An optical system that can add an optical depth information to a two-dimensional image (72) represented by substantially collimated light, e.g. by using a collimated light source in front of a LCD display. The optical system includes a first array of optical lenses (70) arranged at a first distance in front of the two-dimensional image (72), and a second array of optical lenses (71) arranged at a second distance in front of the two-dimensional image (72), the second distance being larger than the first distance. Optical properties, e.g. focal length, can be adjusted for the optical lenses of the first and second array of optical lenses (70, 71) in response to the optical depth information. The optical system can serve as an optical front for 3D multiview displays. Depending on embodiment, both horizontal and vertical angular resolution can be obtained, and the front end exhibits only a small brightness loss.