Effect Of Spherical Aberration Research Articles

Effect of Spherical Aberration of Lens and Laser Intensity Distribution on Beam Quality

Effect of Spherical Aberration of Lens and Laser Intensity Distribution on Beam Quality

Effect of spherical aberration on visual acuity and depth of focus in pseudophakic eyes.

To assess the performance of 4 intraocular lenses (IOLs) in various spherical aberration (SA) conditions, using the VAO adaptive optics simulator. Cullen Eye Institute, Baylor College of Medicine, Houston, Texas. Prospective case series. Distance-corrected visual acuities at distance (CDVA), intermediate (DCIVA), and near (DCNVA) were measured in 42 dilated pseudophakic eyes at baseline and with ocular SA ranging from -0.4 to +0.4 μm in increments of 0.2 μm (6.0-mm pupil). 4 IOL types were assessed: monofocal IOLs with zero-SA, enhanced-monofocal, extended depth-of-focus (EDOF), and continuous range-of-vision. Compared with SA = 0 μm, significant changes (all P < .05) were: (1) zero-SA monofocal IOLs' DCNVA at high contrast improved by 0.13 logMAR with SA = -0.4 μm and worsened by 0.09 and 0.10 logMAR with SA = +0.2 and +0.4 μm, respectively. DCNVA at low contrast worsened by 0.09 logMAR with SA = +0.4 μm; and (2) with SA = -0.4 μm, the enhanced monofocal IOL lost 0.06 logMAR of CDVA at high contrast and gained 0.09 logMAR of DCNVA at low contrast. There were no significant changes from SA = 0 μm for EDOF and continuous range-of-vision IOLs. Zero-SA and EDOF IOLs were the most and least sensitive to SA modulation, respectively. In perfect optical systems where all the optical elements are aligned, induction of targeted amounts of negative SA improved the depth of focus of some IOL types. No benefit was found with positive SA.

Numerical study of satellite image quality in the presence of Seidel aberrations

AbstractWe present estimated images of a hypothetical satellite system in the presence of Seidel aberrations. We exemplified the effects of defocus, spherical, coma, astigmatism, field curvature, and distortion aberrations. Our analysis methods allow the investigation of aberration effects individually and in any combined form. Thereby, we introduce a potentially rich analysis dimension for the imaging chain, image processing, and image quality analyses. For a number of degrees of aberrations, we provide image estimates, show and quantify how individual (field‐dependent) aberrations would introduce degradations on the satellite images. We got correlation coefficient values for defocus, spherical, coma, astigmatism, field curvature, and distortion aberrations as 0.69, 0.71, 0.66, 0.79, 0.76, and 0.60, respectively. Thereby, we identfied the significance order of Seidel aberrations for this system by using image simulations and image similarity measures.

Generation of ultrafast tunable super-oscillation light fields

In this paper, we conceptually propose and numerically demonstrate the generation of ultrafast tunable super-oscillation (SO) light fields by tightly focusing a radially polarized Gaussian femtosecond pulse laser. It is shown that, as the fleeting time goes on within one-half cycle (0 fs < t < 200 fs), the light fields in the focal region can be converted from an Airy spot (>0.61λ/NA, where λ is the wavelength of incident beam and NA is the numerical aperture of objective lens), via a SO spot (<0.36λ/NA), to a super-resolved spot (<0.5λ/NA). We further uncover the rapid evolutions on the full width at half maximum, the normalized central intensity, and the side lobe of focused superoscillatory spots, thus supporting ultrafast adjustable SO light fields. In addition, the effect of primary spherical aberration on the focusing properties of SO spots is examined. The associated mechanism to yield such time-varying SO light fields is elucidated as well. The results presented here expand the flexibility of ultrafast light field manipulation and hold extensive applications in ultrafast and super-resolved imaging, high-density optical data storage, and high-efficiency particle trapping.

Coma Off It: Regularizing Variable Point-spread Functions

We describe a rapid and direct method for regularizing, post facto, the point-spread function (PSF) of a telescope or other imaging instrument across its entire field of view (FOV). Imaging instruments in general blur point sources of light by local convolution with a PSF that varies slowly across the FOV, due to coma, spherical aberration, and similar effects. It is possible to regularize the PSF in post-processing, producing data with a homogeneous “effective PSF” across the entire FOV. In turn, the method enables seamless wide-field astronomical mosaics at higher resolution than would otherwise be achievable, and potentially changes the design trade space for telescopes, lenses, and other optical systems where data uniformity is important. For many kinds of optical aberration, simple and rapid convolution with a locally optimized “transfer PSF” produces extremely uniform imaging properties at low computational cost. PSF regularization does not require access to the instrument that obtained the data, and can be bootstrapped from existing data sets that include starfield images or other means of estimating the PSF across the field.

