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Broadband lightweight flat lenses for long-wave infrared imaging
摘要： We experimentally demonstrate imaging in the long-wave infrared (LWIR) spectral band (8 μm to 12 μm) using a single polymer flat lens based upon multilevel diffractive optics. The device thickness is only 10 μm, and chromatic aberrations are corrected over the entire LWIR band with one surface. Due to the drastic reduction in device thickness, we are able to utilize polymers with absorption in the LWIR, allowing for inexpensive manufacturing via imprint lithography. The weight of our lens is less than 100 times those of comparable refractive lenses. We fabricated and characterized 2 different flat lenses. Even with about 25% absorption losses, experiments show that our flat polymer lenses obtain good imaging with field of view of 35? and angular resolution less than 0.013?. The flat lenses were characterized with 2 different commercial LWIR image sensors. Finally, we show that, by using lossless, higher-refractive-index materials like silicon, focusing efficiencies in excess of 70% can be achieved over the entire LWIR band. Our results firmly establish the potential for lightweight, ultrathin, broadband lenses for high-quality imaging in the LWIR band.
关键词： diffractive lenses,infrared imaging,chromatic aberrations
更新于2025-09-16 10:30:52
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European Microscopy Congress 2016: Proceedings || A closer look at high-resolution electron holography
摘要： In the recent years high-resolution off-axis holography made huge advances in the field of electron microscopy. While the side-band reconstruction is well understood, the influence of aberrations on the reconstructed exit wave is not. Here, we show that the aberrations of the reconstructed exit wave are not dominated by the shot noise anymore. By means of simulations we demonstrate that the aberrations of the reconstructed exit wave can be reduced by a factor of two if the aberrations of the imaging system are known. This is a significant improvement compared to the state of the art.
关键词： aberrations,electron microscopy,exit wave reconstruction,off-axis holography
更新于2025-09-11 14:15:04
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Stability of corneal topography and aberrometry after hyperopic laser in situ keratomileusis with a 500-Hz excimer laser platform: A 3-year follow-up study
摘要： The aim of this study is to analyze the long-term stability of the corneal topography, the functional optical zone, and the refractive stability throughout 3 years following laser in situ keratomileusis surgery for hyperopia using a 500-Hz excimer laser system. This retrospective consecutive observational case series study comprised 66 eyes that underwent laser in situ keratomileusis to correct hyperopia with a postoperative follow-up of 3 years. Laser in situ keratomileusis procedures were performed using the SCHWIND Amaris 500-Hz excimer laser. Main outcomes measured were stability of the functional optical zone at corneal topography and corneal aberrometry. Statistically significant differences were found in simulated keratometry (K2 (steep meridian) and Km (mean keratometry)) between 3 and 36 months postoperatively (p ? 0.01); these differences disappeared at 12 and 36 months (p ? 0.18). No statistically significant changes were observed in the horizontal and vertical diameter of the functional optical zone throughout the whole follow-up (p ? 0.07). A statistically significant difference was found in the spherical aberration between 3 and 36 months (p = 0.02); this difference disappeared when compared between 12 and 36 months (p = 0.72). Statistically significant correlations were detected between the vertical functional optical zone and coma root mean square (r = –0.510, p < 0.01) and between the vertical functional optical zone and spherical aberration (r = 0.441, p = 0.02) 36 months after surgery. Following 3 years of hyperopic laser in situ keratomileusis with a 500-Hz Amaris excimer laser, keratometry, functional optical zone, and corneal aberrations remain stable from 1 year after surgery. Topographical regression is not observed in hyperopic laser in situ keratomileusis with this excimer laser technology from 1 year after surgery.
关键词： corneal topography,refractive surgery,hyperopic laser in situ keratomileusis,hyperopia,Functional optical zone,corneal aberrations,hyperopic regression
更新于2025-09-11 14:15:04
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Optical and neural anisotropy in peripheral vision
摘要： Optical blur in the peripheral retina is known to be highly anisotropic due to nonrotationally symmetric wavefront aberrations such as astigmatism and coma. At the neural level, the visual system exhibits anisotropies in orientation sensitivity across the visual field. In the fovea, the visual system shows higher sensitivity for cardinal over diagonal orientations, which is referred to as the oblique effect. However, in the peripheral retina, the neural visual system becomes more sensitive to radially-oriented signals, a phenomenon known as the meridional effect. Here, we examined the relative contributions of optics and neural processing to the meridional effect in 10 participants at 08, 108, and 208 in the temporal retina. Optical anisotropy was quantified by measuring the eye’s habitual wavefront aberrations. Alternatively, neural anisotropy was evaluated by measuring contrast sensitivity (at 2 and 4 cyc/deg) while correcting the eye’s aberrations with an adaptive optics vision simulator, thus bypassing any optical factors. As eccentricity increased, optical and neural anisotropy increased in magnitude. The average ratio of horizontal to vertical optical MTF (at 2 and 4 cyc/deg) at 08, 108, and 208 was 0.96 6 0.14, 1.41 6 0.54 and 2.15 6 1.38, respectively. Similarly, the average ratio of horizontal to vertical contrast sensitivity with full optical correction at 08, 108, and 208 was 0.99 6 0.15, 1.28 6 0.28 and 1.75 6 0.80, respectively. These results indicate that the neural system’s orientation sensitivity coincides with habitual blur orientation. These findings support the neural origin of the meridional effect and raise important questions regarding the role of peripheral anisotropic optical quality in developing the meridional effect and emmetropization.
