| 摘要 |
PURPOSE:To ensure the application of a polyhedral mirror to the same optical system even with different numbers of mirror surfaces, by giving the mirror finish only to the using number of surfaces of a polyhedron and the resistive process to other surfaces respectively. CONSTITUTION:The mirror finish is applied to all of surfaces 11-112 for a polyhedral mirror 2 having 12 surfaces. While for another polyhedral mirror 3 having 12 surfaces, the mirror finish is applied to 6 surfaces 11, 13-111 with the required accuracy, and no process is applied to other surfaces with the resistive coating material applied to them. The mirror finish surfaces are distributed at exactly same positions to each other between the mirrors 2 and 3. As a result, these two mirrors can be interchanged with each other just by varying the processing speed of the device and the number of revolutions of these mirrors to cope with an optional number of scanning lines or density of the scanning lines. |
