Light-Field Camera for Fast Switching of Time-Sequential Two-Dimensional and Three-Dimensional Image Capturing at Video Rate

In this article, we propose a time-sequential switching light-field (LF) camera for an alternative image capture of the high-resolution two-dimensional (2-D) images and three-dimensional (3-D) LF elemental images as additional functionalities. For image data acquisitions of both the 2-D and 3-D LF imaging of moving objects at a video frame rate (or even higher frame rate up to approximately 1000 f/s), a polarization-dependent-switching microlens array (MLA) is implemented in the LF camera system instead of a conventional passive-type MLA. By controlling the incident polarization conditions using an electrically fast-switching liquid crystal layer, the imaging mode can be time-sequentially switched quite rapidly (switching times of approximately 220 and 290 μs for the mode conversions from the 3-D LF to the 2-D mode, and the reversal mode change, respectively). Using the elemental image sets sampled from the alternating time-sequential imaging results, either the directional-view images or depth-refocused images can be reconstructed and provided at a moving picture frame rate. The depth-refocused images are possible for a wide depth range from 25 to 350 cm. Directional views of 22 × 22 and 9 × 9 in portions can be reconstructed for the single-shot image capture and the time-sequential video-rate image capture, respectively.