The interaction between free electrons and optical near fields is attracting increasing attention as a way to manipulate the electron wave function in space, time, and energy. Relying on currently attainable experimental capabilities, we design optical near-field plates to imprint a lateral phase on the electron wave function that can largely correct spherical aberration without the involvement of electric or magnetic lenses in the electron optics, and further generate on-demand lateral focal spot profiles. Our work introduces a disruptive and powerful approach toward aberration correction based on light-electron interactions that could lead to compact and versatile time-resolved free-electron microscopy and spectroscopy.
Zernike polynomials are one of the most widely used mathematical descriptors of optical aberrations in the fields of imaging and adaptive optics. Their mathematical orthogonality as well as isomorphisms with experimentally observable aberrations make them a very powerful tool in solving numerous problems in beam optics. However, Zernike aberrations show cross-coupling between individual modes when used in combination with Gaussian beams, an effect that has not been extensively studied. Here we propose a novel framework that is capable of explaining the fundamental cross-compensation of Zernike…
Attosecond pulses created by high-order harmonic generation in gases often exhibit strong chromatic aberrations, arising from the broad bandwidth and wavelength-dependent nonlinear light-matter interaction. When the driving laser intensity varies spatially, as for Gaussian driving beams, the apparent source position of the harmonics differs significantly from one order to the next, thus affecting the achievable intensity and duration of the attosecond pulses when they are focused on a target. We show that these chromatic aberrations can be reduced by spatially shaping the fundamental beam to g…
We report on the usage of ultrashort laser pulses in form of aberration-corrected Bessel-like beams for laser cutting of glass with bevels. Our approach foresees to incline the material's entrance surface with respect to the processing optics. The detailed analysis of phase distortions caused by the beam transition through the tilted glass surface allows to pre-compensate occurring aberrations using digital holography. We verify theoretical considerations by means of pump-probe microscopy and present high-quality edges in non-strengthened silicate glass.
We report a novel generalized optical measurement system and computational approach to determine and correct aberrations in optical systems. We developed a computational imaging method capable of reconstructing an optical system's aberration by harnessing Fourier ptychography (FP) with no spatial coherence requirement. It can then recover the high resolution image latent in the aberrated image via deconvolution. Deconvolution is made robust to noise by using coded apertures to capture images. We term this method: coded aperture-based correction of aberration obtained from Fourier ptychography …
Zernike polynomials are widely used mathematical models of experimentally observed optical aberrations. Their useful mathematical properties, in particular their orthogonality, make them a ubiquitous basis set for solving various problems in beam optics. Thus they have found widespread use in adaptive optics realizations that are used to correct wavefront aberrations. However, Zernike aberrations lose their orthogonality when used in combination with Gaussian beams, which are omnipresent in real-world optical applications. As a consequence, Zernike aberrations in Gaussian beams start to cross-…
The aberrations induced by the sample and/or by the sample holder limit the resolution of optical microscopes. Wavefront correction can be achieved using a deformable mirror with wavefront sensorless optimization algorithms but, despite the complexity of these systems, the level of correction is often limited to a small area in the field of view of the microscope. In this work, we present a plug and play module for aberration measurement and correction. The wavefront correction is performed through direct wavefront reconstruction using the spinning-pupil aberration measurement and controlling …
Free electrons moving in an optical standing wave field feel the ponderomotive potential, acting as a refractive-index medium in electron optics. Emerging technologies involving this potential have been proposed and realized in electron microscopy, such as electron phase-contrast imaging using a laser standing wave in an optical enhancement cavity. However, the interaction between electrons with a cylindrically distributed optical field has not been investigated although its suitability for electron-optical imaging systems. In this study, we theoretically show that the divergence and convergen…
Full-field-of-view aberration correction for large arrays of focused beams
Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-Université PSL, Sorbonne Université（卡斯勒-布罗塞尔实验室，法兰西学院，法国国家科学研究中心，巴黎高等师范学院-巴黎文理研究大学，索邦大学）；Institut Universitaire de France（法国高等研究院）
The properties of electron round lenses produced by the ponderomotive potential are investigated in geometrical optics. The potential proportional to the intensity distribution of a focused first-order Bessel or Laguerre-Gaussian beam is exploited to produce an electron round lens and a third-order spherical aberration corrector. Several formulas for the focal length and spherical aberration coefficients in the thin-lens approximation are derived to set the lens properties and associated light beam parameters. When the mode field of the optical beam is small, the electron trajectory calculatio…
Spatiotemporal optical coherence (STOC) imaging is a new technique for suppressing coherent crosstalk noise in Fourier-domain full-field optical coherence tomography (FD-FF-OCT). In STOC imaging, the timevarying inhomogeneous phase masks modulate the incident light to alter the interferometric signal. Resulting interference images are then processed as in standard FD-FF-OCT and averaged incoherently or coherently to produce crosstalk-free volumetric OCT images of the sample. Here, we show that coherent averaging is suitable when phase modulation is performed for both interferometer arms simult…
We present generation of asymmetric aberration laser beams (aALBs) with controlled intensity distribution, using a diffractive optical element (DOE) involving phase asymmetry. The asymmetry in the phase distribution is introduced by shifting the coordinates in a complex plane. The results show that auto-focusing properties of aALBs remain invariant with respect to the asymmetry parameters. However, a controlled variation in the phase asymmetry allows to control the spatial intensity distribution of aALBs. In an ideal ALB containing equal intensity three bright lobes (for $m=3$), by introducing…
TianQin is a planned Chinese space-based gravitational wave (GW) observatory with a frequency band of 10-4 to 1Hz. Optical telescopes are essential for the delivery of the measurement beam to support a precise distance measurement between pairs of proof masses. As the design is driven by the interferometric displacement sensitivity requirements, the stability control of optical path length (OPL) is extremely important beyond the traditional requirement of diffraction-limited imaging quality. In a telescope system, the recurring tilt-to-length (TTL) coupling noise arises from the OPL variation …
The correction of multiple aberrations in an optical system requires different optical elements, which increases its cost and complexity. Metasurfaces hold great promise to providing new functionality for miniaturized and low-cost optical systems. A key advantage over their bulk counterparts is the metasurface's ability to respond to the polarization of light, which adds a new degree of freedom to the optical design. Here, we show that polarization control enables a form-birefringent metalens to correct for both spherical and off-axis aberrations using a single element only, which is not possi…
The separation of complex inner and outer contours of glass articles with curved surfaces using ultrashort pulsed lasers is reported. Single-pass, full-thickness modifications along the entire substrate are achieved using a processing optics that allows for beam shaping of non-diffracting beams and, additionally, for aberration compensation of phase distortions occurring at the curved interface. The glass articles finally separated by thermal stress or via selective etching meet the demands of the medical industry in terms of micro-debris, surface quality and processing speed.
