| 摘要 |
PURPOSE:To avoid delay of response time of a sensor, to suppress stray in parallel prisms and to improve the measuring accuracy. CONSTITUTION:Parallel prisms 8R and 8L are mutually linked with a prism connecting glass plate 12, which is stuck to the inside of incident boundary surfaces 8RC and 8LC. Thin glass plates 10R and 10L are stuck to incident regions S of the incident boundary surfaces 8RC and 8LC with gaps GR and GL being provided with the end parts of the glass plate 12. Two thin glass plates 11R1 and 11R2 (11L1 and 11L2) are stuck on the side of a ridge part (d) with incident total reflection surfaces 8RA (8LA) on outgoing boundary surfaces 8RD (8LD). Thus, a butting surface gR (gL) is formed. The gaps GR and GL and the butting surface gR (gL) constitute the groove or the slit for a stray light trap. |
