Showing papers on "Apochromat published in 2002"

Ophthalmic lenses with reduced chromatic blur

Abstract: The present invention provides single vision and multifocal lenses, as well as methods for their production, having a transverse chromatic aberration enabling provision of a lens the performance of which is equivalent to a refractive lens with a higher Abbe number.

High tolerance to spherical aberrations and defects of focus with a birefringent lens

Abstract: We report a systematic investigation of the imaging behavior of an optical system consisting of a lens from a uniaxial birefringent crystal sandwiched between two linear polarizers into which primary spherical aberration has been introduced. The proposed system has higher tolerance to primary spherical aberration and has a larger depth of focus than an imaging system found with an isotropic lens. Some specific cases are computed and illustrated graphically.

Diffractive lens in 8- to 10-μm forward-looking infrared system

Abstract: We realize for the first time a forward-looking IR (FLIR) sys- tem using a diffractive optical element (DOE) in its optics made of ger- manium in the 8- to 10-mm IR wavelength. We describe the design and the performance of the DOE optics. The IR diffractive lens made of ger- manium is proposed to correct the axial chromatic aberration in optics of the FLIR system. Compared with conventional optics of an FLIR system the optics using a DOE singlet instead of ZnSe achromat, we have a DOE system modulation transfer function (MTF) that is almost equal to the conventional one. The DOE singlet instead of ZnSe achromat ap- pears to be enough to compensate for the chromatic aberration of the optical system. Using the DOE system, the numbers of lens elements, the mass, and the cost are reduced. © 2002 Society of Photo-Optical Instrumen- tation Engineers. (DOI: 10.1117/1.1487365)

Performance of a polarization-masked lens aperture in the presence of spherical aberration

Abstract: This paper suggests the possibility of partial compensation of spherical aberration with a polarization-masked lens aperture. The principle is based on the fact that any pre-specified phase step can be introduced between two zones of a lens aperture masked by suitably oriented linear polarizers and employing an elliptically polarized imaging beam. By comparison of the point-spread function of such a polarization-masked imaging system with that of an ideal lens, it has been shown that the effect of spherical aberration can be appreciably compensated by making an appropriate choice of the polarization parameters involved.

2002 IODC design problem: the diffractive simulator

Abstract: The lens design problem for the 2002 IODC is to design a 100 mm focal length, f/8 all refractive system which simulates the chromatic behavior of a diffractive optical element. The lenses must be all spherical and be made of Schott glasses only. There is no restriction on the number of lenses, the design form, or the length of the overall lens. The merit function comprises the rms spot size at a nominal wavelength and the rms of the focal shift differences between the refractive lens and those of the 100 mm, f/8 diffractive optical element. There were forty two entries to the contest; in general, the results were quite good, with most of the spot sizes well below the diffraction limit, and with the rms focal shift differences being much less than 0.001 mm.

Intraocular diffraction lens

Abstract: ophthalmologic optics; artificial lenses for eyes. SUBSTANCE: lens is made of biocompatible flexible or hard material, type PMMA. It is, essentially, thin plate one of whose surfaces bears microrelief in the form of annular diffraction grating with luminous profile. Desired optical intensity of intraocular lens is ensured due to phenomena of light diffraction on structural surface. Maximal depth of microrelief profile is equal on entire surface of lens. Its absolute value hmax≫lambdao and amounts to several wavelengths of visible part of spectrum. Diffraction lens has equal optical intensity for at least two wavelengths of visible range of spectrum, that is, it is achromatic or apochromatic. In addition lens is split into even number of sectors having different optical intensities or it is aligned with annular diffraction grating at constant spacing to expand pseudo-accommodation of eye. This expansion makes up 0 to 4 diopters. In order to obtain broken optical axis and to project image onto paramacular part of retina (in case of defective macula) diffraction lens is built integral with linear diffraction grating. Cornea aberration is compensated for. Lens can be implanted through small incision which will essentially reduce post- operation astigmatism of cornea. Intraocular lenses may be manufactured using advanced methods of laser technology. Lens photomatrix is synthesized and replicated by way of stamping. EFFECT: enhanced visual activity of eye with implanted lens; reduced cost of artificial lens. 5 cl, 6 dwg

Suitable microscope objectives for multiphoton digital imaging

Abstract: The proper choice of an objective lens can have a profound effect on multiphoton microscopy. Multiphoton requires that the objective have adequate transmission in the IR range. This technology has a requisite to image the specimen near the slide surface next to the cover glass and to of 200 microns or more. Fluor and Plan Apochromat objectives. All lenses suffer from aberrations, which can prevent imaging an exact replica of the object. Most objectives could be used for multiphoton imaging;; however lenses should be selected from Plan Fluors, Plan Apochromats, and Super (S) Fluors. Highly corrected water immersion objectives (WI) permit deep penetration within aqueous environments and living tissues, beyond that of oil immersion objectives. Spectral transmission data is presented for Nikon CFI60 various objective lenses with high Nas, long working distances, and maximum aberration correction.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Optical head device and optical apparatus using the same

Abstract: An objective lens is disclosed, comprising a chromatic aberration correction element (7) for correcting chromatic aberration occurring in the objective lens (1a,1b,907), characterized by a light distribution correction element (6,906) in which a transmittance increases with a distance from a centre of the aperture surface of the objective lens is provided so as to correct a reduction of the intensity of the light incident on the aperture surface of the objective lens with a distance from the centre of the aperture surface.

