| 摘要 |
PURPOSE:To provide a titled attenuator which is highly resistant to heat and has an exact shape in the radial transparent parts having equal central angles by providing a vapor-deposited mask for antireflection so as to form said radial transparent parts on a circular glass plate and changing the central angles between the transparent parts logarithmic-curvilinearly. CONSTITUTION:A vapor-deposited mask layer for antireflection 17 is formed on one surface of a circular glass plate 11 provided with a shaft mounting hole 12 at the center by vapor deposition of a chromium oxide film 20, a chromium film 21 and a chromium oxide film 22 in this order in such a way that many radial transparent parts 13, 14, 15, 16 having equal central angles are formed from the outside circumference 11' to an edge part 12'. The central angles theta1, theta2, theta3 located among the parts 13, 14, 15, 16 change from dense to coarse angles and from coarse to dense angles successively logarithmic-curvilinearly so that the curvilinear change satisfying the equation I is given. The thetax denotes the central angles located among the parts 13, 14, 15, 16 of the layer 17, and K denotes the constant expressed by density dB/the layer 17. The central angle of the mask layer and the central angles of the radial transparent parts are thus made extremely small, whereby the continuous change similar to the change in density is obtained. |
