| 摘要 |
PURPOSE:To improve the degree of optical coupling by providing a pressure ring which is inserted into a lens gripping part and fixed to the lens gripping part while making a lens abut on an end surface of a spacer tube. CONSTITUTION:The spacer tube 25 is inserted into a cylindrical holder 20 and the pressure ring 26 to be inserted into an end part of the lens gripping part 23 after the lens 3 is pressed in the lens gripping part 23 is in a ring shape made of, for example, stainless steel and provided on its outer peripheral surface with a couple of projection pieces 26b which project radially. Those projection pieces 26b are in slidable shapes which are fitted in respective slits 23a and while the ring part of the pressure ring 26 presses the lens 3 to make the lens 3 abut on the end surface of the spacer tube 25, the tips of the projection pieces 26b and the outer peripheral surface of the lens gripping part 23 are laser-welded or soldered to fix the pressure ring 26 to the cylindrical holder 20. Consequently, the optical axis of an optical fiber is aligned with the optical axis of the lens and the end surface of the optical fiber is positioned at the focal length of the lens, so that the degree of optical coupling is improved.
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