Plan-apochromatic high-aperture microobjective of low magnification

Abstract: FIELD: optics. SUBSTANCE: proposed microobjective includes five components. First positive component comes in the form of single meniscus facing space of objects with concavity, second component is single positive meniscus, third component comprises biconvex and negative lenses cemented together, fourth component is single positive lens and fifth negative component includes positive and negative lenses facing space of images with concavity. Positive lens of fifth component can be biconvex. EFFECT: possibility of correction of monochromatic and chromatic aberrations of axial and off-axis beams, enhanced entrance numerical aperture. 1 cl, 1 dwg

Spherical aberration measurement and in-situ correction

Abstract: The continuing demand to decrease device feature dimensions has put pressure on trying to minimize the levels of aberrations in today's lithographic lenses. Though the lenses that are currently used in the most advanced lithography tools have less aberrations than any preceding generations, the impacts of these aberrations are greater because of the smaller geometries being printed. In addition, most of the resolution enhancement techniques (RET), such as phase-shifting masks (PSM) and off-axis illumination (OAI), that have been reported to extend the resolution limit and increase the depth-of-focus (DOF) of optical lithography provide less immunity to aberrations than conventional approaches. Recently, concern has been surfaced from the implications of spherical aberration on printable features. Best focus position shift and isofocal tilt are one of the well known phenomena resulted from spherical aberration. By varying the reticle height, we observed a decrease in the effect of spherical aberration. In this paper, we explore various techniques that provide us a way of measuring spherical aberration. And we also develop a way to correct the spherical aberration without modifying projection optics.

Objective lens used in multi-wavelength, multi-layer and multi-level optical storage

Abstract: With the increasing demand of huge volume, high density and high transmission speed in optical storage, researches on multi-layer storage and multi-wavelength, multi-layer and multi-level storage in a single substrate have started both in China and abroad. This requests new feathers in optical system of optical disks. The objective lens in multi-layer storage needs compensations to varied spherical aberrations produced by varied thickness of storage layers; the objective lens in multi-wavelength and multi-layer storage needs apochromatism to broadband range. If the apochromatism is not ideal, it is needed that the spherical aberrations of multi-wavelength light are uniform and the multi-wavelength light beams are focused separately to obtain better result. A traditional micro-objective whose optical aberration is carefully corrected can be apochromatic to D, F and C in medium numerical aperture and can be used as objective lens of the optical disk of multi-wavelength, multi-layer and multi-level optical storage. This article gives an amended result based on C. G. Wyne's field flattener. The calculation result of optical aberration indicates that the spherical aberration is nearly zero and the secondary spectrum is less than 0.5 times of focal depth. It is also indicated that the MTF of a certain wavelength light matches the ideal MTF curve wherever on axis or off axis, wherever on meridian surface or on sagittal surface.

New abberation properties of two-mirror Cassegrain lenses

Abstract: Analysis of aberration performance of two-mirror lens allowed revealing an interesting relationship between them and the central obscuration coefficient e and the distance δ of the focal plane from the vertex of the primary mirror and introducing the coefficient of complexity of Cassegrain lens.

Longitudinal chromatic aberration in tangent doublets

Abstract: A condition has been theoretically deduced to achieve the correction of the so-called tangent doublets for paraxial chromatism as well as for marginal and zonal chromatism up to the fifth order. Furthermore, results obtained for the chromatic aberrations in these systems confirm the correct behaviour of the theoretical formula deduced to calculate the longitudinal spherical aberration in cemented doublets.

Designing principles for a low chromatic aberration GRIN rod lens

Abstract: In this article, the contributing factors to gradient index (GRIN) rod lens chromatic aberration are discussed, and according to Fantone model, the principles of selecting ion-exchanging pairs and of determining base glass properties for a low chromatic aberration GRIN rod lens prepared by ion exchanging process are presented visually in the optical glass N d-V map. The analysis shows, using the glass with typical optical properties as the base glass, both Na +/Li + exchanging and K +/Cs + exchanging are suitable for preparing a low chromatic aberration GRIN rod lens, while K +/Tl + exchanging and Na +/Ag + exchanging might produce a GRIN rod lens with much higher chromatic aberration. These principles are instructive in the fabrication of a low chromatic aberration GRIN rod lens.