Showing papers on "Apochromat published in 2004"

Schematic eye with a gradient-index lens and aspheric surfaces

Abstract: A new schematic eye with aspheric surfaces and a radially varying refractive-index distribution lens is proposed. Image quality and spherical aberration are determined by use of ray tracing, and the results are presented as spot diagrams and compared with five existing model eyes. The proposed model provides the best image quality and lowest spherical aberration.

Lens Design of Compatible Objective Lens for Blu-ray Disc and Digital Versatile Disk with Diffractive Optical Element and Phase Steps

Abstract: A two-element objective lens which is compatible with for digital versatile disk (DVD) and Blu-ray Disc (BD) and has adequate optical performances in terms of off-axis wavefront and on-axis chromatic aberration for both optical heads has been designed. The first-order diffracted light is used for DVD and the second-order one is used for BD. We analyzed chromatic spherical aberration and found that using first- and second-diffracted lights causes 20 mλ/nm chromatic spherical aberration at a wavelength of 400 nm. However, using 5λ and 10λ phase steps can reduce chromatic spherical aberration to 7 mλ/nm. The designed two-element lens consists of the first plastic lens, on which there is diffractive optical element, and the second plano-convex glass molded lens.

Compatible Objective Lens for Blu-ray Disc and Degital Versatile Disc Using Diffractive Optical Element and Phase-Step Element which Corrects both Chromatic and Spherical Aberrations

Abstract: A compatible lens with a diffractive optical element that overcomes differences in disk thickness and longitudinal chromatic aberration and phase steps that eliminate chromatic spherical aberrations are proposed. Both blue and red parallel incident rays can be converged on both disks; therefore, the servo and readout signals can be detected by a single common photodetector. A compatible optical head, which can write Blu-ray Discs (BDs) and degital versatile discs (DVDs) with only one objective lens assembly and one photodetector, can be achieved. We show the convergence of the blue and red parallel incident rays and signal readout using the compatible objective lens.

Optical pickup device, optical information recording/reproducing device, expander lens, coupling lens, and optical element for chromatic aberration correction

Abstract: PROBLEM TO BE SOLVED: To provide an optical pickup device, an optical information recording/reproducing device, an expander lens, a coupling lens and an optical element for chromatic aberration correction suitable for miniaturization or the like while maintaining compatibility for two or more kinds of optical disks such as a high density optical disk of a different laser light source wavelength. SOLUTION: The optical pickup device is provided with a light source for emitting the luminous fluxes of a wavelength λ1 and a wavelength λ2, an objective lens unit, and an optical unit for chromatic aberration correction and an optical unit for spherical aberration correction arranged in the common optical path of the first luminous flux and the second luminous flux between the light source and the objective lens unit. Then, the optical unit for the spherical aberration correction changes the tilting angle of the marginal light beam of an incident luminous flux on the object lens unit by variably adjusting the interval of the constituting lens group and the objective lens unit. Further, the optical unit for the chromatic aberration correction is provided with a diffraction plane and is designed such that the diffraction order of the second luminous flux having the maximum diffraction efficiency is lower than the diffraction order of the first luminous flux. COPYRIGHT: (C)2005,JPO&NCIPI

The spectral changes of partially coherent light focused by an apertured lens with chromatic aberration

Abstract: The spectral changes of a partially coherent polychromatic light focused by an apertured lens with chromatic aberration are investigated It is demonstrated that the spectrum in the focused field is different from that in the aperture Comparing with the spectrum in the aperture, the spectrum in the focused field shifts to lower or higher frequency, which is defined as a spectral shift The influence of chromatic aberration of the lens, the coherence of the partially coherent light in the aperture, the radius of the aperture, and the spectral width of the spectrum of the aperture on the spectral shift are investigated in detail The numerical results show that these parameters affect the spectral shift noticeably

