Patent ID: 7187449

Claim:
A light-receiving/emitting composite unit comprising: a light source for emitting light; a polarizing beam splitter for splitting the light emitted from the light source into two light beams having different polarized components, then radiating the two light beams to an external optical system, and combining the two light beams reflected from the external optical system to generate combined light; a phase plate arranged between the light source and the polarizing beam splitter and adapted for changing the polarization state of the light emitted from the light source and leading the light to the polarizing beam splitter; a plurality of light splitting means for splitting the combined light generated by the polarizing beam splitter into plural light beams; polarization means for transmitting only a predetermined polarized component of the split combined light; and a plurality of light-receiving means for photoelectrically converting coherent light transmitted through the polarization means and thus generating an interference signal, wherein each of the light-receiving means is dedicated to a respective light splitting means of the plurality of light splitting means.