Compressional Deformation in Indentation Process for Microlens Array Mold

The structure of a microlens array(MLA) can be formed on copper by an indentation process which is a new manufacture approach we applied here instead of a traditional method to test the material property, thereby work time can be saved. Single-indentation and multi-indentation are both conducted to generate a single dimple and dimples array, namely micro lens and MLA. Based on finite element simulation method, factors affecting the form accuracy, such as springback at the compressed area of one single dimple and compressional deformation at the adjacent area of dimples arrays, are determined, and the results are verified by experiments under the same conditions. Meanwhile, indenter compensation method is proposed to improve form accuracy of single dimple, and the relationship between pitch and compressional deformation is investigated by modelling seven sets of multi-indentations at different pitches to identify the critical pitch for the MLA's indentation processing. Loads and cross-sectional profiles are measured and analyzed to reveal the compressional deformation mechanism. Finally, it is found that MLA at pitches higher than 1.47 times of its diameter can be manufactured precisely by indentation using a compensated indenter.