Patent ID: 8031362

Claim:
An optical scanning device for scanning an object scanning surface with a light beam projected from a light source and traveling through an optical system, the optical scanning device comprising: a liquid crystal element configured to modulate a phase of the light beam, the liquid crystal element being driven by electric signals and provided on a light path of the light beam between the light source and the object scanning surface; the liquid crystal element generates power components which, according to temperature variations, vary by different amounts in a main scanning direction of the light path and a sub scanning direction of the light path to cause different amounts of displacement of beam waist positions, according to the temperature variations, in the main scanning direction and the sub scanning direction; the liquid crystal element includes a liquid crystal layer sandwiched by at least two transparent substrates and a seal member sealing the liquid crystal layer between the transparent substrates, the seal member separate from the transparent substrates and enclosing a seal area within a portion of a substrate area enclosed by the transparent substrates; the substrate area enclosed by the transparent substrates has a length “a” in the main scanning direction, a length “b” in the sub scanning direction, and an aspect ratio c=a/b, where c≠1; and the aspect ratio c is specified such that the amounts of displacement of beam waist positions, caused by the temperature variations in the main scanning direction and the sub scanning direction, correct amounts of displacement of beam waist positions resulting from optical components other than the liquid crystal element.