PSF in Microscopy
In microscopy, experimental determination of a PSF's shape is usually tricky, due to the difficulty of finding sub-resolution (point-like) radiating sources. Quantum dots and fluorescent beads are usually considered for this purpose. Theoretical models as described above, on the other hand, allow the detailed calculation of the PSF for various imaging conditions. The most compact diffraction limited shape of the PSF is usually preferred. However by using appropriate optical elements (e.g., a spatial light modulator) the shape of the PSF can be engineered towards different applications.
Read more about this topic: Point Spread Function