A laser source emits a laser beam having a peak wavelength within the range from 800 nm to 820 nm. The laser beam emitted from the source passes through an illumination lens, and then impinges on a Grating Light Valve™. The light valve splits the laser beam into a multiplicity of light beams, modulates the multiplicity of light beams in response to image signals, and produces zero-order diffracted signal beams. The zero-order diffracted beams pass through an imaging lens, and are imaged on a recording medium wrapped on the surface of a drum.