Axial Range Expansion Method for Multi-Differential Confocal Three-Dimensional Imaging

In this study, a novel differential confocal microscopy (DCM) measurement method called the axial range expansion method for multi-differential confocal three-dimensional imaging is proposed. The method solves the problem of effective data extraction for DCM implementation of the multi-differential confocal (MDCM) method by analyzing the constraints of differential signals in DCM with respect to two confocal signals with axial offsets in DCM. And the processed DCM data from multiple locations are fused to realize the larger sensing measurement range. Experiments with a parallel object dual-detector system show that it is an effective method. Under the 10x/0.25 objective, the axial layer sweep step is $14~\mu \text{m}$ , the measurement error of the step height of $29.302~\mu \text{m}$ is $0.402~\mu \text{m}$ , and the error rate is 1.37%.