The refractometer is a piece of equipment for determining the amount of water in liquids. It determines the liquid's refractive index, depending on the moisture level. Let us know the meaning, uses of the refractometer, and who invented the refractometer.

A refractometer is a basic tool for measuring aqueous solution concentrations. It only takes a few drops of liquid to work, and it’s employed in the agricultural, food production, industrial, and manufacturing industries. It works on the concept of refraction, which explains how light bends as it passes through two different mediums. The most common method for determining the properties of a fluid is to use a refractometer. A scientist may be able to recognise a sample solution, evaluate the sample’s purity, and measure the concentration of the solute (that is, dissolved components) in a liquid solution by assessing the refractive index. The Brix scale, which correlates the attention of the solution in water at a specific temperature to the index of refraction of the solution, is a secondary scale used in refractometry

History of Refractometer

Now that we know the meaning of the refractometer, let us know its history and who invented refractometer:

·  In 1869, Ernst Abbé created his first refractometer, which he used to develop a lens for the Carl Zeiss Optical Works in Jena, Germany.

·  Carl Pulfrich constructed and documented another device in 1888 that also used the critical angle, but his design differed drastically from the Abbé refractometer. Max Wolz in Bonn originally manufactured Pulfrich’s refractometer. However, after he joined Carl Zeiss, his refractometer became a Zeiss product. The Pulfrich refractometer has been in use since that period.

·  Although the two major refractometers, Pulfrich and Abbé were able to suit the needs of most analytical laboratories, research and development of better devices continued. Devices appropriate for use outside the laboratory, such as absorption refractometers, which Zeiss has offered since around 1900, and devices that provide superior precision than Abbé refractometers, were among the fresh ideas.

Types of Refractometers

Refractometers are widely used for various purposes, and each has slightly distinct requirements. As a result, refractometers of different designs, precision, and functions have become available over time. The following are some of them:

Handheld Refractometers

Handheld refractometers are quite simple to use. Many applications are conceivable due to the accessibility of various measurement scales. Beekeepers use handheld refractometers to evaluate the water content of honey, winemakers use them to measure the sugar concentration in fruit and grape, and aquarists use them to determine the saltwater level in the ocean.

The refractive index can be determined with just a sample on the measuring prism. The calculated value can be viewed via the scale’s eyepiece when placed against a light source. At the measured value, a horizontal limit line intersects the vertical scale.

Handheld refractometers with inbuilt Automatic Temperature Correction (ATC) are available for temperature adjustment of liquids.

Abbe Refractometer

The Abbe refractometer, designated after its developer Ernst Abbe, was the first scientific tool for determining the refractive index of fluids with pinpoint accuracy. The concept of total reflection governs the measurement of an Abbe refractometer.

Liquids are measured using Abbe refractometers. High refractive indices can be chosen for the reference medium prisms. A mirror reflects light from a source of radiation, which then strikes a double prism. Only a few droplets of the sample are inserted between such a so-called Abbe double prism.

Only if the incident light beams’ angle of incidence at the contact is less than the crucial angle of total reflection boundary do they pass through a double prism and sample.

 Process Refractometer

Process refractometers enable continuous refractive index analysis without transporting samples to a regulated laboratory. These instruments are made up of sensors coupled to a control box and located straight or in a bypass. This control box usually provides digital reading and output. They work on the complete refraction principle, calculating the angle of monochromatic light from a variety of angles of incidence.

Process refractometers can give real-time measurement data and require no human intervention throughout the measuring process. Large industrial activities, such as agricultural, sugarcane, paper making, refinery and chemical, and pharmaceutical corporations, can benefit from these devices.

Digital Refractometer

Digital refractometers work similarly to handheld refractometers, although with the addition of an automatic boundary line determination and printout. They have less inter-operator variability and more precision than manual portable refractometers, and they usually come with a variety of scales.

Automatic Refractometer

Automatic refractometers provide high accuracy by fully eliminating discrepancies in measured values across operators. Contrary to manually refractometric measurement in controllable environmental conditions, the refractive index of a sample can be measured at varying temperatures or light wavelengths. Automatic refractometers are mostly used in laboratories to perform exact measurements under tightly controlled settings.

Uses of Refractometers

·  Refractometers are commonly used to estimate the refractive index of liquid samples and test fluid concentrations like blood protein content, amount of sugar, and salinity.

·  The Abbe refractometer is a measurement device that can measure the refractive index. With refractometry, operates for both solid and liquid substances as far as they are transparent.

·  A refractometer is often used to monitor coolant concentration in the automobile sector.

·  A refractometer is used in the machine industry to determine how much coolant concentrate has been applied to the water-based cooling for the machining operation.

·  The specific gravity of liquids and the total proteins of plasma or any other fluids are determined using refractometers.


A refractometer is a scientific instrument that measures the quantity of light bend when it passes through a sample from the air. The refractive index of a liquid is typically determined using refractometers. Refractometers are divided into three categories. A compact hand-held machine, for example, is used to measure the size in the field. Bench refractometers come in two varieties commonly used in laboratories and factories. Abbe refractometers, which are optical-mechanical instruments based on Abbe’s initial model, are named after the instrument’s designer. Automatic digital refractometers are digital instruments that do measurements with the help of sophisticated software.