Fig. 2.

The effect of plane spacing on the axial-PLAM and the axial-FIM for a MUM setup. The left-hand (right-hand) side plots show the axial-PLAM (axial-FIM) for a 2-plane MUM setup as a function of the z-position of the point source. The figure also shows the axial-FIMs and axial-PLAMs of focal planes 1 and 2. The plane spacings (Δz₁₂) are 0.1, 0.5, 1 and 3 μm from top to bottom. (c) and (d) show the strong coupling spacing whereas (e) and (f) show the weak coupling spacing. (f’) shows the shoulder of the axial-FIM₁ more clearly. The results are calculated for a 100x, NA 1.3 oil immersion objective lens where the photon count is 250 photons/plane and the emission wavelength is 520 nm. The background level is 1 photon/pixel/plane and the standard deviation of the readout noise is 2 e⁻/pixel. The ROI size is 11 × 11 pixels.