Abstract
Point spread function (PSF) engineering has met with lots of interest in various optical imaging techniques, including super-resolution microscopy, microparticle tracking, and extended depth-of-field microscopy. The intensity distributions of the modified PSFs often suffer from deteriorations caused by system aberrations, which greatly degrade the image contrast, resolution, or localization precision. We present an aberration correction method using a spiral-phase-based double-helix PSF as an aberration indicator, which is sensitive and quantitatively correlated to the spherical aberration, coma, and astigmatism. Superior to the routine iteration-based correction methods, the presented approach is iteration-free and the aberration coefficients can be directly calculated with the measured parameters, relieving the computing burden. The validity of the method is verified by both examining the intensity distribution of the conventional Gaussian PSF in three dimensions and observing muntjac skin fibroblast cells. This iteration-free correction method has a potential application in PSF engineering systems equipped with a spatial light modulator.
Highlights
Point spread function (PSF) engineering has been a routine technique in various applications, such as super-resolution microscopy,[1] microparticle tracking,[2] and extended depth-offield microscopy.[3,4] Apart from the conventional imaging systems, PSFs are regularly modified into a variety of shapes, including biplane PSF,[5] Bessel PSF,[6] cubic-phase PSF,[7,8] astigmatic PSF,[9] and double-helix PSF10,11 (DH-PSF), by which improved imaging resolution, axial localization precision, or depth-of-field can be achieved
The emission light is collected by the identical microscopy objective (100×, NA 1⁄4 1.25, Nikon Inc., Japan), of which the back focal plane is reimaged onto the spatial light modulator (SLM) (1920 × 1080 pixels, Pluto II, HoloEye Photonics AG, Germany) with 1:1
We have quantitatively studied the response of the double-helix PSF to different aberrations
Summary
Point spread function (PSF) engineering has been a routine technique in various applications, such as super-resolution microscopy,[1] microparticle tracking,[2] and extended depth-offield microscopy.[3,4] Apart from the conventional imaging systems, PSFs are regularly modified into a variety of shapes, including biplane PSF,[5] Bessel PSF,[6] cubic-phase PSF,[7,8] astigmatic PSF,[9] and double-helix PSF10,11 (DH-PSF), by which improved imaging resolution, axial localization precision, or depth-of-field can be achieved. PSFs of imaging systems are often distorted by system aberrations, which stem from misaligned optical elements, surface-shape error of the optical components, and refractive-index mismatch.[12,13,14,15] As a consequence, imaging performance inevitably degrades, making aberration correction an essential procedure in these applications. Existing aberration measurement techniques can be categorized into direct wavefront sensing and indirect wavefront sensing.[16,17] Direct sensing is usually implemented with a Shack–Hartmann wavefront sensor,[18,19,20,21] which can provide high speed measurement; its requirement of both a wavefront sensor and a correction element increases the cost and complexity of the system.[17] In contrast, indirect sensing methods only require a wavefront correction element, which makes them more economical and convenient for the construction of microscopes.[22,23,24,25] Typically, images of fluorescent beads at Gaussian PSF, due to its weak response to wavefront error
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