US Patent 7673996 Image projection apparatus and image projection system

An image projection apparatus includes: an imaging portion that takes an image of an object; an optical element that is disposed halfway on an optical path between the object and the imaging portion, and that branches the optical path; a projection portion that projects image light onto the object through the optical element; a dust prevention cover that includes an opening on an optical axis between the object and the optical element, and that covers at least the optical element to protect the optical element from dust; and a transparent dust prevention member that is provided in the dust prevention cover to close the opening, and that has a reflection surface preventing reflection light, which is obtained by receiving the image light from the projection portion and reflecting the image light, from being incident on an entrance pupil of the imaging portion.