关键词： peripheral retina,anisotropy,wavefront aberrations,neural adaptation,adaptive optics
更新于2025-09-11 14:15:04
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Analysis of Internal Optical Aberrations in Eyes with Different Types of Cataract
摘要： Purpose: The present study investigates the patterns of internal optical aberrations in eyes with different types of cataract. Methods: Eighty eyes of 70 cataract patients were included in the present study. Internal optical aberrations were measured with a KR-1W wavefront aberrometer before cataract operation. Types of cataract were classified into three groups; cortical, nuclear and posterior subcapsular cataracts. The differences in the results of the wavefront data of 6-mm pupil diameter zones were compared among three groups. The Kruskal-Wallis test and Mann-Whitney U test were used for comparing data. Results: A total of 80 eyes consisting of 30 cortical cataracts, 30 nuclear cataracts and 20 posterior subcapsular cataracts were found. In the 6-mm pupil diameter zone, the average internal spherical aberrations by original value were 0.042 μm of cortical cataracts, -0.092 μm of nuclear cataracts and -0.109 μm of posterior subcapsular cataracts. The average internal spherical aberrations by absolute value were 0.122 μm of cortical cataracts, 0.533 μm of nuclear cataracts and 0.202 μm of posterior subcapsular cataracts. The internal spherical aberrations by original value were not statistically significantly different, but by absolute value were statistically significantly different (p = 0.003, Kruskal-Wallis test). Nuclear cataracts have a much higher positive or negative value than other cataract groups in the distribution of internal spherical aberrations by original value for each type of cataract. Other than this difference, the internal astigmatism and internal high order aberrations were not statistically significantly different. Conclusions: The change in internal spherical aberrations of nuclear cataract from the original value was larger than cortical and posterior subcapsular cataract. Therefore, nuclear cataracts have much higher positive or negative values than other cataract groups.
关键词： Different types of cataract,Internal spherical aberrations,Internal optical aberrations
更新于2025-09-10 09:29:36
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Corneal higher-order aberrations of the anterior surface, posterior surface, and total cornea after small incision lenticule extraction (SMILE): high myopia versus mild to moderate myopia
摘要： Background: To investigate corneal higher-order aberrations (HOAs) of the anterior surface, posterior surface, and total cornea after small incision lenticule extraction (SMILE) in high myopic and mild to moderate myopic patients. Methods: This retrospective study included 197 eyes (101 patients) undergoing SMILE surgery. According to the preoperative spherical equivalent (SE), treated eyes were divided into two groups: a high myopic group (more than ? 6.0 D, Group H) and a mild to moderate myopic group (less than ? 6.0 D, Group M). Corneal HOAs of the anterior surface, posterior surface, and total cornea were measured using a Scheimpflug camera preoperatively and 3 months postoperatively. Pearson’s correlation analysis was conducted to determine relationships between corneal aberrations and the SE. Results: There were no significant differences in third-order to eight-order aberrations (RMS HOAs) of the anterior surface, posterior surface, and total corneal between the two groups before SMILE surgery. However, after SMILE, anterior and total corneal HOAs, especially vertical coma and spherical aberrations, significantly increased in both groups (p < 0.0167), whereas posterior corneal HOAs remained relatively stable (p > 0.0167). The induction of HOAs was significantly greater in Group H than Group M postoperatively (p < 0.0167). Changes in anterior surface and total corneal HOAs, especially vertical coma and spherical aberrations, were related to the SE (p < 0.05). Conclusions: Anterior and total corneal HOAs, particularly vertical coma and spherical aberrations, significantly increased after SMILE in both groups, whereas posterior corneal HOAs remained stable. Aberration changes were related to SE.
关键词： Posterior cornea,SMILE,Higher-order aberrations
更新于2025-09-10 09:29:36
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Aberrated dark-field imaging systems
摘要： We study generalized dark-field imaging systems. These are a subset of linear shift-invariant optical imaging systems that exhibit arbitrary aberrations and for which normally incident plane-wave input yields zero output. We write down the theory for the forward problem of imaging coherent scalar optical fields using such arbitrarily aberrated dark-field systems and give numerical examples. The associated images may be viewed as a form of dark-field Gabor holography, utilizing arbitrary outgoing Green’s functions as generalized Huygens-type wavelets, with the Young-type boundary wave forming the holographic reference.
