Showing papers on "Apochromat published in 2012"

Zoom lens design using liquid lenses for achromatic and spherical aberration corrected target

Abstract: This paper proposes a zoom lens system based on liquid lenses. The system design consists of a fixed lens and four two-chamber liquid lenses. The chambers are filled with different liquids. The design principle is analyzed. Optimization method is used to get the optimal solution. With the solution, the proposed zoom lens system can obtain achromatic and spherical aberration corrected images in a particular zooming range, and no moving element is needed in the proposed zoom lens system. By choosing proper liquids, it can be designed to work within particular working regions with improved optical performance. We give the detailed simulation examples. The results indicate that the proposed design can help to improve the optical performances of zoom lens systems.

Third-order aberration coefficients of a thick lens.

Abstract: In this paper, formulas are described for the calculation of the third-order aberration (Seidel) coefficients for a thick lens in air. The explicit analytic dependence of individual aberration coefficients on a lens thickness is presented. Such formulas make it possible to analyze an influence of the lens thickness on lens aberration properties and the replacement of a thick lens optical system by a thin lens model.

Design of multi-order diffractive THz lenses

Abstract: Quadratic, multi-order diffractive lenses have been designed, fabricated, and demonstrated for the MMW-THz region, with the capability of focusing harmonic wavelengths on to a common focal point. Design wavelength and harmonic spacing can be chosen as design parameters, allowing great flexibility in lens design. Simulations were carried out to determine lens parameters and performance. These lenses reduce both spherical and chromatic aberrations at harmonic wavelengths, and are thinner and lighter than traditional refractive elements. This lens type is potentially useful to sensor fusion architectures.

Infrared imaging system and operating method

Abstract: The invention relates to an infrared imaging system and an operating method. A lens unit (120) shows longitudinal chromatic aberration and focuses an imaged scene into a first image for the infrared range in a first focal plane and into a second image for the visible range in a second focal plane. An optical element (150) manipulates the modulation transfer function assigned to the first and second images to extend the depth of field. An image processing unit (200) may amplify a modulation transfer function contrast in the first and second images. A focal shift between the focal planes may be compensated for. While in conventional approaches for RGBIR sensors contemporaneously providing both a conventional and an infrared image of the same scene the infrared image is severely out of focus, the present approach provides extended depth of field imaging to rectify the problem of out-of-focus blur for infrared radiation. An imaging system can be realized without any apochromatic lens.

Infrared imaging system and method of operating

Abstract: A lens unit (120) shows longitudinal chromatic aberration and focuses an imaged scene into a first image for the infrared range in a first focal plane and into a second image for the visible range in a second focal plane. An optical element (150) manipulates the modulation transfer function assigned to the first and second images to extend the depth of field. An image processing unit (200) may amplify a modulation transfer function contrast in the first and second images. A focal shift between the focal planes may be compensated for. While in conventional approaches for RGBIR sensors contemporaneously providing both a conventional and an infrared image of the same scene the infrared image is severely out of focus, the present approach provides extended depth of field imaging to rectify the problem of out-of-focus blur for infrared radiation. An imaging system can be realized without any apochromatic lens.

Possible optical functions of the central core in lenses of trilobite eyes: spherically corrected monofocality or bifocality.

Abstract: The function of the central core in lenses of certain schizochroal-eyed trilobites is unknown. To understand the possible optical function(s) of this central core, we performed computational ray-tracing on the lens in the schizochroal compound eyes of a Silurian Dalmanites trilobite. We computed the intensity of light focused by the lens versus the distance from the lower lens surface along the optical axis as functions of the refractive indices n(lu) and n(cc) of the lower lens unit and the central core. We determined those values of n(lu) and n(cc) that ensure that the studied central-cored trilobite lens is monofocal, bifocal, or trifocal. The sharpness (as the measure of the correction for spherical aberration) of these focal points was quantitatively studied. We show here that one of the possible optical functions of the central core could be the correction for spherical aberration, independently of the number (1, 2, or 3) of focal points. Another possible optical function of the core could be to ensure bifocality of the lens. In this case the peripheral lens region could have a given focal length and the central lens region could possess a longer or shorter focal length, if the refractive index n(cc) of the core is smaller or larger than the refractive index n(lu) of the upper lens unit. Finally, trifocality of the lenses can be considered only as a theoretical option, but by no means an optically optimally functioning possibility.

