What is a refractometer?
With a refractometer, the refractive index of solid or liquid, transparent fabrics is measured using the refractometry. The behavior of light at the transition between the fabric to be tested and a prism is used with known properties. If the composition of a liquid is known, the refractometer is used to measure the concentration.
Which measurement principles are there?
Refractometry distinguishes three measurement principles:
- Pulling incoming
- Total reflection
The refraction - also called the refraction - or the total reflection of the light is exploited. All measurement principles are based on the known refractive index (NPrisma). When the transition between measurement prism and sample (NFLUID), the light spreads out differently quickly. The unknown refractive index can then be measured via the light dampening. The penalty principle uses the refraction of a parallel bundle of rays on the interface. In the principle of the patrol and the total reflection, the critical angle of a bundle of radiation is measured on the interface with different angles of incidence.
Which refractometers are there?
In the case of refractometers, a difference is generally differentiated between digital and analog measuring devices. Analog refractometers mostly use sunlight or a light bulb, partly with color filters, as a light source. A scale that serves as a detector can then be read via an optics.
To analog refractometers include:
- Hand refractometer
- Abbe refractometer
- Pulfrich refractometer
- Wollastons Refractometer
- Jelley refractometer
- Automatic/semi -automatic refractometer
Digital refractometer On the other hand, LEDs use as a light source. A CCD sensor is considered a detector here. The digital refractometer has an integrated, precise temperature measurement. This can compensate for the temperature -dependent refractive index. Digital refractometers are independent of the location and offer a high degree of reading.
For example, digital refractometers include:
- Hand and Table deviceswhich are suitable for small sample quantities
- Process refractometers that can be installed directly into the process (e.g. in a pipe or tank)
What are refractometers used for?
A refractometer is often used to determine concentrations in a carrier medium - such as the sugar content in aqueous solutions. A refractometer is used in the medical field to determine the protein content in the urine. In chemistry, due purity of organic substances is checked with the refractometer.
Refractometer in ophthalmology
Manual or automatic refractometers also play a major role in ophthalmology because they are used to determine or measure the objective refraction of the eyes. This can be adjusted to correction lenses.