Refractometer knowledge
A refractometer, also known as a refractometer, is an instrument that uses light to test the concentration of a liquid. It is used to measure the refractive index, birefringence, and optical properties. The refractive index is one of the important physical constants of substances. Many pure substances have a certain refractive index. If the substance contains impurities, the refractive index will change, and there will be deviations. The more impurities, the greater the deviation.
Refractometers are mainly composed of high refractive index prisms (lead glass or cubic zirconia), prism mirrors, lenses, scales (internal scales or external scales), and eyepieces.
Refractometers include hand-held refractometers, sugar refractometers, honey refractometers, gemstone refractometers, digital display refractometers, automatic refractometers and online refractometers.
How a refractometer works
Principle: When light enters another transparent medium from one transparent medium, refraction occurs, which is caused by the different speeds of light in various media. Refractive index refers to the ratio of the speed of light in air to the speed in other substances. Refractive index is the ratio of the speed of light in the air to the speed of light in the measured object or the ratio of the sine of the incident angle to the sine of the refraction angle when light passes through the measured object from the air under the conditions of sodium spectrum D line and 20 °C .
In terms of functions, it adopts color liquid crystal display and touch panel, and USB and LAN are standard interfaces to cope with various expansion devices.
Refractometer principle of refraction
If you place a pencil in a glass of water, the tip will appear curved. Then if you put sugar water in a cup and try the same experiment, the tip of the pencil should appear even more curved. This is an example of the phenomenon of refractive index.
The refractometer is put into practical use due to the adoption of a new type of optical system. The solubility of the test solution is measured by converting the corresponding relationship between the refractive index of the solution and its solubility. When the density of a substance increases, its refractive index increases proportionally.
Refractometers utilize the theory of refraction that a prism holds a higher refractive index than the test solution; by conversion to measure the solubility or refractive index of the test solution.
When the test solution is relatively dilute, the refractive index of the test solution is higher than that of the prism, so the angle of refraction is relatively large.
When the test solution is relatively thick, the refractive index of the test solution is lower than that of the prism, so the angle of refraction is relatively small.
The composition of the refractometer
1. Light entering board
2. Refractive prism
3. Zero adjustment screw
4. Eyepiece
5. Rubber sleeve 2. How to use
1) When using a hand-held refractometer, hold the rubber sleeve with four fingers of the left hand and adjust the eyepiece with the right hand to prevent body temperature from entering the instrument and affecting the measurement accuracy.
2) Open the light inlet plate and wipe the refracting prism clean with a soft flannelette.
3) Put a few drops of distilled water on the refracting prism, gently close the light inlet plate, so that the solution is evenly distributed on the surface of the prism, and aim the instrument light inlet plate at the light source or bright place, and observe the field of view through the eyepiece, if If the dividing line between light and dark in the field of view is not clear, rotate the eyepiece to make the field of view clear, and then turn the zero adjustment screw to set the dividing line between light and dark at zero. Then wipe off the distilled water and replace it with the test solution. At this time, the field of view depends on the boundary line, and the corresponding division scale value is the concentration value and density value of the test solution.
4. Precautions This instrument is a precision optical instrument. During use and maintenance, the following items should be paid attention to:
1. In use, you must be careful and use it strictly according to the instructions. Do not loosen the connecting parts of the instrument arbitrarily, and do not drop, collide, or violently vibrate.
2. After use, it is strictly forbidden to put it in water directly for cleaning. It should be wiped clean with a clean soft flannel cloth dampened with water. The surface of optical parts should not be scratched or scratched.
3. The instrument should be stored in a dry, dust-free, oil-free and acid-free place to avoid corrosion or mildew of optical parts.
