Patent ID: 8259379

Claim:
An optical scanning device, which scans a surface to be scanned by light, comprising: a light source; a coupling optical system, which changes light from the light source into approximately parallel light; a light control reflection member which is disposed in an optical path of the light from the coupling optical system, the light control reflection member defining a diameter of a beam of the light which scans the surface to be scanned, and reflecting a part of the light which is not used for the scanning toward the coupling optical system, the light control reflection member includes a light transmission section which transmits incident light, and a light reflection section, different from the light transmission section, which reflects the incident light, an entrance face of the light reflection section includes a reflection diffracting face; and a light detector which receives the light reflected by the light control reflection member via the coupling optical system, wherein the light transmission section comprises an opening, and the light transmission section and the light reflection section are both part of a single structure which is the light control reflection member.