a,b, Artificial aberration introduced with the SLM and corrective wavefront on the DM, respectively. c,d, Axial images of 0.5-μm- and 10-μm-diameter fluorescent beads, respectively, without AO, with AO (phase modulation), and under ideal aberration-free conditions (without artificial aberrations applied to the SLM). Digital gains were applied to No AO images to increase visibility. Post-objective power: 6 and 2.3 mW, respectively. e,f, 2P signal versus iteration number for 0.5-μm- and 10-μm-diameter beads, respectively, using phase and intensity modulation. Scale bars: 1 μm in c and 5 μm in d. Microscope objective used: NA 0.8 16×. n = 1 bead in c and d, respectively.