Higher-order Spherical Aberration Research Articles

Fast, Precise, High Contrast Laser Writing for Photonic Chips with Phase Aberrations

AbstractIntegrated photonic chips have significant potential in telecommunications, classic computing, quantum systems, and topological photonics. Direct laser writing offers unique capability for creating three‐dimensional photonic devices in an optical glass chip with quick prototyping. However, it is a challenge for existing laser writing schemes to create index‐modified structures in glass that precisely match the laser focal shape while also achieving high refractive index contrasts and high scanning speeds. Here, we introduce a refractive index modification scheme that combines the advantages of non‐thermal and thermal regime fabrication methods. We also propose a waveguide formation model that is verified through a thorough study on the effects of phase aberrations. The presented new photonic chip fabrication scheme uses a novel focal intensity distribution, where pulse energy is relocated to the bottom of a laser focus by manipulating primary and higher order spherical aberrations. The technique can produce index modifications with high scanning speed (can be 20 mm/s or higher), high index contrast (ranging from 0.009 to 0.021), and high precision to fabricate with arbitrary cross‐sections. This method has potential to expand the capabilities of photonic chips in applications that require small‐scale, high precision, or high contrast refractive index control.

Higher-order aberrations and their association with axial elongation in highly myopic children and adolescents

BackgroundVision-dependent mechanisms play a role in myopia progression in childhood. Thus, we investigated the distribution of ocular and corneal higher-order aberrations (HOAs) in highly myopic Chinese children and adolescents and...

Corneal Aberrations in Keratoconus: A Pentacam Scheimpflug Imaging Study

Objective
 To investigate high-order corneal aberration alterations at different KC stages using a Pentacam Scheimpflug camera (OCULUS, Wetzlar, Germany), and to compare data with healthy eyes
 
 Materials and Methods
 This retrospective comparative study investigated clinical data of 50 patients (100 eyes) with KC and 59 healthy individuals (118 eyes) who underwent corneal topography using the Pentacam Scheimpflug camera in our clinic. Demographic characteristics, total aberrations, HOAs, coma and spherical aberrations of all participants were extracted and recorded.
 
 Results
 Mean age in the KC group was 29.7±10.3 years and 32.1±12.4 years in the control group. These two groups were compatible in terms of age and sex (P=0.11; P=0.76, respectively,). In the keratometric classification, KC was mild in 63, moderate in 23, and severe in 14 eyes. Differences in low-order astigmatism, trefoil, coma, tetra-foil, high-order astigmatism, high-order spherical aberration, and root mean square values between eyes with KC and healthy eyes were statistically significant (P

Variant myopia: A new presentation?

Purpose:Variant myopia (VM) presents as a discrepancy of >1 diopter (D) between subjective and objective refraction, without the presence of any accommodative dysfunction. The purpose of this study is to create a clinical profile of VM.Methods:Fourteen eyes of 12 VM patients who had a discrepancy of >1D between retinoscopy and subjective acceptance under both cycloplegic and noncycloplegic conditions were included in the study. Fourteen eyes of 14 age- and refractive error-matched participants served as controls. Potential participants underwent a comprehensive orthoptic examination followed by retinoscopy (Ret), closed-field autorefractor (CA), subjective acceptance (SA), choroidal and retinal thickness, ocular biometry, and higher order spherical aberrations measurements.Results:In the VM eyes, a statistically and clinically significant difference was noted between the Ret and CA and Ret and SA under both cycloplegic and noncycloplegic conditions (multivariate repeated measures analysis of variance, P < 0.0001). A statistically significant difference was observed between the VM eyes, non-VM eyes, and controls for choroidal thickness in all the quadrants (Univariate ANOVA P < 0.05). The VM eyes had thinner choroids (197.21 ± 13.04 μ) compared to the non-VM eyes (249.25 ± 53.70 μ) and refractive error-matched controls (264.62 ± 12.53 μ). No statistically significant differences between groups in root mean square of total higher order aberrations and spherical aberration were observed.Conclusion:Accommodative etiology does not play a role in the refractive discrepancy seen in individuals with the variant myopic presentation. These individuals have thinner choroids in the eye with variant myopic presentation compared to the fellow eyes and controls. Hypotheses and clinical implications of variant myopia are discussed.

