Optical element and a scanning optical apparatus using the same
AssigneeCanon Kabushiki Kaisha
InventorManabu Kato
Life of this patent
Estimating the term…
Abstract
An optical element and a scanning optical apparatus using the same capable of correcting for image plane re-positioning caused by internal distortion of the optical element, particularly, refractive index distribution caused by forming the optical element by plastic molding. The optical element has an internal refractive index distribution such that the focal length calculated based on the curvature of the plane thereof, the refractive index of the material, and the thickness along the optical axis, is shorter than the focal length actually measured. The element may be used in the scanning optical apparatus, may be provided with planes of different curvatures in a generating line and a line perpendicular thereto, and may be longer in the generating line.
Claims26
An optical element having a measurable focal length and comprised by an optical material having an internal refractive index distribution,
- wherein a focal length calculated based on a curvature of plane thereof, a refractive index of the optical material, and thickness along the optical axis, is shorter than a focal length actually measured.
A scanning optical apparatus comprising:
- light source means;
- deflector means for deflecting a light beam emitted from said light source means;
- a first optical element for receiving said light beam emitted from said light source means and forming the beam into a linear image extending in a main scan direction on a deflection surface of said deflector means;
- and
- a second optical element for receiving said light beam deflected by said deflector means to form a spot image on a scanned surface,
- wherein a Gaussian imaging plane in a subscan direction of said scanning optical apparatus is positioned between said deflector means and said scanned surface.
A scanning optical apparatus comprising:
- light source means;
- deflector means for deflecting a light beam emitted from said light source means;
- a first optical element for guiding said beam emitted from said light source means to said deflector means;
- and
- a second optical element for receiving said beam deflected by said deflector means to form a spot image on a scanned surface,
- wherein a Gaussian imaging plane in a subscan direction of said scanning optical apparatus is positioned between said deflector means and said scanned surface.
A laser printer apparatus comprising:
- light source means;
- deflector means for deflecting a light beam emitted from said light source means;
- a first optical element for guiding said beam emitted from said light source means to said deflector means;
- a recording medium;
- and
- a second optical element for receiving said beam deflected by said deflector means to form a spot image on the surface of said recording medium,
- wherein a Gaussian imaging plane in a subscan direction of said laser printer apparatus is positioned between said deflector means and the surface of said recording medium.
Dependencies are inferred from the claim text.