Nephelometer with detection system focused on optical dark region

摘要

A nephelometer including an optical excitation system for directing light through a first window area into a cylindrical glass container and an optical detection system for quantitatively monitoring light scattered by a substance within the container and passing therefrom through a second window area. The optical detection system includes a lens system in optical alignment with the second window area and focused on an optical dark region on an inner wall of the container opposite the second window area. The optical dark region is free of internal light reflections. Therefore, the light monitored by the detection system is scattered light from the substance substantially free of internal light reflections representing background error.