Refractometry:
Troubleshooting FAQ's
1. There is no obvious distinction between light and dark regions.
3. Everything is blurry, even the scale and crosshairs.
4. The refractive index measured isn't correct (or at least not consistent with what is expected).
5. The scale doesn't show up when the switch is pressed.
6. The illuminating light doesn't come on.
1. There is no obvious distinction between light and dark regions.
a) Check to make sure that you have enough sample on the measuring prism. Volatile samples may evaporate before you can take a reading.
b) Check that the illuminating light is on and adjusted properly.
c) If you know the approximate refractive index for your sample, depress the scale display switch on the side of the refractometer and turn the adjustment handwheel until you are near the expected refractive index. Then release the scale display switch. If you don't see the light and dark regions try adjusting the compensator dial.
d) If you don't know the approximate refractive index for your sample, clean the refractometer and then add a standard sample with a known refractive index. Follow the instructions for part c above. (If possible choose a standard that is similar in structure to the sample.) Then clean off the standard and add your sample.
e) If even the scale is hard to read, adjust the focus by moving the eyepiece in and out.
2. The borderline between light and dark regions never becomes sharp, even after adjusting the compensator dial.
a) Check to make sure that you have enough sample on the measuring prism. Volatile samples may evaporate before you can take a reading.
b) Try readjusting the illuminating light.
3. Everything is blurry, even the scale and crosshairs.
a) Adjust the focus by moving the eyepiece in and out.
4. The refractive index measured isn't correct (or at least not consistent with what is expected).
a) Repeat the measurement, making sure that you are reading the scale correctly.
b) Make sure you are at the same temperature as the value you are comparing to.
c) Check the calibration of the instrument by using a sample of known refractive index. If this value also isn't correct, have the instructor or appropriate person adjust the calibration.
5. The scale doesn't show up when the switch is pressed.
a) Make sure you are pressing the switch correctly.
a) The light may be burned out. Consult your instructor or service technician to have it replaced.
6. The illuminating light doesn't come on.
a) Make sure the instrument is plugged in, and that it is a live circuit.
b) The light may be burned out. Consult your instructor or service technician to have it replaced.
