Residual modulation reduction in optical sectioning using a suitable spatial light modulator waveform.

We propose a method to improve the axial response of structured illumination microscopy via selection of an illumination pattern with a sinusoidal or square wave within the cutoff frequency of the imaging system. Residual modulation within a sectioned image is mitigated by accurate phase-shifting via the electrical spatial light modulator control signal, which is based on an illumination pattern having a suitable waveform. Reduction in residual modulation is observed in the sinusoidal pattern with a spatial frequency sufficiently below the cutoff frequency of the imaging system. This reduction is larger for the square wave as the spatial frequency approaches one-third of the cutoff frequency.