Fig. 2.

Schematic diagram of the OPC-assisted isotropic focusing system. 532nm laser beam was split into two paths. Both beams were spatially filtered as coupled to single mode fiber and collimated by bulk lenses. One path passing EOM formed an original focal spot through OBJ1 and entered DOPC system, the other path was split into two beams – a reference beam for phase-shifting holography and an OPC beam retracing the original focal spot back. ND, continuous neutral density filter; SF, spatial filter; 1X TS, 1X telescope; PH, pinhole; MFW, motorized filter wheel; OBJ, objective lens; EOM, Electro-optical phase modulator; SLM, spatial light modulator; SCMOS, scientific CMOS camera; CCD, CCD camera; APD, avalanche photo diode.