Note: Calibration should be carried out with the refractometer and RODI water solution at 20°C. To equillibrate, leave the refractometer and solution at 20°C for 30 minutes.

1. Flip open the daylight cover and add 2-3 drops of RODI water on the prism.

2. Close the daylight cover such that the water fully spreads across the surface of the prism, without any dry spots.

3. Wait approximately 30 seconds for the temperature of the sample to reach the same ambient temperature of the prism.

4. Position daylight plate under a light source and look into the eyepiece. Adjust the focus by turning the eyepiece in a clockwise/anticlockwise direction.

5. Using the mini screwdriver, turn the calibration screw until the boundary between the upper blue field and lower white field meets exactly on the zero scale.