Abstract: A projector includes a lamp for providing a light beam, a reflective case for receiving and fixing the lamp, a cover, an image engine, and a projecting lens. The reflective case has an opening for allowing the light beam to be emitted therefrom. The cover includes a transparent portion covering the opening of the reflective case and a sidewall connected to the transparent portion. The sidewall is connected to the reflective case via screw threads. The image engine is positioned to receive light output from the lamp and configured for superimposing spatial information on the light to form image. The projecting lens is configured for receiving the light output of the image engine.