Digital handheld refractometer: Difference between revisions

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A digital handheld refractometer is an instrument for measuring the refractive index of materials.

Principle of operation

Most operate on the same general critical angle principle as a traditional handheld refractometer. The difference is that light from an LED light source is focused on the underside or a prism element. When a liquid 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 a linear array of photodiodes creating a shadow line. The refractive index is directly related to the position of the shadow line on the photodiodes. Once the position of the shadow line has been automatically determined by the instrument, the internal software will correlate the position to refractive index, or to another unit of measure related to refractive index, and display a digital readout on an LCD or LED scale.

The more elements there are in the photodiode array, the more precise the readings will be, and the easier it will be to obtain readings for emulsions and other difficult-to-read fluids that form fuzzy shadow lines.

Digital handheld refractometers are generally more precise than traditional handheld refractometers, but less precise than most benchtop refractometers. They also may require a slightly larger amount of sample to read from since the sample is not spread thinly against the prism.

The result may be displayed in one of various units of measuremeant: Brix, freezing point, boiling point, concentration, etc. Nearly all digital refractometers feature Automatic Temperature Compensation (for Brix at least)

Most have a metal sample well around the prism, which makes it easier to clean sticky samples, and some instruments offer software to prevent extreme ambient light from interfering with readings (you can also shade the prism area to prevent this as well). Some instruments are available with multiple scales, or the ability to input a special scale using known conversion information. There are some digital handheld refractometers that are IP65 (IP Code) water-resistant, and thus washable under a running faucet.

References

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+{{Unreferenced|date=December 2009}}
-'''Digital handheld refractometers''' are becoming more prevalant. Most operate on the same general [[critical angle]] principal as a [[traditional handheld refractometer]]. The difference is that light from an [[LED]] light source is focused on the underside or a prism element. When a liquid 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 a linear array of [[photodiodes]] creating a shadow line. The [[refractive index]] is directly related to the position of the shadow line on the photodiodes. The more elements there are in the photodiode array, the more precise the readings will be, and the easier it will be to obtain readings for [[emulsions]] and other difficult-to-read fluids that form fuzzy shadow lines. Once the position of the shadow line has been automatically determined by the instrument, the internal software will correlate the position to [[refractive index]], or to another [[unit of measure]] related to [[refractive index]], and display a digital readout on an [[LCD]] or [[LED]] scale.
+<!-- Deleted image removed: [[Image:washingdigitalrefractometer.jpg|right|thumb|300px|A modern digital handheld refractometer being cleaned under a faucet.]] -->
+A '''digital handheld refractometer''' is an instrument for measuring the [[refractive index]] of materials.
+==Principle of operation==
-''Digital handheld refractometers'' are generally more precise than traditional handheld refractometers. Users should look for instruments with a digital display that is capable of displaying not just a reading but also the unit of measure of the substance ([[Brix]], freezing point, boiling point, concentration, etc.). A stainless-steel sample well makes it easier to clean and an opaque cover over the sample area can prevent sample evaporation or ambient light from interfering with readings. Some instruments are available with multiple scales. It is important to select an instrument that can be zero set to distilled water and can also accept [[traceable calibrations]] at an upper span point.
+Most operate on the same general ''critical angle'' principle as a [[traditional handheld refractometer]]. The difference is that light from an [[LED]] light source is focused on the underside or a prism element. When a liquid 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 a linear array of [[photodiode]]s creating a shadow line. The refractive index is directly related to the position of the shadow line on the photodiodes. Once the position of the shadow line has been automatically determined by the instrument, the internal software will correlate the position to refractive index, or to another [[unit of measure]] related to refractive index, and display a digital readout on an [[LCD]] or [[LED]] scale.
+The more elements there are in the photodiode array, the more precise the readings will be, and the easier it will be to obtain readings for [[emulsion]]s and other difficult-to-read fluids that form fuzzy shadow lines.
-== Digital immersion-probe refractometers ==
+Digital handheld refractometers are generally more precise than traditional handheld refractometers, but less precise than most benchtop refractometers. They also may require a slightly larger amount of sample to read from since the sample is not spread thinly against the prism.
-A digital fiberoptic refractometer is presently available that works on an entirely different principle. This instrument is a probe type refractometer that is actually inserted into the fluid to be measured. A fiberoptic sensor determines the refractive index.
+The result may be displayed in one of various units of measuremeant: [[Brix]], freezing point, boiling point, concentration, etc. Nearly all digital refractometers feature Automatic Temperature Compensation (for Brix at least)
-== See also ==
+Most have a metal sample well around the prism, which makes it easier to clean sticky samples, and some instruments offer software to prevent extreme ambient light from interfering with readings (you can also shade the prism area to prevent this as well). Some instruments are available with multiple scales, or the ability to input a special scale using known conversion information.
+There are some digital handheld refractometers  that are IP65 ([[IP Code]]) water-resistant, and thus washable under a running faucet.
+==See also==
 *Refractometer Types
-**[[traditional handheld refractometer]]
+**[[Traditional handheld refractometer]]
 **[[Abbe refractometer]]
 **[[Inline process refractometer]]
+==References==
-[[Category:Measuring instruments]]
+{{reflist}}
-[[Category:Optical devices]]
+{{DEFAULTSORT:Digital Handheld Refractometer}}
+[[Category:Refractometers]]