Wavefront Aberrations Research Articles

Quantification and characterization of an ultrasound-induced polarization wavefront aberration in the phase space.

Light propagation wavefront and photon composition variations occur when the beam encounters acoustic waves, bringing mechanical and chemical inhomogeneity-induced light-intensity modulation, while phase variations, which carry more information about the acoustic-optical coupling in the medium, are often overlooked. This paper investigates the coupling of the light beam with the propagating ultrasound and the polarization aberration of the optical wave induced by the ultrasound. A model was developed to express the variation of the ultrasound-induced polarization aberration (UIPA). The ultrasound-induced refractive index variation of the sample was observed in both the simulation and experiments. The phase differences in various ultrasound states (valley dominant state, peak dominant state) are characterized in detail. The UIPA expressed in the phase space provides a way to quantify multidimensional polarization information of the ultrasound-tagged optical waves and allows refraction-sensitive polarization parametric imaging, which may be exploited for directional high-contrast photoacoustic imaging with ultrasound tagging.

Evaluation of Visual Outcomes, Postoperative Angle Alpha, and Angle Kappa After Implantation of Isofocal Intraocular Lenses.

To evaluate the effect of angles kappa and alpha on the visual outcomes after implantation of isofocal intraocular lens (IOL) during cataract surgery. This prospective study involved 66 eyes undergoing cataract surgery with Isopure IOLs. Exclusion criteria comprised irregular corneal astigmatism exceeding 1.0D, and ocular co-morbidities affecting visual outcomes post-surgery. Evaluation parameters included postoperative refraction, uncorrected and corrected-distance visual acuity (UDVA, CDVA), uncorrected intermediate visual acuity (UIVA), and distance-corrected intermediate visual acuity (DCIVA) at 80 cm. Additionally, postoperative angles alpha, kappa, and wavefront aberrations at a 3-mm pupil using ray tracing were assessed post-surgery at least 60 days later. Patients had a mean age of 64.48 ± 9.92 years. Mean postoperative manifest refraction spherical equivalent (MRSE) was -0.21 ± 0.27 D. Mean UDVA and CDVA were LogMAR 0.06 ± 0.04 and 0.02 ± 0.06, respectively. Mean UIVA LogMAR 0.32 ± 0.08 while mean DCIVA was LogMAR 0.29 ± 0.08. Postoperative angles kappa and alpha were 0.39 ± 0.14 mm and 0.45 ± 0.15 mm, respectively. Mean postoperative ocular RMS higher-order aberrations (HOAs) 0.23 ± 0.08. Spherical aberration, coma, and trefoil averaged 0.05 ± 0.07, 0.12 ± 0.03, and 0.07 ± 0.03, respectively. No significant correlations were observed between postoperative angle kappa and alpha with UDVA, CDVA, or HOAs. A non-significant weak positive correlation was noted between angle kappa and UIVA/DCIVA, while no correlation was found between angle alpha and UIVA/DCIVA. No substantial correlations were found between various postoperative angles kappa and alpha values and postoperative visual acuity metrics (UDVA, CDVA, UIVA, and DCIVA) or higher order ocular aberrations (including, spherical aberration, coma, and trefoil with a 3.0 mm diameter) in pseudophakic eyes implanted with isofocal intraocular lenses (IOLs).

Study of wavefront aberration after multi-focal intraocular lens implantation

Study of wavefront aberration after multi-focal intraocular lens implantation

Low Spatio-temporal Frequency Wavefront Aberration Correction Method Based on a Movable Secondary Mirror

Low Spatio-temporal Frequency Wavefront Aberration Correction Method Based on a Movable Secondary Mirror

A high-precision and efficient adaptive alignment method for Cassegrain dual mirror optical system based on machine learning algorithms

