Laser polishing(LP)is considered an effective method for generating ultrasmooth surfaces owing to its precision,flexibility,and material compatibility.However,a lack of understanding of the evolution of surface topogr...Laser polishing(LP)is considered an effective method for generating ultrasmooth surfaces owing to its precision,flexibility,and material compatibility.However,a lack of understanding of the evolution of surface topography during LP significantly limits the achievable surface roughness in practice.In this work,for the first time,by employing optical time-stretch quantitative interferometry(OTS-QI),we recorded the entire evolution of surface topography during LP with nanosecond-level temporal resolution,providing insight into the mechanisms involved in the surface roughness evolution,such as the Marangoni effect and the formation mechanism of mid-frequency waviness(MFW).Assisted by numerical calculations,we reveal that a‘perfect polishing point’exists,i.e.,the optimal interaction time for LP at a specific laser power density,at which the surface roughness can be minimised without the formation of an MFW owing to the Marangoni effect and non-uniform removal.This OTS-QI system harnesses the rapid repetition rate of femtosecond lasers,achieving a remarkable measurement speed exceeding 100,000,000 times per second while preserving a measurement accuracy comparable to that of existing white light interferometers(WLIs),setting a new benchmark as the fastest recorded roughness measurement.In addition to LP,the proposed method can be applied for real-time and in situ monitoring of many machining scenarios involving highly dynamic phenomena.展开更多
基金supported by the National Natural Science Foundation of China(12374295,62075200)the National Key Research and Development Program of China(2023YFB4603803)+2 种基金The Fund of National Key Laboratory of Plasma Physics(6142A04230201)Fundamental Research Funds for the Central Universities(2042023kf0113)the Shenzhen Science and Technology Program(20JCYJ20220530140601003).
文摘Laser polishing(LP)is considered an effective method for generating ultrasmooth surfaces owing to its precision,flexibility,and material compatibility.However,a lack of understanding of the evolution of surface topography during LP significantly limits the achievable surface roughness in practice.In this work,for the first time,by employing optical time-stretch quantitative interferometry(OTS-QI),we recorded the entire evolution of surface topography during LP with nanosecond-level temporal resolution,providing insight into the mechanisms involved in the surface roughness evolution,such as the Marangoni effect and the formation mechanism of mid-frequency waviness(MFW).Assisted by numerical calculations,we reveal that a‘perfect polishing point’exists,i.e.,the optimal interaction time for LP at a specific laser power density,at which the surface roughness can be minimised without the formation of an MFW owing to the Marangoni effect and non-uniform removal.This OTS-QI system harnesses the rapid repetition rate of femtosecond lasers,achieving a remarkable measurement speed exceeding 100,000,000 times per second while preserving a measurement accuracy comparable to that of existing white light interferometers(WLIs),setting a new benchmark as the fastest recorded roughness measurement.In addition to LP,the proposed method can be applied for real-time and in situ monitoring of many machining scenarios involving highly dynamic phenomena.
