Particles 3D tracking with large axial depth by using the 2π-DH-PSF.

Area of Science:

• Optics and Photonics
• Biophysics
• Nanotechnology

Background:

• Accurate three-dimensional (3D) localization of nanoparticles is crucial for various scientific fields.
• Conventional double-helix point spread functions (DH-PSFs) offer 3D imaging capabilities but have limitations in axial range and rotation.
• Developing advanced PSF engineering techniques is essential for enhancing microscopy performance.

Purpose of the Study:

• To introduce and validate a novel 2π-double-helix point spread function (2π-DH-PSF) for improved 3D super-resolution microscopy.
• To demonstrate the enhanced axial tracking range and localization accuracy of the proposed 2π-DH-PSF.
• To evaluate the performance of 2π-DH-PSF in measuring nanoparticle diffusion dynamics.

Main Methods:

• Utilized the Fresnel zone approach to design a 2π-DH-PSF capable of rotating 2π radians.
• Implemented the 2π-DH-PSF in a 100× microscopy system (NA=1.4, λ=514nm) with 16 Fresnel zones.
• Measured the diffusion coefficient of nanospheres in varying glycerol concentrations using the 2π-DH-PSF.

Main Results:

• Achieved particle tracking in an axial range of 10 µm.
• Demonstrated superior 3D localization imaging performance for nanoparticles with the 2π-DH-PSF.
• Obtained diffusion coefficient measurements with an error within 10% compared to theoretical values.
• Showcased a potential rotation angle of 4π radians when combined with defocus phase, four times that of conventional DH-PSF.

Conclusions:

• The proposed 2π-DH-PSF significantly enhances axial tracking range and localization accuracy in 3D imaging.
• The 2π-DH-PSF offers superior performance for nanoparticle tracking and diffusion analysis.
• This advanced PSF engineering approach holds great promise for future developments in super-resolution microscopy and biophysical studies.