Patent ID: 6097421
Filing Date: 2000-08-01
Classification: G02B

Abstract:
A scanning optical system for scanning a scanning surface with a light beam emitted from a light source to form an image thereupon by means of a deflector and an imaging lens, comprising:a first lens unit included in said imaging lens; anda second lens unit included in said imaging lens and including an aspherical lens having, in a scanning direction in which the light beam is deflected by said deflector, no refractive power and having, in a traverse direction perpendicular to said scanning direction, refractive powers that vary asymmetrically between upstream and downstream sides of a scanning path along the scanning direction with respect to an optical axis direction of said first lens unit,wherein a magnification in the traverse direction perpendicular to the scanning direction in which the light beam is deflected by the deflector is approximately constant for both axial rays and off-axial rays in the scanning direction for any light beam deflected by said deflector irrespective of a deflection angle, and is within a range defined by a conditional expression:0.5.ltoreq..beta.s.ltoreq.2.0where.beta.s: magnification in the traverse direction of the scanning optical system as a whole.