Laser sources in direct-view-scanning, tandem-scanning, or nipkow-disk-scanning confocal microscopy.

Laser sources offer a potentially low-cost means of improving thelight throughput in tandem-scanning confocal microscopy because oftheir high beam directionality. We measure and compare the opticalsectioning characteristics of the tandem-scanning microscope (TSM)employing (i) the traditional choice of incoherent light from a Xearc lamp and (ii) a cited alternative-coherent light from a He-Nelaser source. In general the laser source is found to result inaxial responses with pronounced sidelobes, the sizes and locations ofwhich are extremely sensitive to the alignment of the pinholearray. The implications of these results for practical TSM systemsare discussed.

Superresolution in confocal scanning microscopy.

We describe three simple pupil function filters that, in conjunction with a confocal optical system, result in a transfer function that is constant for all spatial frequencies up to the cutoff. We confirm our predictions experimentally by considering a straight-edge object. Edge gradients up to 2.36 times as sharp as the unapodized confocal case are obtained.

Imaging in scanning microscopes with slit-shaped detectors.

We consider the imaging in scanning microscopes employing point and slit-shaped detectors in both the bright-field and fluorescent mode. In particular we consider the three-dimensional aspects of the imaging and show inter alia that acceptable, albeit asymmetrical, images result from a slit detector system at low levels of defocus. The situation becomes worse as the defocus is increased although acceptable extended-focus and isometric images are still possible in some cases.

Use of objective lenses with slit pupil functions in the imaging of line structures.

We consider the imaging of line structures in confocal imaging systems and show that some advantages result if we employ a slit pupil function in one of the lenses. As an example it is found that the gradient of the image of a straightedge is 17.8% sharper than in a traditional confocal microscope. Another attraction is that theoretical imaging calculations are often possible in terms of simple analytic functions. Experimental results and images are presented which are compared with traditional confocal systems as well as those employing incoherent slit detectors.