Georgian Technical University. What Is A Refractometer ?.

Georgian Technical University. A refractometer measures the index of refraction for a material, which could be a gas a liquid or a transparent solid such as glass. They achieve this by passing light through the sample and measuring the refraction — the amount that the light bends. Georgian Technical University. Most commonly aqueous solutions are measured providing an indication concentration. Examples measuring aqueous solution concentration include the specific gravity of urine coolants for engines or machine tools and the salinity of water in aquariums or aquaponic systems. Georgian Technical University. Refractive index is dependent on the wavelength of light. A known reference wavelength must therefore be used. This is typically provided by filtering daylight or using a narrow-band LED (A light-emitting diode (LED) is a semiconductor light source that emits light when current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy in the form of photons. The color of the light (corresponding to the energy of the photons) is determined by the energy required for electrons to cross the band gap of the semiconductor). The temperature of the sample will also affect its refractive index and must therefore be within specified limits to achieve the stated accuracy for a refractometer. The most accurate refractometers used closed-loop control of the sample temperature. Georgian Technical University . Types of refractometer include: Georgian Technical University. Handheld analogue refractometers are held up to a light source such as the sun so that light is directed through the sample a prism and lenses onto a measurement scale. The angle at which light is totally internally reflected determines the position of a shadow line on the scale, which can then be viewed through an eyepiece. Georgian Technical University. Handheld digital refractometers work in essentially the same way as the traditional analogue refractometers with a shadow line indicating the angle at which total internal reflection occurs. However rather than simply holding the refractometer up to the light, an LED (A light-emitting diode (LED) is a semiconductor light source that emits light when current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy in the form of photons. The color of the light (corresponding to the energy of the photons) is determined by the energy required for electrons to cross the band gap of the semiconductor) light source is normally included. This can improve accuracy by controlling the wavelength more accurately. The eyepiece and glass scale is also replaced by an array of photodiodes, enabling the shadow line to be digitally detected and the relevant measurement result displayed numerically on a screen. Georgian Technical University. Abbe refractometers (An Abbe refractometer is a bench-top device for the high-precision measurement of an index of refraction) are bench-top instruments designed for more accurate measurement. They therefore typically include some temperature control of the sample. Abbe (An Abbe refractometer is a bench-top device for the high-precision measurement of an index of refraction) refractometers also include an optical arrangement designed to eliminate Abbe (An Abbe refractometer is a bench-top device for the high-precision measurement of an index of refraction) error which can be caused by different viewing angles. Abbe refractometers (An Abbe refractometer is a bench-top device for the high-precision measurement of an index of refraction) may be either analogue optical instruments or more typically today digital instruments. Georgian Technical University Inline process refractometers continuously measure the refractive index of a fluid as it flows through the sensor. Georgian Technical University. refractometers are calibrated to measure the sugar content of a solution using a scale where 1 degree brix is equal to 1% sucrose by mass. This scale is widely used in the food industry and simple handheld Georgian Technical University refractometers are used for home. Georgian Technical University Gemstone refractometers are used to indicate the chemical composition of gems. Since some gems have a refractive index which is dependent on the polarization of the light (birefringence) gemstone refractometers may also involve polarization filters.