The Cassegrain telescope is widely used in aerospace exploration equipment, characterized by compact structure, complex optical path, and high imaging quality. However, due to the difficulty in establishing an accurate correspondence between the relative pose and imaging quality of a multi mirror group with real machining errors, the current Cassegrain telescope assembly process is very difficult, with blind operation, time-consuming, and low accuracy. This article proposes a high-precision adaptive alignment method for Cassegrain dual mirror optical systems based on machine learning algorisms, and an experimental adaptive alignment system with uncoupled degrees of freedom is developed. Firstly, the overall architecture of the adaptive alignment method is proposed consists of detection, calculation and alignment modules. In the detection module, the Zernike polynomial coefficient of wavefront aberration of the optical system is detected online through the interferometer, meanwhile the pose coordinates of the secondary mirror is accurately fed back through a 6-DOF nanoscale micro mechanism. In the calculation module, machine learning algorithm is applied to build a nonlinear mapping model between the Zernike coefficient and the pose coordinates of the secondary mirror. In the alignment module, the pose coordinates of the secondary mirror can be forced to adjust to the target position. Then, during the real alignment process, the Zernike coefficient test data of the optical system alignment process is monitored in real time, and the nonlinear mapping model is employed to calculate the pose coordinates and then the misalignment of the secondary mirror. Finally, the alignment module is driven to execute the pose correction according to the calculated misalignment value, realizing a high-precision adjustment of the Cassegrain dual mirror optical system. Experimental results shows that the average alignment time cost can be dramatically reduced from around 7 days using the current manual alignment method to just 30 minutes using the proposed adaptive alignment method for achieving a current standard alignment accuracy of wavefront aberration root mean square (RMS) less than 0.1λ, which greatly improves the assembly efficiency. This study proposes a new method for high-precision and efficient alignment of optical systems based on artificial intelligence and contributes to the efficiency improvement for optical assembly.

Современные подходы к хирургии катаракт с высокой остротой зрения на основании анализа волнового фронта

Relevance. Until recently, visual acuity was the main criterion for determining the timing of surgery, but already in the early stages of cataract development, patients may suffer from reduced image quality, which affects the quality of life (“night” myopia, light scattering, blurring). Deterioration in visual function in these patients may be explained by refractive errors. Analysis of internal higher-order aberrations resulting from slight opacification of the lens is important for determining the effect of media opacity on wavefront aberrations (WF) and for determining the indications and timing of surgical treatment, especially in patients with high visual acuity. Purpose. Evaluate the optical system of the eye with initial cataracts and high visual acuity. Evaluate the wavefront and its aberrations, contrast sensitivity and Shtrel coefficient. Material and methods. The study included 111 eyes with cataracts and 42 eyes without signs of cataracts (control group). Patients aged on average 57±5.3 years. Wavefront analysis was performed using an iTrace ray tracing aberrometer (Tracey Tech., USA) in a dark room under maximum drug-induced mydriasis. In each group, total, corneal, and internal wavefront aberrations were measured at a pupil diameter of 6.0 mm. Higher order aberrations were analyzed using Zernike polynomials (3rd to 5th order). The modulation transfer function (MTF) at different spatial frequencies (0–30 c/deg) and the Strehl coefficient in patients in the study groups were also assessed. Results. Total and internal higher-order wavefront aberrations were significant in different cataract groups compared with control patients, while higher-order corneal aberrations were not statistically different. We noted a higher level of total and internal aberrations in the group of patients with posterior subcapsular cataract. In this regard, patients with posterior subcapsular cataract require surgical treatment at an earlier stage, despite high visual acuity. Conclusion. We recommend assessing the optical quality of vision and wavefront aberrations when observing early cataracts in order to decide whether to perform surgery at an earlier date. Key words: initial cataract, quality of vision, higher order aberrations, internal wavefront aberrations

An Efficient Method for Wavefront Aberration Correction Based on the RUN Optimizer

The correction of wavefront aberrations in wavefront sensorless (WFS-less) adaptive optical (AO) systems requires control algorithms that can ensure rapid convergence while maintaining effective correction capabilities. This paper proposes a novel control algorithm based on the RUNge Kutta optimizer (RUN) for WFS-less AO systems that enables the quick and efficient correction of small aberrations, as well as larger aberrations. To evaluate the convergence speed and correction capabilities of a WFS-less AO system based on the RUN control algorithm, we constructed a simulated AO system and an experimental setup with a 97-element deformable mirror (DM), respectively. Additionally, the results obtained with the Particle Swarm Optimization (PSO) algorithm, Differential Evolution Algorithm (DEA), and Genetic Algorithm (GA) are also provided for comparison and analysis. Both the simulated and experimental results consistently demonstrated that our proposed method outperformed several competing algorithms in terms of correction performance and convergence speed. Furthermore, the experimental results further validate the effectiveness of our control algorithm in scenarios involving significant aberrations.

