| 摘要 |
A multi-beam scanning device is disclosed that is able to realize a stable and small beam spot and realize stable scanning line intervals between plural light beams. The multi-beam optical scanning device includes a first optical system which has a first lens for coupling the light beams from the light sources, and a second lens which is an anamorphic element having power at least in a sub scanning direction and for guiding the light beams from the first lens to the deflection unit; and a second optical system. At least the second lens includes a diffracting surface having power. Magnifications of the whole optical system in a main scanning direction (betam 0 ) and in a sub scanning direction (betas 0 ), and a magnification of the second optical system (betas 2 ) in a sub scanning direction satisfy |betam 0 |>|betas 0 |, and |betas 0 |>|betas 2 |, and the power of the diffracting surface of the first lens in the main scanning direction (P 1 m), that in the sub scanning direction (P 1 s), and the power of the diffracting surface of the second lens in the sub scanning direction (P 2 s) satisfy |P 2 s|>|P 1 m| and |P 2 s|>|P 1 s|.
|