Effect of larger corneal spherical aberration in improving the near visual acuity of eyes implanted with the TECNIS Symfony.

To explore the effect of corneal spherical aberration on the visual acuity and visual quality of eyes implanted with the TECNIS Symfony intraocular lens (IOL). A total of 43 patients with age-related cataract (60 eyes) undergoing phacoemulsification and TECNIS Symfony IOL implantation were enrolled in this study. The uncorrected distance (UDVA), intermediate (UIVA), near visual acuity (UNVA), corrected distance visual acuity (CDVA), contrast sensitivity, and ocular spherical aberration were recorded 3 months after surgery. Preoperative and postoperative corneal spherical aberration were also measured using the iTrace device. Objective scattering index (OSI), modulation transfer function cut-off frequency (MTF cut-off), and Strehl ratio (SR) were measured by the Optical Quality Analyzing System. Catquest-9SF questionnaire were applied too. Spearman's correlation analysis was used to evaluate the relationship between spherical aberration and visual quality parameters. Patients were satisfied with their postoperatively visual quality. And the postoperative logMAR UDVA, UIVA, UNVA, and CDVA was 0.05 ± 0.07, 0.04 ± 0.06, 0.15 ± 0.07, and 0.03 ± 0.05, respectively. The mean preoperative corneal spherical aberration was 0.24 ± 0.10 μm, which is the only factor influencing postoperatively UNVA, and it was negatively correlated with UNVA and glare contrast sensitivity under 18 cpd (cycle/degree, cpd) spatial frequency (r = -0.403, -0.300, -0.360; all P < 0.05). Additionally, the greater the residual spherical aberration of the cornea, the better the near vision after operation. The mean postoperative ocular spherical aberration was -0.03 ± 0.07 μm, it was not correlated with visual acuity, contrast sensitivity, and visual quality (all P > 0.05). Preoperative positive spherical aberration can benefit near vision while decrease contrast sensitivities at high spatial frequencies when implanted with the TECNIS Symfony IOL.

Distance and Efficiency Enhancement With Aspherical Retroreflectors for Resonant Beam SWIPT

The resonant beam system (RBS) with double spherical retroreflectors presents a potential mobile simultaneous wireless information and power transfer (SWIPT) technology without any tracking control. However, the movement distance and performance are limited due to the effect of spherical aberration. To improve mobility performance in RBS, including movement distance and output power, we adopt an aspherical lens as the focusing mirror in a retroreflector. By shifting the beam phase distribution, the aspherical lens focuses all passing beams, particularly edge beams, on the focal mirror, enhancing energy concentration in the resonant cavity. The beam field propagation through cat’s-eye retroreflectors, gain medium, and air is studied for analyzing the transfer efficiency and output power, and we demonstrate that the axial movement distance in the aspherical resonator is about 7 m, which is more than twice as far away as the spherical resonator. Within a field of view of 3° at a distance of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1~\rm {m}$ </tex-math></inline-formula> , the output power of the aspherical resonator is greater than that of the spherical resonator with the same movement angle, up to two times. The maximum output electric power and spectral efficiency are approximately <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4~\rm {W}$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$12~\rm {bps/Hz}$ </tex-math></inline-formula> , respectively.

3D time-lapse imaging of a mouse embryo using intensity diffraction tomography embedded inside a deep learning framework.

We present a compact 3D diffractive microscope that can be inserted directly in a cell incubator for long-term observation of developing organisms. Our setup is particularly simple and robust, since it does not include any moving parts and is compatible with commercial cell culture containers. It has been designed to image large specimens (>100×100×100µm3) with subcellular resolution. The sample's optical properties [refractive index (RI) and absorption] are reconstructed in 3D from intensity-only images recorded with different illumination angles produced by an LED array. The reconstruction is performed using the beam propagation method embedded inside a deep-learning network where the layers encode the optical properties of the object. This deep neural network is trained for a given multiangle intensity acquisition. After training, the weights of the neural network deliver the 3D distribution of the optical properties of the sample. The effect of spherical aberrations due to the sample holder/air interfaces are taken into account in the forward model. Using this approach, we performed time-lapse 3D imaging of preimplantation mouse embryos over six days. Images of embryos from a single cell (low-scattering regime) to the blastocyst stage (highly scattering regime) were successfully reconstructed. Due to its subcellular resolution, our system can provide quantitative information on the embryos' development and viability. Hence, this technology opens what we believe to be novel opportunities for 3D label-free live-cell imaging of whole embryos or organoids over long observation times.

