Patent ID: 6639704
Filing Date: 2003-10-28
Classification: G02B

Abstract:
A scanning optical apparatus comprising:incident optical means for causing at least one light beam emitted by light source means to be incident on deflection means; image forming means, having at least one diffraction surface, for forming an image using the at least one light beam reflected and deflected by the deflection means on a surface to be scanned; and limiting means, inserted in an optical path between the at least one diffraction surface of said image forming means and the surface to be scanned, for limiting unnecessary diffraction light of an order different with respect to an order of diffraction light used to form a spot on the surface to be scanned from the diffraction light diffracted by the at least one diffraction surface of said image forming means, wherein a condition: 4&lE;m/n&lE;7 is satisfied, where n represents the order of the diffraction light used and m represents the order of the unnecessary diffraction light.