A point of sale (POS) device, such as an optical scanner, reduces the beam diameters of two light beam components having been emitted from a common light source and split by an optical beam splitter. The optical scanner includes a light source emitting a light beam, a light beam splitter splitting the emitted light beam, a polygon mirror reflecting the split light beam components into mutually different directions, and groups of mirrors. The groups of mirrors are provided for each reading window, allowing the light beam components to be emitted therefrom. The emitted light beam components can then impinge on an object, whereupon the optical scanner detects by detectors and reads a bar code located on the object. The optical scanner also includes beam shaping devices, one of which is placed between the light source and light splitting device and the other of which is placed in one of the optical paths followed by one of the light beam components. Since the beam diameter of the light beam components are reduced, and since the light beams are emitted from multiple reading windows, bar codes with narrow spaces between the bars can be read more easily, even with varying orientations of the bar code on the object.