-free solution, therefore providing much wider commercial applicability. An aim of this project is to develop new LC devices that can reduce the appearance of laser speckle in a range of different applications including laser projection, biomedical imaging, and head-up display technologies. For each of the applications identified, testbeds will be developed, and the most successful LC devices will be incorporated to highlight their commercial impact. Optimised devises consisting of phase masks derived from Hadamard Matrices will be considered as a means to achieving statistically independent speckle patterns with the application of an electric field. This project aims to produce a range of different phase masks at different layers within a LC device using the additive manufacturing process of laser writing, removing the need for moving mechanical parts as different phase masks will be accessed by applying various electric fields. This laser writing manufacturing technique will then be used to explore and create alternative LC devices for potential applications in other laser-based photonics applications. This project falls within the EPSRC theme of Engineering and is closely aligned with the Photonic materials, Light Matter Interaction and Phenomena, Optical Devices and Subsystems, Optoelectronic Devices and Circuits sub-themes.