- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Total keratometry in intraocular lens power calculations in eyes with previous laser refractive surgery
摘要： Importance: Intraocular lens (IOL) calculations in post-refractive cases remain a concern. Our study identifies improved options for surgeons. Background: To evaluate and compare the prediction accuracy of IOL power calculation methods after previous laser refractive surgery using standard keratometry (SK), measured posterior corneal astigmatism (PCA) and total keratometry (TK). Design: Retrospective consecutive cohort Participants: 50 consecutive patients (72 eyes) at a private institution who underwent cataract surgery with prior laser refractive procedures Methods: Methods using SK included ASCRS mean, Barrett True K no history, Haigis-L and Shammas IOL formulae. Barrett True K using posterior values (True K TK), Haigis and Holladay 1 Double-K methods using TK were also assessed. Post-surgery refraction was undertaken at minimum 3 weeks following surgery. Main outcome measures: Arithmetic and absolute IOL refractive prediction errors, variances in mean arithmetic IOL prediction error, and percentage of eyes within ± 0.25D, ± 0.50D, ± 0.75D and ± 1.00D of refractive prediction errors were compared. Results: The Barrett True K (TK) provided the lowest mean refractive prediction error and variance for both prior myopes and hyperopes undergoing cataract surgery. The Barrett True K (TK) exhibited the highest percentages of eyes within ± 0.50D, ± 0.75D and ± 1.00D of the refractive prediction error compared to other formulae for prior myopic patients. Conclusions and relevance: Accuracy of IOL power calculations in post-laser eyes can be improved by the addition of posterior corneal values as measured by the IOLMaster 700. The use of total keratometry may supplement outcomes when no prior refraction history is known.
关键词： Cataract,Refractive surgery,Surgery,Intraocular lenses
更新于2025-09-19 17:13:59
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[IEEE 2019 International Conference on Optical MEMS and Nanophotonics (OMN) - Daejeon, Korea (South) (2019.7.28-2019.8.1)] 2019 International Conference on Optical MEMS and Nanophotonics (OMN) - Micro-optical system for depth-controlled Bessel beam arrays
摘要： We present an integrated, compact micro-optical system capable to generate depth-controlled Bessel beams by integrating a miniaturized adaptive liquid crystal ring aperture array with a micro-lens array, a lensacon, which is a combination of a lens and an axicon. We were able to successfully demonstrate a functional system that is able to generate and control Bessel beams.
关键词： micro-lens arrays,Bessel beam,micro-optical system,aspherical lenses,ring aperture,liquid crystal
更新于2025-09-16 10:30:52
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Speckle reduction by employing two green lasers and two-dimensional vibration of lenses
摘要： A method of speckle reduction suitable for use in a laser projector was proposed in the paper. Speckle contrast ratio (SCR) reduction was achieved by combining wavelength diversity and angular diversity methods. First, wavelength diversity was demonstrated by the use of two green laser sources (a 520 nm laser diode (LD) and a 532 nm diode-pumped solid-state (DPSS) laser) at a power ratio of 4:1. Second, angular diversity was achieved via the vibration of two lenses in two orthogonal directions placed directly after the laser source. The vibrating lenses are small and do not require changes to the beam path of the laser source, allowing for more compact projector designs. The frequency of vibration of these lenses was optimized to minimize the SCR in the output image. A SCR of less than 4% was achieved without the use of optical diffusers, which significantly reduces optical losses. Optical transmission could be further increased with the optimization of optical coatings on the lenses. This result shows great promise for applications such as laser pico-projectors within the realm of heads-up displays (HUDs) and mobile devices.
关键词： two-dimensional vibration of lenses,speckle reduction,mini-/pico-projectors
更新于2025-09-16 10:30:52
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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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Detecting polarization state of arbitrary polarized light by chiral plasmonic lenses with distributed nanoslits
摘要： We devise three chiral plasmonic lenses (PLs) with distributed nanoslits for detecting the complete state of polarization of an arbitrary polarized light. A double-ring arrayed nanocrosses-based plasmonic lens is proposed to focus the surface plasmon polaritons excited by the two circularly polarized components of the incident light, thus enabling the phase difference between the two components to be retrieved. Two Archimedes-spiral arrayed nanoslits-based PLs with opposite chirality are designed to detect the relative strength of the two components. The focusing properties of the three structures are theoretically derived and numerically investigated, demonstrating the effectiveness of the proposed method.
