Refractometer (rear view)

When light travels through a liquid at an angle, it bends or refracts: slowing down and changing direction as it travels through a new medium. This phenomenon can be used to measure the concentration of a liquid solution, as light refracts more when traveling through suspended solids or dissolved components, such as salts or sugars. This Abbe bench-top refractometer, based on a design by Ernst Abbe from the late 1800s, was manufactured by the Bausch & Lomb Optical Company for use in analytical laboratories.https://digitalcommons.njit.edu/instruments/1080/thumbnail.jp