Coherence-gated wavefront sensing for microscopy using fringe analysis

摘要

We have implemented a coherence-gated wavefront sensor on a two-photon excitation microscope. We used the backscattered near-infrared light from the sample to interfere with an optically flat reference beam. By applying a known wavefront tilt in the reference beam, a fringe pattern emerged on the camera. The deformation of the wavefront due to the turbid media under study warps the fringe pattern, similar to frequency modulation. Through Fourier transform analysis of the modulated fringe pattern we were able to determine the wavefront aberrations induced by synthetic and biological samples. By defocussing the microscope objective and measuring the wavefront deformation we established that the errors are reproducible to within λ/227 for the defocus mode.