关键词： surface plasmon polaritons,polarization state,nanoslits,chiral plasmonic lenses
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE 32nd International Conference on Micro Electro Mechanical Systems (MEMS) - Seoul, Korea (South) (2019.1.27-2019.1.31)] 2019 IEEE 32nd International Conference on Micro Electro Mechanical Systems (MEMS) - Flexible $\mu\text{LED}$-Based Optogenetic Tool with Integrated $\mu$-Lens Array and Conical Concentrators Providing Light Extraction Improvements above 80%
摘要： This paper reports on the fabrication and characterization of spherical micro-lenses (μ-lenses) made from polydi-methylsiloxane (PDMS) and their integration into optogenetic implants based on micro light-emitting diodes (μLEDs). The μ-lenses are fabricated using a reusable silicon mold realized by wet chemical HNA (hydrofluoric, nitric and acetic acid) etching. It applies a masking layer with openings as small as 5 μm and was optimized for hemispherical μ-lens cavities of low surface roughness (Ra < 45 nm). The μ-lenses with diameters down to 10 μm are realized by PDMS molding using a polymeric release layer (PRL) improving the μ-lens release and enabling Ra values below 5 nm. Linear μ-lens arrays are transferred onto the emission side of μLEDs comprising integrated conical concentrators (CCs). The PDMS-filled CCs improve the μ-lens emission behavior by light reflection at the interface between the polymeric probe substrate and PDMS, without increasing the overall probe dimensions. Using μLEDs with integrated μ-lens arrays in combination with CCs, the overall light extraction of the optical implants is increased by 115 % and 83 % in air and water, with the peak intensity raised by 145 % and 95 %, respectively.
关键词： optogenetic implants,conical concentrators,PDMS,light extraction,μ-lenses,μLEDs
更新于2025-09-12 10:27:22
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[IEEE 2019 41st Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC) - Berlin, Germany (2019.7.23-2019.7.27)] 2019 41st Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Ultrasonically Steerable Graded-Index Optical Waveguides for Deep Tissue Light Delivery: Theory and Applications
摘要： Graded-index (GRIN) fibers have been used as implantable optical waveguides to guide light and relay images through the depth of the tissue. We have recently shown that non-invasive ultrasound can generate refractive index gradients within the tissue that form virtual GRIN lenses for imaging and photostimulation deep into the tissue. Here we present the theory behind this idea by analyzing the coupled acoustic-photonic system that models the interaction of light with the ultrasonically modulated medium. We will discuss how changing the parameters of ultrasound will change the confinement and guiding of light within the modulated medium. We will also demonstrate that using a custom-designed cylindrical ultrasonic array, the pressure interference can be controlled to sculpt complex patterns of light in the medium, such as dipole and quadrupole shapes, suitable for multisite imaging. Finally, we will discuss experimental results corroborating the theoretical predictions to generate single and multisite in situ virtual lenses that can be used for fluorescent imaging of mouse brain tissue that expresses green fluorescent protein (GFP).
关键词： refractive index gradients,fluorescent imaging,Graded-index fibers,acousto-optic system,ultrasound,virtual GRIN lenses,photostimulation
更新于2025-09-12 10:27:22
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Measurement of the fractional orbital angular momentum of asymmetric laser beams by using two cylindrical lenses
摘要： Here we propose and study both theoretically and experimentally a simple and high-efficient technique for measuring the orbital angular momentum (OAM) of paraxial laser beams. The technique uses two intensity distributions measured in the foci of two perpendicular cylindrical lenses. For these distributions, first-order intensity moments are calculated, which allow the OAM to be easily obtained. The experimental error increases from ~1% for small fractional OAM (up to 4) to ~8% for large fractional OAM (up to 30). We also show numerically that the proposed technique allows to determine the OAM if the beam is distorted by a phase diffuser in the initial plane.
关键词： orbital angular momentum,intensity distributions,laser beams,fractional topological charge,cylindrical lenses
更新于2025-09-12 10:27:22
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Biological Lenses as a Photomask for Writing Laser Spots into Ferroelectric Crystals
摘要： Red Blood Cells on the surface of Lithium Niobate crystal can be used as optical lenses for direct writing of laser-induced refractive index changes. The writing process by such photomask made of biological lenses is due to photorefractive effect. Wavefront analysis by digital holographic microscope is performed for deep and accurate evaluation of local refractive index changes. Different focusing properties can be imprinted on the crystal depending on which type of RBC is employed, discocytes or spherical-like ones. The possibility to fix into a solid material the optical fingerprint of RBCs will have impact on both diagnostics and cell\material interfacing.
关键词： photo-lithography,bio-lenses,photorefractive effect,digital holography,RBC
更新于2025-09-12 10:27:22
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Multiplexing THz vortex beams with a single diffractive 3D printed lens
摘要： We present a novel method for experimentally generating multiplexed THz vortex beams by using a single 3D printed element that combines a set of radially distributed spiral phase plates, and a binary focusing Fresnel lens. With this element we have experimentally demonstrated that THz multiplexing can be tailored to fit within a small space on an optical bench. Results are presented beside numerical simulations, demonstrating the robust nature of the experimental method.
关键词： diffractive lenses,Vortex lenses,Multiplexed vortex beams,Diffraction
更新于2025-09-11 14:15:04