DETECTOR FOR LASER IRRADIATION LIGHT

摘要

PROBLEM TO BE SOLVED: To simplify the mechanism by omitting an external modulating device and to perform the stable detection of signal light by removing external noises by detecting the reflected luminous flux of the pulse laser luminous flux from a target in synchronization with the period of driving pulses. SOLUTION: The irradiation luminous flux of the linearly polarized light emitted from a laser transmitter 1000 is converted into the circularly polarized light through a lens 126 and aλ/4 double refraction member 127 and applied into a rotating part 116. Rotating part 116 deflects the optical axis of the incident luminous flux by 90 degrees and performs emission scanning. The polarized reflected luminous flux reflected from a target 2000 is deflected by 90 degrees with a pentagonal prism 114, applied into a holed mirror 128 and divided into the orthogonal components at a deflection beam splitter 133 through a lens 130 and aλ/4 double-refraction member 131. Photoelectric converters 134 and 135 receive the divided polarized reflected luminous fluxes. A reflected-light detecting circuit 136 identifies whether the incident luminous flux is reflected from the target 2000 or reflected from a polarizing-direction converting reflection part by obtaining the difference between the signals of the photoelectric converters 134 and 135.