| 摘要 |
In an optical output device wherein a beam of light is generated and focused to a spot upon an image plane, such as a photoreceptor in a xerographic printing apparatus, an method for controlling the position of the spot in the slow scan direction of the image plane including the steps of generating a beam of light, deflecting the beam of light by way of an optical beam deflecting element such t hat the optical beam deflecting element deflects the path of the beam of light by an amount that is determined by the wavelength of the light beam, and varying the wavelength of the beam of light such that the amount that the beam of light is deflected by the optical beam deflecting element is varied to achieve control of the position of the spot at which the beam of light is incident on the image plane i n the slow scan direction. The invention may be embodied in an apparatus which include s a light source capable of emitting the beam of light at a selected one of at lea st two selectable wavelengths and prism for refracting the beam of light an amount whic h depends on the wavelength of the beam of light, the amount of refraction determining the position of the spot in the slow scan direction on the image pla ne. The light source may be of the solid state laser type, and may emit a plurality of beams of light the spots from which may be individually or together selectively positioned in the slow scan direction on the image plane. The beam deflecting element may be a semiconductor prism, for example of AlGaAs, and have a controllable bias applied thereto to allow further control of spot positioning.
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