Mutual aid instead of mutual restraint: interactive probing for topological charge and phase of a vortex beam of large aberrations

An imperfect propagation environment or optical system would introduce wavefront aberrations to vortex beams. The phase aberrations and orbital angular momentum in a vortex beam are proved to be mutually restrictive in parameter measurement. Aberrations make traditional topological charge (TC) probing methods ineffective while the phase singularity makes phase retrieval difficult due to the aliasing between the wrapped phase jump and the vortex phase jump. An interactive probing method is proposed to make measurements of the aberrated phase and orbital angular momentum in a vortex beam assist rather than hinder each other. The phase unwrapping is liberated from the phase singularity by an annular shearing interference technique while the TC value is determined by a Moiré technique immune to aberrations. Simulation and experimental results proving the method effective are presented. It is of great significance to judge the characteristics of vortex beams passing through non-ideal environments and optical systems.

Visible Metalenses with High Focusing Efficiency Fabricated Using Nanoimprint Lithography

AbstractMetasurfaces enable precise control over the properties of light and hold promise for commercial applications. However, fabricating visible metasurfaces suitable for high‐volume production is challenging and requires scalable processes. Nanoimprint lithography is a cost‐effective and high‐throughput technique that can meet this scalability requirement. This work presents a mask‐templating nanoimprint lithography process for fabricating metasurfaces with varying fill factors and negligible wavefront aberrations using composite stamps. As a proof‐of‐concept, a 6 mm diameter metalens formed of silicon nitride nano‐posts with a numerical aperture of 0.2 that operates at 550 nm is demonstrated. The nanoimprinted metalens achieves a peak focusing efficiency of (81 ± 1)%, comparable to the control metalens made with electron beam lithography with a focusing efficiency of (89 ± 1)%. Spatially resolved deflection efficiency and wavefront data, which informs design and process optimization, is also presented. These results highlight nanoimprint lithography as a cost‐effective, scalable method for visible metasurface fabrication that has potential for widespread adoption in consumer electronics and imaging systems.

Effect of the focusing system on measurements in gravitational wave detection telescope

Telescopes primarily transmit and receive laser beams over long distances as part of a gravitational wave interferometric measurement system. Due to factors such as optical design, fabrication, and alignment, the wavefront at the exit pupil of the telescope inevitably experiences distortion, resulting in wavefront aberrations that couple with pointing jitter to generate tilt-to-length (TTL) coupling noise. During the process of gravitational wave detection, the large distance between the primary and secondary mirrors and temperature fluctuations in space can cause significant axial misalignment between them. This results in a substantial displacement of the primary-secondary mirror system’s primary focus along the axial direction, further degrading the wavefront at the exit pupil of the telescope. The TTL coupling noise caused in this scenario will affect the detection of gravitational waves, thus requiring the adjustment of the position of the three-four mirror system through the focusing system to minimize TTL coupling noise. In this paper, the model for TTL coupling noise was established using the first 36 orders of Zernike polynomials. The misalignment model of the primary-secondary mirror system was derived using geometric optics theory. The study investigates the influence of the telescope focusing system before and after focusing on the wavefront aberrations and TTL coupling noise at the exit pupil of the telescope. The analysis indicates that with a misalignment of 7.56 μm in the axial distance between the primary and secondary mirrors, the addition of a focusing system reduces the wavefront error at the exit pupil of the telescope from 0.0328 λ to 0.0046 λ. Furthermore, the maximum coupling noise between wavefront distortion and pointing jitter is reduced from 4 pm Hz−1/2 to 0.4 pm Hz−1/2. This provides valuable insights for the design of gravitational wave detection telescopes and the study of focusing systems.

Wavefront Aberration Introduced by DMDs

Wavefront Aberration Introduced by DMDs

Wavefront reconstruction of a non-diffracting structured laser beam

The Structured Laser Beam (SLB) is a pseudo-non-diffracting laser beam that shares many characteristics with a Bessel beam. However, it can theoretically propagate over an unlimited distance while maintaining an extremely low inner core divergence of only 0.01 mrad. This makes it a promising candidate for precise long-distance alignment applications such as the alignment of particle accelerator components at CERN. In this work, a novel method to assess the symmetrical wavefront aberrations induced by an SLB generator is presented. Our approach is based on the analysis of a single-intensity distribution of an SLB. The coefficients of the Zernike polynomials are estimated using artificial intelligence before least-squares fitting is used to refine the result. This approach ensures that the fitting avoids local minima. This method provides a novel way to analyze the optical aberrations induced by the SLB generator.

