A refractometer is an instrument that can measure the refractive index and average dispersion of transparent, translucent liquids or solids. Among them, the refractometer is mainly used to measure transparent liquids. Refractive index is one of the important physical constants of a substance. Measuring the refractive index of a substance can quantitatively find the concentration or purity of the substance. At the same time, refractometer is also an important tool for the study of material structure.
1. Calibration of the instrument
The zero point of the scale of the ditial gem refractometer
sometimes moves, so the zero point needs to be corrected before using the refractometer. For calibration, a standard liquid with known refractive index (such as distilled water) or a standard glass block with known refractive index can be used.
When using pure water as the standard liquid, first measure the refractive index according to the instrument operation steps described below. Compare the measured average value with the standard value, and the difference is the correction value. When pure water is 20 ° C, its refractive index is 1.3325. The temperature coefficient between 15 ~ 30 ℃ is minus 0.0001. In the precise measurement work, several standard liquids with different refractive indexes must be calibrated within the measured range, and a calibration curve is drawn.
Before calibrating with a standard glass block and lifting the measuring prism, add a drop of monaphthalene to the polished surface of the standard glass block. The reading of the adjusting dial is equal to the polishing of the measuring prism attached to the glass block. The light-dark boundary in the telescope is in the middle of the cross. If there is a deviation, use the accessory "square hole adjustment wrench" to turn the indicating adjustment screw on the measuring telescope so that the light-dark boundary is exactly at the intersection of the crosshairs.
2. Maintenance of the instrument
(1) Corrosive liquids such as strong acids, strong bases, and fluorides cannot be measured with a refractometer
(2) The instrument should be placed in a dry, air-circulating room to prevent mold of optical parts after being damp.
(3) After the instrument is used, it must be cleaned and placed in a box with a desiccant silica gel.
(4) Always keep the instrument clean. After lightly wiping with high-grade suede or absorbent cotton, it is strictly forbidden to touch optical parts with oily or sweaty hands. If there is dust on the surface of the optical parts, it can be blown away with a suction ball. Wipe the gasoline lightly, then clean it with xylene or squint.