Dielectric elastomers with low elastic stiffness and high dielectric constant are smart materials that produce large strains (up to 300%) and belong to the group of electroactive polymers. Dielectric elastomer actuators are made from films of dielectric elastomers coated on both sides with compliant electrode material. Poly(3,4-ethylenedioxythiophene) (PEDOT), which is ...

Background:  The aim was to analyse anterior corneal optical irregularity in patients receiving photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) with a conventional broad beam laser. Methods:  Pre- and post-operative anterior corneal aberrations including Zernike coefficients and root mean squares of higher-order aberrations were measured and derived with ...

The two-dimensional analytic optics design method presented in a previous paper [Opt. Express 20, 5576-5585 (2012)] is extended in this work to the three-dimensional case, enabling the coupling of three ray sets with two free-form lens surfaces. Fermat's principle is used to deduce additional sets of functional differential equations which ...

We report a new dual band compact oblique photography camera (LC11) that is the first to benefit from the incorporation of telecentricity. LC11 has a common front end F/6.6 telescope with 280 mm in aperture that forms its electro-optical (EO, F/7.5) and MWIR (F/5.6) modules. The design allows a substantial ...

We present a simple freeform lens design method for an application to LED collimating illumination. The method is derived from a basic geometric-optics analysis and construction approach. By using this method, a highly collimating lens with LED chip size of 1.0 mm×1.0 mm and optical simulation efficiency of 86.5% under ...

A multigrid computational model has been developed to assess the performance of refractive liquid crystal lenses, which is up to 40 times faster than previous techniques. Using this model, the optimum geometries producing an ideal parabolic voltage distribution were deduced for refractive liquid crystal lenses with diameters from 1 to ...

PURPOSE.: To investigate porcine lenses in a lens stretcher with regard to presbyopia corrective procedures. METHODS.: A lens stretching device was designed, which allows to simultaneously determine all relevant geometrical and optical parameters at each stretch position. The setup was used to compare the optical and geometrical lens properties of ...

The spin dependence of the focusing behavior of a spiral slot plasmonic lens can be utilized for a miniature circular polarization analyzer. However, the azimuthal polarization component of the incident circular polarization does not contribute to surface plasmon excitation and focusing because it is TE polarized with respect to the ...

We utilize three diffraction theories to investigate the focal-shift phenomena of plasmonic lenses. By taking the Fresnel number into account, a better accuracy in predicting the relative focal shift can be achieved for low-Fresnel-number systems. On the basis of this focal-shift effect, we present a method to realize an active ...

Spot distortion caused by astigmatism effect in orthogonal cylindrical lenses is utilized to measure axial displacement with 30 nm resolution, strong noise immunity, and compact experiment setup. Axial displacement of the sample surface is determined by four-quadrant difference processing of distorted laser spots' energy distribution images received by CCD. Four-quadrant ...

A new optical design strategy for rotational aspheres using very few parameters is presented. It consists of using the SMS method to design the aspheres embedded in a system with additional simpler surfaces (such as spheres, parabolas or other conics) and optimizing the free-parameters. Although the SMS surfaces are designed ...

The thermal lens induced in an a-cut BaWO₄ crystal by stimulated Raman scattering is measured using lateral shearing interferometry. The strength of the lens is proportional to the Stokes output power. For light polarized parallel to the a-axis, and a Stokes mode radius of 120 μm, the lens is negative ...

We have built a setup with high temporal resolution to measure the very fast photoelastic lensing effect, which is on the scale of microseconds in a Ti:sapphire crystal pumped by very strong laser pulses (up to 5  J/cm²). The experimental results measured by this method and the real multimode beam profile ...

PURPOSE: Comparison of postoperative refraction results using ultrasound biometry with closed immersion shell and optical biometry. PATIENTS AND METHOD: Three hundred and sixty-four eyes of 306 patients (age: 70.6 ± 12.8 years) underwent cataract surgery where intraocular lenses calculated by SRK/T formula were implanted. In 159 cases immersion ultrasonic biometry, in 205 eyes ...

In planar metamaterial lenses, the focal point moves with the frequency. Here it is shown numerically that this movement can be controlled by properly engineering the dimensions of the metamaterial-based phase shifters that constitute the lens. In particular, such lenses can be designed to exhibit unusual chromatic aberration with the ...

We present a standardized procedure to measure the amount of speckle in laser based projection systems. The parameters of the measurement procedure are chosen such that the measured speckle contrast values are in correspondence with the subjective speckle perception of a human observer, independent of the particularities of the laser ...

The design of single element planar hemispherical gradient-index solar lenses that can accommodate the constraints of realistic materials and fabrication techniques are presented, and simulated with an extended and polychromatic solar source for concentrator photovoltaics at flux concentration values exceeding 1000 suns. The planar hemispherical far-field lens is created from ...

