Ultraprecision machining of microlens arrays with integrated on-machine surface metrology

Microlens arrays (MLAs) are increasingly applied in high-end photonics and imaging systems. Advanced diamond turning machining with tool servo technique is a superior method of fabricating micro-structured arrays with sub-micrometer form accuracy and nanometer surface finish. This paper proposes an innovative framework for ultraprecision machining of MLA. The established metrology-integrated machining platform consists of a 3-axis ultraprecision turning machine and a nanometric interferometric probe. On-machine surface measurement enables the in situ inspection and characterization of MLA features while preserving the consistency between the machining and measurement coordinate. The dedicated surface error characterization method and 3D corrective machining strategy are also presented. An experimental study is carried out in order to prove the proposed MLA characterization's and 3D corrective machining's effectiveness in improving the MLA surface accuracy.