Calculation of the higher-order axial spherical aberrations of a high-aperture focusing holographic optical element with the corrected third-order spherical aberration. Part 1

Results of calculating the radius of higher-order spherical aberrations (fifth, seventh and ninth orders) of a high-aperture focusing holographic optical element (HOE) with corrected third-order spherical aberration in the operating spectral range are discussed. As examples, high-aperture axial HOEs with relative apertures close to 1:1 in specified spectral ranges are considered. Coordinates of the point sources of a divergent reference wave and a convergent object wave of the HOE are given. It is shown that when imaging a point source emitting in the 0.250-0.281-μm and 0.500-0.563-μm spectral ranges, the use of an HOE in the first and second diffraction orders makes it is possible to correct the third-order spherical aberration on two wavelengths and the fifth- and seventh-order spherical aberrations on one wavelength. Note that these visible-spectrum wavelengths are different from the HOE's recording wavelength of 0.532 μm.

Ocular, corneal, and internal aberrations in eyes with keratoconus, forme fruste keratoconus, and healthy eyes.

The purpose of this study is to evaluate ocular, corneal, and internal aberration parameters in eyes with keratoconus (KC), forme fruste keratoconus (FFKC), and normal eyes. In a prospective study, one eye of 110 patients with KC, 60 FFKC patients, and 150 healthy participants was evaluated using OPD-Scan II. Ocular, corneal, and internal higher-order aberrations were measured through a sixth-order Zernike polynomial decomposition. Receiver operating characteristic analysis was performed to evaluate the diagnostic ability of the aberration parameters in discriminating KC and FFKC from normal eyes. The root mean square of the all ocular aberration measurements was significantly higher in the KC and FFKC patients than that of normal participants (p<0.05). All of the corneal aberration measurements were significantly higher in KC patients than those of normal patients (p<0.05); however, only corneal total higher-order aberration (HOA), vertical and total coma, and higher-order astigmatism were significantly higher in the FFKC patients than normal participants (p<0.05). The results also showed that internal aberration lower-order astigmatism, total trefoil, and total higher-order spherical aberration were significantly different between KC and normal groups (p<0.05). In comparison, internal total HOA, lower and higher-order astigmatism, total trefoil, and vertical coma were significantly different between FFKC and normal groups (p<0.05). Ocular vertical and total coma had the highest ability in discriminating keratoconic from normal eyes. Ocular total higher aberration and total coma had the highest diagnostic ability in discriminating FFKC from normal eyes. The diagnostic ability of internal aberration, on the other hand, was moderate to poor in discriminating KC and FFKC from normal eyes. Ocular aberration especially vertical and total coma and total HOA were found to be suitable parameters to discriminate KC and FFKC from normal patients. These two parameters could be used as discriminating factors in evaluating the patient for refractive surgery in an attempt to avoid iatrogenic ectasia.

Extended depth of focus contact lenses vs. two commercial multifocals: Part 2. Visual performance after 1 week of lens wear