Luneburg lenses are able to form perfect focus that is free of aberration. Because of the varying refractive index throughout the lens, incoming electromagnetic waves can travel in a curved path and be guided to focus at the back of the lens. The implementation of Luneburg lenses is often difficult ...

We fabricated cylindrical varifocal lenses with fast responses by using the strong Kerr effect of KTa_1-xNb_xO₃ (KTN) single crystals. We observed focus shifts of up to 87 mm with the assistance of a 250 mm focal length lens, which corresponds to a focus shift from infinity to 720 mm by ...

Coherent and incoherent combination of Gaussian beams employing a lens array distributed on the spherical chamber is theoretically analyzed. The output field of each source in the array is coupled through an individual optical system whose local optical axis coincides with the radial direction of the chamber. The resulting intensity ...

In the optical vortex microscopy the focused Gaussian beam with optical vortex scans a sample. An optical vortex can be introduced into a laser beam with the use of a special optical element-a vortex lens. When moving the vortex lens, the optical vortex changes its position inside the spot formed ...

The action of a nanoscopic spherically symmetric refractive index profile on a focused Gaussian beam may easily be envisaged as the action of a phase-modifying element, i.e. a lens: Rays traversing the inhomogeneous refractive index field n(r) collect an additional phase along their trajectory which advances or retards their phase ...

Aspherical surfaces required for focusing collimated and divergent synchrotron beams using a single refractive element (lens) are reviewed. The Cartesian oval, a lens shape that produces perfect point-to-point focusing for monochromatic radiation, is studied in the context of X-ray beamlines. Optical surfaces that approximate ideal shapes are compared. Results are ...

We investigate the focusing properties of a double-ring-shaped azimuthally polarized beam by a high numerical aperture (NA) lens axicon based on vector diffraction theory. We observe that our proposed system generates a sub wavelength focal hole of 0.5λ having large uniform focal depth of 48λ without any annular aperture. We ...

Incorporating optical structures on curved lens surfaces can improve performance, consolidate functions, and create novel, miniaturized devices. Although commonly found in biological systems, patterning of micro- and nano-optical structures on curved surfaces is challenging for conventional methods. Previous works have demonstrated the ability to pattern curved surfaces but have done ...

We study the major factors causing degradation in the lateral resolution of gradient-index-lens-based catheters used for high-resolution optical coherence tomography. Chromatic aberration and astigmatism were taken into account in the propagation of broadband single-mode Gaussian beams through the catheter geometry. It was found that, while chromatic aberration did not preclude ...

In this Letter, we introduce an analytic procedure for designing diffractive lenses using the combination of wavefronts aberrated by Zernike polynomials. We show how to design amplitude-only, phase-only, continuous, and binary lenses providing equivalent results. As an example we apply it to the design of a multiple-axis, multifocal lens. The ...

We report on the realization of an intracavity high harmonic source with a cutoff above 30 eV. The EUV source is based on a high power, hard-aperture, Kerr-lens mode-locked Ti:sapphire oscillator with a repetition rate of 9.4 MHz. The laser is operated in the net negative dispersion regime resulting in ...

Perfect lensing using negative refractive index materials and radiationless electromagnetic interference both provides extreme subwavelength focusing by "amplifying" evanescent wave components that are usually lost. This Letter provides a relation between the achievable focus spot size, the amplification available, and the focal length. This may be considered as a revised ...

The high prevalence of blindness associated with cataract is an urgent public health issue. Femtosecond (FS) laser offers several advantages over conventional laser, such as high penetration, short pulse-duration and micro-precision. Since 2009, several types of FS laser systems have been applied to cataract surgery, offering novel approaches to the ...

Optical lenses with a freeform surface can be designed for diverse illumination profiles with uniformity. However, most of the previous studies formulate the problem for a single point source, and the lens topology has freeform top and spherical bottom surfaces. In this study, the formulation is extended for multiple point ...

BACKGROUND: In a single-blinded study, optical side-effects of a potential femtosecond (fs)-laser therapy in presbyopic human lenses were tested. Simulation of this therapy was carried out by applying fs-laser patterns into standard contact lenses (CL). METHODS: In the first part of the study, the influence of the numerical aperture on ...

In this work, a new two-dimensional optics design method is proposed that enables the coupling of three ray sets with two lens surfaces. The method is especially important for optical systems designed for wide field of view and with clearly separated optical surfaces. Fermat's principle is used to deduce a ...

PURPOSE.: A progressive power lens (PPL) has a relatively complex power distribution, with regions for far, intermediate, and near vision, and also regions affected by aberrations, mainly astigmatism and defocus. Scoring techniques (Sheedy, Optom Vis Sci 2004;81:350-61) have been proposed to mark and classify PPLs according to their optical performance ...