关键词： dark-field imaging,aberrations,linear shift-invariant optical imaging systems,Gabor holography,Huygens-type wavelets
更新于2025-09-09 09:28:46
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Intrasession repeatability of refractive and ocular aberrometric measurements obtained using a multidiagnostic device in healthy eyes
摘要： Purpose: To evaluate the intrasession repeatability of refractive and ocular aberrometric measurements obtained using a new multidiagnostic device in healthy eyes. Patients and methods: A total of 107 eyes of 107 patients, age ranging from 23 to 65 years, were enrolled in this study. A complete eye examination was performed in all eyes, including an ocular examination using the VX120 system. Three consecutive measurements were obtained using this device to assess the intrasession repeatability of different refractive and ocular aberrometric parameters. The within-subject standard deviation (Sw), intrasubject precision (1.96×Sw), and intraclass correlation coefficient (ICC) were calculated. Results: Sw and intrasubject precision for refractive data were below 0.12 and 0.20 D, respectively, in all cases. The ICC ranged from 0.947 for the J45 power vector component to 0.997 for the sphere. Concerning aberrometric measurements Sw and intrasubject precision values were below 0.05 μm and 0.10 μm, respectively. Likewise, the ICC ranged from 0.805 for the quadrafoil root mean square to 0.954 for the primary spherical aberration. Poor correlations were found between most of the refractive parameters and their Sw (–0.033≤r≤0.053, p≥0.064). Moderate and significant positive correlations were found between the magnitude of the aberrometric parameters evaluated and their Sw (r≥0.446, p<0.001). Conclusion: The new multidiagnostic device evaluated is able to provide consistent measurements of refraction and ocular aberrations in healthy eyes. Future studies should confirm if this consistency is also observed in highly aberrated eyes.
关键词： ocular aberrations,intrasession repeatability,refraction,VX120 system,Scheimpflug imaging
更新于2025-09-09 09:28:46
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Intrastromal crosslinking in post-LASIK ectasia
摘要： We describe a case of early post-LASIK ectasia detected in the first 6 months after surgery. The patient was treated by means of intrastromal corneal crosslinking under the flap, without de-epithelialization, which resulted in a positive outcome. At the time of writing, 2 years after the procedure, the patient remained free of progression.
关键词： Keratomileusis, laser in situ,Adult,Case reports,Corneal wavefront aberrations,Corneal stroma,Astigmatism,Postoperative complications,Cross-linking reagent,Refractive surgical procedures,Humans,Female
更新于2025-09-09 09:28:46
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Comparison of Ocular Aberration and Clinical Outcome between Different Aspheric Intraocular Lenses in Both Eyes
摘要： Purpose: We compared the ocular aberration and clinical outcome between different aspheric intraocular lenses (IOL) in both eyes. Methods: This prospective randomized controlled study was comprised of patients with bilateral cataract who received two different aspheric IOLs implanted in both eyes: negatively aspheric Tecnis? ZCB00 and spherically neutral Akreos? MI60. Total and corneal aberrations computed by Wavescan? and Pentacam? were assessed at 6 months to investigate the effects of the IOL’s spherical aberration on the eye and to analyze the incidence and degree of posterior capsule opacification. By using spherical aberration of the cornea and the IOLs, values calculated via Ray-tracing software and Wavescan? were compared. Total spherical aberration was analyzed by the MATLAB program and converting the pupil size to 6.0, 4.5, 3.0 mm. Results: A total of 25 patients were included. Regarding pre-operative corneal aberration, ZCB00 group was 0.232 ± 0.119 μm while MI60 group was 0.240 ± 0.117 μm, and there was no difference between the two IOLs. At 6 months after total ocular spherical aberration, MI60 group (pupil size 6.0 mm; 0.296 ± 0.097 μm, 4.5 mm; 0.094 ± 0.032 μm, 3.0 mm; 0.019 ± 0.006 μm) had more positive values than ZCB00 group (pupil size 6.0 mm; 0.051 ± 0.105 μm, 4.5 mm; 0.009 ± 0.034 μm, 3.0 mm; 0.002 ± 0.007 μm) (p < 0.001). When calculated using the ray tracing method, based on the results after surgery, MI60 group’s total spherical aberrations were higher than ZCB00 group. However, from 1 month to 6 months after surgery, the uncorrected distance visual acuity, spherical equivalent and posterior capsule opacification showed no differences between the two IOLs. Conclusions: In eyes with aspheric IOLs with negative spherical aberration, spherical aberration was lower than spherically neutral aspheric IOLs. Regarding postoperative visual acuity, spherical equivalent and posterior capsule opacification, there were no significant differences between the two groups.
关键词： Posterior capsular opacity,Aspheric intraocular lens,Ocular aberrations,Cataract surgery
更新于2025-09-09 09:28:46