Novel Single-Camera Light Field Imager for Three-Dimensional Measurements

Typical optical setups for three dimensional measurements require several cameras which can be cost prohibitive or even impossible due to limited optical access or space requirements. One alternative is the use of a “plenoptic” or “light field” technique which allows three-dimensional imaging using a single camera by measuring both the spatial and angular information of collected light. These methods have previously been demonstrated for both tomographic PIV and scalar field measurements. Recently, an alternative light field technique has gained popularity in microscopy, dubbed “Fourier Light Field Microscopy” or FLFM the technique directly captures multiple perspective views. By using relatively few views the the angular information is sampled more sparsely which directly leads to higher spatial resolution compared to other plenoptic techniques. This method has been demonstrated for fluid mechanics with 3D molecular tagging velocimetry. Here we present a novel optical setup based on the principles of FLFM to be used for larger scales. With our setup we image a volume up to 14x14x4 mm with seven perspective views. The maximum angularity between views is 28 degrees which is sufficient to perform tomographic PIV with good quality. Directly capturing multiple views also allows the images to be easily split and treated individually so that existing tomography software designed for multiple cameras can be used. We process PIV images acquired with our setup using the commercial software DaVis and demonstrate that the reconstructed volume has low ghost particle intensity.