FIGURE 2.

Experimental layout of a DA-TPEF microscope. A mode-locked Ti:sapphire laser beam is focused into a sample, and the resulting TPEF is epi-collected and routed to a photomultiplier tube (PMT) with a dichroic mirror. The layout of our DA-TPEF is identical to that of a standard TPEF microscope except that a deformable mirror (DM) is inserted in the laser beam path in a conjugate plane to the scanning mirrors and hence to the objective back aperture (i.e., the illumination pupil). As illustrated, two kinds of voltage patterns are applied to the DM, introducing either quadrant or spiral phase aberration profiles in the illumination pupil plane.