Showing papers on "Apochromat published in 2014"

Large‐Field‐of‐View Wide‐Spectrum Artificial Reflecting Superposition Compound Eyes

Abstract: In nature, reflecting superposition compound eyes (RSCEs) found in shrimps, lobsters and some other decapods are extraordinary imaging systems with numerous optical features such as minimum chromatic aberration, wide-angle field of view (FOV), high sensitivity to light and superb acuity to motion. Here, we present life-sized, large-FOV, wide-spectrum artificial RSCEs as optical imaging devices inspired by the unique designs of their natural counterparts. Our devices can form real, clear images based on reflection rather than refraction, hence avoiding chromatic aberration due to dispersion by the optical materials. Compared to imaging at visible wavelengths using conventional refractive lenses of comparable size, our artificial RSCEs demonstrate minimum chromatic aberration, exceptional FOV up to 165° without distortion, modest aberrations and comparable imaging quality without any post-image processing. Together with an augmenting cruciform pattern surrounding each focused image, our large-FOV, wide-spectrum artificial RSCEs possess enhanced motion-tracking capability ideal for diverse applications in military, security, medical imaging and astronomy.

Camera Processing With Chromatic Aberration

Abstract: Since the refractive index of materials commonly used for lens depends on the wavelengths of light, practical camera optics fail to converge light to a single point on an image plane. Known as chromatic aberration, this phenomenon distorts image details by introducing magnification error, defocus blur, and color fringes. Though achromatic and apochromatic lens designs reduce chromatic aberration to a degree, they are complex and expensive and they do not offer a perfect correction. In this paper, we propose a new postcapture processing scheme designed to overcome these problems computationally. Specifically, the proposed solution is comprised of chromatic aberration-tolerant demosaicking algorithm and post-demosaicking chromatic aberration correction. Experiments with simulated and real sensor data verify that the chromatic aberration is effectively corrected.

Aberration design of zoom lens systems using thick lens modules

Abstract: A systematic approach for the aberration design of a zoom lens system using a thick lens module is presented. Each component is treated as a thick lens module at the beginning of the design. A thick lens module refers to a thick lens component with a real lens structure, like lens materials, lens curvatures, lens thicknesses, and lens interval distances. All nine third-order aberrations of a thick lens component are considered during the design. The relationship of component aberrations in different zoom positions can be approximated from the aberration shift. After minimizing the aberrations of the zoom lens system, the nine third-order aberrations of every lens component can be determined. Then the thick lens structure of every lens component can be determined after optimization according to their first-order properties and third-order aberration targets. After a third optimization for minimum practical third-order aberrations of a zoom lens system, the aberration design using the thick lens module is complete, which provides a practical zoom lens system with thick lens structures. A double-sided telecentric zoom lens system is designed using the thick lens module in this paper, which shows that this method is practical for zoom lens design.

A review of skew aberration, the intrinsic polarization aberration in high NA optical systems

Abstract: The skew aberration is a form of polarization aberration causes a rotation of polarization states across the pupil. Skew aberration is intrinsic to the optical system depending on the ray path only and whose magnitude is independent of the coatings or other polarization effects. Skew aberration has a much greater effects in high numerical aperture optical systems. A critical angle corner cube system is analyzed as an example to review the skew aberration’s effects.

Glass selection for infrared lens design

Abstract: The invention relates to process for manufacturing infrared optical lenses that will transmit in multiple infrared bands, for example, lenses with multiple optical elements such as doublet and triplet lenses (i.e., achromatic, apochromatic, and superachromatic optical elements). The lens materials are selected on the basis of dispersion ratios and/or minimum dispersions and minimum dispersion wavelengths as defined herein.

All-Plastic High-Performance Eyepiece Design Utilizing a Spherical Gradient-Index Lens

Abstract: An all-plastic high-performance eyepiece design utilizing a polymer spherical gradient-index optical element is presented. The use of a gradient-index lens in the eyepiece offers better off-axis and chromatic aberration correction, as well as overall performance improvement compared to a similar eyepiece with all homogeneous lenses.

