| 摘要 |
PURPOSE:To simplify the control work and assembly work of a transmitter in the case of exchanging a laser beam source by selecting the focal distance of a first lens, which converts a transmission light emitted from the laser beam source to the parallel beam, and the focal distance of a second lens, which condenses the reception light to a photodetector, in a prescribed relation. CONSTITUTION:An optical space transmitter 30 emits a transmission light LA1, which is modulated by a prescribed information signal, from a laser beam source 2A and converts it to the parallel beam through a lens 32A. The transmission light LA1 converted to the parallel beam is transmitted through a polarized beam splitter 6A and sent out to a transmission object while being transformed to the light equipped with prescribed spread through lens 8A and 10A. In respect to this light, a transmission light beam LA2 coming from the transmission object is converted to the parallel beam through the lens 10A and 8A, afterwards, reflected by the polarized beam splitter 6A and condensed upon the light receiving surface of a photodetector 16A by the lens 32A. Thus, information transmitted from the transmission object is detected. Focal distances f1 and f3 of lens 32A and 34A are set in the relation of the inequality. |
