Showing papers on "Apochromat published in 1995"

Spectral properties of multiorder diffractive lenses

Abstract: Diffractive lenses have been traditionally designed with the first diffracted order. The spectral characteristics of diffractive lenses operating in higher diffracted orders differ significantly from the first-order case. Multiorder diffractive lenses offer a new degree of freedom in the design of broadband and multispectral optical systems that include diffractive optical elements. It is shown that blazing the surface-relief diffractive lens for higher diffraction orders enables the design of achromatic and apochromatic singlets. The wavelength-dependent optical transfer function and the associated Strehl ratio are derived for multiorder diffractive lenses. Experiments that illustrate lens performance in two spectral bands are described, and the results show excellent agreement with the theoretical predictions.

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.

Optical data recording and reproducing apparatus including chromatic aberration correction

Abstract: An optical data recording and reproducing apparatus includes a laser source, a collimating lens made of a single lens having a positive power to collimate the divergent laser beams emitted from the laser source, and an objective lens which is to converge the collimated light onto a data recording surface of a data recording medium. The chromatic aberration of the objective lens is corrected to reduce the back focal distance thereof as the wavelength increases to cancel the chromatic aberration of the collimating lens.

Apochromatic wide-angle objective

Abstract: An apochromatic wide-angle objective has an improved correction of transverse chromatic aberration while at the same providing a high correction of other errors. These corrections are obtained utilizing long-crown and short-flint glasses.

Studies on condenser‐objective lenses

Abstract: SUMMARY Scaling down the dimensions of a conventional magnetic objective lens to reduce aberrations is studied in detail. The values of other aberration coefficients for optimum lens size corresponding to desired minimum aberration are estimated. The possibility of using iron-free condenser–objective lenses at high voltage is examined.

Zoom projection lens

Abstract: Zoom projection lenses have been designed that have an entrance pupil that remains stationary during zooming and an operative aperture stop distinct from the system's physical stop that moves through the lens surfaces as zooming takes place. The fixed entrance pupil allows for efficient coupling to the light source throughout the magnification change. By allowing the stop to move through the lens, the lens element sizes and aberration contributions can be minimized. The concept of the operative stop can be employed for both positive and negative first-group configurations. For wide angle projection of 64 degrees total angle, a lens system with a negative front group followed by a positive zooming group has been designed with a relative aperture of f/4.5. Applications involving large LCD panels as light valves require the use of plastic optical materials with aspherical surfaces to minimize manufacturing costs. Concentrated high wattage light sources introduce temperature variations that impose additional constraints on the optical design. By combining plastic and glass elements the image position and aberration correction are stabilized throughout a plus or minus 25 degree Celsius temperature change.

Compensation of chromatic errors in high na molded objective lenses.

Abstract: High NA molded glass objective lenses are commercially available for use in the 680 nm to 850 nm range. We show that a simple positive lens can be used with an objective lens to compensate for wavelength-induced aberration in the 400 nm to 700 nm range. There is a direct relationship between the optimum power of the corrector lens and the wavelength of interest. We also show that a single positive lens and a holographic optical element can be used with an objective lens to compensate for wavelength-induced aberration over a wide range of wavelengths.

Objective lens system for fluorescence microscopes

Abstract: A semi-apochromatic or apochromatic objective lens system for fluorescence microscopes comprising: a first lens unit which comprises a cemented lens component consisting of a meniscus lens element having a concave surface on the object side and a positive refractive power or a plano-convex lens element, and a meniscus lens element having a concave surface on the object side; a second lens unit which comprises a plurality of cemented lens components; and a third lens unit composed of a cemented lens component which consists, in order from the object side, of a positive lens element and a negative lens element, and has a weak refractive power, This objective lens system has a medium to high magnificaiton and a large numerical aperture, thereby being capable of forming an image having high resolution and high contrast.

Diffraction optical elements with deep phase profile obtained with the use of x-ray parallel intensive beam

Abstract: X-ray lithography with synchrotron radiation was applied for formation of the Fresnel zone structure profile onto a curved surface of a refractive polymer lens to achieve multifocus properties of the lens. First prototypes of the hybrid refractive-diffractive lens were fabricated in such a way and their optical properties were investigated. Some possibilities for creation of diffraction apochromatic optical elements are considered as well.

Ultrahigh-performance long-focal-length lens system with macro focusing zoom optics and abnormal dispersion liquid elements for the visible waveband

Abstract: The optical design of an unconventional telephoto lens, which employs a single front objective element with spherical surfaces, one anomalous dispersion glass element and multiple liquid lens elements, is described. Particular areas of discussion include the utilization of internal zoom optics for constant aperture focusing to macro magnifications and abnormal dispersion liquid lens elements for high order chromatic aberration correction, as well as, passive optical athermalization of back focus and image quality. Other areas concerning lens system size, volume, weight, cost, and spectral transmission are also addressed.

Design of zoom lens with binary optics

Abstract: Binary optics element (BOE) used to correct the aberrations of zoom lens, especially to control secondary spectrum in apochromatic zoom lens, are considered. Principles and methods are presented. The advantages in improving image quality and simplifying construction are illustrated through the design example.

Electrostatic lenses with corrected chromatic and spherical aberrations

Abstract: An electrostatic lens is proposed consisting of a set of cylindrical electrodes with gaps, where the axially symmetric, quadrupole and octopole components of the field are generated by a proper choice of electrode potentials. The conditions are found of correction of the chromatic and spherical aberrations in one direction.

Lens design for a white-light cosine-transform achromat

Abstract: We describe the lens design for a twin-imaging white-light interferometer in which the interference pattern at the exit-pupil plane is the cosine transform of the spatial-intensity distribution of the object. The achromatic condition in terms of optical power is derived. The analysis of the transform aberration shows that the even aberrations, e.g., spherical aberration and field curvature, do not degrade the cosine transform and need not be corrected. This significant simplification permits us to design systems with good performance and uncomplicated lens structures. We present a lens design with three elements and a length of 320 mm. The system is capable of resolving more than 106 pixels with an operating spectral bandwidth of 100 nm. The results of an experiment with an early four-element design are also presented.

Broadband imaging with optical elements composed of radial periodic structures

Abstract: In some white-light imaging applications it is desirable to make the optical elements extremely thin. Numerous practical advantages are derived if the lenses are one to two orders of magnitude thinner than conventional refractive lenses. For example, these lens systems provide minimal weight and compactness, and are potentially low cost. Although diffractive lenses are only a few microns thick, they have severe chromatic aberrations. Approaches are compared for making the lenses thinner and techniques are examined for correcting chromatic aberrations. There are basic limits to the polychromatic MTF and chromatic correction that can be achieved.