Snapshot coherence-gated direct wavefront sensing for multi-photon microscopy.

Area of Science:

• Biomedical Optics
• Microscopy
• Adaptive Optics

Background:

• Deep imaging in scattering media like biological tissue is limited by scattering and optical aberrations.
• Adaptive optics (AO) offers a promising solution for correcting these aberrations.
• Existing wavefront sensing methods may face challenges in turbid environments.

Purpose of the Study:

• To develop and validate a novel wavefront sensing scheme for multi-photon scanning microscopes.
• To enable deeper penetration and clearer imaging in scattering biological tissues.
• To correct both system-induced and sample-induced optical aberrations.

Main Methods:

• Utilized back-reflected light from the sample within a multi-photon scanning microscope.
• Employed coherence gating and a confocal pinhole to isolate light from a specific depth.
• Interfered back-reflected light with a tilted reference beam to generate a fringe pattern.
• Analyzed fringe pattern distortions in the Fourier domain to extract wavefront aberrations.
• Integrated a virtual Shack-Hartmann sensor for aberration smoothing and modal representation.

Main Results:

• Successfully demonstrated wavefront sensing using reflected light in turbid media.
• Corrected system-induced aberrations from a deformable mirror (DM).
• Corrected sample-induced aberrations in biological samples, including rat tail collagen fibers.
• Showcased aberration correction in a Hoechst-stained MCF-7 cancer cell spheroid.

Conclusions:

• The presented wavefront sensing scheme is effective for aberration correction in multi-photon microscopy.
• This technique facilitates deeper and clearer imaging in scattering biological tissues.
• The method shows potential for various applications in deep tissue imaging and optical microscopy.