PurposeTo compare the visual performance of prototype contact lenses designed via deliberate manipulation of higher-order spherical aberrations to extend-depth-of-focus with two commercial multifocals, after 1 week of lens wear. MethodsIn a prospective, participant-masked, cross-over, randomized, 1-week dispensing clinical-trial, 43 presbyopes [age: 42–63 years] each wore AIROPTIX Aqua multifocal (AOMF), ACUVUE OASYS for presbyopia (AOP) and extended-depth-of-focus prototypes (EDOF) appropriate to their add requirements. Measurements comprised high-contrast-visual-acuity (HCVA) at 6m, 70cm, 50cm and 40cm; low-contrast-visual-acuity (LCVA) and contrast-sensitivity (CS) at 6m and stereopsis at 40cm. A self-administered questionnaire on a numeric-rating-scale (1–10) assessed subjective visual performance comprising clarity-of-vision and lack-of-ghosting at various distances during day/night-viewing conditions and overall-vision-satisfaction. ResultsEDOF was significantly better than AOMF and AOP for HCVA averaged across distances (p≤0.038); significantly worse than AOMF for LCVA (p=0.021) and significantly worse than AOMF for CS in medium and high add-groups (p=0.006). None of these differences were clinically significant (≤2 letters). EDOF was significantly better than AOMF and AOP for mean stereoacuity (36 and 13 seconds-of-arc, respectively: p≤0.05). For clarity-of-vision, EDOF was significantly better than AOP at all distances and AOMF at intermediate and near (p≤0.028). For lack-of-ghosting averaged across distances, EDOF was significantly better than AOP (p<0.001) but not AOMF (p=0.186). EDOF was significantly better than AOMF and AOP for overall-vision-satisfaction (p≤0.024). ConclusionsEDOF provides better intermediate and near vision performance than either AOMF or AOP with no difference for distance vision after 1 week of lens wear.

Extended depth of focus contact lenses vs. two commercial multifocals: Part 1. Optical performance evaluation via computed through-focus retinal image quality metrics

PurposeTo compare the computed optical performance of prototype lenses designed using deliberate manipulation of higher-order spherical aberrations to extend depth-of-focus (EDOF) with two commercial multifocals. MethodsEmmetropic, presbyopic, schematic eyes were coupled with prototype EDOF and commercial multifocal lenses (Acuvue Oasys for presbyopia, AOP, Johnson & Johnson & Air Optix Aqua multifocal, AOMF, Alcon). For each test configuration, the through-focus retinal image quality (TFRIQ) values were computed over 21 vergences, ranging from −0.50 to 2.00D, in 0.125D steps. Analysis was performed considering eyes with three different inherent aberration profiles: five different pupils and five different lens decentration levels. ResultsExcept the LOW design, the AOP lenses offered ‘bifocal’ like TFRIQ performance. Lens performance was relatively independent to pupil and aberrations but not centration. Contrastingly, AOMF demonstrated distance centric performance, most dominant in LOW followed by MED and HIGH designs. AOMF lenses were the most sensitive to pupil, aberrations and centration. The prototypes demonstrated a ‘lift-off’ in the TFRIQ performance, particularly at intermediate and near, without trading performance at distance. When compared with AOP and AOMF, EDOF lenses demonstrated reduced sensitivity to pupil, aberrations and centration. ConclusionWith the through focus retinal image quality as the gauge of optical performance, we demonstrated that the prototype EDOF designs were less susceptible to variations in pupil, inherent ocular aberrations and decentration, compared to the commercial designs. To ascertain whether these incremental improvements translate to a clinically palpable outcome requires investigation through human trials.

Four-zone varifocus mirrors with adaptive control of primary and higher-order spherical aberration.

Electrostatically actuated deformable mirrors with four concentric annular electrodes can exert independent control over defocus as well as primary, secondary, and tertiary spherical aberration. In this paper we use both numerical modeling and physical measurements to characterize recently developed deformable mirrors with respect to the amount of spherical aberration each can impart, and the dependence of that aberration control on the amount of defocus the mirror is providing. We find that a four-zone, 4 mm diameter mirror can generate surface shapes with arbitrary primary, secondary, and tertiary spherical aberration over ranges of ±0.4, ±0.2, and ±0.15 μm, respectively, referred to a non-normalized Zernike polynomial basis. We demonstrate the utility of this mirror for aberration-compensated focusing of a high NA optical system.