Super-resolution photoelectric imager based on polarization optics

Abstract: The utility model discloses a super-resolution photoelectric imager based on polarization optics The imager comprises two kinds of laser light sources taking a main controlling computer as the core, a polarizer, a phase plate, a spectroscope, an apochromatic lens, a narrow-band filter, a pinhole and a detector, an imager, electromechanical controlling equipment, a low accuracy translation stage and monitoring, network and man-machine operation equipment, wherein the laser light sources take a main controlling computer as the core; the polarizer, the phase plate, the spectroscope, the apochromatic lens, the narrow-band filter, the pinhole and the detector are arranged according to an optical path; and the imager, the electromechanical controlling equipment, the low accuracy translation stage and the monitoring, network and man-machine operation equipment are arranged according to the controlling and processing purpose The super-resolution photoelectric imager combines the super-resolution photoelectric imaging technology and the super-resolution reconstruction treatment technology, thereby further improving the imaging resolution, reducing the precision requirement on the device, saving the cost and lowering the operation complexity

Reverse chromatic aberration and its numerical optimization in a metamaterial lens

Abstract: 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 focal length increasing, rather than decreasing, with the frequency. It is proposed that such an artificial “reverse” chromatic aberration may optimize the transverse resolution of millimeter wave diagnostics of plasmas and be useful in compensating for the natural “ordinary” chromatic aberration of other components in an optical system. More generally, optimized chromatic aberration will allow for simultaneous focusing of several objects located at different distances and emitting or reflecting at different frequencies.

A Low-cost Optimization Design for Minimizing Chromatic Aberration by Doublet Prisms

Abstract: A low-cost optimal double-prism method is proposed by using the developed MATLAB program to correct chromatic aberration. We present an efficient approach to choose a couple of low-cost glasses to obtain a low aberration double prism. The doublet prisms were made of two lead-free glasses. The relative partial dispersion of the two lead-free glasses is identical and their Abbe numbers are different greatly. The proposed design aims to minimize chromatic aberration, such as in apochromats, for paraxial ray tracing. Finally, an optimization design for real ray tracing can be evaluated by the chromatic aberration curve with a minimal area.

Image Processing Based on Moving Lens with Chromatic Aberration and Monochromatic Image Sensor

Abstract: Embodiments of imaging devices of the present disclosure obtain color images from a monochromatic image sensor based on a series of several images taken at different focal positions of an optical imaging lens possessing a chromatic aberration.

Apochromatic systems made from glasses with ordinary dispersion behavior

Abstract: This paper shows that the secondary spectrum in a two-component system made from glasses with ordinary dispersion behavior can be eliminated by computer modelling. The necessary conditions for this are an air gap between the components that is commensurable with the focal length of the system and large longitudinal chromatism of the second component. Optical layouts are given, along with the aberrations of apochromatic objectives consisting of glasses with ordinary dispersion behavior.

CaF2-free medium flat-field apochromatic metallographic microscope objective

Abstract: The invention discloses a CaF2-free medium flat-field apochromatic metallographic microobjective, consisting of special optical glass convex lenses without a CaF2 material and concave lenses, wherein the number of the convex lenses and concave lenses is six in total; and all the lenses are coaxial with the center of an object surface, and the sequence of all the lenses and the object surface fromright to left is as follows: the object surface, the first convex lens, the second concave lens, the third convex lens, the fourth convex lens, the fifth concave lens and the sixth convex lens. The imaging is at infinity. In the invention, the long working distance W.D is more than 10mm, the amplification factor beta is equal to 8*-10*, the focus distance f' is equal to 20-32mm, the numerical aperture (NA) is more than 0.2, and the aperture angle omega is more than 2 degrees. The CaF2-free medium flat-field apochromatic metallographic microobjective has the following advantages: 1. the flat-field apochromatic effect is achieved; 2. the working distance is long; 3. the cost performance is high; and 4. the structure is simple.

