PURPOSE: To obtain a pickup tube which can never be disturbed in its deflecting operation, while making it possible to manufacture a required outer tube on the inner wall of which a precise deflection electrode having no joint is formed, by repeating two times an exposure process by using a photomask on which a pattern of a semicircular deflection electrode is depicted.
CONSTITUTION: A deflection electrode pattern 4' slightly broader than a semicircle is depicted in the center part of a mask 4 by a phototype process while making a mask sheet 4 provided with the position adjusting marks in the required shape in the prescribed positions 10 and 10' outside the deflection electrode pattern 4' in the axial direction and in the positions 11 and 11' rotated by 180° (in case the mask 4 is rounded into the tubular shape) from said points respectively. Further, when forming a vacuum evaporated metal film 2 on the inner wall of a glass tube 1, the position adjusting marks 13 and 13' equally distant from the mask 4 are formed, the mask 4 is inserted into the glass tube 1 applied with photoresist 3 while the marks 13, 13' and the marks 10, 10' are made to coincide with each other before respectively being exposed. Next, the mask 4 is rotated by 180° and the marks 11, 11' and the marks 13, 13' are made again to coincide with each other before being exposed, and developed in order to obtain a required deflection electrode with no mask joint.
WATANABE KATSUMI
ENDOU TOORU
RINKU KK