Short-term comparison between extended depth-of-focus prototype contact lenses and a commercially-available center-near multifocal

PurposeTo compare the visual performance of prototype contact lenses which extend depth-of-focus (EDOF) by deliberate manipulation of multiple higher-order spherical aberration terms and a commercially-available center-near lens (AIR OPTIX Aqua Multifocal, AOMF). MethodsThis was a prospective, cross-over, randomized, single-masked (participant), short-term clinical trial where 52 participants (age 45–70 years) were stratified as low, medium or high presbyopes and wore EDOF and AOMF on different days. Objective measures comprised high and low contrast visual acuity (HCVA/LCVA, logMAR), and contrast sensitivity (log units) at 6m; HCVA at 70cm, 50cm and 40cm and stereopsis (seconds of arc) at 40cm. HCVA at 70cm, 50cm and 40cm were measured as “comfortable acuity” rather than conventional resolution acuity. Subjective measures comprised clarity-of-vision and ghosting at distance, intermediate and near, overall vision satisfaction and ocular comfort (1–10 numeric rating scale) and lens purchase (yes/no response). Statistical analysis included repeated measures ANOVA, paired t-tests and McNemar's test. ResultsSignificant differences between lens types were independent of strata (p≥0.119). EDOF was significantly better than AOMF for HCVA at 40cm (0.42±0.18 vs. 0.48±0.22, p=0.024), stereopsis (98±88 vs. 141±114, p<0.001), clarity-of-vision at intermediate (8.5±1.6 vs. 7.7±1.9, p=0.006) and near (7.3±2.5 vs. 6.2±2.5, p=0.005), lack-of-ghosting (p=0.012), overall vision satisfaction (7.5±1.7 vs. 6.4±2.2, p<0.001) and ocular comfort (9.0±1.0 vs. 8.3±1.7, p=0.002). Significantly more participants chose to only-purchase EDOF (33% vs. 6%, p=0.003).). There were no significant differences between lens types for any objective measure at 6m or clarity-of-vision at distance (p≥0.356). ConclusionsEDOF provides better intermediate and near vision performance in presbyopes than AOMF with no difference for distance vision during short-term wear.

Intacs with or without same-day corneal collagen cross-linking to treat corneal ectasia

ObjectiveTo compare combined intrastromal corneal ring segment implantation with same-day ultraviolet-A/riboflavin corneal collagen cross-linking (ICRS-CXL) versus ICRS implantation alone in patients with corneal ectasia. DesignRetrospective comparative study. ParticipantsSixty-six eyes from 54 patients with corneal ectasia were included in the study. The groups were composed of 32 eyes from 27 patients and 34 eyes from 27 patients for the ICRS-CXL and ICRS groups, respectively. MethodsWe reviewed the charts of all patients who underwent these procedures from November 2008 to February 2011 for preoperative and for up to 1 year postoperative uncorrected (UDVA) and best corrected distance visual acuity (BDVA), refraction, topographical analysis (mean and steepest keratometry [K]), as well as root mean-square (RMS) of higher-order aberrations (HOAs). ResultsOverall, a significant improvement was seen in both groups for UDVA, BDVA, sphere, cylinder, mean refractive spherical equivalent (MRSE), mean and steepest K, coma, spherical and total HOA at 12 months. Trefoil did not improve, and higher-order astigmatism worsened in the ICRS group (p = 0.0466). There was no statistically significant difference between the 2 groups for visual acuity, sphere, cylinder, coma, trefoil, and spherical HOA. Outcomes were significantly more improved in the ICRS group for MRSE (p = 0.0082), mean K (p = 0.0021), steepest K (p = 0.0152), and total HOAs (p = 0.0208). No complications were observed. ConclusionsICRS-CXL and ICRS alone were both safe and effective in treating corneal ectasia. The ICRS alone group demonstrated better outcomes of MRSE, mean and steepest K, as well as total HOA.