Improving holographic particle characterization by modeling spherical aberration.

Holographic microscopy combined with forward modeling and inference allows colloidal particles to be characterized and tracked in three dimensions with high precision. However, current models ignore the effects of optical aberrations on hologram formation. We investigate the effects of spherical aberration on the structure of single-particle holograms and on the accuracy of particle characterization. We find that in a typical experimental setup, spherical aberration can result in systematic shifts of about 2% in the inferred refractive index and radius. We show that fitting with a model that accounts for spherical aberration decreases this aberration-dependent error by a factor of two or more, even when the level of spherical aberration in the optical train is unknown. With the new generative model, the inferred parameters are consistent across different levels of aberration, making particle characterization more robust.

Correction and verification of x-ray imaging crystal spectrometer analysis on Wendelstein 7-X through x-ray ray tracing.

X-ray ray tracing is used to develop ion-temperature corrections for the analysis of the X-ray Imaging Crystal Spectrometer (XICS) used at Wendelstein 7-X (W7-X) and perform verification on the analysis methods. The XICS is a powerful diagnostic able to measure ion-temperature, electron-temperature, plasma flow, and impurity charge state densities. While these systems are relatively simple in design, accurate characterization of the instrumental response and validation of analysis techniques are difficult to perform experimentally due to the requirement of extended x-ray sources. For this reason, a ray tracing model has been developed that allows characterization of the spectrometer and verification of the analysis methods while fully considering the real geometry of the XICS system and W7-X plasma. Through the use of ray tracing, several important corrections have been found that must be accounted for in order to accurately reconstruct the ion-temperature profiles. The sources of these corrections are described along with their effect on the analyzed profiles. The implemented corrections stem from three effects: (1) effect of sub-pixel intensity distribution during de-curving and spatial binning, (2) effect of sub-pixel intensity distribution during forward model evaluation and generation of residuals, and (3) effect of defocus and spherical aberrations on the instrumental response. Possible improvements to the forward model and analysis procedures are explored, along with a discussion of trade-offs in terms of computational complexity. Finally, the accuracy of the tomographic inversion technique in stellarator geometry is investigated, providing for the first time a verification exercise for inversion accuracy in stellarator geometry and a complete XICS analysis tool-chain.

Controlled processes at laser coating deposition

A description of the method is given of coating deposition under irradiation with a horizontal laser beam of a gas-dust medium which is an ensemble of micro-particles moving in the gas in the form of a free vertical jet. A number of coatings are obtained on various substrates and the results of measurements of their characteristics are presented. A setup based on a cw CO2-laser for the synthesis of diamond coatings in optical discharge plasma in the laser plasmatron mode has been created. The effect of spherical lens aberrations on the discharge maintenance thresholds is established. A diamond film was obtained on the surface of a tungsten substrate when a plasma jet was expelled into atmospheric air. An automatic system for measuring surface temperature in real time has been developed and created. The system was tested for laser cladding of metal powder in a pilot production.

Electrostatic Design and Fabrication a New Tunable Perveance Pierce Electron Gun

The perveance, ${K}$ , one of the Pierce electron gun (PEG) outputs, is completely dependent on geometric features, including the anode-cathode spherical distance, ${D}_{\text {ac}}$ . If the measured ${K}$ is not desirable after assembling, or the center of the cathode is not aligned with the anode axis, the PEG should be disassembled. In this article, with respect to the effects of spherical aberration and thermal velocity, a PEG is designed, simulated by computer simulation technologies (CSTs)-particle studio (PS) software, and manufactured for an ${S}$ -band klystron with ${K} = 1.5\,\,\mu $ and variable ${D}_{\text {ac}}$ . A new part in the PEG is designed that is called the spring film. It can move the cathode ±1 mm in the ${z}$ -direction while the other components are fixed and the vacuum of PEG does not change. The initial design leads to ${D}_{\text {ac }}$ to be 3.6 mm, but since ${K}$ is not expected as what we were looking for, so the desired ${K}$ is obtained by changing ${D}_{\text {ac}}$ , also the other parameters changing with ${D}_{\text {ac}}$ are examined and their values are estimated from the simulation. Finally, it is concluded that with the newly designed electron gun, unlike conventional PEGs, some parameters like perveance, cathode current, cathode lifetime, and body current are not fixed and they can be changed or improved.

