Tham khảo tài liệu 'tribology - lubricants and lubrication part 13', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 232 Tribology - Lubricants and Lubrication damage to the lens surface because the friction force image is made by contact. On the other hand the disadvantage of force modulation methods is that the tip can change shape and is a possible source of contamination because it is always pushed into the sample indentation . Therefore we believe that it is more convenient to use phase images than friction force images or force modulation images for determining the island structures of shapes with similar surface morphologies. Fig. 10. Topographic image left side FFM image right side bright area indicates higher friction darker area indicates lower friction upper image is sample A middle image is sample B lower image is sample C Characterization of Lubricant on Ophthalmic Lenses 233 Fig. 11. Frequency analysis of phase separation by FFM top distribution sample A bottom distribution sample B it shows red histogram for whole area blue area for lubricant phase separation A and green area for lubricant phase separation B Fig. 12. Phase image left side force modulation image right side bright area indicates harder area darker area indicates softer area of sample B Fig. 13. In-phase image input-i left side and quadrature image input-q right side of sample B divided by phase .
