In order to obtain as much reflected light as possible, a layer of reflective film, including metal film and dielectric film, is often coated on the substrate. Commonly used materials for metal films are: aluminum, silver, and gold. Aluminum has high reflectivity from the ultraviolet region to the infrared region. At the same time, a layer of aluminum oxide can be formed on the surface of the aluminum, so the film layer is firm and stable. The silver film has high reflectivity in the visible and infrared regions, and the polarization effect introduced by changing the incident angle is also very small. Gold film has high reflectivity in the infrared region, and its strength and stability are better than silver film, so it is often used for infrared reflection. The metal film is soft and easy to be scratched and damaged, so a protective film is often coated on the metal film. The metal film mirror is not sensitive to the incident angle, it only needs to meet the geometric reflection conditions, and can be used in a relatively wide wavelength range.
Complaint