Physics-Informed Graph Neural Networks for Frequency-Aware Optical Aberration Correction
School of Computer Science, University of Nottingham（诺丁汉大学计算机科学学院）；Photonics Group, Department of Electrical and Electronic Engineering, University of Nottingham（诺丁汉大学电子与电气工程系光子组）；Research Center for Humanoid Sensing, Zhejiang Laboratory（浙江实验室人机感知研究中心）
The aberrations in an optical microscope are commonly measured and corrected at one location in the field of view, within the so-called isoplanatic patch. Full-field correction is desirable for high-resolution imaging of large specimens. Here we present a novel wavefront detector, based on pupil sampling with sub-apertures, which measures the aberrated wavefront phase at each position of the specimen. Based on this measurement, we propose a region-wise deconvolution that provides an anisoplanatic reconstruction of the sample image. Our results indicate that the measurement and correction of th…
The key to optimizing spatial resolution in a state-of-the-art scanning transmission electron microscope is the ability to precisely measure and correct for electron optical aberrations of the probe-forming lenses. Several diagnostic methods for aberration measurement and correction with maximum precision and accuracy have been proposed, albeit often at the cost of relatively long acquisition times. Here, we illustrate how artificial intelligence can be used to provide near-real-time diagnosis of aberrations from individual Ronchigrams. The demonstrated speed of aberration measurement is impor…
In light optics, beams with orbital angular momentum (OAM) can be produced by employing a properly-tuned two-cylinder-lens arrangement, also called $π$/2 mode converter. It is not possible to convey this concept directly to the beam in an electron microscope due to the non-existence of cylinder lenses in commercial transmission electron microscope (TEM). A viable work-around are readily-available electron optical elements in the form of quadrupole lenses. In a proof-of-principle experiment in 2012, it has been shown that a single quadrupole in combination with a Hilbert phase plate produces a …
In this paper we propose and experimentally demonstrate information transfer through free-space using a laser beam encoded with multiple orthogonal aberration modes in its phase profile. We use Zernike polynomials which forms a complete set of basis functions to represent the aberration modes. The user information is encoded as amplitudes of multiple Zernike modes whose linear combination is used to define the wavefront of the laser beam in the transmission station. It therefore requires a single phase modulating device since the multiplexing is done digitally providing flexibility over the nu…
Diffraction-limited focusing deep into biological tissue is challenging due to spherical aberrations that lead to a broadening of the focal spot particularly in axial direction. While the diffraction-limit can be restored employing aberration correction with a deformable mirror or spatial light modulator, a bulky optical setup results due to the required beam-folding. We propose a bi actor adaptive lens, that enables axial scanning and at the same time correction of specimen induced spherical aberrations while offering a compact setup. Using the bi-actor lens in a confocal microscope, we show …
High-resolution retinal matrix imaging via computational motion and aberration correction
PSL University, ESPCI Paris, CNRS, Institut Langevin（巴黎文理研究大学，巴黎高等物理化工学院，法国国家科学研究中心，朗之万研究所）；Institute of Biomedical Optics, University of Lübeck（吕贝克大学生物医学光学研究所）；OWLO SAS（OWLO公司）；Airway Research Center North (ARCN), Member of the German Center for Lung Research (DZL)（北方气道研究中心，德国肺病研究中心成员）
Aberrations limit optical systems in many situations, for example when imaging in biological tissue. Machine learning offers novel ways to improve imaging under such conditions by learning inverse models of aberrations. Learning requires datasets that cover a wide range of possible aberrations, which however becomes limiting for more strongly scattering samples, and does not take advantage of prior information about the imaging process. Here, we show that combining model-based adaptive optics with the optimization techniques of machine learning frameworks can find aberration corrections with a…
This paper demonstrates a method of interpreting the mechanism of aberration of optical systems based on non-Fourier transform optical transfer function (OTF). According to the parameters of object plane cosine fringe, we obtain the position on the pupil plane of the two beams of the interference pair emitted by the cosine fringes. By combining the aberrations of the lens, the phase of the cosine fringe of each interference pair in the image plane can be obtained. Then the intensity of the cosine fringe formed by all the interference pattern is superimposed to obtain the brightness distributio…
