| 摘要 |
PURPOSE:To change directivity approximately into nondirectivity by installing a photodiode and a prism, the whole of which is formed in an annular or truncated cone shape and a cross section of which is formed in an approximately triangle, mounting the prism on the light-receiving front of the photodiode and projecting signal light to the photodiode through the prism from the direction separate from the front axis of the photodiode. CONSTITUTION:A photodiode 1 is set up so that the direction theta=0 deg. of a front axis thereof crosses at a right angle with a cabinet 30 and the photodiode is directed to the outside. A prism 50 corresponding to a prism PRSM is fitted on the front of the light-receiving surface 1R of the photodiode 1. The whole of the prism 50 is formed in an annular shape by a transparent acrylic compound while a cross section thereof is formed in a triangle. An optical filter 60 is fitted on the front of the prism 50. Accordingly, directivity can be acquired in all cross sections including the front axis, thus using characteristics, in which the photodiode is rotated centering around the front axis, as overall directivity. |