Correcting aberration in aspheric surfaces

Abstract: New technique eases aspheric lens fabrication and overcome traditional limitation An aspheric lens has been designed by using optical designing software to replace the achromat (Doublet) lens of eyepiece assembly of telescope The devised physical parameters of aspheric lens have been incorporated into the CNC Aspheric machine to fabricate the lens The antireflection coating for visible region has been carried out on lens by employing PVD technique In this report diminished aberration effects due to non-spherical surface profile and comparison of optical parameters of achromat (doublet) and aspheric lens is presented

Analysis of imaging properties of active lenses with spherical surfaces of independently variable curvature

Abstract: This work presents an algebraic analysis and computer simulations of imaging properties of a refractive tunable-focus fluidic lens with two continuously variable radii of curvature. Such lenses make possible to change aberration properties. It is shown that such a tunable-focus lens makes possible to correct simultaneously its spherical aberration and coma, which is not possible with the conventional fix-focus lens. Formulas are derived for the calculation of paraxial parameters and Seidel aberration coefficients of the lens. Imaging properties are demonstrated on several examples.

Wave front aberration analysis of slit spatial filtering system

Abstract: Aiming to the rectangle beam shape in most high power laser, the influences of the several kinds of geometrical aberrations in slit spatial filtering system have been simulated based on the diffraction theory of aberration. The aberration tolerances of all kinds of geometrical aberrations in the lenses and incident beam are obtained.

Imaging characteristics of ball lens

Abstract: In most digital imaging applications, high-resolution imaging or videos are usually desired for later processing and analysis. The desire for high-resolution stems from two principal application areas: improvement of pictorial information for human interpretation, and helping representation for automatic machine preception. While the image sensors limit the spatial resolution of the image, the image details are also limited by the optical system, due to diffraction, and aberration 1 . Monocentric lens are an attractive option for gigapixel camera because the symmetrical design focuses light identically coming from any direction. Marks and Brady proposed a monocentric lens design imaging 40 gigapixels with an f-number of 2.5 and resolving 2 arcsec over a 120 degrees field of view 2 . Recently, Cossairt, Miau, and Nayer proposed a proof-of-concept gigapixel computational camera consisting of a large ball lens shared by several small planar sensors coupled with a deblurring step 3 . The design consists of a ball element resulting in a lens that is both inexpensive to produce and easy to align. Because the resolution of spherical lens is fundamentally limited by geometric aberrations, the imaging characteristics of the ball lens is expressed by the geometrical aberrations, in which the general equations for the primary aberration of the ball lens are given. The effect of shifting the stop position on the aberrations of a ball lens is discussed. The variation of the axial chromatic aberration with the Abbe V-number when the refraction index takes different values is analyzed. The variation of the third-order spherical aberration ,the fifth-order spherical aberration and the spherical aberration obtained directly from ray tracing with the f-number is discussed. The other imaging evaluation merits, such as the spot diagram, the modulation transfer function(MTF) and the encircled energy are also described. Most of the analysis of the ball lens is carried out using OSLO optics software from Lambda Research Corporation 4 .

Apochromatic large objective lens with long working distance for operating microscope

Abstract: The invention belongs to the technical field of operating microscope optical systems and relates to an apochromatic large objective lens with long working distance for an operating microscope. According to the apochromatic large objective lens with the long working distance for the operating microscope, when focal length is 250mm, the working distance can reach 285mm, replacement of a large objective lens with a large focal length is avoided, hospital cross infection caused by replacement of the large objective lens in the process of minimally invasive surgeries can be removed, and meanwhile a secondary spectrum is corrected by utilizing anomalous dispersion glass. The shortcoming that the working distance of a large objective lens of a traditionally designed operating microscope is overcome, the secondary spectrum is corrected, the resolution ratio is high, an image is clear, and color anamorphose is small. An experiment shows that tissue details of 10 microns can be seen clearly by utilizing the operating microscope comprising the apochromatic large objective lens during the minimally invasive surgeries.

Field curvature aberration

Abstract: This paper provides an overview of field curvature aberration correction. It is known that for sharp imaging on a flat surface the Petzval sum must be zero or nearly so. However, current lenses for mobile phones depart from this principle to some extent. We provide an insightful discussion about some mechanisms for the correction of field curvature aberration.

