91SHG Microscopy and Its Comparison
For laser scanning microscopy, the relative distance between the optical components is strictly regu-
lated. In the ideal case shown in Figure 4.6, they are spaced by the focal length of the lenses except for
the dichroic mirrors and emission lters, which are located in the innity space. is arrangement is
important to maintain both proper beam path (propagation directionality) and correct beam prole
(size and divergence). e laser beam is expanded by the scan lens and the tube lens to ll the micro-
scope objective back aperture for maximum resolution as the beam can then be focused into the tightest
spot (1′ or 2′) at the sample plane. One crucial aspect is that when the scan mirror moves the laser beam ...