| 摘要 |
PURPOSE:To improve reception efficiency by transmitting light from a light- emitting element and a light-receiving element as linear polarized light in one polarization direction and inputting received light to the light-receiving element as linear polarized light in the direction of another polarization. CONSTITUTION:When LD(laser diode) is used for the light-emitting element 1 (vertical direction on paper surface is set to direction of thetart. angle in such a case), most (99.9%) of the light signals pass through a polarization beam splitter 3 as they are, are set to be parallel beams in a lens 5 and are transmitted. On the other hand, most (99.9%) of the received light beams (which are set so that polarized surface differs from transmission light by 90 degrees and which are deflected in the vertical direction as against the paper surface) are reflected on the polarized beam splitter 3 in an upper direction add are inputted to a photodetector 2. Thus, efficient transmission/reception are realized and a light-emitting state is stabilizer since most of the reception light beams do not enter the light-emitting element 1. |
