Advancing plenoptic / lightfield imaging for optical diagnostics

在学术和工业应用中，流体运动、空气动力学和微尺度流动的实验研究现在由数字技术主导。摄像机被用来拍摄注入流体的示踪粒子的图像，以跟踪它们的运动，推断流体的运动。这项基于粒子图像测速（PIV）和粒子跟踪测速（PTV）的技术在过去30年里得到了发展，现在甚至可以与最详细的计算机模拟兼容。重要的是，这些实验技术包括所有的流动问题的物理。然而，它们可能很昂贵，并且需要大量的专业知识来设置和操作。

Experimental research into the motion of fluids, aerodynamics and microscale flows in academic and industrial applications is now dominated by digital techniques. Cameras are used to take images of tracer particles seeded into the flow to track their movement, inferring fluid motion. This technology, based on particle image velocimetry (PIV) and particle tracking velocimetry (PTV) has been developed over the last 30 years to a point where it is now compatible with even the most detailed computer simulations. Importantly, these experimental techniques include all of the physics of the flow problem. However, they can be costly and require significant expertise to set up and operate. _A new approach to collect images of particle locations over three dimensions (3D) from a single camera will be researched, investigated and developed, as part of my continuing research program developing optical instrumentation. It is based on collecting the entire light field seen by the camera, not just what is brought into focus by the main lens. Termed light-field or plenoptic imaging, the camera has a microlens array in front of the sensor that allows small angle perspective viewing of particle locations. In many ways, this is similar to how insects with compound eyes view the world. This type of imaging system, using only a single camera, promises to be significantly easier to install and setup in a flow system, especially where viewing access is limited. It will also allow, for the first time, realistic measurement of three-dimensional flows at the microscale such as the flow in porous media and microscale biological flows where perspective viewing is extremely limited. The evaporation of a water droplet on a surface, which has received much academic interest and is extremely challenging within which to take measurements, will be used to test the limits of the technique and theory of its use. The program will continue to develop this type of camera system for experimental use by addressing a number of fundamental question for which there is limited research available in the literature. These include developing a general calibration procedure, a general optical model based on ray tracing to describe the imaging process, processing of image data to define objects in 3-D space and advanced approaches based on PTV and numerical models of particle motion to provide high-quality flow measurement. Being able to collect high quality data at the microscale flows, for which there are currently limited approaches, will have significant impact both in academia and industry, allowing understanding of the nature and science of important problems such as diffusion and evaporation. The program will also train students in the areas of mechanical engineering, optical instrumentation and fluid mechanics, developing new knowledge and science. Students will work in a professional environment, receiving supplementary training making them highly sought after by industry and academia.