Patent ID: 8035678

Claim:
A light scanning apparatus, comprising: a scanner that scans a light beam from a light source two-dimensionally in first and second directions over an effective scan area to form an image in the effective scan area, wherein the scanner scans the light beam at a first scanning speed in the first direction and scans the light beam at a second speed slower than the first speed in the second direction which is different from the first direction; a light detector that detects light; and a light-introducing member which includes a reflection surface; wherein the light beam scanned by the scanner includes a first light beam which proceeds toward the effective scan area and a second light beam which proceeds toward outside the effective scan area, wherein the light-introducing member is positioned at a position where the second light beam includes within a width of the second light beam in a direction of the second direction an overlapping portion which overlaps an optical path of the first light beam and a non-overlapping portion which does not overlap the optical path of the first light beam, and wherein a partial light beam component of the second light beam in the non-overlapping portion is reflected by the reflection surface of the light-introducing member so as to introduce the partial light beam component to the light detector.