Apochromat

About: Apochromat is a research topic. Over the lifetime, 642 publications have been published within this topic receiving 7934 citations.

Spherical aberration correction using flying lens and method

Abstract: An optical access device for a moving optical data storage media having a flying lens (20) near an outer surface of the media (12), and an objective lens (18) spaced from the flying lens, with the flying lens and objective lens co-operating to substantially offset a variable range of negative spherical aberration occurring in the media by forming a positive spherical aberration which substantially cancels the negative spherical aberration.

Electrostatic lenses with very small spherical aberration

Abstract: A class of electrostatic lenses with extremely low spherical aberration is proposed. The axial potential distribution of these lenses has an asymmetric bell‐shaped form with a lower potential on the image side. A lens with Cso∞/fo=0.51 is presented as an example. The maximum required electrode voltage is only five times larger than the initial accelerating voltage. At 5 mrad acceptance half‐angle, 51 mm focal length, and magnification M=−3.3 the radius of the spherical aberration disk is 6 nm.

F-θ lens

Abstract: An f-θ lens is disclosed which is particularly suitable for use with a color laser printer in which beams of different wavelengths are combined into a single light beam. The combined light beam is scanned by a rotating polygon onto a receiving medium. The f-θ is adapted to operate with 1.) beam shaping optics for shaping the beam in a scan direction prior to the polygon, and 2.) a cylindrical element located behind the f-θ lens, to image the light beam in a cross-scan direction onto the receiving medium. The f-θ lens includes a plurality of lens components. The lens components cooperate to (a) focus a received combination beam of three different wavelengths onto an image surface, the received combination beam having different vergences and different waist locations in the page and line directions, the vergences and the waist locations being substantially the same in each of the three wavelengths; and (b) compensate for chromatic aberration. This compensation renders the f-θ lens an achromatic lens for axial color in both scan and page directions at the image surface. According to the preferred embodiment of the present invention, the θ lens is an apochromatic lens with regards to the axial color. The lateral color is corrected electronically.

Spherical Aberration - Some Fascinating Observations

Abstract: We have recently completed a parametric analysis of f/2, one through four element lenses, relating monochromatic axial performance (spherical aberration) to refractive indices from 1.5 to 2.0. The literature demonstrates clearly that increasing the number of elements and/or the refractive index causes a reduction of the third-order spherical aberration; in fact the literature shows special cases where the third-order spherical aberration transitions through zero. If we consider an optimum balance for all orders of spherical aberration, we observe a surprising result. One and two element solutions maintain a relatively constant high level of aberration residual for all cases (from 5 - 50 waves peak-to-valley). The three-element solution, however, improves in aberration residual by nearly 6 orders of magnitude from 2 waves peak-to-valley at an index of 1.5 to approximately 0.000005 waves at an index of 2.0. The four-element solution shows a similar, yet not so pronounced, behavior. We will discuss the various solution forms, some of which utilize the aplanatic-concentric principal, and we will show how higher order aberration balancing in the three element case is responsible for the 6 orders of magnitude improvement in performance.