| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical space transmission device which restrains a spherical aberration from being worsened, which restrains a light receiving optical system from becoming large-sized and high-cost, and which can enhance the directivity of the light receiving optical system. SOLUTION: A light receiving element 13 is arranged at a position which is defocused on the side of a light receiving optical system 12 from the focal position of the optical system 12. The focal position refers to the position at which a projection optical system 11 is installed at the most distant position from the optical system 12 in the specifications of a product. The defocused position refers to the position at which the spot diameter of a light beam becomes 75% of the diameter of an effective light receiving part in the light receiving element 13 when the light beam emitted from the optical system 11 is converged by the optical system 12. |
