Light field technique for high-speed volumetric velocimetry

Doppler global velocimetry (DGV) is a flow measurement technique that offers significant advantages compared to common approaches like tomography and holography. In order to enable volumetric capability and large measurement rates the light field technique and a high-speed camera (frame rate up to 1 Mfps) are introduced to DGV, for the first time to our knowledge. A microlens array is placed in front of the camera sensor, which allows to reconstruct the light field and to refocus on different focal planes after image acquisition for each single image. As a key for designing the optical system, the depth-of-fields of the refocused image planes are determined at first by optical simulations using ZEMAX. As a result, the main challenge is to balance the complementarity between lateral and depth resolution as well as the refocusing range. The designed setup is validated by experiments.