Potential vision tester using adaptive optics, Maxwellian view, and small pupil.

We demonstrate a free-space, trolley-mounted potential vision tester (PVT), designed to study and improve the accuracy of visual acuity (VA) measurements in the aging eye. Key features include a high-resolution visual display presented in Maxwellian view, a 3 mm pupil to limit wavefront (WF) aberrations, and a moderate cost deformable mirror to induce or correct higher order optical aberrations. The visual display supported accurate measurement of visual acuities down to 20/5. The moderate cost, piezo deformable mirror induced seven nominal aberrations, calibrated as 0, -0.32, -0.23, + 0.27, and +0.39 microns spherical aberration; + 0.49 microns Y coma; and -0.51 microns X coma. A custom Hartmann Shack (HS) calibration (HSc) system demonstrated that induced aberrations were repeatable and stable. A Badal optometer provided the coarse focus. WF aberrations were measured for five normal subjects with a commercially available HS device (HSP) (OCULUS Pentacam AXL Wave), providing estimates of WF errors for 3 mm and other pupil sizes. VA was measured using four alternative forced-choice for a single black on white E stimulus in each trial. Using the method of constant stimuli yielded robust standard deviation measurements. The 50% fit for VA plotted against induced aberration resulted in linear functions for each subject for the range of our positive and negative spherical aberration data. Subjects differed, but higher order terms were unnecessary to describe data across spherical aberrations.

The impact of telescope aberrations on the magnitude of tilt to length coupling noise in space based gravitational wave detectors

Tilt-to-length (TTL) coupling noise is one of the main noise sources that affect space gravitational wave detection, and the Tianqin project requires that the internal TTL coupling noise of the telescope used be less than 0.4 pm/Hz1/2 within the frequency band from 0.1 mHz to 1 Hz. In order to design a telescope that meets the requirements of TTL coupling noise and carry out preliminary error allocation research, it is necessary to analyze and calculate the TTL coupling noise, and then guide the design and optimization of the telescope system. This paper establishes a computational analysis model for the non-geometric TTL coupling noise inside the telescope using the first 36-order edge Zernike polynomials. A method was proposed to reduce the internal TTL coupling noise of the telescope by reducing the proportion of sensitive aberrations caused by non-geometric TTL coupling noise. Simulation results show that, with the RMS value of wavefront aberration at the telescope exit pupil unchanged, reducing the proportion of sensitive aberrations at the telescope exit pupil can effectively reduce the internal TTL coupling noise of the telescope. By optimizing the telescope optical system to reduce the proportion of noise-sensitive aberrations, the non-geometric TTL coupling noise inside the telescope has been reduced from 0.34 pm/Hz1/2 @ 0.1 mHz ∼ 1 Hz to 0.25 pm/Hz1/2. This result can provide some guidance for the design of telescope optics based on the suppression of internal TTL coupling noise in the telescope.

Comparing Effective Optical Zones After Myopic Ablation Between LASIK, PRK, and SMILE With Correlation to Higher Order Aberrations

Purpose: To explore size, decentration, and eccentricity of effective optical zones (EOZs) in laser in situ keratomileusis (LASIK), photorefractive keratectomy (PRK), and small incision lenticule extraction (SMILE) and correlate them to higher order aberrations (HOAs). Methods: This was a retrospective chart review of 188 eyes that underwent refractive surgery for compound myopia (61 LASIK, 84 PRK, 43 SMILE). EOZ measurements were determined using 1-year postoperative Pentacam (Oculus Optikgeräte GmbH) tangential difference maps. HOA data were measured using Pentacam wavefront aberration Zernike polynomials. Correlations between EOZs and HOAs were analyzed. Results: The EOZs of LASIK and PRK are smaller than SMILE at 19.54 ± 1.44, 19.39 ± 1.66, and 22.18 ± 2.61 mm 2 , respectively ( P < .001). No difference existed in absolute decentration from corneal vertex ( P = .078) or pupil center ( P = .131), but horizontal and vertical components differed significantly ( P < .001). Smaller EOZ areas were correlated with greater spherical aberration induction (rLASIK = −0.378, rPRK = −0.555, rSMILE = −0.501) and total HOA induction in all groups. Absolute decentration from corneal vertex positively correlated with total HOA (rLASIK = 0.396, rPRK = 0.463, rSMILE = 0.399) and directional vertical coma induction negatively correlated with vertical decentration from the corneal vertex (rLASIK = −0.776, rPRK = −0.665, rSMILE = −0.576) in all groups. Conclusions: SMILE results in a larger EOZ than LASIK and PRK, and absolute decentration remains comparable regardless of surgical reference center, despite horizontal/vertical differences. Surgical planning to ensure adequate EOZ size and centration may reduce induction of HOAs, including spherical aberrations and vertical coma. [ J Refract Surg . 2023;39(11):741–750.]

