(4) one of the principal rays of the incident beam and the principal ray of the scanning beam travels on one of the upper and lower side of the optical axis L of the first and second scanning lenses 61 and 62, and the other travels on the other side in the sub-scanning section, in...
(4) one of the principal rays of the incident beam and the principal ray of the scanning beam travels on one of the upper and lower side of the optical axis L of the first and second scanning lenses 61 and 62, and the other travels on the other side in the sub-scanning section, in...