GAOTek offers a wide portfolio of high-quality, affordable and accurate refractometers. A refractometer is an optical instrument for determining the refractive index of a substance, i.e. for measuring how light bends as it moves through a substance. GAOTek’s high quality refractometers provide accurate reading for any substance in any surrounding.


A refractometer works on the principle of Snell’s Law or the physical principle of light refraction. It states that light slows down as it passes into an optically dense medium, and speeds up as it passes through a less optically dense medium. The change in speed from a dense medium to a lighter medium, and vice versa, is accompanied by a change in direction and angle. The angle at which this occurs is known as critical angle. A refractometer measures refraction at this angle.

Snell’s law is a formula used to figure out the direction of light through refractive media with varying indices of refraction. As light passes through, the border between media depends upon the relative refractive indices of two medias. There are two possibilities, the light may be refracted to a lesser angle or a greater angle. This is then measured in consideration with the normal line which is perpendicular to its boundary.

There are five types of refractometers - abbe refractometer, traditional handheld refractometer, digital refractometer, automatic refractometer and process refractometer.

Abbe refractometer is used for measuring liquids. Reference prisms can be selected with high refractive indices. Light from a radiation source is reflected by a mirror and creates a double prism. The accuracy of Abbe refractometer is 0.0002

Handheld refractometer is used by beekeepers to determine water content in honey. It is also used by wine producers to determine the amount of sugar content in a fruit or specifically in the grape used. It is also used to determine salt content of water in marine aquaria.

Digital refractometer works in the same way as a hand held refractometer, but offers a more precise reading.

Automatic refractometer provides the highest accuracy. This is used more in laboratories. Modern versions of this equipment have LED lights and interfere with the filter to make sure that wavelengths are correct at 589.3nm. This device can be used to measure even dark, cloudy and opaque samples such as ketchup and other condiments.

Process refractometer allows the refractive index to be continuously analyzed without having to remove the sample. This gives a digital reading and output. This refractometer does not need any human intervention during the measurement process.

There are two main things that influence measurements – wavelength and temperature.

Influence of wave length – Refractive index of a given sample depends on the wavelength of an object. This is non-linear and unique for every material. The decrease in refractive index results in an increase in wavelength. In an infrared wavelength the absorption maxima and fluctuation on the refractive index appear. For a high quality measurement to be made, the accuracy sound be up to 0.00002 in the reflective index, in which the wavelength’s index has to be correctly determined.

Influence of temperature - The temperature of prism and sample has to be controlled. This is the main job of a sensor. Temperature should be precisely measured so it does not cause any detectable change in refractive index.


GAOTek refractometers offer various features, some of which are listed below:

  • Operating Temperature:0- 40C
  • Power supply:5V alkaline batter
  • Operating time:more than 8000 times per battery
  • Operating humidity:lower than 90 percent
  • Operating sea level:lower than 6561.68 feet
  • Other functions:ATC, instant reading,

All GAOTek refractometers are portable and light-weight. This however does not affect their quality and accuracy. Portability allows the user to take these high-quality products anywhere without any hassle.


A refractometer is used for seaway ballast water inspections. It can also be used in veterinary medicine, Gemology, and by beekeepers to determine the water content in honey. It is also used by wine producers to determine the amount of sugar in a fruit used. It is also used to determine the salt content of water in marine aquaria. Automatic refractors are used in food and beverage sector, and in petroleum industry. A process refractometer can be used in sugar, pulp and paper making process and in refining, chemical, and pharmaceutical industries.

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