from The American Heritage® Dictionary of the English Language, 4th Edition
- n. Any of several instruments used to measure the index of refraction of a substance.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. An optical instrument used to measure the refractive index of a substance.
from the GNU version of the Collaborative International Dictionary of English
- n. A contrivance for exhibiting and measuring the refraction of light.
from The Century Dictionary and Cyclopedia
- n. An instrument used for measuring the refractive indiees of different substances.
- n. In the case of transparent solids which can be had in the form of a prism of known angle, the index of refraction may be determined by the deviation of a ray of light passing through the prism, and the index of refraction of transparent liquids may be determined by placing the same within a hollow prism of glass, measurements in both cases being made with an ordinary spectrometer. Where this direct method is impracticable or inconvenient, refractometers based upon other optical principles are employed. For the determination of the index of refraction of transparent solids, with plane and parallel faces, or of liquids contained in a vessel with such faces, the interferometer is sometimes employed. One of the earliest forms of interferometer, known as Jamin's refractometer, was devised by that physicist for this purpose. (See interferometer.) Other refractometers are based upon the principle that the limiting angle of total reflection at the interface between two media depends upon the ratio of their indexes. In Abbe's refractometer, an instrument of this type which is used for the determination of the index of liquids, two right-angled prisms of glass, ABC and DEF (fig. 1), are mounted with the faces AC and EF parallel. If a layer of liquid the index of refraction of which is less than that of the glass is placed between these surfaces, a beam of light from below will be totally reflected at the face EF, provided the angle i is less than the limiting angle. If i exceeds that value, the ray passes on through the liquid and the upper prism. The angle at which this change from transmission to total reflection occurs depends upon the ratio of the indexes of the glass and the liquid, and thus affords a measure of the index of refraction of the latter. Instruments similar in principle have been devised by Wiedemann, Terquem, Kohlrausch, Pulfrich, and others. For the measurement of the refracting power of crystals the method of total reflection is likewise employed. In Czapski's refractometer, a rim of glass is mounted upon the polished end of a cylinder of the same substance, and the specimen S (Fig. 2) is placed in a liquid of higher index, with its lower face parallel to the end of the cylinder. The limiting angle of total reflection at the interface between the crystal and the liquid is determined by observing the angle, i, at which a beam of light, ac, which reaches the face of the crystal at grazing incidence, emerges from the side of the cylinder below. In a similar instrument designed by Abbe for the determination of the indexes of refraction of crystals, the crystal is placed upon the horizontal plane face of a hemisphere of glass, G (Fig. 3), with an intervening layer of liquid the index of refraction of which equals or exceeds that of the glass. The beam of light a is totally reflected downward at the lower face of the crystal C, and its direction is determined by means of the position of a reading telescope which moves around a vertical circle (not shown in the diagram). By turning the specimen about a vertical axis its indexes in various azimuths may be determined.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. measuring instrument for measuring the refractive index of a substance
In order to determine the harvest date, both the vineyard manager and the winemaker take many samples a day from throughout the vineyard: He will pick a berry and put it in a device called the refractometer, which tells the sugar levels.
Nonetheless, the refractometer is a great tool, and I'm thinking about getting one.
A refractometer, which is a telescope-looking contraption that uses a speck of the fruit's juice to measure the Brix.
To test the brix, Smith squirts a drop of grape juice onto the end of a hand-held device called a refractometer and looks through the lens.
An assistant was distressed that some brand new refractometer prisms were ruined when they were glued together by the substance.
An assistant was distressed that some new refractometer prisms were ruined when they were glued together, marking the invention of the popular adhesive.
Add the fruit and zest, and boil until it gels, using whatever test you favor- or to 65 on the refractometer about which I babbled when making apple jam-see link above if interested.
He poured a few drops onto the refractometer and he closed the top.
He got the refractometer, a beaker, and a small piece of equipment that looked like a garlic press.
_ -- This figure is occasionally useful, and is best determined with an Abbé refractometer, at 20° C. _Solubility in Alcohol.