PROBLEM TO BE SOLVED: To reduce the effect of disturbance light using polarized light to improve an S/N ratio.SOLUTION: A light projection unit 1 and a light reception unit 2 are attached to a living body portion 200. The light projection unit projects only polarized light 31 (33) in one polarization direction. The light reception unit has: a polarized light transmission element 21 that transmits only polarized light which is projected from the light projection unit, which has passed through the living body portion, and which has a same polarization direction as that of the polarized light projected from the light projection unit and a light reception element 22 for converting a light reception intensity of the light which has passed through the polarized light transmission element into an electric signal. A light reception part 22a of the light reception element is covered with the polarized light transmission element, so that it is protected from light having a polarization direction different from that of the polarized light projected from the light projection unit.SELECTED DRAWING: Figure 1COPYRIGHT: (C)2018,JPO&INPIT【課題】偏光を利用して外乱光の影響を低減しS/N比を向上させる。【解決手段】生体部位200に装着される投光ユニット1及び受光ユニット2を備える。投光ユニットは、一の偏光方向の偏光31(33)のみを投光し、受光ユニットは、投光ユニットから投光され、生体部位を経由した光であって、投光ユニットが投光する偏光と同じ偏光方向の偏光のみを透過させる偏光透過素子21と、偏光透過素子を透過した光の受光強度を電気信号に変換する受光素子22と、を有し、受光素子の受光部22aは、偏光透過素子で覆われることにより、投光ユニットが投光する偏光と異なる偏光方向の光から遮蔽されている。【選択図】図1
