Patent ID: 6185027
Filing Date: 2001-02-06
Classification: G02B,H04N

Abstract:
A monitoring optical system for a scanning optical device in which a laser beam emitted from a laser source is incident on a deflector through a first anamorphic optical system, such that the deflected laser beam is separated from the incident laser beam in a auxiliary scanning direction, and that the deflected laser beam is converged onto a drawing surface through a second anamorphic optical system that includes a correcting optical system for correcting an effect of skew of said laser beam; said monitoring optical system comprising:a monitoring anamorphic lens for converging a monitor beam that is separated from said deflected laser beam at a separation point between said deflector and said correcting optical system; anda monitoring sensor for detecting said monitor beam converged by said monitoring anamorphic lens, said monitoring sensor generating synchronizing signal when it detects said monitor beam;wherein a main meridian that indicates a direction of main refractive power of said monitoring anamorphic lens is inclined with respect to a z-direction on a plan perpendicular to said monitor beam so that wavefront aberration on said monitoring sensor is minimized, said z-direction being perpendicular to a scanning direction of said monitor beam on said plane.