Communication optical system and free-space optics communication apparatus

Abstract

A communication optical system in accordance with an aspect comprises a light source; a light-receiving element; a first and a second prisms, which are cemented to each other; and a beam-splitting member, which performs one of transmission and reflection towards an incident and emergent port, of a first light beam from the light source, and performs one of reflection and transmission towards the light-receiving element, of a second light beam from the incident and emergent port. The beam-splitting member is arranged at a cemented portion of the first prism and second prisms, and the light source and the light-receiving element are arranged on the same side with respect to the first and second prism. The second prism comprises a first surface cemented to the first prism, a second surface which is parallel to the first surface and a third surface disposed on the opposite side of the first surface with respect to the light source. The third surface is arranged non-perpendicularly to an optical axis of the first light beam extending from the light source to the beam-splitting member and is arranged non-parallel to an incident surface of the first prism on which the first light beam is incident. The third surface does not contribute to a sending or receiving function of the communication optical system.

1 . A communication optical system comprising: 
 a light source;    a light-receiving element;    a first and a second prisms, which are cemented to each other; and    a beam-splitting member, which performs one of transmission and reflection towards an incident and emergent port, of a first light beam from the light source, and performs one of reflection and transmission towards the light-receiving element, of a second light beam from the incident and emergent port,    wherein the beam-splitting member is arranged at a cemented portion of the first prism and second prisms, and the light source and the light-receiving element are arranged on the same side with respect to the first and second prisms;    wherein the second prism comprises a first surface cemented to the first prism, a second surface which is parallel to the first surface and a third surface disposed on the opposite side of the first surface with respect to the light source;    wherein the third surface is arranged non-perpendicularly to an optical axis of the first light beam extending from the light source to the beam-splitting member and is arranged non-parallel to an incident surface of the first prism on which the first light beam is incident;    wherein the third surface does not contribute to a sending or receiving function of the communication optical system.    
   
   
       2 . A free-space optics communication apparatus comprising: 
 the communication optical system according to  claim 1;     a driving circuit modulating the light source in accordance with communication information; and    an output circuit outputting a signal from the light-receiving element.