Extreme volumetric imaging using single-shot optical tomography with compressive sensing

3D成像的标准方法通常依赖于拍摄一系列连续的2D图像并重建3D体。这对可实现的体积帧率设置了上限，因为单独记录单个2D图像需要一定的时间。该项目旨在开发一种成像平台，通过使用经济高效的高速摄像机并行获取多幅图像，能够以每秒超过1000幅的采集速率进行全3D体成像。该方法基于使用4台帧率超过每秒1000帧的高速摄像机。以前，能够以如此高的帧率运行的相机价格昂贵，但最近技术的进步使其价格大幅下降，使其与更标准的科学相机的成本一致。每台相机都将与一种新型光学系统相结合，该系统在相机传感器上产生两幅并排的图像，每幅图像都以略微不同的角度观察样品。四台摄像机将放置在样本周围，以每秒1000帧的速度同时从不同方向获取8张图像。每组8幅图像可以组合起来重建3D场景，产生每秒运行1000个体积的3D数据集。摄像机的具体布置和重建方法将取决于被成像的样品。在这个项目中，我们将把这种极端体积成像系统应用于两个实验研究。为了对半透明生物样品成像，将应用一种类似于x射线计算机断层扫描的技术，称为光学投影断层扫描（OPT）。虽然典型的OPT数据集需要100张角度分辨率的图像，但通过应用先进的计算分析技术，我们将能够从获得的8张图像中重建体积。这将允许未固定（例如无需麻醉）的样品的OPT成像，并且可以在3D中测量非常快速的生物过程，例如瞬态细胞信号事件。虽然高速摄像机在生物成像中的使用受到限制，但它们已被常规用于流体动力学实验，以捕捉非常快的事件（例如液滴表面相互作用）。我们将通过同时从八个不同的方向对它们进行成像，并对每组图像进行3D重建（即以每秒1000s的体积运行），将其扩展到这种相互作用的全3D成像。对于单个液滴的相互作用，我们将采用表面测量和重建技术，而对于喷雾（即大量液滴），我们将采用粒子跟踪和光学散射来量化所有液滴的轨迹和大小。这些实验将用于确认和发展计算流体动力学模拟。

Standard approaches to 3D imaging typically rely on taking a series of 2D images one after another and reconstructing the 3D volume. This puts an upper limit on the volumetric frame rate achievable, since it requires a certain amount of time to record the 10s-1000s of individual 2D images separately. This project aims to develop an imaging platform capable of full 3D volumetric imaging at acquisition rates exceeding 1000 volumes per second by acquiring multiple images in parallel using cost-effective high-speed cameras.The approach is based on the use of 4 high-speed cameras capable of frame rates in excess of 1000 frames per second. Previously, cameras that could operate at such high frame rates were prohibitively expensive, but recent advances in the technology has seen their price reduce significantly and brought them in line with the cost of more standard scientific cameras. Each camera will be combined with a novel optical system that produces two side-by-side images on the camera sensor, each viewing the sample at a slightly different angle. The four cameras will be placed around the sample and acquire eight images from different directions simultaneously, running at 1000s of frames a second. Each set of 8 images can them be combined to reconstruct the 3D scene, producing a 3D data set running at 1000s of volumes per second.The particular arrangement of the cameras and the approach to reconstruction will depend on the sample being imaged. In this project we will apply this extreme volumetric imaging system to two experimental investigations. To image semi-transparent biological samples a technique analogous to X-ray computed tomography, called optical projection tomography (OPT), will be applied. While typical OPT data sets require 100s of angularly resolved images, by applying advances computational analysis techniques we will be able to reconstruct the volume from the eight images acquired. This will permit OPT imaging of samples that have not been immobilized (e.g. no need for anesthesia) and can measure very fast biological processes in 3D, such as transient cell signaling events.While the use of high-speed cameras has been limited in biological imaging, they have been routinely used in fluid dynamics experiments to capture very fast events (e.g. droplet-surface interactions). We will extend this to full 3D imaging of such interactions by imaging them from eight different directions simultaneously and performing 3D reconstructions for every set of images (i.e. running at 1000s of volumes per second). For single droplet interactions we will employ surface measurement and reconstruction techniques, while for sprays (i.e. large number of droplets) we will employ particle tracking and optical scattering to quantify the trajectories and size of all the droplets. These experiments will be used to confirm and develop computational fluid dynamic simulations.