Multispot point spread function for multiphoton fluorescence microscopy.

Area of Science:

• Optics and Photonics
• Biomedical Imaging
• Microscopy

Background:

• Multiphoton fluorescence microscopy offers deep tissue penetration and reduced photodamage.
• Current techniques often face limitations in simultaneously imaging multiple focal planes.
• Existing methods can suffer from out-of-focus excitation (sidelobes).

Purpose of the Study:

• To introduce and validate a novel optical imaging technique for multiphoton fluorescence microscopy.
• To demonstrate the generation of multiple, distinct excitation nanospots along the optical axis.
• To overcome limitations of single-photon excitation variants in 3D imaging.

Main Methods:

• Utilizing an interference method to generate the point spread function (PSF).
• Employing two counterpropagating extended depth of focus beams along the optical axis.
• Operating at an illumination wavelength of 976 nm with a 60-degree aperture angle.

Main Results:

• Successfully generated five distinct nanospots with dimensions of approximately 210 nm along the optical axis.
• The resulting point spread function enables simultaneous excitation of multiple planes.
• The technique effectively overcomes the sidelobe problem inherent in single-photon methods.

Conclusions:

• The proposed multiple-excitation-spot technique enhances multiphoton fluorescence microscopy.
• This method offers a promising solution for advanced nanobioimaging and 3D fluorescence microscopy.
• Simultaneous multiplane excitation improves imaging efficiency and reduces artifacts.