| 摘要 |
PURPOSE:To obtain an optical prism with few foreign noises and high discriminating ability by providing a wave length selecting reflection surface to the inside of the prism. CONSTITUTION:A beam 13 generates light with the light length lambda1, lambda2 and is made incident to the prism 11 through a means 18 such as ordinary lens or the like paralleling luminous flux. The incident beam is separated to the lights with wave length lambda1, lambda2 which are made incident to light detectors, 14, 15 respectively, converted into electric signals and amplified with amplifiers 16, 17, and outputted as output signals V1, V2. The existence discrimination of a liquid is usually made by comparing variation amounts with reference levels of the V1, V2 at the time of full reflection when the surface (a) of the prism 11 contacts the air. |
