3-DIMENSIONAL PARTIALLY-COHERENT IMAGE-FORMATION IN CONFOCAL MICROSCOPES WITH A FINITE-SIZED DETECTOR

The concept of the transmission cross-coefficient (TCC) is used to describe three-dimensional (3D) imaging in transmission and reflection confocal scanning microscopes with a finite-sized detector. The effects of the detector size are studied in detail in terms of the 3D weak-object transfer functions (WOTFs) for weakly scattering objects. As is already known, 3D transmission imaging for an infinitely large detector and for a point detector are identical, whereas it is shown that between two limiting cases the behaviour is different, suggesting that axial phase information can be imaged. It is found that 3D reflection imaging for an infinitely large detector can be equivalent to 3D true confocal imaging using one annular and one circular pupil. The 3D WOTF in reflection reveals negative values which may reverse the contrast of an image at some spatial frequencies.