景深D:物镜的垂直分辨率 (0.15~0.30)n (N.A.)M (uum) Depth of Field Ranges Low NA High NA Object Plane Depth of In a conventional widefield optical epi- Field fluorescence microscope,secondary fluorescence emitted by the specimen often occurs through the excited volume and obscures resolution of features that lie in the objective focal plane. Figure 17 景深Df：物镜的垂直分辨率 In a conventional widefield optical epi￾fluorescence microscope, secondary fluorescence emitted by the specimen often occurs through the excited volume and obscures resolution of features that lie in the objective focal plane