Tuesday, January 26, 2010
There are different types of refractometers:
- Herbert Smith refractometer: Measures the critical angle by total internal reflection, using a glass hemisphere through which light is directed upwards and reflected from the surface. The reflected beam produces an image in the observing telescope, where a scale measures the critical angle. The refractive index is then calculated by Snell's Law.
- Abbé refractometer: Used for determining the refractive index of liquids. It consists of a pair of glass prisms with a film of liquid between them. The line of the critical angle is measured through a fixed telescope and the refractive index is read off a graduated scale calibrated against a glass plate of known refractive index.
- Leitz-Jelley refractometer: Used to determine the refractive index of small amounts of liquid. It consists of a glass prism cemented to a glass slide which can hold the liquid. A beam of light is directed at right angles to the glass and is refracted by the liquid on to a graduated scale from which the refractive index can be read.
http://www2.ups.edu/faculty/hanson/labtechniques/refractometry/intro.htm
http://www.encyclopedia.com/doc/1O13-refractometer.html
+ [ written by SEOWHWEE ] + 3:35 AM