Jerzy Nowak

Investigations of the Influence of Hologram Aberrations on the Light Intensity Distribution in the Image Plane

The aim in this paper is to analyse, for the examples chosen, the influence of particular aberrations of the point-object hologram on the light intensity distribution in the plane which is assumed to be the image plane. The numerical method used for calculating the light intensity at any image point is that presented in an earlier paper. The calculations have been carried out for three cases of holographic imaging. The recording and reconstruction geometry has been chosen so that it was possible to examine the influence of the particular aberration on the image quality. The calculated energy distribution in the aberration spots is consistent with those resulting from using third-order aberration theory as well as from ‘ray-tracing’ calculations.

Placement of a crystalline lens and intraocular lens: retinal image quality

The influence of changes of both crystalline lens and intraocular lens (IOL) misalignment on the retinal image quality was investigated. The optical model of the eye used in investigations was the Liou-Brennan model, which is commonly considered as one of the most anatomically accurate. The original crystalline lens from this model was replaced with an IOL, made of rigid polymethylmethacrylate, in a way that recommend obligatory procedures. The modifications that were made both for crystalline lens and IOL were the longitudinal, the transversal, and the angular displacement.

Correction of chromatic aberration in hybrid objectives

Summary In this paper two hybrid objectives of three-elements are presented. In one of the objectives one lens is made from fluorite and in the other one – from special glass. Both have corrected chromatic aberration in the wavelength range 0.435 μm

Retinal images in a model of a pseudophakic eye with classic and hybrid intraocular lenses

In order to restore clear vision in the case of cataracts the opaque crystalline lens of the diseased eye is extracted and an artificial intraocular lens (IOL) is implanted in its place. Different designs of IOLs are used in practice. The retinal image quality in such an eye (pseudophakic) depends on the parameters of the implanted IOL, in particular on its chromatic aberration. Since the dispersive properties of IOL material differ from that of a crystalline lens, the chromatic aberration of a pseudophakic eye is much greater than in a healthy eye. This paper studies a hybrid (refractive–diffractive) IOL of chromatic aberration chosen in a such way that the overall longitudinal chromatic aberration (LCA) of the pseudophakic eye is equal to that of the healthy eye. Simulated retinal images calculated with the help of typical lens design software ZEMAX® illustrate the usefulness of such a solution.

Hybrid lens with corrected sphero-chromatic aberration

Abstract An optical imaging element is considered, which consists of a plano-convex spherical glass lens and a holographic lens recorded on the flat surface. Such a ‘hybrid lens’ enables one simultaneously to correct spherical aberration and longitudinal chromatism for two given wavelengths. The imaging quality of such an achromatic lens of focal length f = 100 mm and relative aperture 1:10 is evaluated by the ray tracing method. The results ensure that the performance of such a hybrid lens is acceptable for field angles as high as 5:100.

Aberrations of holographic lenses in image quality evaluation

The imaging quality of holographic lenses depends on parameters that include the shape of a holographic lens surface or an input pupil position. Based on the formulas for third-order aberration coefficients derived for such cases, conditions that ensure the correction of aperture and field aberrations are given. The possibility of joint correction of spherical aberration, coma, and astigmatism is discussed. The formulas presented are illustrated with a number of examples; two types of holo-lenses are taken into account: imaging and focusing. For imaging quality assessment an aberration spot calculation method based on numerical evaluation of an appropriate diffraction integral is used. The results of this method are compared with the results of imaging quality estimation using the geometrical ray tracing method.

Holographic optical elements used in spectroscopy: some remarks on image quality.

Because of their significant chromatic aberration, holographic optical elements (HOEs) can be used as narrowband optical filters or scanning spectroscopes. Although it is impossible to obtain aberration free imaging over the whole spectrum of light wavelength, by an appropriate choice of HOE recording and imaging geometries, the aberrations can be seriously minimized. As an example, the imaging quality of several different HOEs used in multichannel spectroscopy is analyzed with the aid of numerical evaluation of the respective diffraction integrals. Such computer modeling of imaging gives more adequate results than the geometric ray tracing method.

Simple achromatic hybrid lens

The simplest achromatic hybrid lens consists of a refractive (glass) lens with a diffractive microstructure deposited on one of its surfaces. In such lens the reasonable aberration correction is possible only for very limited aperture and field angles. Better possibilities of aberration correction appear if we split the refractive lens onto two identical parts separated by certain distance and locate the diffractive element between the glass lenses. We show that in such way it is possible to obtain hybrid lens of the same or even smaller aberrations for substantially greater aperture and field angles.

Characteristics of the retinal images of the eye optical systems with implanted intraocular lenses

Cataract, or opacity of crystalline lens in the human eye is one of the most frequent reasons of blindness nowadays. Removing the pathologically altered crystalline lens and replacing it with artificial implantable intraocular lens (IOL) is practically the only therapy in this illness. There exist a wide variety of artificial IOL types on the medical market, differing in their material and design (shape). In this paper six exemplary models of IOLs made of PMMA, acrylic and silicone are considered. The retinal image quality is analyzed numerically on the basis of Liou-Brennan eye model with these IOLs inserted. Chromatic aberration as well as polychromatic Point Spread Function and Modulation Transfer Function are calculated as most adequate image quality measures. The calculations made with ZemaxTM software show the importance of chromatic aberration correction.

Correction of field aberrations in a hybrid triplet objective

A diffractive structure (holographic lens: HL, diffractive optical element: DOE) can be included into compound objective as one of its parts making a hybrid objective. In this paper a possibility of correcting field aberrations in a triplet hybrid objective is analyzed. The solutions for aplanatic correction in the case of achromate, apochromate and quasi-superachromate are presented and illustrated with exemplary objectives. Correction of field curvature is considered in the case of hybrid triplet achromate.