In order to improve the accuracy of measuring method of insulation surface contamination degree based on optical power loss

a surface contamination degree measurement system based on bare fiber is established. Based on the established system

the influences of salt solution concentration

non-soluble salt solution suspension concentration

fiber shape

light source type and fiber type on the optical power loss caused by the salt deposit are experimentally investigated and the results are analyzed theoretically. The experimental results reveal that the optical power loss increases gradually along with the increase of salt solution concentration; the influence of the non-soluble salt solution suspension concentration on the optical power loss is not obvious; the optical power loss using U-shape optical fiber is more significant than that using linear shape optical fiber; the optical power loss using broadband（multi-longitudinal mode） light source is more significant than that using narrow spectrum light（single longitudinal mode）source; the optical power loss using multi-mode fiber is more significant than that using single mode fiber. The theoretical analysis results explain the experimental results well and verify the reliability of the experimental results. The semiconductor light source

multi-mode fiber and U-type state should be used in the contamination degree measurement based on the bare fiber in order to improve the measuring accuracy.