We demonstrate an improved method for fabricating optical waveguides in bulk materials by means of femtosecond laser writing. We use an LC spatial light modulator (SLM) to shape the beam focus by generating adaptive slit illumination in the pupil of the objective lens. A diffraction grating is applied in a ...

We present a theoretical analysis of an electrostatic triode mirror combined with an einzel lens for the correction of spherical and chromatic aberration. We show that this device adaptively corrects spherical and chromatic aberration simultaneously and independently. Chromatic aberration can be compensated over a relative range of -38% to +100%, ...

When a star is tidally disrupted by a supermassive black hole (SMBH), the streams of liberated gas form an accretion disk after their return to pericenter. We demonstrate that Lense-Thirring precession in the spacetime around a rotating SMBH can produce significant time evolution of the disk angular momentum vector, due ...

We propose a new method for achieving simultaneous operation of laser mode locking and the Q-switch technique using only a single acousto-optic modulator (AOM) with a traveling wave; this AOM was placed inside the cavity of a green-emission Nd:YAG laser. The further shortening of the lasing pulse duration from 40 ...

Gridded electrostatic lenses are frequently used in extraction systems and low energy ion beam transport line. Typically, for numerical simulation the grid is treated as a metal plate transparent for beam particles. The influence of real grid geometry on the beam dynamics in the gridded lens has been investigated by ...

Micro-optical probes, including gradient index (GRIN) lenses and microprisms, have expanded the range of in vivo multiphoton microscopy to reach previously inaccessible deep brain structures such as deep cortical layers and the underlying hippocampus in mice. Yet imaging with GRIN lenses has been fundamentally limited by large amounts of spherical ...

An electrically tunable focusing LC lens with a low voltage and simple planar electrodes is demonstrated. The inhomogeneous electric field of the LC lens without any hole-patterned-electrode is generated by using an embedded polymeric layer with a gradient distribution of dielectric constants (or relative permittivity). LC directors in the LC ...

In this paper we perform a theoretical and numerical study of two-dimensional inside-out Eaton lenses under transverse-magnetic-polarized excitation. We present one example design and test its performance by utilizing full-wave Maxwell solvers. With the help of the WKB approximation, we further investigate the finite-wavelength effect analytically and demonstrate one necessary ...

A theoretical analysis based on scalar diffraction theory about the recently reported focal-shift phenomena in planar metallic nanoslit lenses is presented. Under Fresnel approximation, an axial intensity formula is obtained, which is used to analyze the focal performance in the far field zone of lens. The relative focal shift is ...

Employing artificially structured metamaterials provides a means of circumventing the limits of conventional optical materials. Here, we use transformation optics (TO) combined with nanolithography to produce a planar Luneburg lens with a flat focal surface that operates at telecommunication wavelengths. Whereas previous infrared TO devices have been transformations of free-space, ...

This paper reports integrated tracking (horizontal) and focusing (vertical) actuators using microelectromechanical (MEMS) technology for optical storage. The design, fabrication and characterization of the integrated tracking and focusing actuators are demonstrated. The integrated tracking and focusing lens actuators that consist of springs, a lens holder and comb-drive actuators are implemented ...

The limits of the paraxial approximation for a laser beam under ABCD transformations is established through the relationship between a parameter concerning the beam paraxiality, the paraxial estimator, and the beam second-order moments. The applicability of such an estimator is extended to an optical system composed by optical elements as ...

Different sized/shaped micro protrusive lens arrays atop poly(methyl methacrylate) can be fabricated by a simple two-step method, i.e., indentation followed by immersion in ethanol. Profile and projection of obtained microlenses were characterized. Thermal stability of microlenses was examined at 25°C and 60°C. This work demonstrates a cost effective approach for ...

Typical lenses suffer from Fresnel reflections at their surfaces, reducing the transmitted power and leading to interference phenomena. While antireflection coatings can efficiently suppress these reflections for a small frequency window, broadband antireflection coatings remain challenging. In this paper, we report on the simulation and experimental investigation of Brewster lenses ...

The thermodynamic consistency of kinetic models for non-ideal mixtures in non-isothermal conditions is investigated. A kinetic model is proposed that is suitable for deriving high-order lattice Boltzmann equations by an appropriate discretization of the velocity space, satisfying the Galilean invariance condition and free of spurious terms in the first moment ...

A lattice Boltzmann (LB)-based hybrid method is developed to simulate suspensions of Brownian particles. The method uses conventional LB discretization (without fluid- level fluctuations) for suspending fluid, and treats Brownian particles as point masses with a stochastic thermal noise. LB equations are used to compute the velocity perturbations induced by ...