Refractometers have been widely used as a liquid concentration measuring device in a wide variety of industries. Atago analog and digital refractometers. Schmidt+Haensch Refractometers are high quality digital and Abbe refractometers. Ideal for measuring the Refractive Index(nD) or Brix scale. Vee Gee Refractometers are exceptionally simple to operate, quickly measuring concentrations.