ABSTRACT
When we look at a single, bright point in a conventional wideŽeld microscope, the image of the light is spread out into a complex three-dimensional shape, which resembles a couple of vases placed base to base or the old-fashioned children’s toy called a diabolo (Figure 10.1). At the focal plane (the base of these vases or the center of the diabolo), we see a cross-section of this shape, which is the familiar Airy disk. The overall shape is known as the point spread function (PSF), that is, the function describing the spread of light emanating from a point. It is a much more complex shape than the confocal PSF (Chapter 5).
