Patent ID: 8471883

Claim:
An optical comprising: a light source to emit a light beam; an optical element including a scan lens to convert the light beam into a desirable shape; a deflector to deflect the light beam to scan a photoreceptor with the light beam; a casing to house the light source, the optical element, and the deflector, the casing including an upper opening, walls including a transparent plate defining a deflector compartment to accommodate the deflector, and an optical element mounting portion to accommodate the light source and the optical element; and a first cover to cover the upper opening of the casing, the first cover including a recessed portion recessed toward the bottom of the casing, the recessed portion including a bottom surface that extends outward from the walls of the deflector compartment and includes a first opening facing the deflector, wherein the recessed portion of the first cover and the walls of the deflector compartment are directly or indirectly connected to define a single continuous space isolating the deflector compartment from the optical element mounting portion, and the recessed portion and the deflector compartment communicate via the first opening, and wherein the single continuous space includes the deflector compartment and an upper portion that is above the bottom surface of the recessed portion, and wherein the upper portion of the single continuous space above the bottom surface of the recessed portion has a volume that is greater than a volume of the deflector compartment and has a cross-sectional area, parallel to the bottom surface of the recessed portion, that is greater than a cross-sectional area, parallel to the bottom surface of the recessed portion, of the deflector compartment.