Compact way to generate guide star for wavefront sensing in Bessel two-photon microscopy

We introduce a compact method for generating guide stars to enable direct wavefront sensing in Bessel two-photon microscopy. By sequentially modulating an axicon phase and a thin lens phase using a spatial light modulator (SLM), our approach achieves seamless switching between Bessel and Gaussian illumination beams without requiring mechanical movement or additional optical components. The Bessel beam provides an expanded field of view for imaging, while the Gaussian beam serves as a point-like guide star for wavefront sensing. Experimental validation in a Bessel two-photon light sheet microscope demonstrates that wavefront correction based on our method enhances the signal-to-noise ratio (SNR) by 7.3 times and improves axial resolution by 4.4 times.