Optical design of hyperspectral imager

Abstract: Hyperspectral imaging detection technology involves optics,spectroscopy,machinery,microelectronics,computer and other disciplinesThe design of imaging spectrometer should be compact and apochromaticBased on the aberration theory,theoretical formula of secondary spectrum was derived according to the dispersion characteristics of typical glass materials in 400 nm～1 000 nmFor a system with FOV of 763°,F/# =5,f=60 mm,its secondary spectrum was corrected in design with ZEMAX softwareThe results indicate the MTF of the imaging system is greater than 05 at 60 lp/mm in visible and infrared band,other aberration requirements are met as well

100x Flat field apochromatic metallographic microscope objective without CaF2

Abstract: The utility model discloses a100x Flat field apochromatic metallographic microscope objective without CaF2. The microscope objective comprises lenses and is characterized in that the microscope objective is composed of eight lenses which are arranged coaxially and divided into three optical groups, the lenses are a first convex lens, a first concave lens, a second concave lens, a second convex lens, a third concave lens, a third convex lens, a fourth convex lens and a thick aplanatic meniscus lens which are connected in sequence and do not contain CaF2. Compared with similar domestic and oversea lenses, the microscope objective has the advantages of smaller number of lenses, simpler structure and fitting and adjusting technology, lower cost, high cost performance and the like, besides, the microscope objective provided by the utility model does not contain the CaF2, all performance indexes of the microscope objective are better than the existing similar microscope objectives containing the CaF2 and made of TF3 special glass, so that the microscope objective has broad application prospect and good commercial value.

Algorithm for calculating objective–achromats with separated components for telescopic and collimation systems

Abstract: This paper describes an algorithm for designing objectives with separated components for telescopic and collimation systems. Combinations of various types of optical glasses are presented for objective–apochromats obtained using this algorithm. It is confirmed that inexpensive, easy-to-manufacture glasses can be used to obtain apochromatic correction of the image.

Infrared imaging system and operating method

Abstract: The invention relates to an infrared imaging system and an operating method. A lens unit (120) shows longitudinal chromatic aberration and focuses an imaged scene into a first image for the infrared range in a first focal plane and into a second image for the visible range in a second focal plane. An optical element (150) manipulates the modulation transfer function assigned to the first and second images to extend the depth of field. An image processing unit (200) may amplify a modulation transfer function contrast in the first and second images. A focal shift between the focal planes may be compensated for. While in conventional approaches for RGBIR sensors contemporaneously providing both a conventional and an infrared image of the same scene the infrared image is severely out of focus, the present approach provides extended depth of field imaging to rectify the problem of out-of-focus blur for infrared radiation. An imaging system can be realized without any apochromatic lens.

Apochromatic zoom lens assembly has subsystems arranged starting from object plane, and equipped with negative and converging lenses

Abstract: The apochromatic zoom lens assembly has subsystems (T1-T4) arranged starting from the object plane (OE). The sub-system (T1) and the sub-system (T4) are equipped with converging lenses (L1,L6). The sub-system (T2) is equipped with a negative lens (L2) and a converging lens (L3). The sub-system (T3) is provided with a negative lens (L4) and a converging lens (L5). The condensing lens (L3) is made of high-dispersive glass, and the lens (L2) is made of short flint glass.

Third-Order Apochromatic Drift-Quadrupole Beamline

Abstract: In this paper we present the design of a straight drift-quadrupole system which can transport certain beam ellipses (apochromatic beam ellipses) without influence of the second and of the third order chromatic and geometric aberrations of the beamline transfer map.