Fast camera objective designs for spectrograph of Mont Megantique telescope

Abstract: All-reflective optics is conventionally required for extended spectral region observations in astronomical spectrograph But the spatial resolution is usually not good enough while the large-size CCD will be used for observation in all-reflective optics In this paper, all-refractive optics has been investigated to design a fast (F/155) and wide angle camera objective for large spectral coverage, from UV to VIS and up to NIR, when a large-size CCD is used on the focal plane of the spectrograph of Mont Megantique telescope The case of achromatic and apochromatic condition has been investigated for axial and lateral color controls The new proposed solutions have been optimized from two to three different glass combinations in order to have higher throughputs for large spectral coverage, especially in UV region The used components have been minimized to reduce the light inherent lost The monochromatic aberrations have been corrected and controlled by using optimized lens bending and shapes to make the camera have the CCD pixel resolution Ray tracing results displayed the good optical performance of the camera to cover from 350 nm to 1000 nm spectral region with high resolution The broadband AR coating, enhanced on UV region, will be used on each surface of the lenses in the camera Final throughputs for the designed camera has been estimated and given in the paper

Improvement of Chromatic Aberration of a Plastic Rod Lens Array. 1. Combination-Color Lens Arrays Consisting of Several Kinds of Rod Lenses with Different Gradient Constants and Different Color Filter Functions

Abstract: We propose a new type of rod lens array with improved chromatic aberration. The new rod lens array consists of several kinds of rod lenses with different gradient constants and different color filter functions. The gradient constant of each lens was prepared such that the total conjugate length was identical to the specific wavelength of the lens with a constant lens length. We call our new type of rod lens array a combination-color lens array. The characteristics of this color-type lens array are as follows: high angular aperture, short focal length, and ease of production with established procedures. The optical resolution of the rod lens array is 300 dpi in a wide wavelength range that is high enough to be applied to color scanners.

Analysis of wavelength effects on a spherical-end fiber lens

Abstract: The wavelength of light affects the working distance to the beam waist and the mode field diameter in a spherical-end fiber lens. The compensation effects of the chromatic aberration in the fiber lens are shown, and the predicted results are found to be in good agreement with the experimental values.

Theory of a holographic lens with a high efficiency

Abstract: A two element holographic lens is proposed for obtaining high efficiency in a holographic lens. The two element holographic lens is made up of an off-axis holographic lens and a plane holographic grating. The proposed holographic lens can be used for the correction of chromatic aberration in an achromatic doublet. The theory of the holographic lens and the V-value of the holographic lens are given. The formulae for longitudinal chromatic aberration, transverse chromatic aberration present in a simple holographic lens and a two element holographic lens are derived. It is observed that the expressions for longitudinal chromatic aberration is the same for both the conventional holographic lens and the two element holographic lens proposed in this paper. It is also observed that the expression for the transverse chromatic aberration is the same for both the conventional holographic lens and the two element holographic lens. The two element holographic lens may find application for designing large size achromatic doublet in combination with a glass lens for magnifying purpose.

Flat apochromatic microscope lens

Abstract: The invention relates to a flat apochromatic microscopic lens. Said type of microscopic lens comprises five lens members having a total of ten lenses. The first member with a positive total focus length, which can be seen from the lens plane, contains one lens, the radii centre of curvature thereof being arranged on the lens side. The second member is made of two lenses of a negative-positive' refractive power sequence with a positive total focus length, said lenses being cemented together and are able to be seen from the lens plane . The difference in refractive power between the first and the second member is less than 25 %. The third member is made of two lenses of a negative-positive refractive power sequence, said lenses being cemented together having a total focal length of more than 50mm. The fourth member is made of three lenses of a positive-negative-positive refractive power sequence having a positive total focal length of a maximum 35mm, said lenses being cemented together. The sum of the focal length of the central lens is less than the respective sum of the focal length of the external lens. The fifth member is made of two lenses, which are cemented together, of a positive-negative refractive power sequence having a negative total focal length of between 20mm and 8mm.