Super-resolution optical element for use in image forming apparatus

An optical system comprising:

• means for uniformly passing a light beam therethrough;
• and
• phase-changing means formed on part of the passing means and having a reflectance differing from that of the passing means, for changing the phase of that part of the light beam which passes therethrough;
• wherein the phase-changing means changes the reflectance by absorbing the part of the light beam to be reflected therefrom.

An image-forming apparatus comprising:

• means for generating a light beam;
• means for deflecting the light beam toward an image bearing member generated from the generating means;
• and
• means for changing characteristics of the wavefront of part of the light beam, so as to split the wavefront of the light beam, and to change the beam spot size of the light beam on the image bearing member by deviating the phases of light beam components.

An optical system comprising:

• means for uniformly passing a light beam therethrough;
• and
• phase-changing means formed on part of the passing means and having a refractive index differing from that of the passing means, for changing the phase of that part of the light beam which passes therethrough;
• wherein the phase-changing means includes means for changing the phase of the part of the light beam passing therethrough to deviate by .pi.+2n.pi. measured in radians from the phase of the other part of the light beam passing through the remaining part of the passing means.