Abstract: A laser-beam printer having a drum with a photoconductive surface, and an optical system which includes a laser source generating a laser beam and an optical deflector for deflecting the laser beam over a predetermined angular range. The photoconductive drum surface is scanned by a linear sweep of the laser beam and thereby given an electrostatic image pattern to be transferred onto a recording medium. The optical deflector includes a single substrate which has a waveguide formed therein for guiding the laser beam, and a deflector portion provided on the substrate for deflecting the laser beam which is propagated through the waveguide, so as to cause the laser beam to scan or sweep the photoconductive surface of the drum over the predetermined angular range.