Two-way line monitor

摘要

A two-way line monitor has a signal beam splitter, first and second optical sensors and a mirror. The beam splitter is positioned on the light axis and angled so as to receive first and second input lights at 20 to 40 degrees of the angle of incidence. The first and second optical sensors arranged so as to receive first and second sample lights, reflected from the beam splitter and the mirror, at around 20 degrees of the angle of incidence.