How a refractometer reads
Adjust the interface to a line that passes exactly through the intersection of the oblique crosses. Then read the number to four decimal places.
An instrument for measuring the refractive index ND and average dispersion NF-NC of transparent, translucent liquids or solids. The instrument is connected with a thermostat, which can measure the refractive index ND within the temperature range of 0°C to 70°C, and can measure the percentage of sugar concentration in the sugar solution. Therefore, this instrument is one of the indispensable and commonly used equipment in relevant factories, teaching and scientific research units such as petroleum industry, oil industry, pharmaceutical industry, paint industry, food industry, daily chemical industry, sugar industry and geological survey.
working principle
The Abbe refractometer is designed according to this principle. Figure 1 is a schematic diagram of the instrument structure. Its main part is two rectangular prisms PI and PII. There is a gap of about 0.1 to 0.15mm between the rough surface of prism PI and the optical plane mirror AD of PII, which is used to hold the liquid to be tested and make a gap between PI and PII. book layer.
After the light enters the prism PI from the reflector, it is diffused due to the rough ground glass, and passes through the liquid under test from various angles; enters the prism PII, as we know before, enters the prism PII from all directions All light rays are refracted, and their refraction angles fall within the critical angle rc (because the refractive index of the prism is greater than that of the liquid, all light rays from the angle of incidence from 0 to 10 can pass through the prism and be refracted).
The light with the critical angle rc passes through the prism PII and strikes the eyepiece. At this time, if the reticle of the eyepiece is adjusted to a proper position, half-light and half-darkness will be seen on the eyepiece.
