A mirror is a reflective surface that forms the image of an object when light fall upon it. Usually mirrors are made of plate glass, one side of which is coated with metal or some special preparation to serve as a reflecting surface. The junction of this reflecting surface and the plate glass is called the mirror line. Highly polished metal and other materials also serve as mirrors. Fused silica is used for applications that require high precision because of its very low thermal expansion.The typical mirror types that Photop offers are dielectric and metal coating high reflection mirrors.