Patent attributes
An optical element includes a prism and a light blocking member. The prism has a first surface, a second surface and a third surface. The first surface is connected to the second surface. The third surface is connected between the first and second surfaces and opposite to a light valve of a projection device. The first surface reflects an image light beam from the light valve to allow the image light beam to pass through the second surface. The light blocking member is disposed on the prism and includes a first light blocking portion and a second light blocking portion adjacent to each other. The first light blocking portion shields a part of the first surface adjacent to the second surface, and the second light blocking portion shields a part of the second surface adjacent to the first surface. A projection device using the optical element is also provided.