Refractometers measure the concentration levels of aqueous solutions by analysing the angle of light refraction in a few drops of liquid and plotting it on a refractive index. By calculating this index – the speed at which light passes through a substance - you can analyse a samples purity and establish the concentration of dissolved materials.

How do refractometers work?

Standard refractometers measure the degree to which light changes direction in transparent substances, which is called the angle of refraction. As light passes through a liquid it creates a bending illusion, and the degree to which it bends depends on the amount of dissolved substance present. A refractometer takes the refraction angles and correlates them to refractive index (nD) values. Typically reported to a ten-thousandths place, you can use these values to determine the concentrations of solutions.

Some refractometers use the Brix scale. A Brix refractometer relates the concentration of sucrose in water to the solutions refractive index.

What are the different types of refractometer?

Hand refractometers allow quick and easy measurement in liquid and semi-solid samples. They work on the critical angle principle in which lenses and prisms project a shadow line onto a small glass reticule inside the instrument, which is viewed through a magnifying eyepiece.

The digital handheld refractometer operates on the same principle but with light from an LED focused on the underside or a prism element. When a sample is applied to the measuring surface of the prism some of the light is transmitted through the solution and lost, while the remaining light is reflected onto an array of photodiodes creating a shadow line. Once the position of the shadow line has been automatically determined, the internal software correlates the position to the refractive index to display a reading.

Where are refractometers used?

Refractometers are relied upon for quality control in the food and drink industries. Theyre also used by jewellers to analyse the purity of gemstones and can even be used for home-brewing, monitoring the salinity or specific gravity of water in fish tanks, and making preserves.

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Description Price Refractometer Type Maximum Measurement Minimum Measurement Best Accuracy Resolution Measurement Time Type Battery Type Battery Life Power Source Dimensions Weight Height Length
RS Stock No. 344-5535
Mfr. Part No.300006
Salt 28% 0% ±0.2 % 0.2 % - Optical - - - 1-1/2 (Dia.) x 6-3/4mm 184.3g - 6-3/4in
RS Stock No. 344-5484
Mfr. Part No.300001
Sugar 32% 0% ±0.2 % 0.2 % - Optical - - - 1-1/2 (Dia.) x 6-3/4mm 170.1g - 6-3/4in
RS Stock No. 344-5507
Mfr. Part No.300003
Sugar 80% 0% ±1 % 1 % - Optical - - - 1-1/2 (Dia.) x 7mm 538.6g - 7in