Abstract: An active three-dimensional imaging system for optical apparatus includes a relay lens subsystem with an off-axis rotating aperture placed between an imaging or objective lens and an image recording device such as a CCD camera. According to another aspect, the imaging system can include an off-axis rotating aperture located between field and aperture diaphragms of an illumination subsystem. The rotating aperture allows adjustable non-equilateral spacing between images of out-of-focus object points to achieve higher spatial resolution, increased sensitivity and higher sub-pixel displacement accuracy than other systems.