70 likes | 199 Vues
Reading the polarimeter. The sample. The sample cell MUST be absolutely full there can be no air bubbles seal one end and overfill slide the glass seal across the meniscus so that no air is trapped seal this end dry the cell and place in the holder. Look through the eyepiece.
E N D
The sample • The sample cell MUST be absolutely full • there can be no air bubbles • seal one end and overfill • slide the glass seal across the meniscus so that no air is trapped • seal this end • dry the cell and place in the holder
Look through the eyepiece You should see a pattern like one of those below. If not, turn the knob just below the eyepiece until you do.
Adjust the polarimeter Turn the knob until the image changes from one to the other
Adjust the polarimeter Now turn the knob very slightly back the other way until an overall uniform image is obtained.
Read the scale The scale is a Vernier scale. The outer scale gives you the whole number value. The inner scale gives the decimal place.
10 0 Reading the Vernier scale Where the inner scale 0 points to is the whole number. Here it is somewhere between 11 and 12 Where the inner and outer scale markings line up gives the decimal place from the inner scale value. Here it is 9. The reading here is +11.9 deg. If the reading is 0-90, it is positive. If it is 90-180, subtract 180 from it to give a negative reading.