| 摘要 |
PROBLEM TO BE SOLVED: To reduce parts and processes and to easily perform optical axis adjustment by adding an airtight sealing function to a prism and fixing a lens to the outside of an airtight space of a case inside. SOLUTION: In an optical signal receiving module arranged so that their positional relation between an optical fiber 1 and a photodetector 8 is that the central axis of the optical fiber 1 is orthogonally intersected with a perpendicular from the light receiving surface center of the photodetector 8, a prism 9 is a triangular pillar for connecting an optical signal converged by the lens 7 to the light receiving surface of the photodetector 8, and a total reflection film is vapor deposited on a side surface 17 except a light incident surface from the lens 7 and a light outgoing surface to the photodetector 8 among three pillar side surfaces. Input/output terminals and a case 4 with an optical signal passing hole fix directly or indirectly the photodetector 8. A cover 6 airtight seals the inside of the case 4. The prism 9 is airtight fixed to the optical signal passing hold, and the airtight sealing function is added to the prism 9, and the lens 7 is fixed to the outside of the airtight space in the case 4 inside.
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