usage method1. Open the cover plate2. Carefully wipe off the detection prism with a soft cloth3. Take a few drops of the solution to be tested and place it on the testing prism. Gently close the cover to avoid bubbles and spread the solution over the surface of the prism. Insert the instrument into the optical board4. Aim at the light source or bright spot, observe the field of view through the eyepiece, and rotate the eyepiece to adjust the handwheel5. Make the blue and white boundary of the field of view clear. The scale value of the boundary is the concentration of the solution.matters needing attentionThis instrument is a precision optical instrument. The following items should be noted during use and maintenance:1. During use, it is necessary to be careful and follow the instructions strictly. It is not allowed to loosen the connecting parts of the instrument, drop or collide, and violent vibration is strictly prohibited.2. After use, it is strictly prohibited to directly put it into water for cleaning. A clean and soft cloth should be used to wipe it. For optical surfaces, they should not be bumped or scratched.3. The instrument should be stored in a dry and corrosion-free place.4. Avoid losing spare parts.Packaging content1 * Refractometer1 * Mini screwdriver1 * pipette1 * Cleaning cloth1 * English instruction manual1 * Plastic box