Patent ID: 6624837
Filing Date: 2003-09-23
Classification: B41J,G02B

Abstract:
A scanning optical element for receiving a scanning light beam deflected to scan by a deflecting system and converging the received scanning light beam on a surface to be sscanned such that a beam spot moving in a main scanning direction is formed on the surface to be scanned,said scanning optical element comprising a light transmitting material, said scanning optical element having a first surface that allows the received scanning light beam to pass therethrough so that the scanning light beam proceeds in said scanning optical element, and a second surface that reflects the scanning beam proceeding in said scanning optical element and directs the scanning beam toward said first surface, said first surface having a first intersection point with a first reference plane, said second surface having a second intersection point with a second reference plane, said first reference plane and said second reference plane being perpendicular to a predetermined axis, said first and second intersection points being on said reference axis, said first surface being an optical curved surface which is tangent to said first reference plane at said first intersection point, said second surface being expressed by a SAG amount defined by a two-dimensional polynomial having variables which are two-dimensional coordinates, in the main scanning direction and in an auxiliary scanning direction of the surface to be scanned, on said second reference plane, an origin point of said two-dimensional coordinates on said second reference plane being said second intersection point, coefficients for the two-dimensional polynomial defining said second surface being configured such that, a coefficient for a term having only a first order component with respect to the coordinates in the auxiliary scanning direction has a value other than zero.