Qualitative and Quantitative Studies of the Effects of Spherical Aberration on the Optical System in the Cases of Coherent and Incoherent Illumination

In this paper, we study the effects of coherent and incoherent illumination on the optical imaging system. The effects were studied qualitatively in terms of Point Spread Function (PSF) and Modulation Transfer Function (MTF), and quantitatively in terms of Root Mean Square Error (RMSE). Different values of radius of aperture were investigated in the presence and absence of spherical aberration with various magnitudes of spherical aberration (M=1, 2, and 3). The experiments were performed using homogeneous media.&#x0D; The results show that imaging with incoherent illumination is better than imaging with coherent illumination, especially for small aperture. Also, we found that the effects of spherical aberration were increased under incoherent illumination and large aperture.

Influence of aberrations and roughness on the chromatic confocal signal based on experiments and wave-optical modeling

This paper addresses the effect and influence of wave optical aberrations and surface roughness on the chromatic confocal signal and resulting measurement errors. Two possible approaches exist for implementing chromatic confocal imaging based on either refraction or diffraction. Both concepts are compared and an expression for the expected chromatic longitudinal aberrations when using a diffractive optical element is derived. Since most chromatic confocal sensors are point sensors, the discussion on wave-optical aberrations is focused on spherical aberrations. Against common belief, the effect of spherical aberrations cannot be eliminated in the calibration process using for instance a piezo mounted mirror. It will be shown in the following that even a diffraction limited system with peak to valley spherical aberration smaller than 0.25 wavelength suffers from measurement errors. Experimental results will be shown to highlight this important issue. In order to develop a deeper understanding of the underlying physics, a wave-optical simulation environment has been realized. This wave-optical model furthermore enables the investigation of the influence of roughness. Herethereto the correct choice of numerical aperture when investigating a rough surface is based on a heuristic approach. Using the wave-optical simulations an explanation for the increased noise when employing a low numerical aperture to examine rough surfaces will be derived. Furthermore, a formula is presented to support the selection of the correct numerical aperture with regards to the roughness parameters of the surface under investigation.

Influence of coma and spherical aberration on transmission characteristics of vortex beams in slant atmospheric turbulence

Vortex beam has potential applications in free space optical communication because of its capacity of data transmission. Therefore, it is necessary to study the propagation characteristics of vortex beams in atmospheric turbulence. When the vortex beam propagates in the atmospheric turbulence the beam drift will occur, which has a great influence on the free space optical communication. In this paper, the beam drift of vortex beams with coma and spherical aberration transmitted in atmospheric turbulence is studied by using multi-phase screen and Fourier transform method. The numerical results show that as the transmission distance increases, the effects of both coma and spherical aberration on the beam drift are enhanced. The larger the transmission zenith angle and the coma coefficients, the greater the beam drift of the vortex beam is. However, the beam drift decreases with spherical aberration coefficient increasing. When the zenith angle and the transmission distance are both unchanged, the beam drift of the both vortex beams decrease with topological charges increasing. The influence of coma aberration on beam drift is bigger than that of spherical aberration.

High-Repetition Rate Broadband Pump-Probe Microscopy.

Pump-probe microscopy has recently emerged as an important tool for characterizing the effects of nanoscale chemical and compositional heterogeneity on the optoelectronic properties of material systems. This article describes the development of broadband pump-probe microscopy, which utilizes a high-speed line camera and high repetition rate amplified fiber laser to collect full transient spectra at 30+ kHz and with sub 100 fs temporal resolution. The broadband imaging and spectroscopic capabilities of the technique are demonstrated on individual micron-sized lead halide perovskite domains. Also discussed are several challenges associated with collecting broadband transient spectra from sub-micron sample areas, including the importance of careful design of imaging optics to minimize the effects of spherical and chromatic aberrations, detector considerations, and the importance of spot size effects on absolute signal size.

