Abstract: The present invention intends to enable light path length to be kept the same between sample measurement and reference measurement and thereby improve measurement accuracy, and is an optical analyzer that analyzes a sample flowing through a pipe having translucency. In addition, the optical analyzer includes: a light source unit that has a light source and a condenser lens; a light detection unit that detects light of the light source unit; and a support mechanism that movably supports the light source unit and the light detection unit. Further, the support mechanism moves the light source unit and the light detection unit between a sample measurement position and a reference measurement position.

Abstract: In order to reduce a variation in the light amount of light detected in every reference measurement cycle in an absorption spectrometer 1, it is adapted to tilt at least one surface selected from among incident surfaces and emitting surfaces of all translucent members constituting a reference cell with respect to the light axis of light traveling along a light path.

Abstract: In order to reduce a variation in the light amount of light detected in every reference measurement cycle in an absorption spectrometer 1, it is adapted to tilt at least one surface selected from among incident surfaces and emitting surfaces of all translucent members constituting a reference cell with respect to the light axis of light traveling along a light path.