An adaptive achromatic doublet design by double variable focus lenses

Abstract: We proposed an adaptive achromatic doublet that composed by double variable focus lenses. Both variable focus lenses were the liquid-membrane-liquid structures, but they were filled with different liquid-pairs, so that they could perform low and high dispersion proprieties like the crown-flint doublet. The proposed doublet could perform a tunable focal length, and the chromatic aberration could be corrected at th e same time. A comparison be tween an adaptive singlet and a doublet on the chromatic focal shift plots was conducted in Zemax, and the chromatic improvement was confirmed that the chromatic focal shift range was improved from 2.5% to 0.05%. Keywords: Variable-focus lens, liquid lens, chromatic aberration, achromatic doublet, achromatic design, dispersion. 1. INTRODUCTION Lens is regarded as a classic optical component, whose basi c function is to converge and diverge the light beams. The bending performance of the lens is called lens power, which is defined by two parameters, refractive index of the lens medium material and the curvature of the refractive surface

Analysis of aberration properties of two-components zoom lenses

Abstract: The dimensional relationships in a two-components zoom lenses are obtained. Application of analytical expressions relationship between the main aberration parameters and aberration parameters of the arbitrary position components allows to make an analysis of change the value of aberrations when you change transverse magnification image in the particular case where the distance between axial object and image points is equal to zero.

Gradient-Index Lenses in ImagingApplications Using Zemax Program

Abstract: GRIN lenses represent an interesting alternative to conventional spherical lenses since the lens performance depends on a continuous change of the refractive index within the lens material. This paper using of the high-index-of-refraction lanthanum crown glass (SLS-1.0) which helps to reduce spherical aberration the design and analysis the gradient – index lenses by using Zemax software that we can see the changing in refractive index. wave length extends from (0.500 to 0.600) μm and diffraction limited over a large field of angles with F/#2.5 that have been studied in this research .This paperdeals how to design and analysis work and how to take advantage of gradient index image applications,which helps to reduce the modulation of the refractive-index profile.

Sub-wavelength photon sieve dispersion compensation device and method

Abstract: The invention discloses a sub-wavelength photon sieve dispersion compensation device which comprises a first refraction lens, a second refraction lens and a sub-wavelength photon sieve. A mixed apochromatic lens set is formed by the first refraction lens and the second refraction lens. The second refraction lens is arranged between the first refraction lens and the sub-wavelength photon sieve. The sub-wavelength photon sieve is of a film structure. The first refraction lens is a minus lens and is usually made of flint glass. The second refraction lens is a plus lens and is usually made of crown glass. Compared with the prior art, the sub-wavelength photon sieve dispersion compensation device has the advantages that the defects in the prior art are overcome, F light and C light can be corrected, D light can be further corrected, and the second-stage spectrum correcting capacity is achieved; the spectrum imaging scope of the sub-wavelength photon sieve is further expanded, and theory and experimental foundations are laid for application of the sub-wavelength photon sieve in the wide spectrum imaging field; due to the fact that the sub-wavelength photon sieve belongs to novel diffraction optical elements, the sub-wavelength photon sieve has all the inherent advantages of the diffraction optical elements.

Design of macro-filter-lens with simultaneous chromatic and geometric aberration correction

Abstract: A macro-filter-lens design that can correct for chromatic and geometric aberrations simultaneously while providing for a long focal length is presented. The filter is easy to fabricate since it involves two spherical surfaces and a planar surface. Chromatic aberration correction is achieved by making all the rays travel the same optical distance inside the filter element (negative meniscus). Geometric aberration is corrected for by the lens element (plano–convex), which makes the output rays parallel to the optic axis. This macro-filter-lens design does not need additional macro lenses and it provides an inexpensive and optically good (aberration compensated) solution for macro imaging of objects not placed close to the camera.

Design of a First-order Radial GRIN Achromat

Abstract: Beginning with the expression for the focal length of a GRIN element that is valid under paraxial approximations, we derive an expression for chromatic aberration. Together with the expression for focal length, we derive the design equations for a GRIN achromat.

Design of two-glass for apochromatic optical system

Abstract: Apochromatic designs of lens systems utilizing two optical materials are described. A method of glass selection for apochromatic optical systems with reduced chromatic aberration is present. This method is based on the glass maps by using a glass database (Schott glass) and an optical design program (OSLO) to help the optical designer to select optical glass types in a more efficient way. 'Active' glass maps can be used to compare glasses for special properties and to change glasses in the optical design process , and then using computer program(OSLO) to aid in the design of a lens and the validation results. The goal for this paper is to make glass selection easier to understand.

Near-diffraction-limited F-3.1 apochromat singlet lens design enabled by spherical gradient index

Abstract: A refractive singlet lens design that is near-diffraction-limited across the F, d, C wavelengths, hence across most of the visible spectrum, is presented. The lens is a reasonably fast F/3.1. An offset spherical gradient index (GRIN) and careful choice of GRIN materials enables this performance.