At-wavelength alignment and testing of the 0.3 NA MET optic

Extreme ultraviolet (EUV) interferometry has been successfully performed for the first time at 0.3 numerical aperture (NA). Extensive EUV “at-wavelength” testing including alignment, was performed on a newly created Micro Exposure Tool (MET) optic designed for sub-50-nm EUV lithographic imaging experiments. The two-mirror, 0.3 NA MET is among the highest resolution light-projection lithography tools ever made. Using both lateral shearing and phase-shifting point-diffraction interferometry, the wavefront was measured across the field of view, and the alignment was optimized in preparation for imaging. The wavefront quality reached 0.55nm RMS (λEUV∕24.5) in a 37-term annular Zernike polynomial series, dominated by higher-order spherical aberration. Measurements included calibrations of the interferometer accuracy, assessment of repeatability, and cross-comparisons of visible and EUV interferometric measurements.

Efficient, 15-W output power, diode-end-pumped Nd:YAG laser

The design and performance of a 15-W output-power, diode-pumped cw Nd:YAG laser is described. With the use of geometrically multiplexed end pumping, the combined power of four 10-W diode-laser bars is deposited in the active-medium mode volume with an efficiency of 80%. While operating on several transverse modes the laser has a threshold of 3 W, an optical slope efficiency of 60%, and an overall electrical efficiency of 10.5%. Thermally induced higher-order spherical aberration of 1.2 waves limits the output power in the TEM(00) mode to approximately 6 W.

Effect of Higher-Order Spherical Aberration Term on Transfer Function in Electron Microscopy

The effect of the higher-order spherical aberration coefficient on the transfer function in transmission electron microscopy was calculated. In order to simplify the system, the optical illumination system was assumed to be perfectly coherent and axially symmetric. The result shows that the effect of the fifth-order spherical aberration coefficient, C5, on the usual transfer function with the third-order spherical aberration coefficient C5≡C3=0.5 mm for 100 keV electrons cannot be neglected, if high-order Bragg reflections from net planes with smaller lattice spacings than 0.1 nm are utilized for lattice imaging. The effect of the higher-order term due to the defocussing on the transfer function is also discussed.

Spherical Aberration of Monocentric Doublet Lenses

A computer programme has been compiled which, for given pairs of refractive indices, sets up a monocentric doublet lens of unit focal length having zero primary spherical aberration, and traces a marginal ray through the system at a relative aperture of f/8. The results, presented graphically, show the pairs of refraction index values that give minimum higher-order spherical aberration.

An Extension of the Lens-Mirror System of Maksutov

THE lens-mirror system described by D. D. Maksutov1, in which the aberrations of a spherical mirror are corrected by a single sphericalsurfaced meniscus lens, while eminently suitable for telescope objectives of moderate relative aperture, combining the coma correction of the refractor with a virtual absence of secondary spectrum, suffers from two sets of limitations which restrict its possible application in other fields. In the first place, the higher order spherical aberration is too great to yield the highest resolving power at very great relative apertures (except at very small focal lengths). Secondly, since the system has only three variables apart from meniscus thickness, the oblique aberrations other than coma cannot be corrected simultaneously with spherical aberration and axial achromatism, thus restricting its use over large angular fields. The former limitation may be reduced by increased thickness of the meniscus, but this necessarily involves larger unconnected oblique aberrations.

Wide-aperture aplanatic single lenses

This paper represents an essay in Aspheric surface optics. Chretien's theory of the aplanatic telescope suggests that the theory of aplanatic single lenses can be worked out on similar lines. The polar equation of an aspheric surface of such a lens is given in series form, and two numerical examples are studied, one of these being an aplanat, the other an anastigmatic singlet free from primary and higher-order spherical aberration, offence against the sine condition, primary astigmatism, and curvature of field. The shape of the latter lens is, however, predicted by Burch's four-plate theorem, the results of which (as far as they concern primary aplanatism) are shown to agree with the formulae given in the paper.