| 摘要 |
PURPOSE:To prevent any light from leaking, and carry out an accurate exposure of a pattern by providing a slit near the center of a light shielding plate, and attaching the said plate around the outer surface of an emission tube so that the entire outer surface is coated with the said plate. CONSTITUTION:A light shielding plate 20 is made of a stainless steel, and has a rectangular shape. A rectangular slit 21 is provided almost in the center of the plate 20. After the plate 20 is fixed over the entire outer surface of an emission tube 1, fine wires 22 are wound around both ends of the plate 20 so as to make the plate 20 to become in close contact with the emission tube 1. Light emitted from the luminous part of the tube 1 is discharged only forward from the slit 21. |
