Showing papers on "Apochromat published in 2010"

Information transfer in a TEM corrected for spherical and chromatic aberration.

Abstract: For the transmission electron aberration-corrected microscope (TEAM) initiative of five U.S. Department of Energy laboratories in the United States, a correction system for the simultaneous compensation of the primary axial aberrations, the spherical aberration Cs, and the chromatic aberration Cc has been developed and successfully installed. The performance of the resulting Cc /Cs-corrected TEAM instrument has been investigated thoroughly. A significant improvement of the linear contrast transfer can be demonstrated. The information about the instrument one obtains using Young's fringe method is compared for uncorrected, Cs-corrected, and Cc /Cs-corrected instruments. The experimental results agree well with simulations. The conclusions might be useful to others in understanding the process of image formation in a Cc /Cs-corrected transmission electron microscope.

Generalized refractive tunable-focus lens and its imaging characteristics

Abstract: Conventional lenses made from optical glass or plastics have fixed properties (e.g. focal length) that depend on the index of refraction and geometrical parameters of the lens. We present an approach to the problem of calculation of basic paraxial parameters and the third order aberration coefficients of compound optical elements analogical to classical lenses which are based on refractive tunable-focus lenses. A detailed theoretical analysis is performed for a simple tunable-focus lens, a generalized tunable-focus lens, a generalized tunable-focus lens with minimum spherical aberration, and three-element tunable-focus lens (a tunable-focus doublet).

Design of achromatic and apochromatic plastic micro-objectives

Abstract: The possibility and the efficiency of using a single diffractive lens to achromatize and apochromatize micro-objectives with plastic lenses are shown. In addition, recommendations are given on assembling the starting configurations of the objectives and calculating the design parameters required for subsequent optimization. It is also shown that achievable optical performance of achromatic and apochromatic micro-objectives with plastic lenses satisfy the qualifying standards for cell-phone objectives and closed-circuit television (CCTV) cameras.

IOL with varying correction of chromatic aberration

Abstract: An ophthalmic lens includes an optical filter operable to filter out at least visible light having a wavelength less than 450 nm. The lens also includes a first diffractive structure adapted to produce a focus for visible light in a first wavelength range above 550 nm and to reduce longitudinal chromatic aberration to less than one diopter for incoming visible light in the first wavelength range. The lens also includes a second diffractive structure outside the first diffractive structure in a radial direction and adapted to produce a focus for visible light in a second wavelength range between 450 nm and 550 nm. The second diffractive structure is also adapted to reduce longitudinal chromatic aberration for incoming visible light in the second wavelength range to less than one diopter while allowing longitudinal chromatic aberration in the first wavelength range in an amount greater than the first diffractive structure.

The infrared imaging spectrograph (IRIS) for TMT: imager design

Abstract: We describe an optical design of an imager mode of the IRIS instrument for the Thirty Meter Telescope IRIS is a fully-cryogenic diffraction-limited infrared camera and integral field spectrograph working in the wavelength coverage from 084 to 24 microns The imager mode covers 164" × 164" FOV with a 4096 × 4096 detector array with sampling 4 milli-arcsec/pix There are two challenges in performance which the science cases require in the imager mode 1) rms wavefront error should be less than 30 nm, and 2) optical distortion should be corrected sufficiently to achieve astrometric accuracy of 10 micro-arcsec Among possible optical configurations consisting of reflective and refractive solutions, a refractive solution with apochromatic triplets best meets the requirements The optical system consists of a collimator and camera both of which have a BaF2-Fused Silica- ZnSe apochromatic triplet and a single BaF2 lens near the focus The rms wavefront error of the system including the telescope, adaptive optics, and imager mode is less than 22 nm with ideal optical parameters A sensitivity analysis shows that reasonable amount of errors in fabrication and alignment will give the rms wavefront error of less than 30 nm in 90 % of all cases We also investigate accuracy of the distortion correction and how movable parts affect the correction accuracy We find that uncorrectable distortion correction errors are well below 10 micro-arcsec with reasonable stability and repeatability of the movable parts

Optimizing optical aberrations in ophthalmic lenses

Abstract: An ophthalmic lens includes spherical aberration in an amount that accounts for spherical aberration introduced into the lens during the manufacturing process and/or spherical aberration differences in the manufactured lens measured off of the eye and measured on the eye The result is a lens-and-eye optical system is free or substantially free of spherical aberration, ie, having only negligible spherical aberration Because the optical system is free or substantially free of spherical aberration, there is no or only negligible coma induced by the normal misalignment of the lens optical axis and the eye's primary line of sight The result is a lens-and-eye optical system that provides enhanced optical performance and visual quality Also disclosed are methods of designing and manufacturing lenses with spherical aberration adjustments to account for manufacturing process changes and off-eye to on-eye differences

Influence of ocular longitudinal chromatic aberration on the selection of aspheric intraocular lenses.

