1. Measurement of toothpaste abrasion Anders Liljeborg Gunnar Johannsen

5. Earlier measurements HeNe laser Plexi-sample Photo diode Voltmeter

6. Surface profilometer, KLA-Tencor P15 Diamond stylus, 2 micron radius Vertical resolution a few nanometers

7. 117 mm 25 mm 20 mm Blank profile

8. Center profile, 2000 points

9. Center, +20mm and -20mm profiles

10. Nonflat plexi surface

11. Compensated by fit of 3:rd order polynomial to 50 first and last points

12. Comparison with “blank” profile at lower end of plexi sample, note bad fit to the left, good fit to the right.

13. RA (Roughness Average) = mean deviation from mean depth value RA = sum ( abs( mean – y ) ) / length RA and mean depth computed for center 20% of profile