A 3D imaging system comprises a phase detection autofocus (PDAF) image sensor, a lens for imaging a cross-section of a 3D object on the PDAF image sensor and an actuator for driving the lens for focusing each cross-section of the 3D object on the PDAF image sensor. The actuator drives the lens until the PDAF image sensor identifies an image of a first cross-section of the 3D object in-focus and records the image of the first cross-section. The PDAF image sensor records images of subsequent cross-sections of the 3D object formed by the lens driven by the actuator on the PDAF image sensor. The recorded images of each cross-section of the 3D object are stacked to form a 3D image of the 3D object.