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Refractometers
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A refractometer is a laboratory or field device for the measurement of an index of refraction (refractometry).
The refractive index of a certain sample varies for nearly all materials for different wavelengths.
This dispersion relation is characteristic for every material.
Temperature has a very important influence on the refractive index measurement.
Therefore, the temperature of the prism & the temperature of the sample have to be controlled with high precision.
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 Automatic
refractometer
Automatic
refractometers automatically measure the refractive index of a sample. The
automatic measurement of the refractive index of the sample is based on the
determination of the critical angle of total reflection.An LED light source is
imaged under a wide range of angles onto a prism surface which is in contact
with a sample. Depending on the difference in the refractive index between
prism material and sample the light is partly transmitted or totally reflected.
The critical angle of total reflection is determined by measuring the reflected
light intensity as a function of the incident angle
This method of detecting the angle of total reflection is
independent on the sample properties. It is even possible to measure the
refractive index of optically dense strongly absorbing samples or samples
containing air bubbles or solid particles . Furthermore, only a few microliters
are required and the sample can be recovered. This determination of the
refraction angle is independent of vibrations and other environmental
disturbances.
Watch: How to use a refractometer https://www.youtube.com/watch?v=Qd9uJ9JitJw
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