Design and characterization of a varifocal camera system with an extended depth of field and focal range

This paper presents the design and characterization of a compact and affordable varifocal camera system. With its entrance pupil located in front as the first element for easy access, the camera system offers a working F/# as low as 2, is capable of focusing across a wide depth range from optical infinity to as close as 4 diopters through an electrically tunable lens, and maintains nearly constant angular magnification through the focus range by placing the focusing element at proximity to the entrance pupil. These unique features can find a myriad of applications such as image-based head-mounted display calibration and extended depth of field (EDOF) imaging. The paper further demonstrates a single-shot EDOF imaging function by utilizing its property of nearly constant angular magnification through focus scanning.