Wide field of view monocentric lens and image sensor system for infrared aerial reconnaissance camera systems

Abstract: Wide field of view optical systems are disclosed for an infrared aerial reconnaissance camera. The optical systems include a curved focal surface and a wide field of view monocentric lens system. The monocentric lens system includes front and rear lens shell elements and a core lens element, with the number of front and rear shell lens elements depending on the IR band of interest (LWIR, MWIR or SWIR). Infrared radiation entering the monocentric lens passes sequentially through the front shell lens element(s), the core lens element, and the rear shell lens element(s) and is focused onto the curved focal surface. The front shell lens element(s) and the rear shell lens element(s) are made of material having a relatively higher refractive index or a relatively higher optical dispersion, or both, in the band of interest, as compared to the core lens element. The materials are carefully selected to minimize chromatic and spherical aberration as well as secondary chromatic aberration and spherochromatism, and pass radiation in the band of interest. The core lens element is made from a material having a relatively lower refractive index or a relatively lower optical dispersion or both, in the band of interest, and is carefully selected to compensate for spherical and chromatic aberration as well as secondary chromatic aberration and spherochromatism.

The Chromatic Field Aberration of Monopole, Dipole and Quadrupole Magnetic Lenses

Abstract: The chromatic field aberration of magnetic lenses with field distribution in the form of inverse law has been theoretically studied by using analytical method. Analytical expressions for magnification and rotation chromatic aberration coefficients, for all magnetic lenses at the focus, are given. The results of calculations show that the increasing in the order of multipole "n" leads to increasing the magnification chromatic aberration coefficient although the rotation chromatic aberration coefficient is slightly decreasing.

Chromatic Aberrations in Optical Systems: Prediction and Correction

Abstract: The variation of refractive index with wavelength, known as dispersion, was what redirected Isaac Newton from refractive telescope designs toward a reflective one, since he found the chromatic effect incurable. Later it was shown that different materials demonstrate different chromatic characteristics and refractive optical elements can compensate each other’s chromatic contributions. This promoted the simple dispersion effect to the field of formulizing and categorizing chromatic aberrations and their corrections. In this study an introduction to this process is provided, where the historical aspects are followed by the mathematical derivation and description of different kinds of chromatic aberrations accompanied with a variety of approaches to correct the chromatic effects in different levels. The provided mathematical basis is employed in studying three distinctive topics. In the first one the flexibility of refractive elements is used to provide a middle-sized catadioptric telescope design with all-spherical surfaces. Employing a new combination of chromatic lens correctors, the image quality can be improved so that it becomes comparable to an equivalent aspheric Ritchey-Chrétien telescope design. As the second topic the atmospheric dispersion and its effect in extremely large telescopes are discussed, where a new atmospheric dispersion corrector design is proposed. In the third task the chromatic behavior in an inhomogeneous medium is considered. A new gradient refractive index lens model for the crystalline lens of the eye is established and a different approach in characterizing its chromatic effects is developed. These three research topics are underpinning the main goal of the theses, that is the role of chromatic aberration in image formation in various optical systems.

The chromatic dispersion module with large chromatic focal shift

Abstract: This paper integrates micro-lenses to develop a miniature chromatic dispersion module with 1.89 mm (400–800 nm) chromatic focal shift for the application of the profile and roughness detection of roll to roll process. The dimension of the designed and fabricated lens module is about 6 mm (long) × 2 mm (diameter) which is far smaller to the commercial system with 136 mm (long) × 25.4 mm (diameter). The module includes two lenses and self-alignment lens holder for assembling and alignment. The system design is based on the principle of afocal, transmission, stacked and refractive type lenses. This paper also compares the commercial lenses (3mm) and self-fabricated micro lenses (2mm) system for spot size and focal shift length. White light source was used to test the module could have similar spot sizes after light through the 10X/0.25 objective lenses at individual wavelength (500–650 nm). And the polymer convex lenses have 95 % high transparence in 400–800 nm. As a result of its long chromatic dispersion distance, causes the system could linearity operating at the region not to need the mechanical vertical scanning.

CaF2-free low power flat field apochromatic metallographic microobjective

Abstract: The invention provides a CaF2-free low power flat field apochromatic metallographic microobjective, comprising lenses The microobjective is characterized by comprising three lenses, namely a first plus lens, a second minus lens and a third plus lens, and the three lenses are coaxial The first plus lens, the second minus lens, the third plus lens and an object plane are arranged in sequence fromleft to right, and the imaging is formed at infinity in opposite direction The CaF2-free low power metallographic microobjective has the advantages of achieving the effect of flat field apochromatism, and having long operating distance, high cost performance and simple structure