Patent ID: 7218434

Claim:
An optical scanning apparatus comprising: light source means; deflecting means; a first optical system for guiding a light beam emitted from the light source means to the deflecting means; and a second optical system for guiding the light beam reflected and deflected by the deflecting unit to a surface to be scanned through reflecting unit including n (n is an integer equal to or larger than 1) reflecting members, wherein the following conditions are satisfied: 70< Fno main , and (0.004/ S min)× n< 0.03 where Fno main (mm) is the F-number in a main scanning cross section of an exit side of the second optical system, and Smin (mm 2 ) is the smallest beam area among beam areas on reflecting surfaces of the n reflecting members on which the light beam is reflected during traveling on the optical axis of the second optical system.