Optical scanning device and image forming apparatus

An optical scanning device comprising:

• a light source;
• a deflector configured to deflect and scan a light beam emitted from the light source;
• an optical element configured to guide the light beam scanned by the deflector to a scanned member;
• a casing including a bottom surface on which the deflector and the optical element are mounted, and a side wall which stands from the bottom surface and on which the light source is mounted;
• and
• a fixing member configured to position the optical element to the casing and to fix an end portion of the optical element in a longitudinal direction of the optical element,
• wherein the casing, the optical element and the fixing member are made of resin,
• wherein the optical element includes an incident surface permitting incidence of the light beam deflected and scanned by the deflector, an emergent surface permitting emission of the light beam incident from the incident surface, a first crossing surface contacting the bottom surface in a state in which the optical element is fixed by the fixing member and crossing the incident surface and the emergent surface, and a second crossing surface crossing the incident surface and the emergent surface and opposite to the first crossing surface,
• wherein in a state in which the optical element is fixed to the casing by the fixing member, the casing includes a first contacting surface contacting the incident surface in the end portion of the optical element in the longitudinal direction, a side surface of an outside of the casing in the side wall, and a second contacting surface of an inside of the casing in the side wall,
• wherein the side surface includes a projecting portion projecting toward the outside of the casing, and
• wherein in a state in which the optical element is fixed to the casing, the fixing member includes a first portion including an engaged portion engaged with the projecting portion and extending in a direction toward the bottom surface, a second portion including a first surface contacting the second contacting surface and a second surface contacting the emergent surface and extending toward the bottom surface, and a third portion including a third surface contacting the second crossing surface and extending toward the bottom surface.