| 摘要 |
PURPOSE:To make a titled prism applicable to optical function parts which require high accuracy, by constituting it so that a reflection film is not provided on its Dach-surface constituting a 90 degree edge angle part, and the reflection film is provided on only the front reflection surface. CONSTITUTION:A penta-prism 1 has 8 planes such as a bottom part incident surface 1a, Dach-surfaces 1c and 1d constituting a 90 degree edge angle part 1b, a front reflection surface 1e, a front upper inclined surface 1f, both left and right side surfaces 1g, 1h, and an exit surface 1i, and is formed in the shape of a pentagonal roof. Among these surfaces, 3 planes of the Dach-surfaces 1c, 1d, and the front reflection surface 1e are reflection surfaces having a function for reflecting an optical image, and among these reflection surfaces, no reflection film is provided on the Dach-surfaces 1c and 1d constituting the 90 degree edge angle part 1b, and on only the front reflection surface 1e for receiving a reflected optical image which has been made incident from the side A shown in the figure and has been reflected by the Dach-surfaces 1c, 1d, and reflecting it in the direction B shwon in the figure, a reflection film 2 consisting of aluminum, silver, etc. is provided by means of vapor-deposition and spattering. |
