China
Africa
Explore chapters and articles related to this topic
Optical Components
Published in Christoph Gerhard, Optics Manufacturing, 2018
Optical components are the basis of any optical system and can generally be classified into lenses, prisms, and plates. Lenses are the most important and commonly used optical components and are characterized by the basic surface shape of the optically active surfaces, spherical, aspherical, toric, or cylindrical. All types of lenses are further specified by the lens material and the center thickness, where thin lenses are distinguished from thick lenses. Spherical lenses are further defined by the radii of curvature of the optically active surface whereas aspherical lens surfaces are described by appropriate mathematical functions. Toric lens surfaces feature two different radii of curvature perpendicular to each other, and cylindrical lenses can be described as a segment of cylinder walls.
Micro-Optics for Illumination Light Shaping in Photolithography
Published in Fred M. Dickey, Todd E. Lizotte, Laser Beam Shaping Applications, 2017
The ideal configuration of the microlens arrays is a trade-off between NA, which is large enough to resolve the subapertures, and the off-axis imaging properties, namely, the useable FOV of the microlens. In the ideal case, the microlens array would consist of lens doublets or triplets, well corrected for off-axis imaging. Unfortunately, no cost-efficient technology exists to manufacture arrays of microlens doublets or triplets on planar substrates. For reasons of simplicity and cost, most Köhler integrators are built using plano-convex microlenses with a spherical or aspherical lens profile. Typically, the microlens arrays are manufactured on the front and backside of a wafer made of fused silica, as shown in Figure 5.17. Fused silica is the preferred glass material due to its high transparency from 190 nm to the mid-infrared wavelength region and its robustness against high laser power. A drawback of fused silica is the relative low refractive index, ranging from 1.56 (193 nm) to 1.44 (2 µm). Due to the low refractive index, a plano-convex lens made of fused silica needs to have a relatively high lens sag to achieve a large NA. A high lens sag leads to severe spherical aberrations that can only be corrected using aspherical lens profiles. Microlenses with an aspherical lens profile show excellent performance for on-axis operation, but the aspherical profile might lead to strong aberrations for off-axis operation, as required for a larger FOV.
On codimension one special Anosov endomorphisms
Published in Dynamical Systems, 2023
So to conclude the proof, it remains to consider the case of n = 4. The classifying map is a homotopy equivalence, since is a space. Then by the main theorem of section 11.5 of Freedman and Quinn [8] (this theorem shows the classification of aspherical manifolds with poly-(finite or cyclic) fundamental group), ϕ is homotopic to a homeomorphism, since all finitely generated abelian groups are polycyclic and is a space, so is aspherical. In other words, is topologically unique in -spaces.
Large field-of-view microlens array with low crosstalk and uniform angular resolution for tabletop integral imaging display
Published in Journal of Information Display, 2023
Daerak Heo, Beomjun Kim, Sungjin Lim, Woonchan Moon, Dongkil Lee, Joonku Hahn
The concept of the MLR-MLA is introduced using only the chief ray, and one of the surfaces of the lens is supposed to be a spherical surface. This approach is insufficient for the crosstalk analysis in the tabletop 3D display because the crosstalk is calculated from the visibility of each view represented as the intensity distribution. The crosstalk is related to the collimation ability of the lens over the FOV [19–21]. Therefore, it is essential to consider the entire ray bundles between the marginal and the chief rays to analyze the collimation ability over the FOV. In this paper, we design an aspherical surface to reduce the crosstalk. The sag of the aspheric surface is generally represented as the extended polynomial [22], defined as where is the curvature of the surface. is the -th extended polynomial term in and , which is the coordinate at the stop, and is the coefficient of the extended polynomial. is the number of polynomial terms in the series. The design parameters of the MLR-MLA are listed in Table 1.
Optical design of a null test for off-axis three-mirror system based on refractive-diffractive zoom hybrid compensator
Published in Journal of Modern Optics, 2022
Lai Xiaoxiao, Chang Jun, Li Yiting, Ji Zhongye, Cao Jiajing, Li Dongmei
The principle of the null test is depicted in Figure 2. The collimator collimates the light source from a laser into a parallel beam, then the light beam incidents on the reference mirror of the interferometer. A part of the beam is reflected by the reference mirror and the splitter, finally images on the detector by an imaging lens. Other rays continue to transmit, and also image on the detector after being modulated by the compensator, and reflected by the tested aspheric mirror. The compensator is used to generate an aspherical wavefront to nullify the surface normal wavefront of the tested aspheric mirror. This test light will interfere with the reference light, so interferograms will be seen on the detector. If there is no surface error in the aspheric surface to be tested, a null fringe will be observed on the detector. Otherwise, a non-null fringe will be observed, which carries the surface information of the tested aspheric mirror, and the specific surface error of the tested aspheric mirror can be obtained by analyzing the non-null fringe.