In a vacuum, light travels at 300.000 km/s while travelling through water, the speed is about 225.000 km/s,
which is 25 % less. In a sapphire it will only reach 170.000 km/s.
A refractometer is a measuring instrument for the speed of light. The result will not be indicated directly but related to the speed of light in air. This comparison is called refractive index. The indication, that a certain material has a refractive index of 1.5 thus means, that the speed of light travels 50 % faster through air than through this material.
Who is interested in the speed of light in samples?
The refractive index is a value specific to a material. It depends on temperature and wavelength (colour) of the light. Thus using a refractometer, will enable you to determine the concentration of a material, if temperature and wavelength are known. But it is also possible, that different materials have the same refractive index at various concentrations. Thus a clear determination of liquid substances may only be successful with binary mixtures (Mixtures consisting of two compounds).
In practice, the refractive index determines the mixing ratio also of multicompound solutions quite exactly and easily as in general only the concentration of one of the componends needs to be determined. Thus it is a quantitative measurement. With known compounds, also quality may be determined. For mixtures like for example olive oil or orange juice, the measuring value within a certain range corresponds to a certain quality.
Thus refractometry is a quality control of substances.
There is a definite correlation between the refractive index and the composition of many two-compound solutions. The best known example for such a mixture is a solution of sucrose in water, which has been studied throughly. A refractometer can be grated in a way that the value may be indicated directly as dry substance % RTS. For sucrose, this unit is also named Brix (abb. Bx).
The determination of the density of samples can also be done with refractometry. As a rule in optical measuments density and dry substance corresponds to each other.
Refractometers convert the measured refractive indices in concentration or density.
VariRef the New Laboratory Refractometer
The VariRef combines proven S&H technology with the modularity of the VariFamily.
The new double isolated Peltier systems allows fastest temperature control and reduces the influence of environment temperature, resulting in fast and precise measurements.
The VariRef has the well-established S&H sample room. Its flat shape is ideal for easy cleaning. When dealing with hard to clean or hazardous materials we offer you a special covered version to ensure a long and proper product life.
The LED light source and the self-checking capabilities for cleanliness, environment temperature effects, calibration and more result in a virtually maintenance free product life.
To ensure highest precision over the long product life, the VariRef enables you to make a multi-point calibration for the complete measurement range. Thus giving you the tools for a fast and economic maintenance at your side.
With the VariRef you have access to the complete scale library of Schmidt + Haensch offering readymade solutions for numerous applications.
Compact laboratory refractometer for versatile applications
Digital multiple wavelength refractometer
Digital handheld refractometer – Brixmeter
Inline Process Refractometers measure the refractive index continuously and in real time, thus determining the concentration of liquids or the mixing ratios of binary or quasi-binary mass ratios.
The measurement is independent of turbidity, color, absorption and viscosity, which ensures maximum precision and better process control.
Process refractometers can be installed in pipelines, mixing tanks, reaction boilers, storage vessels, cooking appliances or evaporators using various flange connections.
Find more information on the following Schmidt-Heinsch webpage
|Calibration Standards for Refractometer at 589nm in 10ml glass bottles|
|Substance||Refractive index||Temperature range||Certificate||Tolerance of RI|
|De-ionised water||20°C ≈ 1.333||20°C and 25°C||factory certificate||dnD=0.00005|
|De-ionised water||20°C ≈ 1.333||5 to 95°C||factory certificate||dnD=0.00005|
|Silicon Oil||20°C ≈ 1.404||20°C and 25°C||factory certificate||dnD=0.00005|
|Silicon Oil||20°C ≈ 1.404||5 to 95°C||PTB certificate||at 20°C dnD=0.00001|
|Paraffin Oil||20°C ≈ 1.446||20°C and 25°C||factory certificate||dnD=0.00005|
|Paraffin Oil||20°C ≈ 1.446||5 to 95°C||PTB certificate||at 20°C dnD=0.00001|
|Technical White Oil||20°C ≈ 1.474||20°C and 25°C||factory certificate||dnD=0.00005|
|Technical White Oil||20°C ≈ 1.474||5 to 95°C||PTB certificate||at 20°C dnD=0.00001|
|CRM-R Custom||10 ml factory certified reference material, customer specified RI in the range 1.36 bis 1.70 RI, calibrated to dn=0.00005 accuracy|
|Certified Reference Material (CRM) Sugar|
|CRM-R Saccharose B||Sugar reference solution, different concentrations, separate containers for saccharose and distilled water, after shuffle one week durable (concentration range: 0 - 55 Bx --> please specify desired concentration when ordering)|
|CRM-R Saccharose P||Sugar reference solution, different concentrations, separate containers for saccharose and distilled water, after shuffle one week durable (concentration range: 0 - 55 Bx --> please specify desired concentration when ordering), with factory certificate|