Abstract: Polychromatic defocus could affect the optimal residual spherical aberration that could yield the best image quality for patients with intraocular lenses (IOLs). Modulation transfer functions (MTFs) were generated using a model that included polychromatic defocus. The maximum MTF volume occurred at + 0.05 μm of overall ocular spherical aberration. For 3 case studies, the optimal overall ocular spherical aberration was ~0.05 μm more positive with the contribution of polychromatic defocus than without it. Overall, the model indicated that image quality was usually best when IOLs allowed overall ocular spherical aberration that was slightly positive, rather than strongly positive, zero, or negative.

X-ray Microfocusing by Combination of Grazing-Incidence Spherical-Concave Mirrors

Abstract: An optical system for X-ray microfocusing that consists of a pair of spherical mirrors has been developed. In grazing incidence optics with spherical (cylindrical) mirrors, focused beam size is generally restricted by spherical aberration. However, the spherical aberration can be corrected by the sequential reflection of two spherical mirrors, and submicrometer beam size can be obtained by total-reflection mirror optics with spherical concave mirrors. A sub-200 nm focusing has been achieved at an X-ray energy of 8 keV.

Spherical aberration gauge for human vision.

Abstract: Spherical aberration affects vision in varying degrees depending on pupil size, accommodation, individual eye characteristics, and interpretations by the brain. We developed a spherical aberration gauge to help evaluate the correction potential of spherical aberration in human vision. Variable aberration levels are achieved with laterally shifted polynomial plates from which a user selects a setting that provides the best vision. The aberration is mapped into the pupil of the eye using a simple telescope. Calibration data are given.

Optical design of non-CaF2 of middle and low power flat-field apochromatic metallographic micro-objective

Abstract: Based on the optical apochromatic system theory and referencing photographic objective to make similar innovation, the middle and low power apochromatic metallographic microobjective is constructed. In the design of low power objective, triplet photographic objective(+, -, +) is transplanted and applied to 5×objective. Referencing parameters of Orthometar processor objective and complication of triplet graphic objective are applied to middle power objective. The 8×and 10× objectives with flat-field and apochromatic can be designed successfully using iterative optimization in OSLO.

Apochromatic Beam Transport in Drift-Quadrupole Systems

Abstract: Though a straight drift-quadrupole system can not be made an achromat, there exists an example of a bend-free drift-quadrupole system which can transport certain incoming beam ellipses without introducing first-order chromatic distortions. In this paper we show that such a possibility is not a rare special case, but a general property. For every drift-quadrupole system there exists an unique set of Twiss parameters, which will be transported through that system without first order chromatic distortions. Moreover, we prove that at the same time these Twiss parameters minimize the absolute values of the system chromaticities and also bring the second order effect of the betatron oscillations on the longitudinal dynamics to the minimal possible value.

Design of cemented panoramic annular lens

Abstract: A new improved design method of the panoramic annular lens(PAL) with cemented lenses was introduced.The structure was not only helpful to improve the freedom of design of PAL which could take charge of partial chromatic aberration,simplify the structure of relay lens group,but also reduce stray light and the volume of the whole optical system while enlarging the field of view of system.The chromatic aberration and the field of view of PAL was investigated theoretically.Method of selecting new cemented glasses of PAL was also discussed.A doublet PAL and its relay lens group with a total effective focal length of 10.3 mm were designed.The total length was 170 mm,and the diameter of PAL was 70 mm.The spectral range was from 0.486 μm to 0.656 μm,which was coincident with the visible light.To get bright and clear image,the aperture of the system was set to f/3.7.Relay lens group consisted of 8 pieces of lenses,with a back focal length(BFL) of 17 mm.The result shows that the aberrations are corrected well.

Planar, high numerical-aperture lens using sub-wavelength high contrast grating

Abstract: Planar lenses using sub-wavelength high contrast grating are investigated. By designing the phase of the grating, high numerical aperture lenses can be achieved, with small spherical aberration and low insertion loss.

Metallic-Dielectric Lenses Chromatic Aberration Analysis

Abstract: Metallic-dielectric lenses permit sub-wavelength focusing of light in the visible and near-infrared. The chromatic aberration of these nanoslits lenses by using the finite-element method in conjunction with the perfectly matched layers is analyzed in detail.

Objective lens for parallel stereo-microscope

Abstract: PROBLEM TO BE SOLVED: To provide an Apochromat objective lens for a parallel stereo-microscope, wherein the objective lens has a long working distance and high numerical aperture, and chromatic aberration is prevented from occurring as much as possible. SOLUTION: The objective lens includes, sequentially from a side of a variable magnification optical system to a side of an object surface: a first lens group G1 having a negative lens L1 the concave surface of which faces the side of the variable magnification optical system and at least one positive lens (in Fig.1, a lens L2 corresponds to the positive lens); and a second lens group G2 having two groups or more cemented lens (in Fig.1, a cemented lens composed of lenses L3 to L5 and a cemented lens composed of lenses L6 to L7 correspond to the cemented lens), and as a whole having a positive refractive power, wherein the conditional expressions of 39 COPYRIGHT: (C)2011,JPO&INPIT

Illustrating Method of Triplet Prisms for Minimizing the Chromatic Aberration

Abstract: We present an illustrating method for triplet prisms combination that can minimize the chromatic aberration. The apochromatic aberration equation, relation between relative partial dispersion and glass V-number can be quickly analyzed and found the combination.