| 摘要 |
PURPOSE:To provide the strength of a lens against vibration and obtain a high resolution, by fixing either a top or bottom pole piece of the pole piece assembly unit formed as an integral unit to a magnetic path and floating the other piece from the magnetic path. CONSTITUTION:A top pole piece 1 is firmly held between an inside protruding part 15a constructed in the central part of a magnetic path spacer 15 formed as an integral unit with the first magnetic path by the method of welding and a pole piece retainer 4. To place a bottom pole piece 2 floating from the magnetic path including a pole piece spacer 3, a gap is provided between the bottom pole piece 2 and an inner magnetic path 8. In this consitution, a change of relative position between the top and bottom pole pieces can be eliminated. |
