Rotary polyhedral mirror

Abstract

Abstract PURPOSE:To improve reflectivity as well as speed for recording and reading out an information signal by forming an even number of protective layer of >=2 kinds of materials on the reflecting surface of a rotary polyhedral mirror. CONSTITUTION:An Al reflecting film 14 and a low refractive film 16 as a protective film are formed on the circumferential surface 13 which is the reflecting surface of a rotary polyhedral mirror body 11 having the surface subjected to an electroless Ni plating treatment. A high refractive film 17 which is the 2nd protective film is formed on the film 16. The film 16 is formed of SiO2 (refractive index n=1.45) and the film 17 of TiO2 (n=2.3). Such mirror has 95-97% reflectivity and is provided with the high reflectivity by the interference effect of light between the multiple layers. Since the film of the uppermost layer is of TiO2, the film is hard and is resistant to scratching on the surface.

Inventors

• 👤 Rokuro Watabe
• 👤 渡部　六郎

Bibliographic Details