| Refractometers are measuring instruments which put | | | | measure solid samples – something that standard |
| the phenomenon of light refraction (bending) to | | | | digital refractometers cannot do. Circulating water |
| practical use. They are based on the principle that as | | | | baths can be added to control instrument and fluid |
| the density of a substance increases (such as when | | | | temperature in Abbe refractometers. Newer |
| sugar is dissolved in water), its refractive index rises | | | | versions of Abbe refractometers have recently been |
| proportionately. Refractometers were devised by Dr. | | | | upgraded to include solid state Peltier elements to both |
| Ernst Abbe, a German/Austrian scientist in the early | | | | heat and cool the refractometer so that you no longer |
| 20th century. | | | | need to use a waterbath. Another modern feature is |
| The prism in a refractometer has a greater refractive | | | | the ability to link the Abbe refractometer to a |
| index than the sample solution. Measurements are | | | | computer to control the instrument and to record |
| read at the point where the prism and solution meet. | | | | readings. |
| With a low concentration solution, the refractive index | | | | Some Abbe refractometers can measure at |
| of the prism is much greater than that of the sample, | | | | wavelengths other than the standard 589 nanometers, |
| causing a large refraction angle and a low reading. The | | | | using filters on up to the near infrared range. They |
| reverse (lower refraction angle and higher reading) | | | | are referred to as Multi-wavelength Abbe |
| would happen with a highly concentrated solution. | | | | refractometers. Multi-wavelength Abbe |
| Abbe Refractometers are a type of refractometer | | | | refractometers can be used to easily determine a |
| used for measuring the refractive index of solid | | | | sample's Abbe number, which is a measure of the |
| samples, such as glass, plastics and polymer films. | | | | material's dispersion (variation of refractive index with |
| There are two detection systems for refractive index: | | | | wavelength) in relation to the refractive index. These |
| transparent systems and reflection systems. Hand-held | | | | multi-wavelength Abbe refractometers can be used to |
| refractometers and Abbe refractometers use | | | | test eyeglass lenses, contact lens materials, optical |
| transparent detection systems, and digital | | | | plastics for optical communication, compact disk |
| refractometers use reflection detection systems. | | | | materials and insulating oil. |
| Abbe refractometer readouts can be either digital or | | | | Other accessories that are available include digital |
| analogue. | | | | printers, extra filters and near-IR viewers. |
| Abbe refractometers are used most often to | | | | |
