Effect of secondary aberration induced by actual objective lens on 3D direct laser writing

The most problematic aberrations in 3D DLW are related to mismatched refractive index at surface of the sample. Adaptive optical element placed in a plane conjugate to the objective pupil can be used to apply the correcting phase, providing a promising aberration correction. Currently, the calculation of correcting phase are all based on the assumption of ideal objective lens. In practice, secondary aberration is introduced due to the use of actual objective lens, and has not been researched. In this paper, we compare ideal objective lens and actual objective lens in theory, and simulate the energy distribution inside of sample. The effect of secondary aberration on DLW performance is reported. We make compensation for the secondary aberration, and contract the energy distribution of correcting secondary aberration and without correcting secondary aberration. Correction of secondary aberration caused by actual objective lens provides a more accurate correcting method of 3D DLW.