Patent ID: 6856438

Claim:
An optical scanning lens used in a multi-beam scanning optical apparatus that scans a recording surface with multiple scanning beams that form light spots running on the recording surface, the optical scanning lens comprising: an incident surface configured to input said multiple scanning beams; and an output surface configured to output said multiple scanning beams to said recording surface, wherein said optical scanning lens having an uneven refractive index profile, and satisfying a formula (m−1)×PLs×V/WLs≦2.3×10 −6 , where m is a number of light emission points of a light source providing light for forming said multiple scanning beams, PLs is a pitch of main light rays of the multiple scanning beams in a sub-scanning direction on the incident surface of the optical scanning lens, V represents the refractive index profile of the optical scanning lens, W [mm] represents an effective recording width of the recording surface, within which the light spots scan, and WLs represents an effective range of the optical scanning lens in a sub-scanning direction corresponding to the effective recording width W.