| 摘要 |
PURPOSE:To realize the usage of a reception circuit small in dynamic range, by expressing the radiation luminance emitted to the optical axis of a transmitter in a prescribed direction in a linear function. CONSTITUTION:The output light of a light emitting element 52 is modulated by a transmission circuit 51, and light to be modulated is converted to beams of light with a spread angle of 2beta t, and a part of them is shielded by a douser 11, and other transmitted light are propagated to a space as optical signals 3, and arrive at a receiver 5. Incident light to a light receiving element 56 in the receiver 5, after being converted to an electrical signal, is converted to a requested signal by the reception circuit 57. In such a case, as for the area of a shielding area for the area of effective diameter of the lens 53, when a light shielding ratio arrives at about 0.5, linear relation is established between an angle D (mrad) and the radiation luminance P(theta) in an area of ¦theta¦<=beta t. |
