Design and optimization of heterogeneous pupil filters for super-resolution differential confocal microscopy

To address the difficulty in simultaneously improving the lateral resolution and axial response sensitivity in differential confocal microscopy, this study proposes a differential confocal measurement method based on the collaborative optimization of the heterogeneous pupil filters in the illumination and detection paths. An analytical model of the heterogeneous pupil differential confocal system is established, achieving the coordinated enhancement of the lateral resolution and axial response sensitivity. A fast evaluation mechanism is introduced to improve the computational efficiency by 65%. Based on the optimized parameters, the heterogeneous pupil filters are fabricated. Experimental results demonstrate that the lateral full width at half maximum of the focal spot is reduced by approximately 14%, and the slope of the axial differential response within the linear region is increased by approximately 13%, consistent with the simulation results. The proposed method achieves the simultaneous enhancement of the lateral resolution and axial response sensitivity while maintaining a compact system structure, providing an effective optical enhancement strategy for high-precision three-dimensional surface profile measurement.