[Stepan]

Hello, I have standard ABBE refractometer and oils with nD from 1.49 to 1.70. How do I use all this to measure refractive index of a polymer film or block? What is a procedure? Thanks

[Stepan]

Just want to share how I resolved the problem:

Now I can measure refractive index using something called Dispersion Staining microscopy. This is a microscopy technique often used in geology to measure refractive index of minerals. On this video, I do it for asbestos fibers:

http://www.youtube.com/watch?v=wEf9-lsxVvQ

Fibers have refractive index of 1.55. the same as oil used in this test. If refractive indexes are the same, under "dark field" condition the sample has purple or magenta-blue colour. If the difference between RI of oil and of the sample is more than 0.02 the sample turns white or yellow. I tried on a few polymers and it worked fine. But is takes a lot of time, because you basically need to try different oils with known RI before you match the colour to magenta.