Influence of Defocusing on the Correctness of Detection of Wavefront Aberrations Using a Matched Filter

Influence of Defocusing on the Correctness of Detection of Wavefront Aberrations Using a Matched Filter

Comparative Analysis of the Interferogram Sensitivity to Wavefront Aberrations Recorded with Plane and Cylindrical Reference Beams

Comparative Analysis of the Interferogram Sensitivity to Wavefront Aberrations Recorded with Plane and Cylindrical Reference Beams

Method for testing freeform surfaces based on a Shack-Hartmann sensor with plane wavefront scanning and stitching.

Currently, the surface error measurement technology for freeform faces a significant contradiction between measurement accuracy and dynamic range. The study proposes a non-null testing method for measuring freeform surfaces by utilizing a Shack-Hartmann wavefront sensor to emit a small aperture parallel beam and scan along the normal direction at the center of subapertures for stitching (SHPSS). A mathematical model based on ray tracing and the reflection theorem is established to calculate the sampling points on an ideal freeform surface, the reference spot array on CCD, and the corresponding relationship between microlens array and spots. An algorithm is proposed to iteratively calculate the wavefront aberration and gradually approach the actual sampling points using the established model. Theoretical analysis and numerical simulation results indicate that SHPSS can increase the dynamic range and improve the accuracy of wavefront reconstruction. The error analysis of the SHPSS method is carried out, the measurement accuracy of full aperture freeform surface is 11.45 nm. A testing system is set up and experiments are conducted on a 100 mm aperture freeform reflective mirror. The RMS of the SHPSS test results is less than λ/30 (λ=635 nm) compared to the interferometric test results. By analyzing five groups of repeated measurement experiments, the repeatability accuracy of SHPSS method is less than 1/80 λ (RMS). This demonstrates the feasibility and measurement capabilities of the method for freeform surface testing.

Changes in pupil size, ocular wavefront aberrations, and accommodation in healthcare workers using FFP3 masks.

To evaluate changes in pupil size, ocular wavefront aberrations (WA), and accommodation in healthcare workers after 4-h usage of Filtering Facepiece class 3 (FFP3) masks. This prospective study included 22 healthy healthcare workers. Pupil size, ocular WA, and accommodation changes before and after FFP3 mask usage were evaluated using a Hartmann Schack aberrometer. Accommodative responses to stimulus ranging from 0 to 5 diopters (D) in increments of 0.5 D were assessed. Ocular high-order aberrations (HOAs) were recorded at baseline and at every accommodative stimulus. Oxygen saturation (SpO2) was measured by pulse oximetry before and after the mask usage. The mean age was 36.6 ± 8.5 years. The SpO2 significantly decreased from 98.95 to 97.95% after usage of the FFP3 mask (p < 0.001). The mean pupil size did not significantly differ before (6.22 ± 0.75 mm) and after (6.38 ± 0.83 mm) the 4-h mask usage (p = 0.093). The mean total RMS of the total HOAs was 0.36 ± 0.17 before and 0.39 ± 0.15 after the mask usage (p = 0.071). Post-mask accommodation showed a significant decrease at the 2 D (p = 0.041), 2.5D (p = 0.022), and 3 D (p = 0.025) stimuli. The present study shows that after 4 h-usage of FFP3 mask, both SpO2 and accommodative response to increasing stimuli might be significantly decreased.

Direct wavefront reconstruction with the cone wavefront sensor using the inverse radon transform.

The cone wavefront sensor consists of a cone (or axicon) placed at the focal plane of the imaging system, from which an annular intensity image is formed. Typically, the wavefront phase is estimated using inversion of an interaction matrix relating the intensity image to different aberration modes. In this paper, we show that the intensity image for the cone wavefront sensor is related to the radon transform of the wavefront phase. A reconstruction method using the inverse radon transform (filtered back-projection) is shown to be able to directly approximate the wavefront phase without the need for an interaction matrix for small wavefront aberrations.