SCANNING OPTICAL SYSTEM, OPTICAL SCANNER EQUIPPED WITH THE SAME, IMAGE FORMING APPARATUS AND LENS USED FOR SCANNING OPTICAL SYSTEM THEREOF

摘要

PPROBLEM TO BE SOLVED: To provide a scanning optical system having a superior optical characteristic and easily being manufactured, an optical scanner equipped with the scanning optical system, an image forming apparatus and a lens used for the scanning optical system of the image forming apparatus. PSOLUTION: The scanning optical system is provided with a deflector which deflects a luminous flux from a light source and a lens for focusing the light from the deflector onto a face to be scanned, wherein the scanning lens is provided at least having one diffraction face. The scanning optical system satisfies the Expression (1), lossSBMAX/SB0.005, where lossSBMAX/SBis given by Expression (2): (h/p)tanθ when the power of the diffraction face is positive, and on the other hand, given by the maximum value of Expression (3) (h/p)tanθ' in a scanning range, when the power of the diffraction face is negative. PCOPYRIGHT: (C)2008,JPO&INPIT