Evaluation of Visual Quality in Pseudophakic Eyes with Different Ocular Spherical Aberrations

ABSTRACT Purpose To evaluate the effects of different residual total ocular spherical aberration (SA) on objective and subjective visual quality in pseudophakic eyes. Methods This prospective consecutive study comprised 171 patients with age-related cataract and undergone unilateral uneventful phacoemulsification. All participants were divided into four groups based on residual ocular SA at 6 mm pupil: negative SA (≤−0.10 μm, group A), neutral SA (0.00 ± 0.05 μm, group B), slightly positive SA (0.10 ± 0.05 μm, group C), and more positive SA (0.20 μm, group D), respectively. Subjective visual acuity and contrast sensitivity, and objective optical quality and ocular aberrations were analyzed 3 months postoperatively. Results There was no significant difference in baseline measurements across all groups. Postoperatively, no statistically significant differences were found in visual acuity between groups (P > .05), while differences reached statistical significance in mesopic contrast sensitivity at 12 and 18 cpd (P < .01). There were significant differences in ocular SA and higher-order aberrations at 6 mm pupil, as well as in optical quality parameters (P < .05). Group C showed a minimum value of objective scatter index (1.17 ± 0.55) but maximum values of modulation transfer function cutoff (31.94 ± 9.18) and optical quality value OV 100% (1.07 ± 0.31), indicating lower intraocular scattering and superior optical quality. Conclusions This comprehensive evaluation is conducive to deepening the understanding of visual and optical performance of pseudophakic eye. A modest amount of positive ocular SA seemed to be a more preferable option for enhancing visual quality after aspheric ntraocular lense (IOL) implantation.

Adaptive optics aberration correction for deep direct laser written waveguides in the heating regime

We demonstrate the negative effect of depth-dependent spherical aberration on femtosecond laser written waveguides fabricated in the high pulse repetition rate regime (1 MHz). Writing inside borosilicate Eagle 2000 glass, we show that, even in the cumulative heating regime, the focal distortion encountered at greater depths prevents the formation of single-mode waveguides. A liquid crystal spatial light modulator was incorporated for adaptive optics aberration correction, enabling low-loss single-mode waveguides to be written at various depths up to 1 mm. This result allows the accurate fabrication of 3D photonic devices consisting of uniform waveguides located at different depths.

Безаберрационная ширина углового спектра зондирующего слоистый объект поля в конфокальной микроскопии

The effect of the numerical aperture of a light beam probing an object on the value measured by a confocal interference microscope when determining the thickness of a layered object for the case of a significant effect on the signal of the spherical aberration arising in the probe beam at its propagation through an object has been theoretically and experimentally investigated. Taking into account the influence of spherical aberration on the signal the dependence of the measured value on the numerical aperture has been obtained. The criterion of the “aberration-free” propagation of the beam probing an object has been established and the condition under which the effect of spherical aberration on the signal of a confocal microscope can be neglected has been determined. An approximate analytical expression which allows to determine the “aberration-free” width of angular spectrum of the probing light beam taking into account the empirical correction factor has been obtained. The limits of applicability of the analytical dependence of the measured value on the numerical aperture, which was obtained earlier for the case of negligible influence of spherical aberration on the signal of a confocal microscope, have been determined.

Creating correct blur and its effect on accommodation.

Blur occurs naturally when the eye is focused at one distance and an object is presented at another distance. Computer-graphics engineers and vision scientists often wish to create display images that reproduce such depth-dependent blur, but their methods are incorrect for that purpose. They take into account the scene geometry, pupil size, and focal distances, but do not properly take into account the optical aberrations of the human eye. We developed a method that, by incorporating the viewer's optics, yields displayed images that produce retinal images close to the ones that occur in natural viewing. We concentrated on the effects of defocus, chromatic aberration, astigmatism, and spherical aberration and evaluated their effectiveness by conducting experiments in which we attempted to drive the eye's focusing response (accommodation) through the rendering of these aberrations. We found that accommodation is not driven at all by conventional rendering methods, but that it is driven surprisingly quickly and accurately by our method with defocus and chromatic aberration incorporated. We found some effect of astigmatism but none of spherical aberration. We discuss how the rendering approach can be used in vision science experiments and in the development of ophthalmic/optometric devices and augmented- and virtual-reality displays.